US3725251A

US3725251A - Two-stage hydrodesulfurization of a high metal content hydrocarbon feed

Info

Publication number: US3725251A
Application number: US00196338A
Authority: US
Inventors: M Chervenak; G Nongbri; S Alpert; R Wolk
Original assignee: Hydrocarbon Research Inc
Current assignee: HRI Inc
Priority date: 1971-11-08
Filing date: 1971-11-08
Publication date: 1973-04-03
Anticipated expiration: 1990-04-03
Also published as: CA978128A

Abstract

A multi-stage process for the hydrodesulfurization of high metals content hydrocarbon feed materials wherein the first reaction zone is an ebullated bed contacting system using a powdered contact agent having particles in the size range from 40 to 325 U. S. mesh whereby superior metals removal is effected. The reduced metals content effluent is passed to subsequent stages wherein deep desulfurization is obtained due to low metals contamination of the catalyst. Build up of carryover contaminated catalyst from the first reaction zone is prevented by either an intermediate catalyst separation step between zones or use in the subsequent zones of ebullated bed systems incorporating catalyst of sufficiently large particle size whereby the powdered first zone catalyst is carried through and out of the subsequent zones.

Description

United States Patent 1 1 1 1 3,725,251

Alpert et al. 1451 Apr. 3, 1973 54] TWO-STAGE 3,418,234 12/1968 Chervenak et al. ..208/210 HYDRODESULFURIZATION ()F A 3,530,066 9 1970 Kuwata et al ..208/210 HIGH METAL CONTENT 3,622,500 11/1971 Alpert 6t Inventors? Seymour B- Alpert, L05 Altos, Primary Examiner-Delbert E. Gantz Calif.; Ronald B. Wolk, Lawrence Township; Michael C. Chervenak, Pennington, both of N.J.; Govanon Nongbri, Newtown, Pa.

[73] Assignee: Hydrocarbon Research, Inc., New

York, NY.

[22] Filed: Nov. 8, 1971 [21] Appl. No.: 196,338

Related US. Application Data [63] Continuation-impart of Ser. No. 13,739, Feb. 24,

1970, abandoned.

[52] US. Cl ..208/210 [51] Int. Cl. ..Cl0g 23/02 [58] Field of Search ..208/210, 89, 213, 216

[56] References Cited UNITED STATES PATENTS 3,297,563 1/1967 Doumani ..208/210 Assistant Examiner-G. J. Crasanakis Attorney-Nathaniel Ely et al.

57 ABSTRACT A multi-stage process for the hydrodesulfurization of high metals content hydrocarbon feed materials wherein the first reaction zone is an ebullated bed contacting system using a powdered contact agent having particles in the size range from 40 to 325 U. S. mesh whereby superior metals removal is effected. The reduced metals content effluent is passed to subsequent stages wherein deep desulfurization is obtained due to low metals contamination of the catalyst. Build up of carryover contaminated catalyst from the first reaction zone is prevented by either an intermediate catalyst separation step between zones or use in the subsequent zones of ebullated bed systems incorporating catalyst of sufficiently large particle size whereby the powdered first zone catalyst is carried through and out of the subsequent zones.

10 Claims, 3 Drawing Figures PATEPITEUAPRS I973 SHEET 1 UP 2 T W TL m MA MC 0 m R m U 0 R WT OX PE 0o 0 n n E 4 2 l 0 O O 0 FRACTION OF SULFUR REMOVED Tl S mm Y T MA NC n 0 A ND 1 o m WT OX PE 0 GO 0 O 8 6 4 2 0 0 O 0 INVENTORS FRACTION OF SULFUR REMOVED SEYMOUR ALPERT RONALD H. WOL K GOVANON NONGBRI Mg C.C ERVENAK Sulfur in Feed PATEHH UAPM 1515 7 5,251

SJEET 2 BF 2 Sulfur in Product Metals m Feed Metals in Product FIG.3

INVENTORS SEYMOUR a. ALPERT RONALD H. WOLK GOVANON nowsam MICHAEL C..CHERVENAK ATTORNEY TWO-STAGE HYDRODESULFURIZATION OF A HIGH METAL CONTENT HYDROCARBON FEED CROSS-REFERENCE TO RELATED APPLICATION This is a continuation-in-part of application Ser. No. 13,739, filed Feb. 24, 1970 and now abandoned.

BACKGROUND OF THE INVENTION This invention pertains to the processing of high metal hydrocarbon feeds for the purpose of removing contaminating impurities, such as sulfur and nitrogen and their respective compounds. More particularly, it pertains to the desulfurization of residuum and distillate gas oil feeds in both ebullated and fixed bed systems. Such feeds include petroleum atmospheric bottoms, petroleum vacuum distillation bottoms, shale oil, shale oil residues, tar sands, distillate oils and coal derived hydrocarbons and hydrocarbon residues and distillate gas oils.

Substantial advancement has been achieved as a result of the development of the ebullated bed contacting system as disclosed in the Johanson U.S. Pat. No. Re. 25,770. In such ebullated bed contacting systems, a liquid hydrocarbon feed material is passed upwardly with a hydrogen-rich gas through a reaction zone at high temperatures and pressures, said reaction zone containing a particulate contact agent which may or may not possess catalytic activity and the velocities of the liquid and gaseous feed materials being such as to place the contact agent particles in a random motion and to cause at least percent expansion of the bed over its rest volume. The ebullated systems result in improved temperature uniformity across the bed, increased catalyst life, and extend the desulfurization and conversion limits on feeds which normally give severe operability problems.

With respect to the use of the above systems in desulfurization processes, past workers in the field have found that the use of multi-stage processes utilizing the ebullated bed concept, allow increased desulfurization over that obtained with prior known fixed and slurry bed processes. Such developments are exemplified by the disclosures of the Schuman U.S. Pat. No. 3,183,179.

Improvements in desulfurization processes have also resulted from the discovery that'acontact agent or catalyst having a preponderance of large size channels, commonly known as access channels, give improved operability since they allow the large molecular weight asphaltene materials to enter into the interior surface of the catalyst, rather than plugging and inactivating the micropore structure of the catalyst.

The improvements in desulfurization of residuum feeds realized from the above developments, while substantial, still fall short of the desired level when it comes to processing high metal content feeds. The main problem presented by "such feeds is that the metals contained'therein, usually vanadium and nickel, are rapidly deposited on the contact agent, thereby poisoning or inactivating said contact agent. In a multistage process, even those utilizing the ebullated bed, a portion of the contaminated contact material from the first stage may be carried over into the second stage. This causes a continuous build-up of the'contaminated solid in the second and subsequent'stages,

resulting in an overall inefficient utilization of the contact agent. In the case of the porosity controlled and the high access channel materials as described above, the extremely high concentration of metals in these feeds rapidly overcome the advantage of the access to the interior of the contact agent of the large molecular weight materials, so that the advantages of this feature cannot be fully realized.

SUMMARY OF THE INVENTION We have discovered a multi-stage process for the desulfurization of high metal-containing feeds which allows one to take advantage, not only of the two or more stages utilized in the processes with its resultant initial metal removal capacity, but also to take full advantage of high access channel contact agent without being limited by severe metal deposition.

More particularly, we have discovered that the use of a fine mesh or powdered contact agent in the first stage of a multi-stage fixed or ebullated bed desulfurization process, gives increased metals removal over that which would be obtained by the use of a larger size material. As a result of the significantly improved metals removal, the effluent from the first stage can be treated in a subsequent catalytic stage using a variety of catalysts with resultant deep desulfurization, free from the limitations imposed by metal deposition and catalyst deactivation in the subsequent stage. The contact agent carryover from the first stage is prevented or negated by either interstage removal of the solids with a separation device, e.g., liquid cyclone, settling drums, etc. or use of a relatively large size catalyst in an ebul' lated contacting system in the subsequent stages, whereby the fine metal-containing contaminated solid in the effluent from the first stage is carried through the ebullated catalystic bed of the subsequent stages without retention of said contaminated material therein. Thus, there is no build'up of metal-containing solids in the subsequent stages and the overall catalytic activity of said subsequent stages remains at a consistently high level.

It is a further object of this invention to utilize high access channel and low access channel contact and high and low density materials in combination to effect I increased improvement in removal. of metals from the feedwith increased depth of overall desulfurization.

DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERRED EMBODIMENT The invention described herein may be utilized with any one of a number of typical desulfurization processes, utilizing both fixed and ebullated bed contacting systems. Such processes consist of passing a feed material with hydrogen through a reaction zone, said reaction zone containing a particulate contact agent which, in the case of our invention, would consist of particles having a narrow size distribution in the range from about 40 U. S. mesh to about 325 U. S. mesh. The gaseous and liquid effluents are removed from the first reaction zone, either separately or together. In some cases, a gaseous effluent is removed separately from the liquid effluent whereas an alternative method would be to remove a total effluent and separate the gaseous from the liquid products in an external separation unit. The liquid effluent is then introduced to the second stage reaction vessel. If desired, of course, the combined gaseous and liquid effluent may be passed on to the subsequent stages. If a powdered catalyst is used in the subsequent zone, then the liquid effluent will pass through a solids separation step to remove contaminated solids such as filtration, liquid cyclone, settling drums, etc. The second stage reactor contains a particulate catalyst which may be similar to that in the first reactor, except that it is not limited to a fine mesh catalyst. It may include sizes in the range larger than 40 U.S. mesh including extrudates. Particles larger than 40 mesh usually do not exceed one-eighth inch in size in order that they may be ebullated. Preferably, in particles sizes running from one-sixteenth inch to one-thirty-second inch, the catalyst is usually extrudated and has a dimension of about 3 diameters in length. For example, an extrudate of 1/16 inch diameter would be about three-sixteenth inch in length as disclosed in U.S. Pat. No. 3,183,178. The effluents from the subsequent stage may then be treated in additional subsequent stages in a like manner or the effluents may be removed as products.

Typical reaction conditions for the desulfurization process described above would include a temperature ranging from about 700 to about 900F., total pressures from about 800 to about 3,000 psig, hydrogen throughputs from about 2,500 to about 8,000 standard cubic foot per barrel and total space velocities of greater than 0.1 V,/hr/V, (volume of feed per hour per volume of reactor). The combination of the reaction conditions may be so adjusted as to control the total conversion of charge stock boiling above 975F. to material boiling below 975F. at any desired level. It is usually preferable, however, in desulfurization processes, to maintain the conversion below 50 percent, so as to minimize the naphtha and light hydrocarbon yield.

The catalyst used in the reaction stages described above, are composed of alumina or silica and alumina promoted with metals and their compounds selected from groups VIb and VIII from the periodic table of the elements. As mentioned, contact materials with lessor negligible catalytic activity such as silica gel, boria alumina, alumina, silica-magnesia, diatomaceous earth, etc. may also be used in the first stage. 1

Additionally, proper pore distribution and structure, as hereinafter defined, give even improved metals removal.

In the case where an interstage separation is not used and where the subsequent stages consist of ebullated bed systems using large size cata1yst,,we have found that the powder catalyst must have a transport velocity equivalent to that which would give about toabout 100 percent expansion of the large size catalyst. This parameter insures that the powdered contact agent will flow through and out of the ebullated stage. If the transport velocity is too low, metals removal is not optimum. 1f the transport velocity is too high, the possibility of build-up of contaminated powdered contact agent exlsts.

With respect to the ebullated bed type contacting system, the transport velocity of a particulate solid is that velocity of liquid upwardly through the bed which is required to achieve infinite expansion of the bed. Essentially this means that at a velocity equivalent to or greater than the transport velocity of particulate solid, no solid will be retained in the reactor.

FIGS. 1 and 2 both illustrate the basic discovery of this invention in that they show the improved de-metallization obtained by the use of a powdered catalyst, as opposed 'to an extrudate or large size catalyst. FIG. 1 pertains to removal of vanadium from a feed material for a given percent of desulfurization. FIG. 2 pertains to the removal of nickel relative to the amount of desulfurization of the feed. There are, of course, other metals contained in residuum feed materials, however, vanadium and nickel are the most prevalent and bothersome. The phenomenon of improved metal removal, however, using a powdered catalyst is applicable also to the other types of metals and our invention is not necessarily limited to only vanadium and nickel. Generally, however, operability difficulties exist on feeds having greater than about an ppm total metals content.

Example I is a comparison of single stage desulfurization runs showing the substantially improved de-metallization obtained with the powdered contact stage of our invention.

EXAMPLE I Kuwait Feed 1/ 32 inch Contact agent size, U.S. mesh -200 extrudate Operating Conditions H, pressure, psig 2250 2250 Temperature, F 835 835 Space Velocity, V,/hr/V,. 0.6 0.6 11, Rate, SCF/bbl 5000 5000 Inspections on collected liquid Vanadium 80 12 14 Nickel, pp 20 1.5 2.5 5

EXA M PLE II Feed: Venezuelan Atmospheric Residuum 1 1A P1 2.8% S

425 ppmV 75 ppmNi Reactor Conditions:

Temperature, "F 780 Pressure, Psig 2000 Space Velocity, V,/hr/V, 1.0 Conversion, 975F plus Components less than 50% Run 1 Run 2 1st stage contact agent non-access access powder powder 2nd stage catalyst access access powder powder I: desulfurization in 1st 40 40 stage demetallization lst stage (V AN:) 25 50 Overall desulfurization 60 75 at equilibrium Example II shows the improvement that can be obtained in a multi-stage desulfurization process by using an access channel powdered contact agent in the first stage as opposed to a non-access channel powder. In this example, both reactors contain access channel powders and carryover solids in the liquid effluent from the first stage are separated prior to introducing the liquid to the second stage.

For purposes of definition, an access channel catalyst or contact agent is a material having rnicropores and access channels wherein the access channels are interstitially spaced throughout the rnicropores and wherein to 40 percent of the total pore volume is composed of access channels having diameters greater than 1,000 angstroms and wherein 10 to 40 percent of the total pore volume is composed of access channels having diameters between about 100 and about 1,000 angstroms and wherein the remainder of the pore volume is composed of rnicropores having diameters less than 100 angstroms and said remainder comprises to 80 percent of the total pore volume and wherein the accesschannels are substantially uniform as to their parameters and are relatively straight with minimum bending and constrictions.

As shown in this example, the use of an access channel powder gives substantial improvement in the amount of demetallization obtained in the first stage reaction zone for an equivalent amount of desulfurization over that obtained with a non-access channel powder. As further shown, the overall desulfurization obtainable because of the increase activity of the second stage catalyst without the consequent poisoning is substantially improved. Of course, the actual level of vanadium on the catalyst is a function of the catalyst addition rate. At an addition rate of about 0.15 lbs.per barrel, the catalyst contains about 0.5 lbs. of vanadium per lb. of fresh catalyst, which is a highly contaminated catalyst. If an intermediate separation stage is not used, the first stage solids will overflow and mix with the second stage catalyst. The overflow catalyst from the second stage, then, will be a mixture of both highly contaminated solid from the first stage and relatively active catalyst from the second stage, i.e., having only about one-half as much vanadium as the first stage catalyst also separated into vaporous and liquid products. The

Example III gives a series of four runs, all utilizing the same feed, temperature conditions and percent desulfurization in the first stage as stated above in Example II. In Example III, however, the second stage catalyst consists of access channel extrudates, with the first stage material being varied as shown.

Runs 3 and 4 give a comparison of the improvement in overall desulfurization and first stage demetallization that can be obtained by the use of a powder as opposed to an extrudate, neither material possessing access channels. Comparison of

runs

5 and 6 show the improvement that can be obtained over a first stage access channel extrudate solids by using an access channel powder. In each case, use of powdered solids as opposed to an extrudate having the same pore structure gives substantial improvement in overall desulfurization level at equilibrium. In the runs of Example III, of course, no intermediate separation between the zones is required, since the extrudated solids in the first zone in runs 4 and 5 are not carried over into the second zone and in the case of

runs

3 and 6, the powdered solids from the first zone while carried over into the second zone, flow through and out of the second zone without displacing said extrudate and may be separated from the effluent of the second reaction zone.

Numerous combinations of catalysts and staging of the gaseous and liquid effluent may be used in our invention. For example, selected fractions from the liquid effluent from the subsequent reaction stages may be recycled as gas oil diluents to the first reaction stage. Also, separate subsequent stage treatment of the vaporous products from the various reaction zones may be used.

A particular example of the latter combinationis a process having a powdered solids de-metallization zone in series with a second stage extrudate catalyst, deep desulfurization zone, both stages being ebullated systems with intermediate separation of the vaporous and liquid products from the first zone. Only the liquid products from the first zone are introduced to the second stage. The effluents from the second zone are vaporous products from both zones are then combined and treated with hydrogen in a third zone which is a fixed bed, non-access channel catalyst, vapor phase zone. We have found that while the non-access channel catalyst deactivate in the presence. of the metallic impurities much more rapidly than those containing such channels, they do possess higher initial desulfurization activity. Since the vaporous products contain insignificant amounts of metals as a result of their previous treatment, advantage can be taken of the high desulfurization activity of the non-access channel catalyst.

A third combination is the use of a powder having a large porosity, i.e., low density as the first stage contact agent. As shown in FIG. 3, such catalysts, although possessing relatively poor desulfurization activity,. have rather high de-metallization efficiency. The second deep desulfurization stage would contain'a high density catalyst which FIG. 3 shows to have a relatively high desulfurization efficiency, although possessing rather poor de-metallization ability. Typically, a low density material for such processes would have porosity of at least 0.20 cc./g cumulativepore volume for pores having diameters larger than 300A. with the range preferably being about 0.25 to about 0.5 cc/g cumulative pore volume for pores having diameters larger than 300A. The preferred high density catalyst would have a porosity no greater than about 0.1 cc/g cumulative pore volume for pores having diameters larger than 300A., with the preferable range being from about 0.03 to about 0.07 cc/g cumulative pore volume for pores having diameters larger than 300A.

Although the above example and discussion discloses a preferred mode of embodiment of applicants invention, it is recognized that from such disclosure, many modifications will be obvious to those skilled in the art and, it is understood, therefore, that applicants invention is not limited to only those specific methods, steps or combination or sequence of method steps described, but covers all equivalent steps or methods that may fall within the scope of the appended claims.

We claim:

1. A two stage process for the hydrodesulfurization ofa high metal content hydrocarbon feed containing at least 25 Vol. percent of components boiling above 975F wherein:

a. introducing said hydrocarbon feed and hydrogen into a first reaction stage which is maintained at a temperature in the range of about 700F. to about 900F. and a total pressure from about 800 psig to about 3,000 psig under liquid phase conditions, said hydrogen and hydrocarbon feed passing upwardly at a rate to maintain a particulate catalyst in random motion in the liquid;

b. said catalyst having a narrow size distribution within the range from about 40 to about 325 US. mesh, and being a material selected from the group consisting of alumina and silica promoted with metals and their compounds from group Vlb and group VIII of the periodic table;

0. said catalyst having micropores with access channels interstitially spaced therethrough, 10 to 40 percent of the total pore volume being composed of access channels having diameters greater than 1,000A. and 10 to 40 percent of the total pore volume being composed of access channels having diameters between about 100 and about 1,000A.

and the remainder of the pore volume being micropores of less than 100A. said remainder comprising 20 to 80 percent of the total pore volume;

d. removing a liquid effluent from said first reaction stage and passing said effluent with hydrogen into a second reaction stage;

e. said second reaction stage being maintained at a temperature in the range of about 700F to about 900F and a total pressure from about 800 psig to about 3,000 psig under liquid phase conditions, said hydrogen and liquid effluent passing upwardly at a rate to maintain a particulate catalyst in random motion in the liquid;

f. said second stage catalyst having a narrow size distribution within the range of about one-sixteenth inch to about 325 mesh and being a material I velocity of about 1.0 V,/hr/V,.

selected from the group consisting of alumina and silica promoted with metals and their compounds selected from group Vlb and group VIII of the periodic table; g. said second stage catalyst being of high density having a porosity not greater than 0.1 cc/g of cumulative pore volume for pores having diameters larger than A., and

h. wherein combination of reaction conditions are used in steps (a) and (e) so that less than 50 percent of those components boiling above 975F are converted to materials boiling below 975F.

2. The process as claimed in claim 1 wherein said catalysts in steps b) and f) are composed of an aluminasilica carrier promoted with metals and their compounds from group Vlb and group VIII of the periodic table.

3. The process as claimed in claim 1 wherein the feed is a material selected from the group consisting of petroleum atmospheric bottoms, petroleum vacuum distillation bottoms, shale oil, shale oil residues, tar sands, distillate oils and coal derived hydrocarbons and hydrocarbon residues and distillate gas oils.

4. The process as claimed in claim 1 wherein the catalyst in the first reaction zone has a porosity of at least 0.20 cubic centimeters per gram of cumulative pore volume for pores having diameters larger than 100 Angstrom units.

5. The process as claimed in claim 1 wherein the conditions in each reaction zone are substantially the same, said conditions being a temperature of about 780F., a total pressure of about 200 psig and an overall space 6. The process as claimed in claim 1 wherein the catalyst carried over in the liquid material in the effluent from said first reaction stage is removed in a separation device prior to introducing the liquid to said second reaction stage.

7. The process as claimed in claim 1 wherein the liquid feed and hydrogen gas are passed upwardly through said second stage at velocities such that the catalyst contained therein exist in an expanded and ebullated state and wherein the first stage catalyst is in powdered form in said first stage and has a transport velocity equivalent to that required to achieve between about 20 to about 100 percent expansion of the ebullated bed in said second stage whereby said first stage catalyst material carried over in the liquid material in the effluent from the first reaction stage passes through said second stage and is not retained therein.

8. The process as claimed in claim 1 wherein said second stage particulate catalyst is-of the same narrow size distribution of said first stage catalyst.

9. The process of claim 1 wherein said second stage particulate catalyst has a narrow size distribution within the range of about 325 mesh to 40 mesh.

10. The process of claim 1 wherein said second stage particulate catalyst is composed of a narrow size distributionwithin the range of about 40 mesh toone-sixteenth inch.

Claims

2. The process as claimed in claim 1 wherein said catalysts in steps b) and f) are composed of an alumina-silica carrier promoted with metals and their compounds from group VIb and group VIII of the periodic table.
3. The process as claimed in claim 1 wherein the feed is a material selected from the group consisting of petroleum atmospheric bottoms, petroleum vacuum distillation bottoms, shale oil, shale oil residues, tar sands, distillate oils and coal derived hydrocarbons and hydrocarbon residues and distillate gas oils.
4. The process as claimed in claim 1 wherein the catalyst in the first reaction zone has a porosity of at least 0.20 cubic centimeters per gram of cumulative pore volume for pores having diameters larger than 100 Angstrom units.
5. The process as claimed in claim 1 wherein the conditions in each reaction zone are substantially the same, said conditions being a temperature of about 780*F., a total pressure of about 200 psig and an overall space velocity of about 1.0 Vf/hr/Vr.
6. The process as claimed in claim 1 wherein the catalyst carried over in the liquid material in the effluent from said first reaction stage is removed in a separation device prior to introducing the liquid to said second reaction stage.
7. The process as claimed in claim 1 wherein the liquid feed and hydrogen gas are passed upwardly through said second stage at velocities such that the catalyst contained therein exist in an expanded and ebullated state and wherein the first stage catalyst is in powdered form in said first stage and has a transport velocity equivalent to that required to achieve between about 20 to about 100 percent expansion of the ebullated bed in said second stage whereby said first stage catalyst material carried over in the liquid material in the effluent from the first reaction stage passes through said second stage and is not retained therein.
8. The process as claimed in claim 1 wherein said second stage particulate catalyst is of the same narrow size distribution of said first stage catalyst.
9. The process of claim 1 wherein said second stage particulate catalyst has a narrow size distribution within the range of about 325 mesh to 40 mesh.
10. The process of claim 1 wherein said second stage particulate catalyst is composed of a narrow size distribution within the range of about 40 mesh to one-sixteenth inch.