US3617481A

US3617481A - Combination deasphalting-coking-hydrotreating process

Info

Publication number: US3617481A
Application number: US884181A
Authority: US
Inventors: Alexis Voorhies Jr; Glen P Hamner
Original assignee: Exxon Research and Engineering Co
Current assignee: ExxonMobil Technology and Engineering Co
Priority date: 1969-12-11
Filing date: 1969-12-11
Publication date: 1971-11-02
Anticipated expiration: 1988-11-02

Abstract

A heavy hydrocarbon residuum is hydrotreated or deasphalted to form a heavy bottoms fraction in which the metals are concentrated. The high-metals fraction is coked to form coke containing the metals and the coke is activated by gasification to form water gas. The activated coke containing the metals, with or without fortification by additional catalytic elements is used as catalyst in a hydrotreating step which may be the hydrotreating step used to concentrate the metals or may be a separate step in which the raffinate with or without the coker gas oil is used as feed. The deasphalting step may be preceded by a vacuum distillation step in which additional gas oil may be formed which can be used as at least part of the feed to the hydrotreating step.

Description

United States Patent Alexis Voorhies, Jr.;

Glen P. Hamner, both of Baton Rouge, La. [21] App]. No. 884,181

[22] Filed Dec. 11, 1969 [45] Patented Nov. 2, 1971 [73] Assignee Esso Research and Engineering Company [72] Inventors [54] COMBINATION DEASPHALTING-COKING- HYDROTREATING PROCESS 16 Claims, 2 Drawing Figs.

[52] U.S. Cl 208/50,

2,388,055 10/1945 Hemminger 208/55 Primary Examiner-Herbert Levine Attorneys-Pearlman and Stahl and C. D. Stores ABSTRACT: A heavy hydrocarbon residuum is hydrotreated or deasphalted to form a heavy bottoms fraction in which the metals are concentrated. The high-metals fraction is coked to form coke containing the metals and the coke is activated by gasification to form water gas. The activated coke containing the metals, with or without fortification by additional catalytic elements is used as catalyst in a hydrotreating step which may be the hydrotreating step used to concentrate the metals or may be a separate step in which the raffinate with or without the coker gas oil is used as feed. The deasphalting step may be preceded by a vacuum distillation step in which additional gas oil may be formed which can be used as at least part of the feed to the hydrotreating step.

SEPARATOR HYDROTREATER SHIFT REACTION CATALYST KPREPARATION PATENTEUuuv 2 Ian ,517, 4 1

sum 2 [IF 2 GLEN P HA NER VACUUM TOWER STEAM FEED COMBINATION DEASPIIALTING-COKING- HYDROTREATING PROCESS BACKGROUND OF THE INVENTION It is known to produce marketable coke from various petroleum fractions by processes such as fluid coking and delayed coking. In such processes the amount and value of the coke obtained depends on the character of the materials being processed and to some extent upon the coking conditions. In the case of high Conradson carbon stocks such as heavy vacuum crude residua, the coke yield may be 20 weight percent or higher on the residuum. One of the major uses of coke has been in the manufacture of electrodes. For this purpose petroleum coke is preferable to metallurgical coke made from coal because of the high ash content of the latter. For this reason it has not been profitable to use petroleum residua having high metals content as the source of the petroleum coke, since the resulting coke will have a high content of ash consisting principally of metals.

SUMMARY OF THE INVENTION It has now been found that the coke prepared from residua having high metals content can be profitably utilized by activating the coke and employing the activated coke with the metals deposited thereon, and with or without the further addition of catalytic materials such as sulfur resistant hydrogenating components, as the catalyst in a subsequent hydroprocessing step.

In one embodiment of the invention an atmospheric residuum is vacuum distilled to separate a gas oil fraction and a bottoms fraction. The bottoms fraction is deasphalted to concentrate the metals in the extract.

The extract is then coked by fluid or delayed coking and the coke is steam or catalytically gasified to produce synthesis gas, C and activated coke. The activated coke containing the metals, with or without the addition of externally supplied catalytic components is then used as the catalyst in the hydroprocessing of the deasphalted oil with or without the addition of gas oil obtained from the coking step and the gas oil from the vacuum distillation step. If desired the gas oil from the vacuum distillation step may be separately hydrodesulfurized and the resulting desulfurized gas oil may then be mixed with the deasphalted oil with or without the coker gas oil as feed to the hydroprocessing step as described in copending application Ser. No. 813,223 filed Apr. 3, 1969 for Moritz and Welch.

In another embodiment a residuum having a high metals content is first subjected to catalytic hydrotreating. The bottoms product from the fractionation of the hydrotreated product contains most of the metals and is subjected to fluid or delayed coking. The resulting coke is activated by partial gasification with steam and the activated coke containing the metals with or without fortification with additional sulfur resistant hydrogenation catalysts is used as the catalyst in the P16. 1 represents, in diagrammatic form, one embodiment of the invention in which the residuum is hydrotreated in the presence of activated coke containing metals from the feed and in which the hydrotreater bottoms are coked and the coke activated to form the hydrotreating catalyst.

FIG. 2 represents another embodiment in which the residuum is distilled to separate a gas oil fraction and a bottoms fraction which is deasphalted, the asphalt coked and the coke activated and used as the catalyst in a hydrotreating step in which the deasphalted oil with or without the vacuum gas oil and coker gas oil are used as feed.

DETAILED DESCRIPTION OF THE DRAWINGS Referring now to FIG. 1, a residuum having a high Conradson carbon and a high metals content is introduced into the bottom of hydrotreating zone 1 by line 2 together with sufficient hydrogen introduced by line 3. Hydrotreating zone 1 contains a mass of fine particles of coke, (e.g., 12-16 mesh), supporting a suitable hydrogenation catalyst such as a Group VB or VIB metal compound, specifically a molybdenum compound, a tungsten compound or vanadium compound, such as the oxide or sulfide and mixtures of these, alone, or together with a Group VIII compound, specifically a nickel or cobalt compound, such as the oxide or sulfide.

The feed is preferably a low value, high-boiling residuum of about 10 to +20 API gravity, about 5 to 50 wt. percent or higher Conradson carbon, containing from 50 to 1000 ppm. of metals, such as nickel, vanadium, and the like and boiling above 900 to 1,200 F. However any stock having a Conradson carbon above 5 may be used. The oil entering the bottom of reactor 1 through line 2 flows upwardly through the catalyst bed at a rate of, say, 25 gallons per minute per square foot of horizontal cross section of reactor 1. At this flow rate the catalyst particles are randomly buoyed and moved by the flowing oil. The ebullated catalyst particles give intimate contact to the reactants, provide temperature uniformity throughout the reactor 1, offer extremely little resistance to the flow of the reactants through the reactor 1 and remain active over an extended operating period.

Reactor 1 is maintained at a temperature not to exceed 1000 F., preferably between 725 and 950 F. while the pressure will not exceed 5,000 p.s.i.g. and preferably will be in the range of 800 to 3,000 p.s.i.g. If it is desired to suppress cracking and emphasize only desulfurization then milder conditions should be employed, namely pressures between 600 and 1,500 p.s.i.g. and temperatures between 550 and 800 F., preferably between 600 and 750 F. The hydrogen recycle rate is maintained at about 500 to 10,000, preferably 1,000 5,000 s.c.f./bbl. offeed.

Treated oil is withdrawn through line 4 and after conventional cooling is passed to separator 22 from which recycle hydrogen is removed through line 5. The oil is then passed by line 6 to fractionator 7 from which a gas oil is removed by line 8 for subsequent processing, such as feed for hydrocracking or catalytic cracking. Bottoms from fractionator 7 boiling above about 1,050 F. are removed by line 9 and passed to fluid coker 10 where they are introduced to fluid bed 11 maintained at a temperature of 850 1,200 F., preferably 900l, 050 F. and under a pressure ranging from 5 to p.s.i.g. The fluid bed consists of particulate coke particles and are maintained as a fluid bed by the hydrocarbon vapors produced by coking supplemented by the upward passage of fluidizing gas such as steam which enters the lower portion of coking zone 10 through line 12. The contact of the heavy feed and the coke results in the feed being converted to lower boiling vaporous hydrocarbons and more coke which is deposited on the surface of the fluidized coke in the bed along with the metals in the feed. The vaporous hydrocarbons and steam are removed overhead through line 13 while the fluid coke particles descend in bed 11 and are withdrawn from the bottom of coking zone 10 through line 14 and are introduced into the bottom of gasifier 15 where they are introduced into fluidized bed 16. Heat may be supplied to gasifier 15 by means ofa conventional coke burner (not shown) or by any other external heat source. The reactions in the gasifier may be effected at a temperature of 1,lO0-l,800 F. substantially atmospheric pressure or up to pressures of 150 p.s.i.g., if desired, although it is preferable to operate at substantially atmospheric pressure in order to prevent the saturating effect of hydrogen on any volatile conversion products in the gasifier. Steam for fluidizing bed 16 and for gasifying the coke is introduced through line 17.

It is highly important that no nitrogen be present in the gasifier. Hence care must be maintained to remove it prior to the introduction of the coke-metal contaminated catalyst to the gasifier. The presence of nitrogen will contaminate the synthesis gas product, requiring an extra costly step for its removal. 5 in the range of 3 to feet per second and depends upon oil The gas composition leaves vessel through line 18 and feed rate, p f f Pressure has h f ll i typical composition on adry basis; A stream comprising light ends and steam 1S recovered by line 105. Steam can be recovered and recycled by means not H 565 shown. A residuum fraction having an initial boiling point of c2) l6 l0 1,050 F. is recovered by line 107. A vacuum gas oil boiling 2 650-1,050 F. is removed by line 108. a :1 a"? 'Tiiis'idiuih'ifiiiifi' in line 107 is passed through cooler i 109 to deasphalting zone 110. The deasphalting step may be a The carbon monoxide may be converted to more H and CO Patch l uiing one or more vessFls or a b means of the well-known shift reaction with steam. The 15 unuous lulmd'hqmd countelicurrqm Opel-anon usmg anleatmg y tower having baffles or rotating CllSC contactors. The residuum can be and the i hydrogen mtmduced is introduced into the top of the particular vessel used and to hydfogen [me 5 for m the contacted with a suitable deasphaltin g solvent. This solvent resldenfze i of coke m vessel 15 1s sufficient to may be any of the conventional solvents but is preferably such obtain the desired increase 111 surf ace area of the coke, i.e., to solvents as aliphatic hydrocarbons having between two and 9" the coke After actwanon' the coke pamcles are eight carbon atoms per molecule or a mixture thereof. Certain withdrawn through line 19 and recycled to the hydrotreater. 1f additives Such as heavy coker gas n ammafic wash n m desired a portion or all of the coke may be removed by line 20 ganic acids and halogens may be addad to the when to and passed to catalyst preparation zone 21 where any desired prove the deasphalting operation by increasing the yieId and hydrogenation component may be added to the catalyst It is 25 quality of the deasphalted fraction which is free of metallic however within the spirit of this invention to limit the catalytic Contaminants and h hi matefial5 A commercial metal content of the coke catalyst to the metal compounds, deasphalting Solvent comprises propane or a mixture f 65 such as those of vanadium and nickel, which are deposited percent propane d percent b g thereon l the residuum feed- T h?asphalt phase from dea s phalter l fil is removed by 'mf If desired Products from fraefienator 7 flowing through 3 111 and passed to coker 112 which is identical in all respects line 8 and from the coker 10 flowing hrollgh line 13 y be with coker 10 of FIG. 1. Coke containing deposited metals is separately or simultaneously hydrodesulfurized in a separate removed from the bottom of coker 112 by line 113 and passed zone (not shown) and the desulfurized product partially recyto gasifier 114 where the coke is activated by steam incled as a diluent for the residuum fed to hydrotreater l by line troduced through line 115 in the same manner as described in 2 as described in application Ser. No. 813,223 filed Apr. 3, 35 connection with gasifier 15 of FIG. 1. The activated coke from 1969, for Moritz and Welch, incorporated herein by coker 114 passes by line 116 to hydrotreater 117 as catalyst reference. therein which operates with a slurry or ebullating bed as The following represents a typical reaction scheme. described in connection with hydrotreater 1 of P10. 1. A por- Process Step 11" (reactor 1) B" (coker 10) "C" (gasificr 15) "D hydrodesuliuri- Feed hydrotreating coking gaslficntlon zation Fee 650 F. plus resid- 1050 F. plus Coke from "B". Gas Oil f om A" and no. from vac. dist. I Catalyst CoMo-NiV-coke... zvonenw. Alkali salts for CoMo-alummalslhca.

1,400 F. operation, no catalyst required Process conditions:

Temperature,F vreresstu'e, p.s.i Gas rate, s.c.1./b Steam, wt. percent on feed 10-2 Product inspections:

Gas 011 and lighter, wt. percent Inspections on gas oil:

SulIur, wt. percent 2. 2 Ni, p.p.m 5 p.p.m. 13s 1""a 2 p us, w percent 50 1,060 )3. plus, inspections:

SuIIur, wt. percent 3. 1 N1, p.p.m 100 V, p.p.m 700 Con. carbon, wt. percent. 24 18-22...

Coke, wt. percent Coke Inspections:

S wt. percent N1, p.p.m

Pore vol of the tower to enhance separation of distillable oil from the bottoms. This steam may amount to l to 20 pounds per barrel of oil feed. The velocity of the flow of vapors through the trays or other entrainment barriers above the flash zone is normally above 1,500 F.

Referring now to P16. 2, an atmospheric residuum boiling above 650 F. is fed by line 101 into vacuum distillation tower 103. Steam is fed by line 104 into vacuum tower 103. The feed is preheated to 725 to 875 F. prior to its introductiop to tower 103 which is operated to maximize the recovery of a fraction amenable to continuous hydrotreating. Typical vacuum distillation conditions include a temperature in the range of 550 to 850 F. and a pressure in the range of 20 to tion or all of the activated coke flowing in line 116 may be withdrawn through line 118 and passed to catalyst preparation unit 119 where it is impregnated with desired hydrogenation catalysts as described in connection with unit 21 of FIG. 1. It is then returned to line 116 and introduced to hydrotreater 117.

The raffinate from deasphalting zone is withdrawn through line 120 and mixed with the coker gas oil withdrawn from coker 112 by line 121 and also with virgin gas oil from 100 mm. Hg. Steam is added with the feed and to the bottom 75 line 108. The mixture is then fed to the bottom of hydrotreater 117 by line 122 as described in connection with hydrotreater l of FIG. 1, hydrogen being introduced through line 123.

Treated product is removed from hydrotreater by line 124 and after cooling is passed to separator 125 from which hydrogen is removed and recycled by line 126.

The following represents a typical reaction scheme.

following conditions, showing sulfur removal data on the stabilized liquid product.

B (zone 110) A (tower 103) de asifihalting (3/1 Process step vac. distilllitlon to o coking gasification hydrodesulfurizatlon (1) \Argin gas oil from Feed 650 F. plus 1,050 F.+ Deasphalting Coke from C (2) Deasphalting residue. extract. raffinate from B.

(3) C(pker gas oil from Catalyst None None None Alkali salts for CoMo-NiV-Coke.

1400 F. or no catalyst above 1,500 F. Process conditions:

Temperature, F 500-850 80-200 00-1.,100 1,100-1,800 500-850. Pressure, psi. -100 mm. Hg 150-1,000 0-150 0-200 400-2, 500.

vac. W/W/hr 0.2-5 0.5-5 0.5-5 0. 2-10.

Gas rate, s.c.f./bbl None. Steam, wt. percent on feed 1-5 do 5-10 Product yields and inspections:

1,050 F. and lighter, wt. percent 50 Raffinate, 50-80. -55 100-102. 1,050 F. and lighter inspections:

Sulfur, wt. percent 2.2 1.5-1.8 1.0-1.3 0.5-1.0. Ni, p.p.nL 1.

1,050 F. plus, Wt. percent- Sulfur, wt. percent.

Pore vol- The deasphalting operation shown in FIG. 2 may be employed in FIG. 1 as replacement for the vacuum tower operation downstream from the hydrotreater. If required, the raffinate from deasphalting may be partially recycled to the hydrotreater in FIG. 1. The extract from deasphalting is fed to coking in place of the 1,050 F.+ vacuum bottoms. EXAMPLE I To demonstrate the utility of the high surface area coke catalyst, a high metals coke from coking Tia Juana medium residuum was gasified with percent steam in the presence of Kgcoa promoter at 1,400 F. to obtain a surface area of approximately 400 square meters/gram and pore volume of approximately 0.25. The activated metal coke was impregnated with a solution of CoCl NiCl ammonium molybdate and vanadate to give a catalyst having the following composition of metal components and physical properties.

1.8 v, wta. 2.4 Co, Wt.% 2.4 Mo, Wt.% 5.2 K, Wt.% 018 C, Wt.% 88.0

Surface Area 265 Pure Volume 0.2l

Reduced metal basis prior to sulfiding.

l V/V/Hr. 800 p.s.i.g. 4,000 SCF H,/bbl. Without Steam With Steam (l0 Wtflr on Feed) Stabilized Feed Liquid Product Gravity, API 19.0 2 l .4 22.1 Sulfur. Wt.% 3.! 2.27 L

Ni, Wtfl 0.24 V, Wt.% 0.37 Co, Wt.% L9 Mo, Wt.% 2.4 Fe, Wt.% 0.37 K, Wt.% 0.36 C. Wt.% 94.0

Surface Area 380 Pore Volume 0.26

"E (hydrotreater 117) The gas oil feed used in example 11 was processed over this catalyst at the following conditions. Sulfur removal data on the stabilized liquid product are shown.

800 F. I VIVIHr. 1,000 p.s.i.g. 7 4,000 SCF HJbbl.

lnlpectiom Feed Stabilized Liquid Product Gravity, API l9.0 25.0

Sulfur, Wtfl; 3.l L42 I 1,. A seli sustaining integrated process for the hydrotreating of residual hydrocarbon fractions having a metals content of at least 50 ppm. which comprises selecting a feed suitable for coking from the group consisting of the bottoms from the hydrofining of said high-metals residuum and the extract from the deasphalting of said residuum, coking said feed to form coke containing said metals and cracked hydrocarbons, subjecting said coke to treatment with steam and/or oxygen-containing gas to increase the surface area of said coke and produce water gas, using said activated coke as a catalyst and hydrogen from said water gas in the hydroprocessing of a feed chosen from the group consisting of said high-metals residuum and the raffinate from the deasphalting of said residuum.

2. A self-sustaining integrated process for the hydroprocessing of residual hydrocarbon fractions having a metals content of at least 50 ppm. which comprises hydrotreating said high-metals residuum in the presence of coke having a surface area of at least 50 square meters per gram and containing at least 0.5 percent by weight of metals derived from said residua, coking the effluent from said hydroprocessing step to form coke containing said metals and cracked hydrocarbons, subjecting said coke to treatment with steam and/or oxygen-containing gas to increase the surface area of said coke and produce water gas, recycling said activated coke and hydrogen from said water gas to said hydroprocessing step as the catalyst and hydrogen source respectively.

3. A self-sustaining the integrated process for hydroprocessing of residual hydrocarbon fractions having a metals content of at least $0 p.p.m. which comprises deasphalting a heavy residuum to form a rafiinate and an extract containing the metal from said residuum, coking the extract from the deasphalting step to form coke containing said metals and cracked hydrocarbons, including a gas oil fraction, subjecting said coke to treatment with steam and/or oxygencontaining gas to increase the surface of said coke and produce water gas, and hydrotreating either or both the raffinate from the deasphalting step and the gas oil from the coking step in presence of the metals-containing coke from the coking step as a catalyst.

4. The process of claim 3 in which a residuum boiling 650 F.+ is subjected to vacuum distillation prior to the deasphalting step to separate at least a gas oil fraction and a bottom fraction boiling l,050 F using the bottoms fraction as feed to the deasphalting step and hydrotreating a mixture of the gas oil fraction from the vacuum distillation, the gas oil from the coking step and the rafi'lnate from the deasphalting step with the said metals-containing coke.

5. The process of claim 1 wherein said activated coke employed in said hydroprocessing additionally contains a Group VB or VIB metal compound alone or in combination with a Group VIII metal compound.

6. The process of claim 5 wherein said Group VB or VIB metal compound is an oxide or sulfide of molybdenum, tungsten or vanadium.

7. The process of claim 6 wherein said Group VIII metal compound is an oxide or sulfide of nickel or cobalt.

8. The process of claim I wherein the treatment of said coke with steam and/or oxygen-containing gas is continued in the further presence of an alkali metal salt.

9. The process of claim 8 wherein said alkali metal salt is potassium carbonate.

10. The process of claim 1 wherein said hydroprocessing is conducted in the presence of steam.

11. The process of claim 2 wherein said activated coke employed in said hydrotreating additionally contains a Group VB or VIB metal compound alone or in combination with a Group VIII metal compound.

12. The process of claim ll wherein said Group VB or VIB metal compound is an oxide or sulfide of molybdenum, tungsten or vanadium.

13. The process of claim 12 wherein said Group VIII metal compound is an oxide or sulfide of nickel or cobalt.

14. The process of claim 2 wherein the treatment of said coke with steam and/or oxygen-containing gas is continued in the further presence of an alkali metal salt.

l5-The process of claim 14 wherein said alkali metal salt is potassium carbonate.

16. The process of claim 2 wherein said hydrotreatin g is conducted in the presence of steam.

* i I i

Claims

2. A self-sustaining intEgrated process for the hydroprocessing of residual hydrocarbon fractions having a metals content of at least 50 p.p.m. which comprises hydrotreating said high-metals residuum in the presence of coke having a surface area of at least 50 square meters per gram and containing at least 0.5 percent by weight of metals derived from said residua, coking the effluent from said hydroprocessing step to form coke containing said metals and cracked hydrocarbons, subjecting said coke to treatment with steam and/or oxygen-containing gas to increase the surface area of said coke and produce water gas, recycling said activated coke and hydrogen from said water gas to said hydroprocessing step as the catalyst and hydrogen source respectively.
3. A self-sustaining integrated process for the hydroprocessing of residual hydrocarbon fractions having a metals content of at least 50 p.p.m. which comprises deasphalting a heavy residuum to form a raffinate and an extract containing the metal from said residuum, coking the extract from the deasphalting step to form coke containing said metals and cracked hydrocarbons, including a gas oil fraction, subjecting said coke to treatment with steam and/or oxygen-containing gas to increase the surface of said coke and produce water gas, and hydrotreating either or both the raffinate from the deasphalting step and the gas oil from the coking step in presence of the metals-containing coke from the coking step as a catalyst.
4. The process of claim 3 in which a residuum boiling 650* F.+ is subjected to vacuum distillation prior to the deasphalting step to separate at least a gas oil fraction and a bottom fraction boiling 1,050* F.+, using the bottoms fraction as feed to the deasphalting step and hydrotreating a mixture of the gas oil fraction from the vacuum distillation, the gas oil from the coking step and the raffinate from the deasphalting step with the said metals-containing coke.
5. The process of claim 1 wherein said activated coke employed in said hydroprocessing additionally contains a Group VB or VIB metal compound alone or in combination with a Group VIII metal compound.
6. The process of claim 5 wherein said Group VB or VIB metal compound is an oxide or sulfide of molybdenum, tungsten or vanadium.
7. The process of claim 6 wherein said Group VIII metal compound is an oxide or sulfide of nickel or cobalt.
8. The process of claim 1 wherein the treatment of said coke with steam and/or oxygen-containing gas is continued in the further presence of an alkali metal salt.
9. The process of claim 8 wherein said alkali metal salt is potassium carbonate.
10. The process of claim 1 wherein said hydroprocessing is conducted in the presence of steam.
11. The process of claim 2 wherein said activated coke employed in said hydrotreating additionally contains a Group VB or VIB metal compound alone or in combination with a Group VIII metal compound.
12. The process of claim 11 wherein said Group VB or VIB metal compound is an oxide or sulfide of molybdenum, tungsten or vanadium.
13. The process of claim 12 wherein said Group VIII metal compound is an oxide or sulfide of nickel or cobalt.
14. The process of claim 2 wherein the treatment of said coke with steam and/or oxygen-containing gas is continued in the further presence of an alkali metal salt.
15. The process of claim 14 wherein said alkali metal salt is potassium carbonate.
16. The process of claim 2 wherein said hydrotreating is conducted in the presence of steam.