Combination Hydroconversion, Fluid Coking and Gasification

1. Field of the Invention

This invention relates to a combination process for upgrading carbonaceous materials to produce normally liquid hydrocarbonaceous products. It particularly relates to a combination slurry hydroconversion, coking and coke gasification process wherein the catalytic metal component, which may be a component of a single metal or of more than one metal, of the hydroconversion process is recovered from the hydroconversion oil product by subjecting the oil product to a fluid coking and coke gasification process. The solid fines recovered from the gasification process comprise the catalytic metal component of the hydroconversion catalyst. The fines are recycled to the hydroconversion process as catalyst. The term "fines" is intended herein to designate particles having an average diameter of less than 10 microns.

2. Description of the Prior Art

Catalytic slurry processes for the hydrogenative conversion of heavy oils are known. See, for example, U.S. Pat. Nos. 3,617,503; 3,297,563 and 3,622,498.

It is also known to produce hydrogen-containing gases and coke by integrated fluid coking and coke gasification processes such as those disclosed in U.S. Pat. Nos. 3,661,543; 3,702,516; and 3,759,676, the teachings of which are hereby incorporated by reference.

A process is known for upgrading heavy mineral oils by reaction with hydrogen in the presence of a catalyst comprising a solid carbon-containing material and an alkali metal component. See, U.S. Pat. No. 3,923,635.

U.S. Pat. No. 3,617,481 discloses a contamination hydrotreating, coking and coke gasification process in which the metals-containing coke gasification residue is used as catalyst in the hydrotreating stage.

U.S. Pat. No. 4,066,530 discloses a hydroconversion process for hydrocarbonaceous oil utilizing as catalyst an iron component and a catalyst prepared in the oil from an oil soluble metal compound.

It has now been found that a combination slurry hydroconversion process, fluid coking and coke gasification in which the solid fines resulting from the gasification are used as a catalyst in combination with a catalyst prepared from an oil soluble metal compound for the hydroconversion process will provide advantages that will become apparent in the ensuing description.

In accordance with the invention there is provided, a process for upgrading a carbonaceous chargestock, which comprises: (a) adding to said carbonaceous chargestock an oil soluble metal compound of a metal selected from the group consisting of Groups IVB, VB, VIB, VIIB and VIII of the Periodic Table of Elements and mixtures thereof; (b) converting said oil soluble metal compound to a solid catalyst within said chargestock in the presence of a hydrogen-containing gas by heating said chargestock to an elevated temperature; (c) reacting the chargestock containing said catalyst with hydrogen under hydroconversion conditions, in a hydroconversion zone to produce a hydrocarbonaceous oil product; (d) separating a heavy oil fraction from said hydrocarbonaceous oil product; (e) contacting at least a portion of said heavy oil fraction with a bed of fluidized solids maintained in a fluid coking zone under fluid coking conditions to form coke, said coke depositing on said fluidizing solids; (f) introducing a portion of said solids with a coke deposit thereon into a heating zone operated at a temperature greater than said coking zone temperature to heat said portion of solids; (g) recycling a first portion of heated solids from said heating zone to said coking zone; (h) introducing a second portion of said heated solids to a fluid bed gasification zone maintained at a temperature greater than the temperature of said heating zone; (i) reacting said second portion of heated solids in said gasification zone with steam and a molecular oxygen-containing gas to produce a hot gaseous stream containing hydrogen; (j) introducing said hot gaseous stream containing hydrogen and entrained solids into said heating zone; (k) recovering from said heating zone the resulting cooled gaseous stream containing hydrogen and entrained solid carbonaceous fines; (1) separating at least a portion of said solid carbonaceous fines from said cooled gaseous stream, said separated fines having an average particle size of less than 10 microns in diameter, and (m) recycling at least a portion of said separated fines to such chargestock of step (a).

The FIGURE is a schematic flow plan of one embodiment of the invention.

Referring to the FIGURE, a carbonaceous material is passed by line 10 to a mixing zone 12. Suitable carbonaceous material for introduction into the mixing zone include hydrocarbonaceous oils such as heavy and reduced petroleum crudes, atmospheric distillation bottoms, vacuum distillation bottoms, pitch, asphalt, bitumen, other heavy hydrocarbon residua, liquids derived from coal liquefaction processes, shale oil, tar sand oil; slurries of coal in hydrogen donor solvents; slurries of coal in other non-aqueous liquid media such as petroleum residua; and mixtures of any of these carbonaceous materials. Catalytic solid fines produced as will hereinafter be described are introduced into mixing zone 12 by line 14. Optionally, the liquid feed may be used to scrub the gases from the heater, after partial cooling, and to recover the catalytic fines. Desirably, a sufficient amount of catalytic solid fines are added to the mixing zone to provide a content of the solid fines from about 0.05 to 10 weight percent based on the carbonaceous chargestock to the mixing zone, preferably to provide solid fines from about 0.10 to about 5 weight percent based on the carbonaceous chargestock, more preferably from about 0.20 to about 2 weight percent solid fines based on the chargestock.

To the carbonaceous chargestock via line 11 is added from about 10 to about 950 wppm, preferably from about 25 to about 300 wppm, more preferably from about 25 to about 100 wppm of an oil soluble metal compound, wherein the metal is selected from the group consisting of Group IVB, Group VB, Group VIB, Group VIIB, Group VIII and mixtures thereof of the Periodic Table of Elements, said weight being calculated as if the compound existed as the elemental metal, based on the initial carbonaceous chargestock.

Suitable oil soluble metal compounds convertible (under process conditions) to solid catalysts include (1) inorganic metal compounds such as halides, oxyhalides, heteropoly acids (e.g. phosphomolybdic acid, molybdosilicic acid); (2) metal salts of organic acids such as acyclic and alicyclic aliphatic carboxylic acid containing two or more carbon atoms (e.g. naphthenic acids); aromatic carboxylic acids (e.g. toluic acid); sulfonic acids (toluenesulfonic acid); sulfinic acid, mercaptans; xanthic acid; phenols, di and polyhydroxy aromatic compounds; (3) organic metallic compounds such as metal chelates, e.g. with 1,3, diketones, ethylenediamine, ethylenediaminetetraacetic acid, phthalocyanines, etc.; (4) metal salts of organic amines such as aliphatic amines, aromatic amines and quarternary ammonium compounds.

The metal constituent of the oil soluble metal compound that is convertible to a solid catalyst is selected from the group consisting of Groups IVB, VB, VIB, VIIB, and VIII and mixtures thereof of the Periodic Table of Elements, in accordance with the table published by E. H. Sargent & Co., copyright 1962, Dyna Slide Co., that is, titanium, zirconium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, rhenium, iron, cobalt, nickel and the noble metals including platinum, iridium, palladium, osmium, ruthenium and rhodium. The preferred metal constituent of the oil soluble metal compound is selected from the group consisting of molybdenum, vanadium and chromium. More preferably, the metal constituent of the oil soluble metal compound is selected from the group consisting of molybdenum and chromium. Most preferably, the metal constituent of the oil soluble metal is molybdenum. Preferred compounds of the given metals include the salts of acrylic (straight or branched chain) aliphatic carboxylic acids, salts of alicyclic aliphatic carboxylic acids, heteropoly acids, carbonyls, phenolates and organoamine salts. The more preferred metal compounds are salts of alicyclic aliphatic carboxylic acids such as metal naphthenates. The most preferred compounds are molybdenum naphthenate, vanadium naphthenate and chromium naphthenate.

When the oil soluble metal compound is added to the carbonaceous chargestock, it first dissolves and subsequently under pretreatment or under hydroconversion conditions herein described is converted to a solid catalyst comprising from about 10 to about 950 wppm, preferably from about 25 to about 300 wppm, more preferably from about 25 to about 100 wppm of the same metal or metals as the metal or metals added as oil soluble compounds, calculated as the elemental metal, based on the initial carbonaceous chargestock. The resulting mixture is removed from mixing zone 12 by line 16 and, optionally, passed to a pretreatment zone 18 where the mixture is contacted with a gas comprising hydrogen sulfide alone or a gas comprising hydrogen and from about 1 to about 90 mole percent hydrogen sulfide introduced via line 20. The pretreatment zone, when used, is operated at a temperature ranging from about 615.degree. to 780.degree. F. and at a pressure ranging from about 500 to 5000 psig. Under pretreatment conditions, the oil soluble metal compound is converted to a solid catalyst. The pretreated slurry is removed from pretreatment zone 18 by line 22 and passed to hydroconversion zone 24. When no pretreatment is used, the slurry is passed from the mixing zone to the hydroconversion zone where the oil soluble metal compound is converted to a solid catalyst.

The term "hydroconversion" is used herein to designate a process conducted in the presence of hydrogen in which at least a portion of the heavy constituents of the chargestock is converted to lower boiling hydrocarbon products. A hydrogen-containing gas is introduced into the hydroconversion zone 24 by line 26. As will readily be apparent, this gas could be introduced into the feed line entering the hydroconversion zone. Optionally, the hydrogen-containing gas may also comprise from about 1 to about 10 mole percent of hydrogen sulfide, preferably from about 2 to about 7 mole percent hydrogen sulfide. The hydroconversion zone is maintained at a temperature ranging from about 650.degree. to about 1000.degree. F., preferably from about 775.degree. to about 900.degree. F., more preferably from about 800.degree. to about 875.degree. F. and at a hydrogen partial pressure ranging from about 500 to about 5000 psig, preferably from about 1000 to about 3000 psig. The slurry of carbonaceous feed and catalytic solids is introduced into the hydroconversion zone at a space velocity ranging from about 0.1 to 10 volumes of chargestock per hour per volume of reactor, preferably from about 0.25 to about 6 V/Hr/V. The hydroconversion zone effluent is removed by line 28 and passed to a gas-liquid separation zone 30. The gaseous effluent of separation zone 30 is removed by line 32. Since this gas comprises hydrogen, it may be recycled, if desired after prior cleanup, for use as hydrogen in the hydroconversion zone. The liquid product is removed by line 34 and passed to a separation zone 36 from which a lighter carbonaceous oil, such as, for example, a fraction boiling below 1050.degree. F. at atmospheric pressure is recovered by line 38. The bottoms portion or heavy oil fraction is removed by line 40 and passed as feed to a coking zone 42 in which is maintained a fluidized bed of solids (e.g. coke particles of 40 to 1000 microns in size) having an upper level indicated at 44. A fluidizing gas, e.g. steam, is admitted at the base of the coking reactor through line 46 in an amount sufficient to obtain a superficial fluidizing gas velocity in the range of 0.5 to 5 feet per second. Coke at a temperature above the actual coking temperature, for example, at a temperature from about 100 to about 800 Fahrenheit degrees in excess of the actual operating temperature of the coking zone, is admitted into the coking zone by line 48 in an amount sufficient to maintain the coking temperature in the range of about 850.degree. to about 1400.degree. F., preferably at a temperature ranging from 900.degree. to 1200.degree. F. The pressure in the coker is maintained in the range from about 5 to about 150 psig, preferably from about 5 to about 45 psig. The lower portion of the coker serves as stripping zone to remove occluded hydrocarbons from the coke. A stream of coke is withdrawn from the stripping zone by line 50 and circulated to a heater 52. Coker vapor phase products are removed via line 43.

In heater 52, stripped coke from the coker is introduced by line 50 to a fluid bed of hot coke having an upper level indicated at 54. The bed is partially heated by passing a gaseous stream into the heater by line 72. This gaseous stream is the effluent of a gasification zone as will be described hereinafter. Supplemental heat is supplied by coke circulating in line 56. The gaseous effluent of the heater is removed by line 58. The heater gaseous effluent, containing entrained solid carbonaceous fines, is passed by line 58, if desired, through an indirect heat exchanger 76, and then into a cyclone 78 in which a portion of the entrained solid fines is separated and removed from the cyclone as dry fines by line 80. A gaseous hydrogen-containing stream, including the remaining entrained solids, is removed from cyclone 78 by line 82 and passed to a wet scrubber 84 such as, for example, a venturi scrubber, a packed bed, a wet cyclone or other conventional equipment, in which the solids-containing gas is scrubbed with a liquid introduced by line 86. Optionally, the liquid used may be the carbonaceous feed of the process. At least a portion of the solids present in the gaseous stream is separated from the gas to form with the scrubbing liquid a solid fines-liquid slurry which is removed from the scrubber by line 88. The carbonaceous solid fines are recovered from the liquid slurry by conventional means. The recovered fines have an average particle size of less than about 10 microns in diameter, preferably a particle size of less than 5 microns in diameter, and have surface areas of less than 50 square meters per gram. Instead of recovering the fines by a wet scrubbing method, the fines may be recovered by electrostatic precipitation. These recovered carbonaceous solid fines comprise the metal constituents of the oil as well as the metal constituent of the added oil soluble metal compound and are used as the catalyst for the hydroconversion stage of the present invention. Alternatively, the separated carbonaceous fines may be burned by heating them in the presence of a molecular oxygen-containing gas to remove most of the carbon present therein and to produce an ash having an average particle size of less than about 5 microns in diameter which also may be used as catalyst for the hydroconversion stage of the present invention. Furthermore, if desired, the carbonaceous fines or the ashes derived therefrom may be sulfided in a conventional way prior to passing them to the hydroconversion stage. Hot coke is removed from the fluidized bed in heater 52 and recycled to the coking zone by line 48 to supply heat thereto. Another portion of the coke is removed from heater 52 by line 57, and passed to a gasification zone 62 in gasifier 60 in which is maintained a bed of fluidized coke having a level indicated at 64. The gasification zone is maintained at a temperature ranging from about 1200.degree. to about 2000.degree. F. and at a pressure ranging from about 5 to about 150 psig, preferably at a pressure ranging from about 10 to about 60 psig.

A molecular oxygen-containing gas, such as air, commercial oxygen or air enriched with oxygen, is introduced into line 68 by line 66 and steam is introduced into line 68 by line 70. The stream of line 68 is passed into the gasifier. Contact of the coke with the steam and oxygen-containing gas under gasification conditions in the gasifier produces a hydrogen-containing gas and a carbonaceous solid residue. The hydrogen-containing gas, which comprises entrained solid fines, is removed from the gasifier by line 72 and passed into heater 52 from which the stream will be recovered by line 58. Alternatively, at least part of the gases may be passed into a separate solids recovery system (not shown). The solid fines contain metals derived from the oil or coal feed, that is, usually vanadium, iron and nickel, and, in addition, the metal constituent of the added oil soluble metal compound. The gaseous effluent removed by line 58 from the heater comprises hydrogen. A carbonaceous residue is removed as purge stream from the gasifier by line 74.

After the recycling of the solid fines to the hydroconversion zone, the addition of fresh oil soluble metal compound to the hydroconversion zone may be decreased or discontinued or the addition of fresh oil soluble metal compound may be intermittent with only a sufficient amount of fresh oil soluble metal compound added to maintain the desired level of activity.

Hydroconversion experiments were conducted utilizing a Cold Lake Crude feed. The conditions and results are summarized in the following Table.

Runs 30-R-73 and 30-R-54 are runs in accordance with the present invention. In run 30-R-73, a molybdenum catalyst derived from an oil soluble compound is used in combination with carbonaceous fines. In run 30-R-54, a molybdenum catalyst derived from an oil soluble compound is used in combination with burned solids. Runs 30-R-73 and 30-R-54 gave better results particularly in the suppression of coke formation than the results of run R-129 (molybdenum catalyst alone) or runs 21-R-03 (carbonaceous fines alone) and 21-R-12 (burned solids alone).