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Industry Glossary

The definitions contained in this "Chemical Glossary" are merely generic definitions that may prove helpful to those using this Web site. They do not supercede, nor are they intended to supercede, the definitions or specifications that may apply to various technical terms as they are used in specific Chevron Phillips Chemical documents, agreements, proposals or offerings, or in Chevron Phillips Chemical or third party patents.

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Degradation	The degeneration of the chemical structure, physical properties, or appearance of a chemical substance such as a plastic due to exposure to light, heat, oxygen, or other reagents.
Delayed Coking	A process by which heavier crude oil fractions can be thermally decomposed under conditions of elevated temperatures and pressure to produce a mixture of lighter oils and petroleum coke. The light oils can be processed further in other refinery units to meet product specifications. The coke can be used either as a fuel or in other applications such as the manufacturing of steel or aluminum.
Density	The mass per unit volume. A common specification for chemical substances.
Desulfurization	The removal of sulfur, as from molten metals, petroleum oil, or flue gases. Petroleum desulfurization is a process that removes sulfur and its compounds from various streams during the refining process. Desulfurization processes include catalytic hydrotreating and other chemical/physical processes such as adsorption. Desulfurization processes vary based on the type of stream treated (e.g., naphtha, distillate, heavy gas oil, etc.) and the amount of sulfur removed (e.g., sulfur reduction to 10 ppm). See Catalytic Hydrotreating.
Dimethyl-terephthalate	A.k.a DMT. An intermediate petrochemical derived from p-xylene. DMT is a traditional raw material for polyester resins but production facilities are being phased out in favor of more efficient terepthalic acid (TPA) plants.
Disposition	The components of petroleum disposition are stock change, crude oil losses, refinery inputs, exports, and products supplied for domestic consumption.
Disproportionation	A chemical reaction in which a single compound serves as both oxidizing and reducing agent, such as the dealkylation of toluene to give benzene (the more reduced product) and xylene (the more oxidized product).
Distillate Fuel Oil	A general classification for one of the petroleum fractions produced in conventional distillation operations. It includes diesel fuels and fuel oils. Products known as No. 1, No. 2, and No. 4 diesel fuel are used in on-highway diesel engines, such as those in trucks and automobiles, as well as off-highway engines, such as those in railroad locomotives and agricultural machinery. Products known as No. 1, No. 2, and No. 4 fuel oils are used primarily for space heating and electric power generation. No. 1 Distillate: A light petroleum distillate that can be used as either a diesel fuel or a fuel oil. No. 1 Diesel Fuel: A light distillate fuel oil that has a distillation temperature of 550 degrees Fahrenheit at the 90-percent recovery point and meets the specifications defined in ASTM Specification D 975. It is used in high speed diesel engines generally operated under frequent speed and load changes, such as those in city buses and similar vehicles. See *No. 1 Distillate.* No. 1 Fuel Oil: A light distillate fuel oil that has distillation temperatures of 400 degrees Fahrenheit at the 10-percent recovery point and 550 degrees Fahrenheit at the 90-percent recovery point and meets the specifications defined in ASTM Specification D 396. It is used primarily as fuel for portable outdoor stoves and portable outdoor heaters. See *No. 1 Distillate.* No. 2 Distillate: A petroleum distillate that can be used as either a diesel fuel or a fuel oil. No. 2 Diesel Fuel: A distillate fuel oil that has a distillation temperature of 640 degrees Fahrenheit at the 90-percent recovery point and meets the specifications defined in ASTM Specification D 975. It is used in high-speed diesel engines that are generally operated under uniform speed and load conditions, such as those in railroad locomotives, trucks, and automobiles. See *No. 2 Distillate.* Low Sulfur No. 2 Diesel Fuel: No. 2 diesel fuel that has a sulfur level no higher than 0.05 percent by weight. It is used primarily in motor vehicle diesel engines for on-highway use. High Sulfur No. 2 Diesel Fuel: No. 2 diesel fuel that has a sulfur level above 0.05 percent by weight. No. 2 Fuel Oil (Heating Oil): A distillate fuel oil that has a distillation temperature of 640 degrees Fahrenheit at the 90-percent recovery point and meets the specifications defined in ASTM Specification D 396. It is used in atomizing type burners for domestic heating or for moderate capacity commercial/industrial burner units. No. 4 Fuel: A distillate fuel oil made by blending distillate fuel oil and residual fuel oil stocks. It conforms to ASTM Specification D 396 or Federal Specification VV-F-815C and is used extensively in industrial plants and in commercial burner installations that are not equipped with preheating facilities. It also includes No. 4 diesel fuel used for low- and medium-speed diesel engines and conforms to ASTM Specification D 975. No. 4 Diesel Fuel: See No. 4 Fuel. No. 4 Fuel Oil: See No. 4 Fuel.
Distillation	A common manufacturing process for separation/purification in which a liquid is converted to a vapor and the vapor is then condensed to a liquid.