GB2121817A - Two-stage hydroprocessing of heavy oils - Google Patents

Abstract

The hydroprocessing of heavy hydrocarbonaceous oils containing liquid components boiling above 500 DEG C is effected by a process which comprises: (a) contacting in a first reaction zone 20 said oil feed 5 with hydrogen 15 & 50 under hydrogenation conditions including a hydrogen partial pressure above 35 atmospheres to produce a first liquid effluent 25 comprising liquid components boiling above 500 DEG C; (b) contacting in a second reaction zone 30 at least a portion of said first effluent 25, said first effluent portion containing liquid components boiling above 500 DEG C, with hydrogen under hydroprocessing conditions in the presence of a hydrogenation catalyst to produce a second effluent 35 comprising liquid components boiling above 500 DEG C; and (c) recycling at least a portion 90 of said second effluent to said first reaction zone, said recycled portion containing a substantial quantity of liquid components boiling above 500 DEG C. The heavy oil can contain added solids such as porous metal getter particles, dispersed hydrogenation catalysts, and/ or coal or coal-containing particles. <IMAGE>

Description

SPECIFICATION Two-stage hydroprocessing of heavy oils This invention relates to the hydroprocessing of heavy hydrocarbonaceous oils and more particularly to the hydroprocessing of oils containing significant quantities of components boiling above 500"C.

A number of heavy oil hydrogenation processes have been proposed which involve recycle of hydrogenated fractions. U.S. Patent 3,147,206 discloses a process wherein a heavy oil feed is reacted with a hydrogen-donor solvent in a first stage and a gas-oil fraction ofthe first stage product is hydrocracked in a second stage. A heavy portion of the first stage product is recycled to the first stage. U.S. Patent 3,238,118 discloses a process wherein a gas-oil fraction separated from a crude oil feed is hydrocracked and the hydrocrackate bottoms are used as a hydrogen-donorfor thermal conversion of a residual fraction. U.S. Patent4,028,221 discloses a coal liquefaction process wherein low-rank coal is heatsoaked at low pressure in a pasting solvent prior to liquefaction. A portion of residual product is recycled.

U.S. Patent 4,083,769 discloses a two-stage coal liquefaction process wherein solids-containing oil is withdrawn from a high temperature dissolver and recycled. British Patent 1,551,177 discloses a twostage coal liquefaction process wherein a product oil containing heavy components is recycled from a second catalytic stage.

U.S. Patent 3,839,187 discloses a heavy oil treatment process employing a recycled hydrogen-donor gas-oil fraction and particulate solids. U.S. Patent 4,090,947 discloses a hydrogen-donor diluent cracking processemployinga premium cokergas-oil as the hydrogen-donordiluent. U.S. Patent 4,11 1,787dis- closes conversion of coal/oil mixtures utilizing an oil-soluble catalyst.

U.S. Patents 3,183,180,3,412,010 and 4,116,819 disclose single stage processes employing bottoms recycle, and U.S. Patent3,635,814 discloses a onestage coal-liquefaction process employing recycle of a whole boiling product.

In the present invention, heavy oil is hydrotreated in a two-stage process, and residual components, i.e.

components boiling above 500,C, are recycled from the second stage productto the first stage. It is believed that certain of the 500,C+ components are hydrogenated in the second stage, and the presence of recycled residual components in the first stage enhances hydrogen transfer to the fresh feed components. In addition recycle of residual components provides further opportunityfortheir conversion to lower boiling components.

More specifically,this invention provides a process for hydroprocessing a heavy hydrocarbonaceous oil containing liquid components boiling above 500"C comprising: (a) contacting in a first reaction zone said hydro carbonaceous oil with hydrogen under hydrogenation conditions including a hydrogen partial pressure above 35 atmospheres to produce a first effluent comprising liquid components boiling above 500"C;; (b) contacting in a second reaction zone at least a portion of said first effluent, said portion containing liquid components boiling above 500"C, with hydrogen under hydroprocessing conditions in the presence of a hydrogenation catalystto produce a second effluent comprising liquid components boiling above 500 C, and (c) recycling at least a portion of said second effluent to the first reaction zone, said recycled portion containing a substantial quantity of liquid components boiling above 500"C. The phrase "liquid components boiling above 500"C", includes hydrocarbonaceous components which are in a dissolved or liquid state at the temperature and pressure of the system, and which do not boil below 500,C at atmospheric pressure, including non-distillable com ponentswhich decompose before reaching their boiling points in vacuum distillation. The heavy oil can contain added solids such as porous metal getter particles, dispersed hydrogenation catalysts, and/or coal or coal-containing particles.

Suitable heavy oil feedstocks for the process of this invention include crude petroleum, petroleum residua, such as atmospheric and vacuum residua, reduced crudes, deasphalted residua, heavy hydrocarbonaceous oils derived from coal, including bituminous, sub-bituminous, brown coals and lignite, as well as hydrocarbonaceous liquids derived from oil shale, tar sands, gilsonite, etc. Typically, the hydrocarbonaceous liquid feeds will contain at least 10 and preferably more than 20 weight percent liquid components boiling above 500"C.

The process of this invention is particularly effective for hydroprocessing heavy oil feed which contains soluble metals compounds, at least 5 ppmwtotal Ni+ and V, or even 50 ppmwor more Ni + V, which is typical of crude petroleum, petroleum residua and shale oil or shale oil fractions.

In the accompanying drawings, Figure lisa schematic flow diagram illustrating the process of this invention when solids are not added; Figure 2 is a schematicflowdiagram illustrating the process ofthis invention when porous metal getter particlesareadded; and Figure 3 is a schematic flow diagram illustrating the process of this invention when coal or coal-containing particles are added.

Figure 1 depicts the process when no solids or only small quantities of solids are added to the feed.

Referring to Figure 1, heavy oil feed is added in line 5 and mixed with hydrogen added through line 15 and a recycle oil (to be hereinafter described) and hydrogenated in first hydroprocessing zone 20. If desired, entrained catalyst and/or contract particles can be added through line 10.First stage hydroprocessing conditions suitable for use according to this invention include a hydrogen partial pressure above 35 atmopheres; a temperature in the range of 350 to 500"C, preferably 400 to 455 C; a pressure of about 40 to 680 atmospheres, preferably 100 to 340 atmospheres; and a hydrogen gas rate of 355 to 3550 liters/liter of oil feed, preferably 380 to 1780 liters/I iter ofoilfeed, and a residence time of more than 0.01 hours, preferably 0.1 to 10 hours, more preferably 0.1 to 1 hour. The first stage hydroprocessing zone is preferably operated in the absence of carbon monox ide; however, small amounts of carbon monoxide may be present e.g. in internally recycled gas to the hydroprocessing zone.If desired, the first stage hydroprocessing zone may be sufficiently elongated to attain plugflow conditions; however,turbulentflow conditions in the first stage may also be employed.

Preferably, the feed will flow upwardlythrough the first stage hydroprocessing zone. A suitable feed distribution system is described in our British Patent Application No.8118041 (Serial No.2078537).

If desired a finely-divided catalyst, to be hereinafter described can be added through line 10. Alternatively, the first stage hydroprocessing zone can be operated in the absence of externally-provided catalyst or contact particles.

All or a portion of the product of the first stage reactor 20 is passed through line 25 to catalytic reactor 30. The feed to catalytic reactor30 contains at least a portion of the first stage product which boils above 500 C,and preferablycontains all oratleastthemajor portion ofthe 200"C+ first stage product. If desired, light gases and low boiling hydrocarbon fractions, such as a C5-C8 naphtha cut, or a heavier cut, can be removed before passage of the remaining first stage productto catalyticstage30.

The catalytic reaction zone 30 is a second hydroprocessing zone and contains catalys in the form of a fluidized, packed orfixed bed. Preferably the catalyst is present in an ebullating bed. The entire liquid feed to the second stage preferably passes upwardly through a packed catalyst bed. Aflow distriutor, as described in the above-mentioned British patent application, may be used if desired. The packed bed can move periodically, if desired, to permit catalyst replacement.

The preferred catalyst for the second stage compris- es at least one hydrogenation componentselected from GroupsVIB and VIII, ofthe PeriodicTableofthe Elements, Handbook of Chemistryand Physics, 45th Ed. Chemical Rubber Co. (1964). The hydrogenation components can be present as metals, oxides or sulfides. The hydrogenation component is supported on a refractory inorganic base, for example, alumina, silica and composites of alumina-silica, alumina-bora, silica-alumina-magnesia, orsilica-alumina-titania.

Phosphorous promoters can also be present in the catalyst. The suitable catalyst can contain, for exam ple,1 to 10% Co,1 to20% Mo,and O.5to 5% Pona gamma alumina support. Such a catalyst can be prepared according to the teachings of U.S. Patent 4,113,661.

The second hydrogenation zone 30 is operated at a temperature lowerthan the first hydrogenation zone 20, generally at 315 to 455"C, preferably 340 to 425"C, more preferably 360 to 400"C; a pressure generally 40 to 340 atmospheres, preferably 70 to 210 atmospheres, and more preferably 140 to 190 atmospheres; a space velocity of generally 0.1 to 2, preferably 0.2 to 1.5, and more preferably 0.25 to 1 hr.-1 t a hydrogen feed rate of generally 170 to 3400 liters/liter of feed, and preferably 340 to 2700 liters/liter, and more preferably 550 to 1700 liters/liter.

The productfrom the second stage 30 exits through line 35 and passes to high pressure separator 40, where a gaseous fraction is removed through line 50 for recycle after removal of light hydrocarbon gases, sulfuroxides, carbon oxides, and water. A light liquid product can be recovered from the high pressure separatorthrough line 45 and a heavier liquid product fraction is removedthrough line 55.

At least a portion of the heavy liquid product exiting catalytic reactor30 is recycled through line 90 to the first hyrogenation zone 20. If desired, light liquids, e.g.

200"C- can be separated from the liquid of line 55 before recycle of the heavier fraction to zone 20. The recycled portion contains a substantial quantity of liquid components boiling above 500"C. By"substantial quantity" is meant more than the carry-over of heavy fractions to distillate cuts in a distillation or fractionation process. The recycled fraction should contain at least 5 percent byweightmaterials boiling above 500 Cand generallywill cont in morethan 10 weight percent or even more than 20 weight percent materials boiling above 500"C. The net liquid product passes through line 60 tofractionator 85 where it is fractioned into product cuts 86,87,88 and 89.If desired, all or a portion ofthe heavier cuts can be recycled through line 90.

The amount of recycle 500"C+ material will generally rangefrom about5to 1000 kilograms per 100 kilogram of heavy oil feed to the process, more preferably, lOto 100 kilograms per 100 kilograms of feed.

Figure 2 depicts an embodiment of this invention wherein contact particles are added to the heavy oil feed to the first stage. In Figures 2 and 3, the elements correspondtothe like numbered elements in Figure 1, and the process can operate in the same manner as in Figure 1. The solids can be a wide variety or materials, such as coal, oil shale fines, coal treated with a catalyst, such as described in U.S. Patent4,176,054,fly ash, separated coal ash, or bottom ash particles, coal liquefaction residues or other solid materials. The solid contact particles are preferably porous, i.e.

non-glassy, such as coal, alumina, silica gel, clays, etc.

and can be totally or substantially free of catalytic transition metals ortransition metal compounds added to impart catalytic activity to the solids. Waste catalystfines which only incidently contain catalytic metals as a result oftheir priorservice are suitablefor use, when economicallyjustified. The contact particles can contain added catalytic metal components.

The contact particles are preferably added through line 12 and are suspended in the heavy oil feed, however, the particles can be present in a bedwithin the first stage hydroprocessing zone, if desired. When the particles are suspended in the feed to thefirst stage, they should be added in sufficient quantity to provide 0.5 to 200 kilograms solids per 'IQO kilograms of oil in the first hydroprocessing zone 20. The contact particles are passed through the catalytic stage 30 and will exit with the liquid portion of the catalytic stage productthrough line 55. Solids can be separated before or afterthe recycle oil is separated from the net liquid product in line 55. If desired light liquids, e.g.

200"C-, can be separated from the liquid of line 55 before recycle ofthe heavierfraction to zone 20. As shown in Figure 2, a portion ofthe liquid product from line 55 is passed to solid separation zone 70, e.g., a conventional settler, filter, hydroclone, or centrifuge, wherein it is separated into a solids-rich fraction 75 and a solids-lean fraction 80. The remainder of the liquidfrom line 55 is recycled through line90tothe first stage hydroprocessing zone 20. If desired, all or a portion of the separated solids from solids-rich stream 75 can be recycled to line 90, as shown by dotted line 77.

Thecontactparticlesfunction in the process as coke deposition sites and as a getter for metals, such as nickel, and vanadium, present in contaminated feedstocks. As the contact particles are recycled, they can accumulate sufficient metals to be economically recoverable by conventional technology.

In addition to the porous contact particles, a finely-divided dispersed hydrogenation catalyst can be added to the first stage, e.g., through line 10. The dispersed catalyst can be added as a finely-divided transition metal compound such as a transition metal suffide, nitrate and acetate, etc. Suitable transition metal compounds include Ni(NO3)2-6H20, NiCO3, (NH4)6 Mo7024-4H20, (NH4)2MoO4, CO(NO3)2-6H20, CoCO3 and various oxides and sulfides of iron, cobalt and nickel. The finely-divided catalytic material may alternatively be added as an aqueous solution of one or more water solubletransition metal compounds such as molybdates, tungstates or vanadates of ammonium or alkali metals.Suitable emulsion catalysts and a methodfortheir introduction is described in U.S. Patent4,172,814 issued October30, 1979 to Moll etal for "Emulsion Catalystfor Hydrogenation Catalyst".

Alternatively the dispersed hydrogenation catalyst can be added as an oil soluble compound, e.g.

organometallic compounds, such as molybdenum naphthanates, cobalt naphthanates, molybdenum oleates, and others as are known in the art. If finely-divided iron compounds are employed, the feed can be contacted with H2S in sufficient quantity to convert the iron species to catalytic species. The finely-divided catalystwill pass through thefirst and second hydroprocessing zones and a portion will be recycled with the recycle oil stream in line 90.

The concentration of dispersed hydrogenation catalysts is preferably less than 20 weight percent of the feed calculated as catalytic metal and more preferably 0.001 to 5 weight percent of the feed to the firststage. When the finely divided catalyst is added as an emulsion, the emulsion should contain about 0.00005-0.005 kilogram of catalytic metal per kilogram offeed. The emulsion is preferably mixed by rapid agitation with the feed prior to entry into the first hydroprocessing zone wherein contact is made with any porous contact particles which may be used. In addition,the finely divided hydrogenation catalyst can be added with the recycled stream to the first hydroprocessing zone.The added hydrogenation catalyst is preferably added in an amoumtsufficientto suppress coke formation within the first stage hydroprocessing zone, and this amount can be readily determined for a particular system by routine experimentation.

When coal or coal-containing particles are added to the feed to first hydroprocessing zone 20, the carbonaceous matter in the coal will be at least partially converted to liquids and the coal minerals will be passed through the system. It is preferred that at least a portion of the minerals are removed before recycle of heavy liquid to prevent the build-up of minerals in the system. An example of a suitable system is depicted in Figure 3. Liquid productfrom high pressure separator 40 exits through line 55 to primary solid separation zone 100, which can bea settler, filter, centrifuge, hydroclone, etc., to provide a solids-rich stream 103 and a solids-lean stream 105. A portion ofthe solids-lean stream is recycled through line 90.As previously described, light liquids can be removed by fractionation or flashing prior to recycle of the remaining heavy components. Solids-lean stream 105 or a portion thereof is optionally treated in a secondary solid separation zone 110, and a solidsrich fraction is rejected through line 112. The solids- lean fraction 115 is fractionated in fractionation zone 85 into cuts 86,87,88 and 89. If desired, all or a portion of the heavy cuts can be recycled to zone 20 or elsewhere. The coal or coal-containing solids can be added to the feed in an amount of 1 to 50 kilograms per 100 kilograms of oil feed.

The following Examples illustrate the invention.

EXAMPLE 1 Again referring to Figure 1, a heavy hydrocarbonaceous oil feed, such as petroleum vacuum residuum, in line 5, is mixed with an emulsion prepared by the dispersing aqueous ammonium heptamolybdate solution and fuel oil, and added through line 10.

The amount of molybdenum in the emulsion is sufficientto provide 0.00005 to 0.005 kilogram, preferably about .0002-0.0007 kilogram of molybdenum as metal per kilogram of residuum feed. The feed containing dispersed catalyst is passed through to the first stage hydrogenation zone 20 wherein it is contacted with hydrogen at a temperature of 400 to 450"C, a pressure of 170 to 200 atmospheres, a hydrogen pressure of 150 to 190 atmospheres, a hydrogen rate of 1500 to 1800 liters/liter of feed, and a residence time of 0.5 to 2 hours. Hydrogenation zone 20 is an upflowvessel which can contain a packed bed of attapulgite clay. The entire effluentfrom hydrogenation zone 20 is passed to second hydrogenation zone 30 through a conduit 25.The second hydrogenation zone 30 is an upflowvessel containing a fixed bed of hydrogenation catalyst comprising cobalt, molybdenum, and phosphorous on a gamma alumina support. The second hydrogenation zone 30 is preferably operated at a temperature below the first stage, and in the range of 360-400"C, a pressure of 170 to 200 atmospheres, a residence time of 1 to 5 hours and a hydrogen pressure of 150to 190 atmospheres.

The effluent from the second hydrogenation zone 30 is passed through conduit 35 to high-pressure separator 40, where a recycle gas rich in hydrogen gas is removed, treated to remove acid gases, and recycled through line 50. A hydrocarbon gas stream is removed through line 45 and the normally liquid product is recovered through line 55. A portion ofthe liquid product is passed through line 60 to fractionator85. Another portion of the liquid product is recycled through line 90.The recycled portion can be a whole boiling range liquid (C5+), or a higher boiling fraction, e.g. 200'C+ or 350 C+. The recycle portion typically contains at least about 10 and up to about 50 weight percent components boiling about 500"C. When a whole boiling range portion ofthe C5+ product of zone 30 is recycled, 5 to 100 kilograms is recycled per kilogram of feed oil.

EXAMPLE 2 Referring to Figure 3, heavy oil, such as a petroleum residuum, is mixed with particulate bituminous coal (30meshTylersieve) added through line 12 in a slurryingzone, not shown. The ratio of coal to residuum can vary from 0.01 kilogram of coal per 100 kilograms of residuum to 50 or more kilograms of coal per 100 kilograms of residuum feed. The mixture passes to the first hydroprocessing zone 20, which preferably contains no externally-supplied catalyst or contact particles. In zone 20, the mixture is contacted with hydrogen at a temperature of 400 to 450"C, a pressure of 170 to 200 atmospheres, a hydrogen pressure of 150 to 190 atmospheres, a hydrogen rate of 1500 to 1800 liters/literoffeed, and a residence time of 0.5 to 2 hours.The entire effluentfrom zone 20 is passed to the second hydrogenation zone 30 which is an upflowvessel containing a fixed bed of hydrogenation catalyst comprising cobalt, vanadium, and phosphorous on a gamma-aluminum support. The second hydrogenation zone 30 is preferably operated at a temperature of 360 to 400"C, a pressure of 170 to 200 atmospheres, a residence time 1 to 5 hours, and a hydrogen pressureof 150to 190 atmospheres. The effluentfrom the second hydrogenation zone 30 is passed through conduit 35 to high pressure separator 40 wherein recycled gas rich in hydrogen is removed and recycled through line 50. A gaseous hydrocarbon stream is recovered via line 45.The normally liquid product plus ash and undissolved coal are passed through line 55to separator 100. A solids-rich fraction is rejected through line 103. A portion ofthe solids-lean stream 105 is recycled through line 90. If only a whole boiling Cg+ stream is recycled through line 90, the ratio of recycled oil to heavy oil feed is preferably 5to 100 kilograms recycle oil per 100 kilograms of residuum feed.

Regardless of whether contact particles or suspended catalysts are employed,the conditions within the hydroprocessing zones, and the compositions of the recycle can vary approximately within the limits herein described. It will be recognized by those familiarwith the art of petroleum processing thatthe process ofthis invention can be carried out in a variety of embodiments other than those specifically described herein, without departing from the scope ofthis invention.

Claims (17)

1. A process for hydroprocessing a heavy hydrocarbonaceous oil feed containing liquid components boiling above 5000C,which process comprises: (a) contacting in a first reaction zone said oil feed with hydrogen under hydrogenation conditions including a hydrogen partial pressure above 35 atmos pheresto produce a first liquid effluent comprising liquid components boiling above 500"C; (b) contacting in a second reaction zone at least a portion of said first effluent, said first effluent portion containing liquid components boiling above 500"C, with hydrogen under hydroprocessing conditions in the presence of a hydrogenation catalystto produce a second effluent comprising liquid components boil ing above 500"C;; and (c) recycling at least a portion of said second effluentto saidfirst reaction zone, said recycled portion containing a substantial quantity of liquid components boiling above 500"C.

2. A process according to Claim 1, wherein said hydrogenation conditions in said first reaction zone include a temperature in the rangefrom 350 to 500"C, a pressure in the rangefrom 40 to 680 atmospheres, a residence time in the range from 0.1 to 10 hours and a hydrogen gas rate offrom 355 to 3550 liters/liter of feed; and said hydroprocessing conditions in said second reaction zone include a temperature lower thanthetemperature in thefirst reaction zone and in the range from 315 to 455"C, a pressure in the range from 40to 340 atmospheres, a space velocity in the range from 0.1 to 2 hours-', and a hydrogen feed rate of from 170 to 3400 liters/liter of feed.

3. A process according to Claim 1 or 2, wherein said hydrocarbonaceous oil feed contains at least 10 weight percent liquid components boiling above 500"C.

4. A process according to Claim 1,2 or 3, wherein said second stage hydrogenation catalyst is present in an ebullating bed.

5. A process according to Claim 1,2 or3,wherein said second stage hydrogenation catalyst is present in a packed bed.

6. A process according to any preceding claim, wherein said second stage catalyst comprises a hydrogenation component selected from Groups VIB and VIII of the Periodic Table on a refractory inorganic oxide support.

7. A process according to Claim 6, wherein the catalyst comprises cobalt, molybdenum and phos phorus on a gamma alumina support.

8. A process according to any preceding claim, wherein said recycled portion contains at least 5 weight percent of the liquid components boiling above 500"C.

9. A process according to Claim 8, wherein said recycled portion contains at least 10 weight percent of components boiling above 500"C.

10. A process according to any preceding claim, wherein said first hydrogenation zone contains exter nally-supplied porous contact particles.

11. A process according to Claim 10, wherein the first effluent portion contains at least a portion of said contact particles.

12. A process according to Claim 11, wherein the recycled portion of said second effluent contains at least a portion of said contact particles.

13. A process according to any preceding claim, wherein the hydrogenation in the first reaction zone is carried out in the presence of a finely-divided dispersed hydrogenation catalyst.

14. A process according to Claim 13, wherein the hydrogenation catalyst is passed from the first reaction zone to the second reaction zone.

15. A process according to any preceding claim, wherein thefeed comprisesa slurrycontaining said heavy hydrocarbonaceous oil and coal and wherein said first effluent comprises undissolved solids and liquid components boiling above 500"C and said second effluent comprises undissolved solids and liquid components boiling above 500"C.

16. A process according to Claim 15, wherein the recycled portion of said second effluent contains at least a portion of said undissolved solids.

17. Atwo-stage hydroprocessing processfor heavy hydrocarbonaceous oil feeds substantially as hereinbefore described with reference to Figure 1, or Figure 2, or Figure 3 of the accompanying drawings.