Mineral oils: processes and products – Chemical conversion of hydrocarbons – With preliminary treatment of feed
Patent
1981-09-01
1984-02-28
Thomas, Earl C.
Mineral oils: processes and products
Chemical conversion of hydrocarbons
With preliminary treatment of feed
208 86, 423210, 423244, 502 38, C10G 2500, B01D 5334
Patent
active
044340443
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
Crude oil from which desired gaseous and liquid fuels are made contain a diverse mixture of hydrocarbons and other compounds which vary widely in molecular weight and therefore boil over a wide range. For example, crude oils are known in which 30 to 60% or more of the total volume of oil is composed of compounds boiling at temperatures above 650.degree. F. Among these are crudes in which about 10% to about 30% or more of the total volume consists of compounds so heavy in molecular weight that they boil above 1025.degree. F. or at least will not boil below 1025.degree. F. at atmospheric pressure.
Because these high boiling components of crude oil boiling above 650.degree. F. are unsuitable for inclusion in gasoline and some higher boiling liquid hydrocarbon fuels, the petroleum refining industry has developed processes for separating and/or breaking the molecules of the high molecular weight, high boiling compounds into smaller molecules which do boil over an appropriate boiling range. The cracking process which is most widely used for this purpose is known as fluid catalytic cracking (FCC). Although the FCC process has reached a highly advanced state, and many modified forms and variations have been developed, their unifying factor is that a restricted boiling range hydrocarbon feedstock is caused to be cracked at an elevated temperature in contact with a cracking catalyst that is suspended in the feedstock under cracking conditions in a temperature range of 950.degree. to 1100.degree. F. Upon attainment of a desired degree of molecular weight and boiling point reduction the catalyst is separated from the desired catalytic conversion products.
Crude oils in the natural state contain a variety of materials which tend to have quite troublesome effects on FCC processes, and only a portion of these troublesome materials can be economically removed from the crude oil. Among these troublesome materials are coke precursors (such as asphaltenes, polynuclear aromatics, etc.), heavy metals (such as nickel, vanadium, iron, copper etc.), lighter metals (such as sodium, potassium, etc.), sulfur, nitrogen and others. Certain of these, such as the lighter metals, can be economically removed by desalting operations, which are part of the normal procedure for pretreating crude oil for fluid catalytic cracking. Other materials, such as coke precursors, asphaltenes and the like, tend to break down into coke during the cracking operation, which coke deposits on the catalyst, impairing contact between the hydrocarbon feedstock and the catalyst, and generally reducing its potency or activity level. The heavy metals transfer almost quantitatively from the feedstock to the catalyst surface.
If the catalyst is reused again and again for processing additional feedstock, which is usually the case, heavy metals in the feedstock can accumulate on the catalyst to the point that they unfavorably alter the composition of the catalyst and/or the nature of its effect upon the feedstock. For example, vanadium tends to form fluxes with certain components of commonly used FCC catalysts, lowering the melting point of portions of the catalyst particles sufficiently so that they begin to sinter and become ineffective cracking catalysts. Accumulations of vanadium and other heavy materials, especially nickel, also "poison" the catalyst. They tend in varying degrees to promote excessive dehydrogenation and aromatic condensation, resulting in excessive production of carbon and gases with consequent impairment of liquid fuel yield. An oil such as a crude or crude fraction or other oil that is particularly abundant in nickel and/or other metals exhibiting similar behavior, while containing relatively large quantities of coke precursors, is referred to herein as a carbo-metallic oil, and represents a particular challenge to the petroleum refiner.
There has been a long standing interest in the conversion of carbo-metallic oils into gasoline and other liquid fuels. For example, in the 1950's it was suggested that a variety of
REFERENCES:
patent: 2455419 (1948-12-01), Johnson
patent: 3699037 (1972-10-01), Annesser et al.
patent: 4177158 (1979-12-01), Blue
patent: 4263128 (1981-04-01), Bartholic
Busch Lloyd E.
Walters Paul W.
Zandona Oliver J.
Ashland Oil Inc.
Farnsworth Carl D.
Thomas Earl C.
Willson, Jr. Richard C.
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