eGlossary
Absolute viscosity a term used interchangeably with viscosity to distinguish it from either kinematic viscosity or commercial viscosity.
Absorbent a material having the power, capacity, or tendency to absorb.
Absorption the assimilation of one material into another; in petroleum refining, the use of an absorptive liquid to selectively remove components from a process stream; a process in which fluid molecules are taken up by a liquid or solid and distributed throughout the body of that liquid or solid.
Accelerated corrosion test method designed to approximate, in a short time, the deteriorating effect under normal long-term service conditions.
Acid any substance containing hydrogen in combination with a nonmetal or nonmetallic radical and capable of producing hydrogen ions in solution.
Acid catalyst a catalyst having acidic character; the aluminas are examples of such catalysts.
Acid deposition acid rain; a form of pollution depletion in which pollutants, such as nitrogen oxides and sulfur oxides, are transferred from the atmosphere to soil or water; often referred to as atmospheric self-cleaning. The pollutants usually arise from the use of fossil fuels.
Acid embrittlement a form of hydrogen embrittlement that may be induced in some metals by acid.
Acidity denotes the presence of acid-type constituents whose concentration is usually defined in terms of total acid number. The constituents vary in nature and may or may not markedly influence the behavior of the lubricant.
Acid number the quantity of base (potassium hydroxide) expressed in milligrams of potassium hydroxide that is required to neutralize the acidic constituents in 1 g of sample; a measure of the reactivity of petroleum with a caustic solution and given in terms of milligrams of potassium hydroxide that are neutralized by one gram of petroleum.
Acid rain the precipitation phenomenon that incorporates anthropogenic acids and other acidic chemicals from the atmosphere to the land and water; see Acid deposition.
Acid sludge the residue left after treating petroleum oil with sulfuric acid for the removal of impurities; a black, viscous substance containing the spent acid and impurities.
Acid treating a refining process in which unfinished petroleum products, such as gasoline, kerosene, and lubricating oil stocks, are contacted with sulfuric acid to improve their color, odor, and other properties.
Acid value a measure of acidity. It is normally expressed as milligrams of potassium hydroxide per gram (KOH/g) of sample.
Activated alumina a highly porous material produced from dehydroxylated aluminum hydroxide, is used as a desiccant and as a filtering medium.
Active a state in which a metal tends to corrode (opposite of passive); the negative direction of electrode potential; also used to describe corrosion and is associated with the potential range when an electrode potential is more negative than an adjacent depressed corrosion rate (passive) range; (i) the negative direction of electrode potential; (ii) a state of a metal that is corroding without significant influence of reaction product.
AD atmospheric pressure distillation.
Additive a chemical substance added to a petroleum product to impart or improve certain properties.
Adiabatic a change occurring without loss or gain of heat.
Adsorption adhesion of the molecules of gases, liquids, or dissolved substances to a solid surface, resulting in relatively high concentration of the molecules at the place of contact; e.g., the plating out of an anti-wear additive on metal surfaces; transfer of a substance from a solution to the surface of a solid resulting in relatively high concentration of the substance at the place of contact; see also Chromatographic adsorption.
Adsorptive filtration the attraction to, and retention of particles in, a filter medium by electrostatic forces, or by molecular attraction between the particles and the medium.
ADT atmospheric distillation tower; the primary distillation tower of a crude distillation unit which operates at or above atmospheric pressure.
ADU atmospheric distillation unit; generally, a unit for distilling crude at or above atmospheric pressure as opposed to operating under a vacuum.
Aeration the state of air being suspended in a liquid such as a lubricant or hydraulic fluid.
Agglomeration the potential of the system for particle attraction and adhesion.
Alicyclic hydrocarbons compounds containing carbon and hydrogen only which has a cyclic structure (e.g., cyclohexane); also collectively called naphthenes.
Aliphatic hydrocarbons compounds containing carbon and hydrogen only which has an open chain structure (e.g., as ethane, butane, octane, butene) or a cyclic structure (e.g., cyclohexane).
Alkali any substance having basic (as opposed to acidic) properties. In a restricted sense it is applied to the hydroxides of ammonium, lithium, potassium, and sodium. Alkaline materials in lubricating oils neutralize acids to prevent acidic and corrosive wear in internal combustion engines.
Alkaline a high pH usually of an aqueous solution; aqueous solutions of sodium hydroxide, sodium orthosilicate, and sodium carbonate are typical alkaline materials used in enhanced oil recovery.
Alkalinity the capacity of a base to neutralize the hydrogen ion (H+).
Alkali treatment see Caustic wash.
Alkanes hydrocarbons that contain only single carbon–hydrogen bonds. The chemical name indicates the number of carbon atoms and ends with the suffix “ane.”
Alkenes hydrocarbons that contain carbon–carbon double bonds. The chemical name indicates the number of carbon atoms and ends with the suffix “ene.”
Alkylation the combination of an unsaturated hydrocarbon (olefin) with a saturated hydrocarbon (paraffin or isoparaffin) to form branched chain saturated hydrocarbons; may also apply to the combination of aromatic hydrocarbons with unsaturated hydrocarbons to form branched chain aromatics.
Alkyl groups a group of carbon and hydrogen atoms that branch from the main carbon chain or ring in a hydrocarbon molecule. The simplest alkyl group, a methyl group, is a carbon atom attached to three hydrogen atoms.
Alumina (Al2O3) used in separation methods as an adsorbent and in refining as a catalyst.
Ambient temperature temperature of the area or atmosphere around a process (not the operating temperature of the process itself).
American Petroleum Institute (API) a trade association that promotes US petroleum interests, encourages development of petroleum technology, cooperates with the government in matters of national concern, and provides information on the petroleum industry to the government and the public.
American Society for Testing and Materials (ASTM) a professional society that is responsible for the publication of test methods and the development of test evaluation techniques as well as designing standard test methods for petroleum and other industrial products.
Amine an organic compound containing basic nitrogen; may be toxic and corrosive and the lower molecular weight amines have a smell similar to ammonia.
Amphoteric possession of the quality of reacting either as an acid or as a base.
Anaerobic free of air or uncombined oxygen.
Anhydrous the absence of water.
Aniline point the minimum temperature for complete miscibility of equal volumes of aniline and the sample under test (ASTM D611). A product of high aniline point will be low in aromatics and naphthenes and, therefore, high in paraffins. Aniline point is often specified for spray oils, cleaning solvents, and thinners, where effectiveness depends upon aromatic content. In conjunction with API gravity, the aniline point may be used to calculate the net heat of combustion for aviation fuels.
Antifouling preventing fouling; see Fouling.
Atmospheric corrosion the gradual degradation or alterations of a material by contact with substances present in the atmosphere, such as oxygen, carbon dioxide, water vapor, and sulfur and chlorine compounds.
API American Petroleum Institute—a trade association of petroleum producers, refiners, marketers, and transporters, organized for the advancement of the petroleum industry by conducting research, gathering and disseminating information, and maintaining cooperation between government and the industry on all matters of mutual interest.
API gravity a gravity scale established by the American Petroleum Institute and in general use in the petroleum industry; a measure of the lightness or heaviness of petroleum which is related to density and specific gravity.
Apparent viscosity the ratio of shear stress to rate of shear of a non-Newtonian fluid such as lubricating grease, or a multi-grade oil, calculated from Poiseuille’s equation and measured in poises; the apparent viscosity changes with changing rates of shear and temperature and must, therefore, be reported as the value at a given shear rate and temperature (ASTM D1092).
Aromatic derived from, or characterized by, the presence of the benzene ring.
Aromatic hydrocarbon a hydrocarbon characterized by the presence of an aromatic ring or condensed aromatic rings; benzene and substituted benzene, naphthalene and substituted naphthalene, phenanthrene and substituted phenanthrene, as well as the higher condensed ring systems; compounds that are distinct from those of aliphatic compounds (q.v.) or alicyclic compounds (q.v.).
Aromatization the conversion of nonaromatic hydrocarbons to aromatic hydrocarbons by: (i) rearrangement of aliphatic (noncyclic) hydrocarbons (q.v.) into aromatic ring structures and (ii) dehydrogenation of alicyclic hydrocarbons (naphthenes).
Ash A measure of the amount of inorganic material in petroleum or a petroleum fraction or petroleum product; determined by burning the sample in air weighing the residue; the results expressed as percent by weight.
Ash content erroneous name for the ash produced from the mineral matter content of petroleum or a petroleum derived product—petroleum and petroleum products do not contain ash; more correctly, ash yield which is the percent by weight of residue remaining after combustion of a sample of petroleum.
Asphalt the nonvolatile product obtained by distillation and treatment of an asphaltic crude oil; a manufactured product.
Asphalt cement asphalt especially prepared as to quality and consistency for direct use in the manufacture of bituminous pavements.
Asphalt emulsion an emulsion of asphalt cement in water containing a small amount of emulsifying agent.
Asphalt flux an oil used to reduce the consistency or viscosity of hard asphalt to the point required for use.
Asphalt primer a liquid asphaltic material of low viscosity which upon application to a nonbituminous surface to waterproof the surface and prepare it for further construction.
Asphaltene (asphaltene constituents) the brown-to-black powdery material produced by treatment of petroleum, heavy oil, petroleum residua, or bituminous materials with a low boiling liquid hydrocarbon, e.g., n-pentane or n-heptane; soluble in benzene (and other aromatic solvents), carbon disulfide, and chloroform (or other chlorinated hydrocarbon solvents).
ASTM American Society for Testing Materials; a society for developing standards for testing petroleum and petroleum products; now known as ASTM International.
Atmospheric pressure pressure exerted by the atmosphere at any specific location. (Sea level pressure is approximately 14.7 pounds per square inch absolute.)
Atmospheric residuum a residuum (q.v.) obtained by distillation of a crude oil under atmospheric pressure and which boils above 350°C (660°F).
Atmospheric equivalent boiling point (AEBP) a mathematical method of estimating the boiling point at atmospheric pressure of nonvolatile fractions of petroleum.
Attapulgus clay see Fuller’s earth.
Austenite a solid solution of one or more elements in face-centered cubic iron; unless otherwise designated (such as nickel austenite), the solute is generally assumed to be carbon.
Austenitic steel steel with a microstructure at room temperature that consists predominantly of austenite.
Barrel a unit of liquid volume of petroleum oils equal to 42 US gallons or approximately 35 imperial (UK) gallons.
Base a material which neutralizes acids. An oil additive containing colloidally dispersed metal carbonate, used to reduce corrosive wear.
Base number the amount of acid, expressed in terms of the equivalent number of milligrams of potassium hydroxide, required to neutralize all basic constituents present in 1 g of sample.
Basic nitrogen nitrogen (in petroleum) which occurs in pyridine form.
Basic sediment and water (bs&w, bsw) the material which collects in the bottom of storage tanks, usually composed of oil, water, and foreign matter; also called bottoms, bottom settlings.
Bell cap a hemispherical or triangular cover placed over the riser in a (distillation) tower to direct the vapors through the liquid layer on the tray; see Bubble cap.
Bentonite montmorillonite (a magnesium–aluminum silicate); used as a treating agent.
Benzene a colorless aromatic liquid hydrocarbon (C6H6).
BFOE barrels fuel oil equivalent based on net heating value of 6,050,000 BTU per BFOE.
Biocide any chemical capable of killing bacteria and bioorganisms.
Biocorrosion biocorrosion processes at metal surfaces are associated with microorganisms, or the products of their metabolic activities including enzymes, exopolymers, organic and inorganic acids, as well as volatile compounds such as ammonia or hydrogen sulfide. These can affect cathodic and/or anodic reactions, thus altering electrochemistry at the biofilm/metal interface; see Microbial corrosion, Microbiologically influenced corrosion.
Biogenic sulfide corrosion the process of forming hydrogen sulfide gas and the subsequent conversion to sulfuric acid (in the presence of moisture) which then causes corrosion of metal pipelines; see Microbial corrosion.
Biological corrosion deterioration of metals as a result of the metabolic activity of microorganisms.
Biomass biological organic matter.
Bitumen also (incorrectly) called asphalt, pitch, or tar; occurs in nature as asphalt lakes (such as the Trinidad Asphalt Lake) and tar sands (such as the Athabasca Tar Sands or Athabasca Oil Sands in Alberta, Canada); consists of high molecular weight hydrocarbonaceous compounds which contain sulfur and nitrogen compounds.
Bituminous containing bitumen or constituting the source of bitumen.
Bituminous rock see Bituminous sand.
Bituminous sand a formation in which the bituminous material (see Bitumen) is found as a filling in veins and fissures in fractured rock or impregnating relatively shallow sand, sandstone, and limestone strata; a sandstone reservoir that is impregnated with a heavy, viscous black petroleum-like material that cannot be retrieved through a well by conventional production techniques.
Black oil a name applied to any oil that is dark colored; generally an indistinct and meaningless term that cannot be applied to the nomenclature and/or classification of petroleum.
Blister a raised area, often dome shaped, resulting from (i) loss of adhesion between a coating or deposit and the base metal or (ii) delamination under the pressure of expanding gas trapped in a metal in a near-subsurface zone; very small blisters are known as pinhead blisters or pepper blisters.
Blushing whitening and loss of gloss of a coating, usually organic, caused by moisture (also known as blooming).
Boiling point the temperature at which a substance boils or is converted into vapor by bubbles forming within the liquid; it varies with pressure.
Boiling range for a mixture of substances, such as a petroleum fraction, the temperature interval between the initial and final boiling points.
Bottoms the nonvolatile portion of crude oil, usually referred to as residuum; the liquid which collects in the bottom of a vessel (tower bottoms, tank bottoms) during distillation; also the deposit or sediment formed during storage of petroleum or a petroleum product; see also Residuum and Basic sediment and water.
Brine seawater containing a higher concentration of dissolved salt than that of the ordinary ocean.
Brittle fracture fracture with little or no plastic deformation.
Bromine number a test which indicates the degree of unsaturation in the test sample.
BS&W bottom sediment and water; the heavy material which collects in the bottom of storage tanks; composed of oil, water, and foreign matter.
British thermal unit (BTU) the amount of heat required to raise the temperature of 1 pound of water 1 degree Fahrenheit.
Bubble cap an inverted cup with a notched or slotted periphery to disperse the vapor in small bubbles beneath the surface of the liquid on the bubble plate in a distillation tower.
Bubble plate a tray in a distillation tower.
Bubble point the temperature at which incipient vaporization of a liquid in a liquid mixture occurs, corresponding with the equilibrium point of 0% vaporization or 100% condensation.
Bubble tower a fractionating tower so constructed that the vapors rising pass up through layers of condensate on a series of plates or trays (see Bubble plate); the vapor passes from one plate to the next above by bubbling under one or more caps (see Bubble cap) and out through the liquid on the plate where the less volatile portions of vapor condense in bubbling through the liquid on the plate, overflow to the next lower plate, and ultimately back into the reboiler thereby effecting fractionation.
Bubble tray a circular perforated plate having the internal diameter of a bubble tower (q.v.), set at specified distances in a tower to collect the various fractions produced during distillation.
Bunker C oil see No. 6 fuel oil.
Burner fuel oil any petroleum liquid suitable for combustion.
C1, C2, C3, C4, C5 fractions a common way of representing fractions containing a preponderance of hydrocarbons having 1, 2, 3, 4, or 5 carbon atoms, respectively, and without reference to hydrocarbon type.
C or cent. centigrade or celsius.
Carbon residue the amount of carbonaceous (coke-like) residue remaining after thermal decomposition of petroleum, a petroleum fraction, or a petroleum product in a limited amount of air; also called the coke- or carbon-forming propensity; often prefixed by the terms Conradson or Ramsbottom in reference to the inventor of the respective tests; often called thermal coke.
Carbon type the distinction between paraffinic, naphthenic, and aromatic molecules. In relation to lubricant base stocks, the predominant type present.
Cascade tray a fractionating device consisting of a series of parallel troughs arranged on stair-step fashion in which liquid from the tray above enters the uppermost trough and liquid thrown from this trough by vapor rising from the tray below impinges against a plate and a perforated baffle and liquid passing through the baffle enters the next longer of the troughs.
Catalyst a substance that initiates or increases the rate of a chemical reaction, without itself being used up in the process; a chemical substance, usually present in small amounts relative to the reactants, that increases the rate at which a chemical reaction (e.g., corrosion) would otherwise occur, but is not consumed in the reaction.
Catalyst selectivity the relative activity of a catalyst with respect to a particular compound in a mixture, or the relative rate in competing reactions of a single reactant.
Catalytic cracking the conversion of high boiling feedstocks into lower boiling products by means of a catalyst which may be used in a fixed bed (q.v.) or fluid bed (q.v.).
Cat cracking see Catalytic cracking.
Catalytic dewaxing a catalytic hydrocracking process which uses catalysts such as molecular sieves to selectively hydrocrack the waxes present in hydrocarbon fractions.
Caustic (i) burning or corrosive, (ii) a hydroxide of a light metal, such as sodium hydroxide (NaOH) or potassium hydroxide (KOH).
Caustic wash the process of treating a product with a solution of caustic soda to remove minor impurities; often used in reference to the solution itself.
Cetane index an approximation of the cetane number (q.v.) calculated from the density (q.v.) and mid-boiling point temperature (q.v.); see also Diesel index.
Cetane number a number indicating the ignition quality of diesel fuel; a high cetane number represents a short ignition delay time; the ignition quality of diesel.
Centipoise (cP) a unit of absolute viscosity. 1 centipoise=0.01 poise.
Centistoke (cSt) a unit of kinematic viscosity. 1 centistoke=0.01 stoke.
Characterization factor an index of feedstock quality used for correlating data based on physical properties; the Watson (UOP) characterization factor is defined as the cube root of the mean average boiling point in degrees Rankine divided by the specific gravity.
Chevron pattern a V-shaped pattern on a fatigue or brittle fracture surface—the pattern can also be one of straight radial lines on cylindrical specimens.
Chloride stress corrosion cracking cracking of a metal under the combined action of tensile stress and corrosion in the presence of chlorides and an electrolyte (usually water).
Chromatographic adsorption selective adsorption on materials such as activated carbon, alumina, or silica gel; liquid or gaseous mixtures of hydrocarbons are passed through the adsorbent in a stream of diluent, and certain components are preferentially adsorbed.
Chromatographic separation the separation of different species of compounds according to their size and interaction with the rock as they flow through a porous medium.
Chromatography a method of separation based on selective adsorption; see also Chromatographic adsorption.
Clad metal a composite metal containing two or more layers that have been bonded together; the bonding may have been accomplished by co-rolling, co-extrusion, welding, diffusion bonding, casting, heavy chemical deposition, or heavy electroplating.
Clay silicate minerals that also usually contain aluminum and have particle sizes <0.002 micron; used in separation methods as an adsorbent and in refining as a catalyst.
Clay filtration a refining process using fuller’s earth (activated clay), bauxite, or other mineral to absorb minute solids from lubricating oil, as well as remove traces of water, acids, and polar compounds.
Clay refining a treating process in which vaporized gasoline or other light petroleum product is passed through a bed of granular clay such as fuller’s earth (q.v.).
Clay regeneration a process in which spent coarse-grained adsorbent clays from percolation processes are cleaned for reuse by deoiling them with naphtha, steaming out the excess naphtha, and then roasting in a stream of air to remove carbonaceous matter.
Clay treating a clay adsorption process operated at elevated temperature and pressure used to neutralize or improve the color and stability of a lube base oil.
Cleveland open cup a flash point test in which the surface of the sample is completely open to the atmosphere, and which is therefore relatively insensitive to small traces of volatile contaminants.
Cloud point the temperature at which waxy crystals in an oil or fuel form a cloudy appearance.
Coke a gray to black solid carbonaceous material produced from petroleum during thermal processing; characterized by having a high carbon content (95%+ by weight) and a honeycomb type of appearance and is insoluble in organic solvents.
Coke drum a vessel in which coke is formed and which can be cut from the drum prior to drum cleaning.
Coke number used, particularly in Great Britain, to report the results of the Ramsbottom carbon residue test (q.v.), which is also referred to as a coke test.
Coker the processing unit in which coking takes place.
Coking a process for the thermal conversion of petroleum in which gaseous, liquid, and solid (coke) products are formed; the undesirable accumulation of carbon (coke) deposits in a refinery; the process of distilling a petroleum product to dryness.
Condensate a mixture of light hydrocarbon liquids obtained by condensation of hydrocarbon vapors predominately butane, propane, and pentane with some heavier hydrocarbons and relatively little methane or ethane; see also Natural gas liquids.
Conradson carbon residue the residue remaining as the result of a test method used to determine the amount of carbon residue left after the evaporation and pyrolysis of the test sample at specified conditions.
Contaminant any foreign or unwanted substance that can have a negative effect on system operation, life, or reliability.
Conversion the thermal treatment of petroleum which results in the formation of new products by the alteration of the original constituents.
Conversion factor the percentage of feedstock converted to light ends, gasoline, other liquid fuels, and coke.
Copper strip corrosion the gradual eating away of copper surfaces as the result of oxidation or other chemical action. It is caused by acids or other corrosive agents.
Corrosion the irreversible chemical deterioration of a material, usually a metal or a metal alloy, because of a reaction with its environment; the name for chemical erosion; the disintegration of an engineered material into its constituent atoms due to chemical reactions with its surroundings; commonly this is the electrochemical oxidation of metals in reaction with an oxidant such as oxygen—the formation of an oxide of iron due to oxidation of the iron atoms in solid solution is a well-known example of electrochemical corrosion, commonly known as rusting.
Corrosion control the measures used to prevent or considerably reduce the effects of corrosion. Some practices for corrosion control involve cathodic protection, chemical inhibition, chemical control (removal of dissolved gases such as hydrogen sulfide, carbon dioxide, and oxygen), oxygen scavenging, pH adjustment, deposition control (e.g., scales), and coatings. The corrosion rate will vary with time depending on the particular conditions to which the pipeline is subjected, such as the amount of water present and pressure variations; corrosion control is a continuous process in pipeline operations.
Corrosion fatigue fatigue-type cracking of metal caused by repeated or fluctuating stresses in a corrosive environment characterized by shorter life than would be encountered as a result of either the repeated or fluctuating stress alone or the corrosive environment alone.
Corrosion inhibitor additive for protecting lubricated metal surfaces against chemical attack by water or other contaminants; there are several types of corrosion inhibitors. Polar compounds wet the metal surface preferentially, protecting it with a film of oil.
Corrosion protection Every measure which serves to reduce or prevent corrosion damages is called corrosion protection. In surface technology, protective coatings, e.g., paint/lacquer or metallic top coats, are applied frequently.
Corrosion rate the amount of corrosion occurring in unit time—for example, mass change per unit area per unit time; penetration per unit time; the weight loss of a corrosion coupon after exposure to a corrosive environment, expressed as mils (thousandths of an inch) per year penetration. Corrosion rate is calculated assuming uniform corrosion over the entire surface of the coupon.
mpy=(weight loss in grams)×(22,300)/(ADT)
mpy is corrosion rate (mils per year penetration)—a mil is one thousandth of an inch.
A is area of coupon (sq. in.)
D is metal density of coupon (g/cm3)
T is time of exposure in corrosive environment (days).
It is important to note that the calculated values using this formula are not representative in cases of severe pitting. Therefore, a complete report, including a visual inspection, is required to determine either the type of attack or the appropriate corrosion control program. Corrosion rate is also known as corrosion ratio.
Corrosion resistance ability of a material, usually a metal, to withstand corrosion in a given system.
Corrosion resistant alloy a specially formulated material used for components in pipelines likely to present corrosion problems.
Corrosiveness (corrosivity) the tendency of an environment to cause corrosion.
Counterpoise a conductor or system of conductors arranged beneath a power line, located on, above, or most frequently, below the surface of the earth and connected to the footings of the towers or poles supporting the power line.
Coupon a specimen of material exposed to tests or real environments to assess the effect of degradation on the material.
cP centipoise, unit of dynamic viscosity.
Cracked residua residua that have been subjected to temperatures above 350°C (660°F) during the distillation process.
Cracking the process whereby large molecules are broken down by the application of heat and pressure to form smaller molecules.
Cracking activity see Catalytic activity.
Cracking pressure the pressure at which a pressure operated valve begins to pass fluid.
Cracking temperature the temperature (350°C; 660°F) at which the rate of thermal decomposition of petroleum constituents becomes significant.
Crevice corrosion caused by a difference of oxygen availability between two sites on a passive metal that leads to the formation of an electrochemical cell—a selective attack within cracks and at other sites of poor oxygen access is frequently observed; localized corrosion of a metal surface at, or immediately adjacent to, an area that is shielded from full exposure to the environment because of close proximity between the metal and the surface of another material. Chemical deterioration of a material, usually a metal, because of a reaction with its environment.
Crude still distillation (q.v.) equipment in which crude oil is separated into various products.
cSt centistokes, unit of kinematic viscosity.
Cut the portion or fraction of a crude oil boiling within certain temperature limits.
Cut point the temperature limit of a cut or fraction, usually but not limited to a true boiling point basis; the boiling temperature division between distillation fractions of petroleum.
Deactivation reduction in catalyst activity by the deposition of contaminants (e.g., coke, metals) during a process.
Deaerator a separator that removes air from the system fluid through the application of bubble dynamics.
Dealloying the selective corrosion of one or more components of a solid solution alloy (also known as parting or selective dissolution).
Deasphalted oil the extract or residual oil from which asphaltene and resin constituents have been removed by an extractive precipitation process called deasphalting; typically the soluble material after the insoluble asphaltic constituents have been removed; commonly, but often incorrectly, used in place of deasphaltened oil; see Deasphalting.
Deasphaltened oil the fraction of petroleum after only the asphaltene constituents have been removed.
Deasphaltening removal of a solid powdery asphaltene fraction from petroleum by the addition of the low boiling liquid hydrocarbons such as n-pentane or n-heptane under ambient conditions.
Deasphalting the removal of the asphaltene fraction from petroleum by the addition of a low boiling hydrocarbon liquid such as n-pentane or n-heptane; more correctly the removal asphalt (tacky, semisolid) from petroleum (as occurs in a refinery asphalt plant) by the addition of liquid propane or liquid butane under pressure; also, a commercial process for removing asphalt from reduced crude or vacuum residua (residual oil) which utilizes the different solubility of asphaltic and nonasphaltic constituents in low boiling hydrocarbon liquids, e.g., liquid propane.
Dehydrator a separator that removes water from the petroleum system.
Delayed coking a coking process in which the thermal reaction is allowed to proceed to completion to produce gaseous, liquid, and solid (coke) products.
Density the mass of a unit volume of a substance; the numerical value varies with the units used.
Desalting removal of mineral salts (mostly chlorides) from crude oils.
Desorption the converse of absorption or adsorption; in filtration, it relates to the downstream release of particles previously retained by the filter.
Desulfurization the removal of sulfur or sulfur compounds from a feedstock.
Dewaxing removal of wax from a petroleum product in order to reduce the pour point; solvent dewaxing is the process in which a number of different solvents can be used has the following steps: feedstock is mixed with solvent and chilled; wax precipitated from solution is separated; solvent is recovered from wax and dewaxed oil; wax separation is accomplished by filtration, centrifuging, or settling; see Solvent dewaxing.
Dew point pressure the pressure at which the first drop of liquid is formed, when it goes from the vapor phase to the two-phase region.
Dew point temperature the temperature at which the first drop of liquid is formed, when it goes from the vapor phase to the two-phase region.
Dissolved gases gases that enter into solution with a fluid and are neither free nor entrained gases.
Dissolved water water which is dispersed in the fluid to form a mixture.
Distillation a process for separating liquids with different boiling points.
Distillation curve see Distillation profile.
Distillation loss the difference, in a laboratory distillation, between the volume of liquid originally introduced into the distilling flask and the sum of the residue and the condensate recovered.
Distillation Method (ASTM D95) A method involving distilling the fluid sample in the presence of a solvent that is miscible in the sample but immiscible in water. The water distilled from the fluid is condensed and segregated in a specially designed receiving tube or tray graduated to directly indicate the volume of water distilled.
Distillation range the difference between the temperature at the initial boiling point and at the end point, as obtained by the distillation test.
Distillation profile the distillation characteristics of petroleum or petroleum products showing the temperature and the percent distilled.
Domestic heating oil see No. 2 fuel oil.
Downcomer a means of conveying liquid from one tray to the next below in a bubble tray column (q.v.).
Electric desalting a continuous process to remove inorganic salts and other impurities from crude oil by settling out in an electrostatic field.
Electrical precipitation a process using an electrical field to improve the separation of hydrocarbon reagent dispersions. May be used in chemical treating processes on a wide variety of refinery stocks.
Electrochemical reaction any chemical transformation that implies the transfer of charge across the interface between an electronic conductor (the electrode) and an ionic conductor (the electrolyte).
Electrostatic precipitators devices used to trap fine dust particles (usually in the size range 30–60 microns) that operate on the principle of imparting an electric charge to particles in an incoming air stream and which are then collected on an oppositely charged plate across a high-voltage field.
Electrostatic separator a separator that removes contaminant from dielectric fluids by applying an electrical charge to the contaminant that is then attracted to a collection device of different electrical charge.
Embrittlement steel and other metals and alloys can be embrittled by environmental conditions (environmentally assisted embrittlement); the forms of environmental embrittlement include acid embrittlement, caustic embrittlement, corrosion embrittlement, creep-rupture embrittlement, hydrogen embrittlement, liquid embrittlement, neutron embrittlement, solder embrittlement, solid metal embrittlement, and stress corrosion cracking.
Emulsion intimate mixture of oil and water, generally of a milky or cloudy appearance.
Emulsions may be of two types oil-in-water (where water is the continuous phase) and water-in-oil (where water is the discontinuous phase).
Emulsion breaking the settling or aggregation of colloidal-sized emulsions from suspension in a liquid medium.
Environment the surroundings or conditions (physical, chemical, mechanical) in which a material exists.
EP End point, usually end point of a distillation process.
EPA United States Environmental Protection Agency.
Erosion the progressive removal of a machine surface by cavitation or by particle impingement at high velocities; abrasive metal loss caused by high surface velocity of the transported media, particularly when entrained solids or particulates are present.
Erosion corrosion the result of an electrochemical reaction combined with a material loss by mechanical wear due to impingement of solids or a fluid; corrosion which is increased because of the abrasive action of a moving stream; the presence of suspended particles greatly accelerates abrasive action.
Exfoliation a thick, layer-like growth of loose corrosion products (observed in some cases on steel and aluminum alloys).
Exfoliation corrosion localized subsurface corrosion in zones parallel to the surface that result in thin layers of uncorroded metal resembling the pages of a book.
Expanding clays clays that expand or swell on contact with water, e.g., montmorillonite.
Extract the portion of a sample preferentially dissolved by the solvent and recovered by physically separating the solvent.
Extractive distillation the separation of different components of mixtures which have similar vapor pressures by flowing a relatively high boiling solvent, which is selective for one of the components in the feed, down a distillation column as the distillation proceeds; the selective solvent scrubs the soluble component from the vapor.
Extra heavy oil crude oil with relatively high fractions of heavy components, high specific gravity (low API density), and high viscosity but mobile at reservoir conditions; thermal recovery methods are the most common form of commercially exploiting this kind of oil.
FCCU fluid catalytic cracking unit.
Feedstock petroleum as it is fed to the refinery; a refinery product that is used as the raw material for another process; the term is also generally applied to raw materials used in other industrial processes.
Filiform corrosion corrosion that occurs under a coating in the form of randomly distributed thread-like filaments.
Filter any device or porous substance used as a strainer for cleaning fluids by removing suspended matter.
Filter efficiency method of expressing a filter’s ability to trap and retain contaminants of a given size.
Filtration the physical or mechanical process of separating insoluble particulate matter from a fluid, such as air or liquid, by passing the fluid through a filter medium that will not allow the particulates to pass through it.
Fire point (Cleveland open cup) the temperature to which a combustible liquid must be heated so that the released vapor will burn continuously when ignited under specified conditions.
Fixed bed a stationary bed (of catalyst) to accomplish a process (see Fluid bed).
Flash point (Cleveland open cup) the temperature to which a combustible liquid must be heated to give off sufficient vapor to form momentarily a flammable mixture with air when a small flame is applied under specified conditions (ASTM D92).
Flexicoking a modification of the fluid coking process insofar as the process also includes a gasifier adjoining the burner/regenerator to convert excess coke to a clean fuel gas.
Flocculation threshold the point at which constituents of a solution (e.g., asphaltene constituents or coke precursors) will separate from the solution as a separate (solid) phase.
Floc point (flocculation point) the temperature at which wax or solids separate in oil.
Fluid bed a bed (of catalyst) that is agitated by an upward passing gas in such a manner that the particles of the bed simulate the movement of a fluid and has the characteristics associated with a true liquid; c.f. Fixed bed.
Fluid catalytic cracking cracking in the presence of a fluidized bed of catalyst.
Fluid coking a continuous fluidized solid process that cracks feed thermally over heated coke particles in a reactor vessel to gas, liquid products, and coke.
Fouling an accumulation of deposits; this includes accumulation and growth of marine organisms on a submerged metal surface and the accumulation of deposits (usually inorganic) on heat exchanger tubing.
Fractional composition the composition of petroleum as determined by fractionation (separation) methods.
Fractional distillation the separation of the components of a liquid mixture by vaporizing and collecting the fractions, or cuts, which condense in different temperature ranges.
Fractionating column a column arranged to separate various fractions of petroleum by a single distillation and which may be tapped at different points along its length to separate various fractions in the order of their boiling points.
Fractionation the separation of petroleum into the constituent fractions using solvent or adsorbent methods; chemical agents such as sulfuric acid may also be used.
Fuel oil also called heating oil is a distillate product that covers a wide range of properties; see also No. 1 to No. 4 fuel oils.
Fuller’s earth a clay which has high adsorptive capacity for removing color from oils; attapulgus clay is a widely used fuller’s earth.
Functional group the portion of a molecule that is characteristic of a family of compounds and determines the properties of these compounds.
Furnace oil a distillate fuel primarily intended for use in domestic heating equipment.
Gaseous corrosion corrosion with gas as the only corrosive agent and without any aqueous phase on the surface of the metal, also called dry corrosion.
Gasoline fuel for the internal combustion engine that is commonly, but improperly, referred to simply as gas.
Gas oil a petroleum distillate with a viscosity and boiling range between those of kerosine and lubricating oil.
General corrosion corrosion in a uniform manner; corrosion that is distributed more or less uniformly over the surface of a material.
Graphitic corrosion deterioration of gray cast iron in which the metallic constituents are selectively leached or converted to corrosion products, leaving the graphite intact.
Gravimetric analysis a method of analysis whereby the dry weight of contaminant per unit volume of fluid can be measured showing the degree of contamination in terms of milligrams of contaminant per liter of fluid.
Gravity see Specific Gravity; API Gravity.
Gravity separation a method of separating two components from a mixture. Under the influence of gravity, separation of immiscible phases (gas–solid, liquid–solid, liquid–liquid, solid–solid) allows the denser phase to settle out.
Gray clay treating a fixed bed (q.v.), usually fuller’s earth (q.v.), vapor phase treating process to selectively polymerize unsaturated gum-forming constituents (diolefins) in thermally cracked gasoline.
Gray iron a broad class of ferrous casting alloys (cast irons) normally characterized by a microstructure of flake graphite in a ferrous matrix; gray iron usually contains 2.5–4% (w/w) C, 1–3% (w/w) Si, and additions of manganese, depending on the desired microstructure (as low as 0.1% w/w Mn in ferritic gray iron); sulfur and phosphorus are also present in small amounts as residual impurities.
Guard bed a bed of an adsorbent (such as, e.g., bauxite) that protects a catalyst bed by adsorbing species detrimental to the catalyst.
Gum an insoluble tacky semisolid material formed as a result of the storage instability and/or the thermal instability of petroleum and petroleum products.
Hard vacuum a term used to denote a high vacuum.
Heat affected zone (HAZ) an area adjacent to a weld where the thermal cycle has caused microstructural changes which generally affect corrosion behavior.
Heat exchanger a device which transfers heat through a conducting wall from one fluid to another.
Heavy ends the portions of a petroleum distillate fraction which are highest boiling, and therefore distill over last if the temperature is raised progressively.
Heavy fuel oil fuel oil having a high density and viscosity; generally residual fuel oil such as No. 5 and No 6. fuel oil (q.v.).
Heavy oil typically petroleum having an API gravity of <20°.
Heavy petroleum see Heavy oil.
Hematite (i) an iron mineral crystallizing in the rhombohedra1 system, the most important ore of iron and (ii) an iron oxide (Fe2O3) corresponding to an iron content of approximately 70% (w/w).
Heteroatom compounds chemical compounds which contain nitrogen and/or oxygen and/or sulfur and/or metals bound within their molecular structure(s).
Hot corrosion an accelerated corrosion of metal surfaces that results from the combined effect of oxidation and reactions with sulfur compounds and other contaminants, such as chlorides, to form a molten salt on a metal surface that fluxes, destroys, or disrupts the normal protective oxide.
Hydrocarbon an organic compound containing carbon and hydrogen only.
Hydrocarbon compounds (hydrocarbons) chemical compounds containing only carbon and hydrogen.
Hydroconversion a term often applied to hydrocracking (q.v.).
Hydrocracking a catalytic high-pressure high temperature process for the conversion of petroleum feedstocks in the presence of fresh and recycled hydrogen; carbon–carbon bonds are cleaved in addition to the removal of heteroatomic species; a process combining cracking or pyrolysis, with hydrogenation; feedstocks can include crude oil, distillates, heavy oil, tar sand bitumen, and residua.
Hydrocracking catalyst a catalyst used for hydrocracking which typically contains separate hydrogenation and cracking functions.
Hydrodenitrogenation the removal of nitrogen by hydrotreating (q.v.).
Hydrodesulfurization the removal of sulfur by hydrotreating (q.v.).
Hydrofinishing a process for treating raw extracted base stocks with hydrogen to saturate them for improved stability.
Hydrogenation the chemical addition of hydrogen to a hydrocarbon in the presence of a catalyst; a severe form of hydrogen treating. Hydrogenation may be either destructive or nondestructive.
Hydrogen blistering the formation of subsurface planar cavities, called hydrogen blisters, in a metal resulting from excessive internal hydrogen pressure; growth of near-surface blisters in low strength metals usually results in surface bulges.
Hydrogen damage a general term for the embrittlement, cracking, blistering, and hydride formation that can occur when hydrogen is present in some metals.
Hydrogen embrittlement a loss of ductility of a metal resulting from absorption of hydrogen; hydrogen-induced cracking (HIC) or severe loss of ductility caused by the presence of hydrogen in the metal; often generated from atomic hydrogen produced from cathodic reactions.
Hydrogen-induced cracking stepwise internal cracks that connect adjacent hydrogen blisters on different planes in the metal or to the metal surface (also known as stepwise cracking).
Hydrogen probes probes designed to measure the permeation rate of atomic hydrogen H+ (measured as hydrogen gas, H2) associated with hydrogen-induced cracking.
Hydrogen refining lube oil hydrorefining and hydrocracking or severe hydrotreating processes.
Hydrolysis breakdown process that occurs in anhydrous hydraulic fluids as a result of heat, water, and metal catalysts (iron, steel, copper, etc.).
Hydrophilic compounds with an affinity for water.
Hydrophobic compounds that repel water.
Hydroprocessing a term often equally applied to hydrotreating (q.v.) and to hydrocracking (q.v.); also often collectively applied to both.
Hydrotreating the removal of heteroatomic (nitrogen, oxygen, and sulfur) species by treatment of a feedstock or product at relatively low temperatures in the presence of hydrogen.
Hydrovisbreaking a noncatalytic process, conducted under similar conditions to visbreaking, which involves treatment with hydrogen to reduce the viscosity of the feedstock and produce more stable products than is possible with visbreaking.
Immiscibility the inability of two or more fluids to have complete mutual solubility; they coexist as separate phases.
Immiscible incapable of being mixed without separation of phases. Water and petroleum oil are immiscible under most conditions, although they can be made miscible with the addition of an emulsifier.
Impingement corrosion a form of erosion corrosion generally associated with the local impingement of a high velocity, flowing fluid against a solid surface.
Incompatibility the immiscibility of petroleum products and also of different crude oils which is often reflected in the formation of a separate phase after mixing and/or storage.
Incompatible fluids fluids which when mixed in a system will have a deleterious effect on that system, its components, or its operation.
Incubation period a period prior to the detection of corrosion while the metal is in contact with a corrosive agent.
Infrared spectroscopy an analytical technique that quantifies the vibration (stretching and bending) that occurs when a molecule absorbs (heat) energy in the infrared region of the electromagnetic spectrum.
Inhibitor a chemical substance or combination of substances that, when present in the proper concentration and forms in the environment, prevents or reduces corrosion.
Inhibitor a substance, the presence of which, in small amounts, in a petroleum product prevents or retards undesirable chemical changes from taking place in the product, or in the condition of the equipment in which the product is used.
Initial boiling point the recorded temperature when the first drop of liquid falls from the end of the condenser.
Instability the inability of a petroleum product to exist for periods of time without change to the product.
Interface the thin surface area separating two immiscible fluids that are in contact with each other.
Interfacial film a thin layer of material at the interface between two fluids which differs in composition from the bulk fluids.
Interfacial tension the strength of the film separating two immiscible fluids, e.g., oil and water or microemulsion and oil; measured in dynes (force) per centimeter or millidynes per centimeter.
Interfacial viscosity the viscosity of the interfacial film between two immiscible liquids.
Iodine number a measure of the iodine absorption by oil under standard conditions, used to indicate the quantity of unsaturated compounds present, also called iodine value.
IP Institute of Petroleum (UK).
ISO International Standards Organization which sets viscosity reference scales.
Jet fuel fuel meeting the required properties for use in jet engines and aircraft turbine engines.
Kaolinite a clay mineral formed by hydrothermal activity at the time of rock formation or by chemical weathering of rock with high feldspar content; usually associated with intrusive granite rock with high feldspar content.
Kata-condensed aromatic compounds compounds based on linear condensed aromatic hydrocarbon systems, e.g., anthracene and naphthacene (tetracene).
Kerosene (kerosine) a fraction of petroleum that was initially sought as an illuminant in lamps; a precursor to diesel fuel.
K-factor see Characterization factor.
Kinematic viscosity the ratio of viscosity (q.v.) to density, both measured at the same temperature; the time required for a fixed amount of an oil to flow through a capillary tube under the force of gravity. The unit of kinematic viscosity is the stoke or centistoke (1/100 of a stoke). Kinematic viscosity may be defined as the quotient of the absolute viscosity in centipoises divided by the specific gravity of a fluid, both at the same temperature.
Lamellar corrosion see Exfoliation corrosion.
Light ends low boiling volatile materials in a petroleum fraction. They are often unwanted and undesirable, but in gasoline the proportion of light ends deliberately included is used to assist low temperature starting.
Light hydrocarbons hydrocarbons with molecular weights less than that of heptane (C7H16).
Light oil the products distilled or processed from crude oil up to, but not including, the first lubricating oil distillate.
Light petroleum petroleum having an API gravity >20°.
Liquid any substance that flows readily or changes in response to the smallest influence. More generally, any substance in which the force required to produce a deformation depends on the rate of deformation rather than on the magnitude of the deformation.
Liquid petrolatum see White oil.
Liquid chromatography a chromatographic technique that employs a liquid mobile phase.
Liquid/liquid extraction an extraction technique in which one liquid is shaken with or contacted by an extraction solvent to transfer molecules of interest into the solvent phase.
Localized corrosion the corrosion process in which an intense attack takes place only in and around particular zones of the metal, leaving the rest of the metal unaffected; an example is pitting corrosion.
Low carbon steel steel having <0.30% carbon and no intentional alloying additions.
Lubricating oil a fluid lubricant used to reduce friction between bearing surfaces.
Mahogany acids oil-soluble sulfonic acids formed by the action of sulfuric acid on petroleum distillates. They may be converted to their sodium soaps (mahogany soaps) and extracted from the oil with alcohol for use in the manufacture of soluble oils, rust preventives, and special greases. The calcium and barium soaps of these acids are used as detergent additives in motor oils; see also Brown acids and Sulfonic acids.
Maltenes that fraction of petroleum that is soluble in, e.g., pentane or heptane; deasphaltened oil (q.v.); also the term arbitrarily assigned to the pentane-soluble portion of petroleum that is relatively high boiling (>300°C, 760 mm) (see also Petrolenes).
Mass spectrometer an analytical technique that fractures organic compounds into characteristic “fragments” based on functional groups that have a specific mass-to-charge ratio.
Magnetite a naturally occurring magnetic oxide of iron (Fe3O4).
Material Safety Data Sheet (MSDS) a publication containing health and safety information on a hazardous product (including petroleum). The OSHA Hazard Communication Standard requires that an MSDS be provided by manufacturers to distributors or purchasers prior to or at the time of product shipment. An MSDS must include the chemical and common names of all ingredients that have been determined to be health hazards if they constitute 1% or greater of the product’s composition (0.1% for carcinogens). An MSDS also included precautionary guidelines and emergency procedures.
Microbial corrosion (bacterial corrosion) corrosion caused or promoted by microorganisms. It can apply to both metals and nonmetallic materials, in both the presence and lack of oxygen. Sulfate-reducing bacteria are common in anaerobic conditions (lack of oxygen) and produce hydrogen sulfide which can cause sulfide stress cracking. Under aerobic conditions (presence of oxygen), some bacteria directly oxidize iron to iron oxides and hydroxides which other bacteria oxidize sulfur and produce sulfuric acid causing biogenic sulfide corrosion. Concentration cells can form in the deposits of corrosion products, causing and enhancing galvanic corrosion; see Biocorrosion, Microbiologically influenced corrosion.
Microbiologically influenced corrosion (MIC) corrosion which is substantially increased as the result of the presence of bacteria, such as sulfate-reducing bacteria (SRB) or acid producing bacteria (APB).
Microcarbon residue the carbon residue determined using a themogravimetric method; see also Carbon residue.
Microemulsion a stable, finely dispersed mixture of oil, water, and chemicals (surfactants and alcohols).
Microemulsion or micellar/emulsion flooding an augmented waterflooding technique in which a surfactant system is injected in order to enhance oil displacement toward producing wells.
Microorganisms animals or plants of microscopic size, such as bacteria.
Mid-boiling point the temperature at which approximately 50% of a material has distilled under specific conditions.
Middle distillate distillate boiling between the kerosene and lubricating oil fractions.
Mill scale the oxide layer formed during hot fabrication or heat treatment of metals.
Mineral hydrocarbons petroleum hydrocarbons, considered mineral because they come from the earth rather than from plants or animals.
Mineral oil oil derived from a mineral source, such as petroleum, as opposed to oils derived from plants and animals; the older term for petroleum; the term was introduced in the nineteenth century as a means of differentiating petroleum (rock oil) from whale oil which, at the time, was the predominant illuminant for oil lamps.
Mineral seal oil a distillation fraction between kerosene and gas oil, widely used as a solvent oil in gas adsorption processes, as a lubricant for the rolling of metal foil, and as a base oil in many specialty formulations. Mineral seal oil takes its name—not from any sealing function—but from the fact that it originally replaced oil derived from seal blubber for use as an illuminant for signal lamps and lighthouses.
Miscibility an equilibrium condition, achieved after mixing two or more fluids, which is characterized by the absence of interfaces between the fluids. (i) First-contact miscibility: miscibility in the usual sense, whereby two fluids can be mixed in all proportions without any interfaces forming. Example: At room temperature and pressure, ethyl alcohol and water are first-contact miscible. (ii) Multiple-contact miscibility (dynamic miscibility): miscibility that is developed by repeated enrichment of one fluid phase with components from a second fluid phase with which it comes into contact. (iii) Minimum miscibility pressure: the minimum pressure above which two fluids become miscible at a given temperature, or can become miscible, by dynamic processes.
Miscible capable of being mixed in any concentration without separation of phases; e.g., water and ethyl alcohol are miscible.
Mitigation identification, evaluation, and cessation of potential impacts of a process product or by-product.
MSDS Material Safety Data Sheet, a document required by several government agencies which typically lists the composition of a product along with hazard information, first aid measures, toxicological information, and regulatory information.
NACE (NACE International) National Association of Corrosion Engineers.
Naphtha a generic term applied to refined, partly refined, or unrefined petroleum products and liquid products of natural gas, the majority of which distills below 240°C (464°F); the volatile fraction of petroleum which is used as a solvent or as a precursor to gasoline.
Naphthenes a group of cyclic hydrocarbons also termed cycloparaffins; polycyclic members are also found in the higher boiling fractions.
Naphthenic a type of petroleum fluid derived from naphthenic crude oil, containing a high proportion of closed-ring methylene groups.
Naphthenic crude oil class designation of crude oil containing predominantly naphthenes or asphaltic compounds.
Natural gas the naturally occurring gaseous constituents that are found in many petroleum reservoirs; there are also those reservoirs in which natural gas may be the sole occupant.
Natural gas liquids (NGL) the hydrocarbon liquids that condense during the processing of hydrocarbon gases that are produced from oil or gas reservoir; see also Natural gasoline.
Natural gasoline a mixture of liquid hydrocarbons extracted from natural gas (q.v.) suitable for blending with refinery gasoline.
Neutralization a process for reducing the acidity or alkalinity of a waste stream by mixing acids and bases to produce a neutral solution, also known as pH adjustment.
Neutralization number the weight, in milligrams, of potassium hydroxide needed to neutralize the acid in 1 g of oil; an indication of the acidity of crude oil or crude oil products; this number (as determined) includes organic or inorganic acids or bases or a combination thereof (ASTM D974).
Nonionic surfactant a surfactant molecule containing no ionic charge, a neutral surfactant.
Normal paraffin (n-paraffin) a hydrocarbon consisting of molecules in which any carbon atom is attached to no more than two other carbon atoms, also called straight chain paraffin and linear paraffin.
Nuclear magnetic resonance spectroscopy an analytical procedure that permits the identification of complex molecules based on the magnetic properties of the atoms they contain.
Number 1 Fuel oil (No. 1 Fuel oil) very similar to kerosene (q.v.) and is used in burners where vaporization before burning is usually required and a clean flame is specified.
Number 2 Fuel oil (No. 2 Fuel oil) also called domestic heating oil; has properties similar to diesel fuel and heavy jet fuel; used in burners where complete vaporization is not required before burning.
Number 4 Fuel oil (No. 4 Fuel oil) a light industrial heating oil and is used where preheating is not required for handling or burning; there are two grades of No. 4 fuel oil, differing in safety (flash point) and flow (viscosity) properties.
Number 5 Fuel oil (No. 5 Fuel oil) a heavy industrial fuel oil which requires preheating before burning.
Number 6 Fuel oil (No. 6 Fuel oil) a heavy fuel oil and is more commonly known as Bunker C oil when it is used to fuel oceangoing vessels; preheating is always required for burning this oil.
Oil the portion of petroleum that exists in the liquid phase in reservoirs and remains as such under original pressure and temperature conditions. Small amounts of nonhydrocarbon substances may be included.
Oil shale a fine-grained impervious sedimentary rock which contains an organic material called kerogen.
Olefin synonymous with alkene.
Overhead that portion of the feedstock which is vaporized and removed during distillation.
Oxidation a process which can be used for the treatment of a variety of inorganic and organic substances; also: (i) loss of electrons by a constituent of a chemical reaction. (ii) Corrosion of a metal that is exposed to an oxidizing gas at elevated temperatures.
P Poise, unit of dynamic viscosity.
Paraffin any hydrocarbon identified by saturated straight (normal) or branched (iso) carbon chains, also called an alkane. The generalized paraffinic molecule can be symbolized by the formula CnH2n+2. Paraffins are relatively nonreactive and have excellent oxidation stability. In contrast to naphthenic oils, paraffinic lubricating oils have relatively high wax content and pour point, and generally have a high viscosity index (VI). Paraffinic solvents are generally lower in solvency than naphthenic or aromatic solvents.
Paraffinic a type of petroleum fluid derived from paraffinic crude oil and containing a high proportion of straight chain saturated hydrocarbons; often susceptible to cold flow problems.
Patina a thin layer of corrosion product, usually green, that forms on the surface of metals such as copper and copper-based alloys exposed to the atmosphere.
Partitioning in chromatography, the physical act of a solute having different affinities for the stationary and mobile phases.
Partition ratios, K the ratio of total analytical concentration of a solute in the stationary phase, CS, to its concentration in the mobile phase, CM.
Pericondensed aromatic compounds compounds based on angular condensed aromatic hydrocarbon systems, e.g., phenanthrene, chrysene, and picene.
Petrochemical any chemical substance derived from crude oil or its products, or from natural gas. Some petrochemical products may be identical to others produced from other raw materials such as coal and producer gas.
Petrolenes the term applied to that part of the pentane-soluble or heptane-soluble material that is low boiling (<300°C, <570°F, 760 mm) and can be distilled without thermal decomposition (see also Maltenes).
Petroleum (crude oil) a naturally occurring mixture of gaseous, liquid, and solid hydrocarbon compounds usually found trapped deep underground beneath impermeable cap rock and above a lower dome of sedimentary rock such as shale; most petroleum reservoirs occur in sedimentary rocks of marine, deltaic, or estuarine origin.
Petroleum refinery see Refinery.
Petroleum refining a complex sequence of events that result in the production of a variety of products.
pH measure of alkalinity or acidity in water and water-containing fluids. pH can be used to determine the corrosion-inhibiting characteristic in water-based fluids. Typically, pH>8.0 is required to inhibit corrosion of iron and ferrous alloys in water-based fluids.
pH adjustment neutralization by the addition of acid or alkali.
Phase a separate fluid that coexists with other fluids; gas, oil, water, and other stable fluids such as microemulsions are all called phases in EOR research.
Phase behavior the tendency of a fluid system to form phases as a result of changing temperature, pressure, or the bulk composition of the fluids or of individual fluid phases.
Phase separation the formation of a separate phase that is usually the prelude to coke formation during a thermal process; the formation of a separate phase as a result of the instability/incompatibility of petroleum and petroleum products.
Physical and chemical properties the results from several analytical tests that measure various physical characteristics and ingredients (constituents) of an engine oil.
Pipe still a still in which heat is applied to the oil while being pumped through a coil or pipe arranged in a suitable firebox.
Pipestill gas the most volatile fraction that contains most of the gases that are generally dissolved in the crude. Also known as pipestill light ends.
Pipestill light ends see Pipestill gas.
Pitch the nonvolatile, brown to black, semisolid to solid viscous product from the destructive distillation of many bituminous or other organic materials, especially coal.
Pitting highly localized corrosion resulting in deep penetration at only a few spots; a type of corrosion in which there is loss of metal in localized areas—the corrosion rate in the pits is many times greater than the corrosion rate on the entire surface—and the resultant pits can be large and shallow or narrow and deep. Pitting is a more dangerous problem than general corrosion because the pitted areas can be easily penetrated.
Pitting corrosion observed on passive metals in presence of certain anions (in particular chloride) when the potential exceeds a critical value. This process typically produces cavities with diameters on the order of several tens of micrometers.
Pitting factor the ratio of the depth of the deepest pit resulting from corrosion divided by the average penetration as calculated from mass loss.
PNA (polynuclear aromatic) any of numerous complex hydrocarbon compounds consisting of three or more benzene rings in a compact molecular arrangement. Some types of PNAs are formed in fossil fuel combustion and other heat processes such as catalytic cracking.
Poise (absolute viscosity) a measure of viscosity numerically equal to the force required to move a plane surface of one square centimeter per second when the surfaces are separated by a layer of fluid one centimeter in thickness.
Polar aromatics resins; the constituents of petroleum that are predominantly aromatic in character and contain polar (nitrogen, oxygen, and sulfur) functions in their molecular structure(s).
Polar compound a chemical compound whose molecules exhibit electrically positive characteristics at one extremity and negative characteristics at the other.
Polycyclic aromatic hydrocarbons (PAHs) polycyclic aromatic hydrocarbons are a suite of compounds comprised of two or more condensed aromatic rings. They are found in many petroleum mixtures, and they are predominantly introduced to the environment through natural and anthropogenic combustion processes.
Polynuclear aromatic compound an aromatic compound having two or more fused benzene rings, e.g., naphthalene and phenanthrene.
Pour point the lowest temperature at which oil will pour or flow when it is chilled (cooled) without disturbance under prescribed conditions (ASTM D97); the pour point is 3°C (5°F) above the temperature at which the oil in a test vessel shows no movement when the container is held horizontally for 5 s.
Pour point depressant an additive which retards the adverse effects of wax.
ppm parts per million (1/ppm=0.000001); generally by weight (ppm w/w); 100 ppm=0.01%; 10,000 ppm=1%.
Precipitation number the number of milliliters of precipitate formed when 10 ml of lubricating oil is mixed with 90 ml of petroleum naphtha of a definite quality and centrifuged under definitely prescribed conditions.
Pressure, absolute the sum of atmospheric and gage pressures.
Pretreatment usually refers to the treatment of a crude oil or crude oil product prior to refining.
Primary treatment the first step in re-refining used lubricating using dehydration in which the oil is stored to allow water and solids to separate out from the oil, then the oil is heated to approximately 120°C (248°F) in a closed vessel to boil off any emulsified water and some of the fuel diluents.
Propane asphalt see Solvent asphalt.
Propane deasphalting solvent deasphalting using propane as the solvent.
Propane decarbonizing a solvent extraction process used to recover catalytic cracking feed from heavy fuel residues.
Propane dewaxing a process for dewaxing lubricating oils in which propane serves as solvent.
Propane fractionation a continuous extraction process employing liquid propane as the solvent; a variant of propane deasphalting (q.v.).
Protopetroleum a generic term used to indicate the initial product formed and changes have occurred to the precursors of petroleum.
psia pounds per square inch absolute (psig+14.696); absolute, unit of pressure (pressure above total vacuum).
psid pounds per square inch differential.
psig pounds per square inch gage (psia−14.696); unit of pressure (pressure above atmospheric).
Quench the sudden cooling of hot material discharging from a thermal reactor.
Radiography (X-ray) use of X-rays to measure thickness or imperfection within solid materials.
Ramsbottom carbon residue an alternate test method for measuring the carbon residue of petroleum fractions (see Conradson carbon, Carbon residue).
Reaction a chemical transformation or change brought about by the interaction of two substances.
Reactive metal a metal that readily combines with oxygen at elevated temperatures to form very stable oxides, e.g., titanium, zirconium, and beryllium.
Reduced crude a residual product remaining after the removal, by distillation or other means, of an appreciable quantity of the more volatile components of crude oil.
Reducing agent a compound that causes reduction, thereby itself becoming oxidized.
Reducing atmosphere an atmosphere which tends to (i) promote the removal of oxygen from a chemical compound and (ii) promote the reduction of immersed materials.
Refinery a series of integrated unit processes by which petroleum can be converted to a slate of useful (salable) products.
Refinery gas a gas (or a gaseous mixture) produced as a result of refining operations.
Refining the processes by which petroleum is distilled and/or converted by application of a physical and chemical processes to form a variety of products are generated.
Relative humidity the ratio, expressed as a percentage, of the amount of water vapor present in a given volume of air at a given temperature to the amount required to saturate the air at that temperature.
Rerunning the distillation of an oil which has already been distilled.
Residuum (resid; pl:. residua) the residue obtained from petroleum after nondestructive distillation has removed all the volatile materials from crude oil, e.g., an atmospheric (345°C, 650°F+) residuum; the highest boiling (usually the highest molecular weight) components or bottoms remaining from distilling an oil, especially crude oil.
Resins that portion of the maltenes (q.v.) that is adsorbed by a surface active material such as clay or alumina; the fraction of deasphaltened oil that is insoluble in liquid propane but soluble in n-heptane.
Ringworm corrosion localized corrosion frequently observed in oil well tubing in which a circumferential attack is observed near a region of metal “upset.”
Riser (i) the section of pipeline extending from the ocean floor up the platform, (ii) the vertical tube in a steam generator convection bank that circulates water and steam upward; the part of the bubble plate assembly which channels the vapor and causes it to flow downward to escape through the liquid; also the vertical pipe where fluid catalytic cracking reactions occur.
ROSE Process Residual Oil Supercritical Extraction Process (Kellogg Brown and Root).
Rust a corrosion product consisting primarily of hydrated iron oxide; a term properly applied only to ferrous alloys.
Rust bloom discoloration indicating the beginning of rusting.
Rusting the formation of an oxide of iron due to oxidation of the iron atoms in solid solution is a well-known example of electrochemical corrosion.
Salinity the concentration of salt in water.
Saponification number the number of milligrams of potassium hydroxide (KOH) that combine with one gram of oil under specified conditions (ASTM D94); an indication of the amount of fatty saponifiable material in compounded oil. Caution must be used in interpreting test results if certain substances—such as sulfur compounds or halogens—are present in the oil, since these also react with KOH thereby increasing the apparent Saponification number.
SARA analysis a method of fractionation by which petroleum is separated into saturates, aromatics, resins, and asphaltene fractions.
SARA separation see SARA analysis.
Saturates paraffins and cycloparaffins (naphthenes).
Saybolt Furol viscosity the time, in seconds (Saybolt Furol Seconds, SFS), for 60 ml of fluid to flow through a capillary tube in a Saybolt Furol viscometer at specified temperatures between 70 and 210°F; the method is appropriate for high viscosity oils such as transmission, gear, and heavy fuel oils (ASTM D88).
Saybolt Universal viscosity the time, in seconds (Saybolt Universal Seconds, SUS), for 60 ml of fluid to flow through a capillary tube in a Saybolt Universal viscometer at a given temperature (ASTM D88).
Scaling (i) the formation at high temperatures of thick corrosion product layers on a metal surface; (ii) the deposition of water-insoluble constituents on a metal surface.
Sediment an insoluble solid formed as a result of the storage instability and/or the thermal instability of petroleum and petroleum products.
Selective corrosion (selective leaching or dealloying) the selective dissolution of one of the components of an alloy that forms a solid solution. It leads to the formation of a porous layer made of the more noble metal; the selective corrosion of certain alloying constituents from an alloy (as dezincification) or in an alloy (as internal oxidation).
Selective solvent a solvent which, at certain temperatures and ratios, will preferentially dissolve more of one component of a mixture than of another and thereby permit partial separation.
Separation process an upgrading process in which the constituents of petroleum are separated, usually without thermal decomposition, e.g., distillation and deasphalting.
Siderite an iron ore (FeCO3) occurring in various forms and colors and crystalline with perfect rhombohedral cleavage.
Sidestream a liquid stream taken from any one of the intermediate plates of a bubble tower.
Sidestream stripper a device used to perform further distillation on a liquid stream from any one of the plates of a bubble tower, usually by the use of steam.
Sludge insoluble material formed as a result either of deterioration reactions in crude oil (crude oil product) or of contamination of the oil, or both; a semisolid to solid product which results from the storage instability and/or the thermal instability of petroleum and petroleum products.
Solvency ability of a fluid to dissolve inorganic materials and polymers, which is a function of aromaticity.
Solvent a material with a strong capability to dissolve a given substance. The most common petroleum solvents are mineral spirits, xylene, toluene, hexane, heptane, and naphtha. Aromatic-type solvents have the highest solvency for organic chemical materials, followed by naphthenes and paraffins. In most applications, the solvent disappears, usually by evaporation, after it has served its purpose. The evaporation rate of a solvent is very important in manufacture.
Solvent asphalt the asphalt (q.v.) produced by solvent extraction of residua (q.v.) or by light hydrocarbon (propane) treatment of a residuum (q.v.) or an asphaltic crude oil.
Solvent deasphalting a process for removing asphaltic and resinous materials from reduced crude oils, lubricating oil stocks, gas oils, or middle distillates through the extraction or precipitant action of low molecular weight hydrocarbon solvents; see also Propane deasphalting.
Solvent decarbonizing see Propane decarbonizing.
Solvent deresining see Solvent deasphalting.
Solvent dewaxing a process for removing wax from oils by means of solvents usually by chilling a mixture of solvent and waxy oil, filtration or by centrifuging the wax which precipitates, and solvent recovery.
Solvent extraction a process for separating liquids by mixing the stream with a solvent that is immiscible with part of the waste but that will extract certain components of the waste stream; a refining process used to separate components (unsaturated hydrocarbons) from lube distillates in order to improve the oil’s oxidation stability, viscosity index, and response to additives.
Solvent naphtha a refined naphtha of restricted boiling range used as a solvent, also called petroleum naphtha, petroleum spirits.
Solvent refining see Solvent extraction.
Sour crude oil crude oil containing an abnormally large amount of sulfur compounds; see also Sweet crude oil.
Sour gas a gaseous mixture containing hydrogen sulfide and carbon dioxide.
Sour water waste water containing fetid materials, usually sulfur compounds.
Spalling the spontaneous chipping, fragmentation, or separation of a surface or surface coating.
Specific gravity the ratio of the weight of a given volume of material to the weight of an equal volume of water.
Specific gravity (liquid) the ratio of the weight of a given volume of liquid to the weight of an equal volume of water.
Spent catalyst catalyst that has lost much of its activity due to the deposition of coke and metals.
SSU Saybolt Universal Seconds (or SUS), a unit of measure used to indicate kinematic viscosity, e.g., SSU @ 100°F.
St Stokes, unit of kinematic viscosity.
Stabilization the removal of volatile constituents from a higher boiling fraction or product (q.v. stripping); the production of a product which, to all intents and purposes, does not undergo any further reaction when exposed to the air.
Stoke (St) kinematic measurement of a fluid’s resistance to flow defined by the ratio of the fluid’s dynamic viscosity to its density.
Straight mineral oil petroleum containing no additives.
Straight oil mineral oil containing no additives.
Straight-run asphalt the asphalt (q.v.) produced by the distillation of asphaltic crude oil.
Straight-run products obtained from a distillation unit and used without further treatment.
Stress corrosion (stress-accelerated corrosion) corrosion which is accelerated by stress.
Stress corrosion cracking results from the combined action of corrosion and of mechanical stress; manifested by crack formation at stress levels well below the ultimate tensile strength of a material.
Sulfidation the reaction of a metal or alloy with a sulfur-containing species to produce a sulfur compound that forms on or beneath the surface on the metal or alloy.
Sulfide stress cracking cracking of a metal under the combined action of tensile stress and corrosion in the presence of water and hydrogen sulfide (a form of hydrogen stress cracking).
Sulfonic acids acids obtained by petroleum or a petroleum product with strong sulfuric acid.
Sulfur a common natural constituent of petroleum and petroleum products; limitations of the amount of sulfur are specified in the quality control of fuels, solvents, and other products.
Surface active material a chemical compound, molecule, or aggregate of molecules with physical properties that cause it to adsorb at the interface between two immiscible liquids, resulting in a reduction of interfacial tension or the formation of a microemulsion.
Surface tension the contractile surface force of a liquid by which it tends to assume a spherical form and to present the least possible surface. It is expressed in dynes/cm or ergs/cm2.
Surfactant surface active agent that reduces interfacial tension of a liquid; used in petroleum may increase the oil’s affinity for metals and other materials; a chemical, characterized as one that reduces interfacial resistance to mixing between oil and water or changes the degree to which water wets reservoir rock.
SUS (SSU): Saybolt Universal Seconds a measure of lubricating oil viscosity in the oil industry. The measuring apparatus is filled with a specific quantity of oil or other fluid and its flow time through a standardized orifice is measured in seconds. Fast flowing fluids (low viscosity) will have a low value; slow flowing fluids (high viscosity) will have a high value.
Sweet crude oil crude oil containing little sulfur; see also Sour crude oil.
Synthetic crude oil (syncrude) a hydrocarbon product produced by the conversion of coal, oil shale, or tar sand bitumen that resembles conventional crude oil; can be refined in a petroleum refinery (q.v.); the product of a thermal reaction rather than by extraction or refining.
Tar the volatile, brown to black, oily, viscous product from the destructive distillation of many bituminous or other organic materials, especially coal; a name used for petroleum in ancient texts.
Thermal coke the carbonaceous residue formed as a result of a noncatalytic thermal process, the Conradson carbon residue, the Ramsbottom carbon residue.
Thermal cracking a process which decomposes, rearranges, or combines hydrocarbon molecules by the application of heat, without the aid of catalysts.
Thermal process any refining process which utilizes heat, without the aid of a catalyst.
Thermal stability (thermal instability) the ability (inability) of a liquid to withstand relatively high temperatures for short periods of time without the formation of carbonaceous deposits (sediment or coke); the ability of crude oil or a crude oil product to resist degradation or oxidation under high temperature operating conditions.
Thin layer chromatography (TLC) a chromatographic technique employing a porous medium of glass coated with a stationary phase. An extract is spotted near the bottom of the medium and placed in a chamber with solvent (mobile phase). The solvent moves up the medium and separates the components of the extract, based on affinities for the medium and solvent.
Ton a short ton is 2000 lbs (907.2 kg); a long ton is 2240 lbs (1016 kg).
Tonne A metric tonne of 1000 kg, equivalent to 2205 lbs.
Topped crude petroleum that has had volatile constituents removed up to a certain temperature, e.g., 250°C+ (480°F+) topped crude; not always the same as a residuum (q.v.).
Topping the distillation of crude oil to remove light fractions only.
Total acid number (TAN) the quantity of base, expressed in milligrams of potassium hydroxide, that is required to neutralize all acidic constituents present in 1 gram of sample (ASTM D974); see Acid Number.
Total base number (TBN) the quantity of acid, expressed in terms of the equivalent number of milligrams of potassium hydroxide that is required to neutralize all basic constituents present in 1 gram of sample (ASTM D974); see Base Number.
Tower equipment for increasing the degree of separation obtained during the distillation of oil in a still.
Treatment any method, technique, or process that changes the physical and/or chemical character of petroleum.
True boiling point (True boiling range) the boiling point (boiling range) of a crude oil fraction or a crude oil product under standard conditions of temperature and pressure.
Tuberculation the formation of localized corrosion products scattered over the surface in the form of knob-like mounds called tubercles.
UK United Kingdom of Great Britain.
Ultimate analysis elemental composition.
Ultrasonic measurement The timing of the transmission of ultrasonic sound waves through a material to determine the material’s thickness.
Underfilm corrosion see Filiform corrosion.
Uniform corrosion the loss of material distributed uniformly over the entire surface exposed to the corrosive environment; metals in contact with strong acids are sometimes subject to uniform corrosion.
Unstable usually refers to a petroleum product that has more volatile constituents present or refers to the presence of olefin and other unsaturated constituents.
Upgrading the conversion of petroleum to value-added salable products.
US or USA United States of America.
Vacuum dehydration a method which involves drying or freeing of moisture through a vacuum process.
Vacuum distillation a distillation method which involved reducing the pressure above a liquid mixture to be distilled to less than its vapor pressure (usually less than atmospheric pressure); this causes evaporation of the most volatile liquid(s)—those with the lowest boiling points; distillation (q.v.) under reduced pressure.
Vacuum residuum a residuum (q.v.) obtained by distillation of a crude oil under vacuum (reduced pressure), that portion of petroleum which boils above a selected temperature such as 510°C (950°F) or 565°C (1050°F).
Vacuum separator a separator that utilizes subatmospheric pressure to remove certain gases and liquids from another liquid because of their difference in vapor pressure.
Vapor pressure pressure of a confined vapor in equilibrium with its liquid at specified temperature, thus a measure of a liquid’s volatility.
Vapor pressure-Reid (RVP) a measure of the pressure of vapor accumulated above a sample of gasoline or other volatile fuel in a standard bomb at 100°F (37.8°C).
VDT (vacuum distillation tower) generally applies to a crude distillation tower which operates at below atmospheric pressure.
VDU (vacuum distillation unit) generally includes a VDT and associated equipment for producing distillates from the bottoms of an atmospheric distillation tower (ADT) by operating at below atmospheric pressure.
Visbreaking a process for reducing the viscosity of heavy feedstocks by controlled thermal decomposition.
Viscometer (viscosimeter) an apparatus for determining the viscosity of a fluid.
Viscosity a measure of the ability of a liquid to flow or a measure of its resistance to flow; the force required to move a plane surface of area 1 m2 over another parallel plane surface 1 m away at a rate of 1 m/s when both surfaces are immersed in the fluid; measurement of a fluid’s resistance to flow; the common metric unit of absolute viscosity is the poise, which is defined as the force in dynes required to move a surface one square centimeter in area past a parallel surface at a speed of one centimeter per second, with the surfaces separated by a fluid film 1 cm thick. In addition to kinematic viscosity, there are other methods for determining viscosity, including Saybolt Universal Viscosity (SUV), Saybolt Furol viscosity, Engler viscosity, and Redwood viscosity. Since viscosity varies in inversely with temperature, its value is meaningless until the temperature at which the viscosity is determined is also reported.
VGC (viscosity-gravity constant) an index of the chemical composition of crude oil defined by the general relation between specific gravity, sg, at 60°F and Saybolt Universal viscosity, SUV, at 100°F:
The constant, a, is low for the paraffin crude oils and high for the naphthenic crude oils.
Viscosity-gravity constant see VGC.
Viscosity index (VI) a commonly used measure of a fluid’s change of viscosity with temperature. The higher the viscosity index, the smaller the relative change in viscosity with temperature.
Viscosity–temperature relationship the manner in which the viscosity of a given fluid varies inversely with temperature.
Viscous frequently used to imply high viscosity.
Void (i) a holiday, hole, or skip in a coating, (ii) a hole in a casting or weld deposit usually resulting from shrinkage during cooling.
Volatile compounds a relative term that may mean (i) any compound that will purge, (ii) any compound that will elute before the solvent peak (usually those <C6), or (iii) any compound that will not evaporate during a solvent removal step.
Volatility this property describes the degree and rate at which a liquid will vaporize under given conditions of temperature and pressure. When liquid stability changes, this property is often reduced in value.
VPS (vacuum pipe still) generally includes a vacuum tower and associated equipment for the distillation of crude into lube distillates or cracking feedstocks and vacuum residua; see VDU.
Watson characterization factor see Characterization factor.
White oil a generic name applied to highly refined, colorless hydrocarbon oils of low volatility, and covering a wide range of viscosity; a colorless and odorless mineral oil used in medicinal and pharmaceutical preparations and as a lubricant in food and textile industries.
White rust zinc oxide (ZnO); the powdery product of the corrosion of zinc or zinc-coated surfaces.
Zeolite a crystalline aluminosilicate used as a catalyst and having a particular chemical and physical structure.