US3433732A - Catalytic hydrocracking process and steam regeneration of catalyst to produce hydrogen - Google Patents

Description

March 18, 1969 r w. K. LEAMAN CATALYTIC HYDROCRACKING ATION PROCESS AND STEAM REGENER OF CATALYST TO PRODUCE HYDROGEN Filed May 17, 1967 B SQQm 2398a :9

m 5 m I IN VEN TOR BY VV/Ybu/ K. Lea/7700 fiw fl M Attorney United States Patent Oflice 3,433,732 CATALYTIC HYDROCRACKING PROCESS AND STEAM REGENERATION F CATALYST TO PRODUCE HYDROGEN Wilbur K. Leaman, Medford Lakes, N.J., assignor to Mobil Oil Corporation, a corporation of New York Filed May 17, 1967, Ser. No. 639,135 US. Cl. 208-111 11 Claims Int. Cl. Cg 13/02, 11/28, 11/02 ABSTRACT OF THE DISCLOSURE Petroleum hydrocarbons are upgraded and recovered from a catalytic hydrocracking step conducted under hydrogen pressure in the presence of a catalyst containing crystalline aluminosilicate having a hydrogenation component associated therewith. The catalyst from the hydrocracking step contains coke and is heated and then contacted with steam in a steam reforming step to produce hydrogen rich gas while at the same time regenerating the catalyst. The regenerated catalyst as well as at least a portion of the hydrogen rich gas produced in the steam reforming step are recycled to the hydrocracking step.

BACKGROUND OF THE INVENTION Field of invention Description of the prior art It is known to catalytically convert even heavy petroleum hydrocarbons in the presence of hydrogen. Most suggested processes employ hydrogen partial pressures ranging from several hundred p.s.i. to several thousand p.s.i. In these processes, a petroleum hydrocarbon is contacted, in the presence of hydrogen, with solid particulate material to produce lower boiling upgraded hydrocarbons and small amounts of coke. The catalyst is then regenerated to remove substantially all of the coke therefrom to thereby improve its activity. The catalyst regeneration is usually conducted in a manner to oxidatively burn the coke therefrom. The regenerated catalyst is then recycled to the hydroconversion zone.

It is also known that coke can be removed from solid particulate material by contact with steam to effect the water-gas reaction which produces hydrogen and gaseous carbon oxides. In US. Patent 2,888,395 issued May 26, 1959, a catalytic coking process is disclosed whereby catalytic contact material from the coking step is subsequently steam reformed to produce hydrogen. A heavy hydrocarbon feed is converted in a coking zone in the presence of hydrogen and a catalyst to produce lower boiling distillates and coke. The coked catalyst is directed to an oxidative regeneration zone to burn a portion of the coke and to partially regenerate the catalyst. A portion of the partially regenerated catalyst is recycled to the coking zone while the remainder of the catalyst is directed to a steam reforming zone. In the steam reform- 3,433,732 Patented Mar. 18, 1969 ing zone a second portion of the coke is converted to hydrogen and gaseous carbon oxides. Catalyst and hydrogen from the steam reforming zone are recycled to the coking zone. Thus, the catalyst recycled to the coking zone has widely varying coke concentration and widely varying activities.

It is desirable to remove substantially all of the coke from the catalyst prior to recycling to the hydrocracking zone. In this manner a uniformly high catalyst activity in the hydrocracking zone is effected with a resultant increased yield of lower boiling distillates. According to the process of the present invention, substantially all of the coke is removed from the catalyst by partial oxida tive regeneration followed by steam reforming. In addition, in the process of this invention, the hydrocracking zone is maintained under conditions to effect an overall exothermic reaction. The heat requirement for incoming catalyst to the hydrocracking zone is thereby reduced and thus permits steam reforming under endothermic conditions of substantially all the coke on the catalyst obtained from the oxidative regeneration step.

SUMMARY OF THE INVENTION Briefly, the present invention comprises a combination catalytic hydrocracking step and steam reforming step, both operated at pressures greater than atmospheric, employing a catalyst containing crystalline aluminosilicate. For effective hydrocracking both an acidic catalytic function and a hydrogenation catalytic function are required. The hydrogenation function can be an integral part of the acidic function and its base as fully described hereinafter, or the hydrogenation component can be partially or entirely on a separate base. Having the two functions on separate bases permits selective replace ment of that catalyst function which has deteriorated most through use and thus maintaining close to the optimum balance of the two functions. Accordingly, a petroleum hydrocarbon to be converted is contacted with a crystalline aluminosilicate catalyst in a hydrocracking zone to produce lower boiling hydrocarbons and coke. The coked catalyst is then heated to a temperature in the range of from about 1000" F. to about 1600 F. At least a portion of this heat is acquired by oxidatively burning some of the coke with a dilute mixture of air or oxygen under pressure. The heated catalyst is then contacted with steam in a steam reforming step under conditions to convert the coke remaining thereon to hydrogen and carbon oxides while regenerating the catalyst. The regenerated catalyst is then directed to the hydrocracking step. The hydrogen produced in the steam reforming step after separation is recycled to the hydrocracking step. The carbon monoxide produced in the steam reforming zone can be further processed if desired to form additional hydrogen and carbon dioxide.

By the process of this invention, a heavy petroleum hydrocarbon can be catalytically hydrocracked in a pressure balanced and heat balanced system while a part of the coke produced is converted to hydrogen in a cyclic continuous process.

BRIEF DESCRIPTION OF THE DRAWINGS The attached drawing is a flow illustrative of a moving bed process for practicing the present invention.

DESCRIPTION OF SPECIFIC EMBODIMENTS Referring now to the figure, a heavy petroleum hydrocarbon feed is directed through conduit 1 and is then mixed with hydrogen rich gas from conduit 2. The resultant mixture is preheated in preheating zone 3 and then directed to hydrocracking zone 4 through conduit 5. In hydrocracking zone 4 the feed is contacted with crystalline aluminosilicate catalyst under hydrocracking conditions to produce lower boiling hydrocarbons and coke on the catalyst. Vaporous hydrocarbon product and unreacted hydrogen are removed from hydrocracking zone 4 through conduit 6 and directed to a high pressure separator 7. To assist in separating vaporous products from catalysts in reactor 4, steam can be introduced into reactor 4 and conduit 12 through conduits 39 and 40. In separation step 7, hydrogen rich gas is separated from hydrocarbon product and directed through conduit 8 to hydrogen/purification zone 30. In purification zone 30, hydrogen is separated from the remaining product gases and unreacted steam. The remaining product gases are removed from purification zone 30 through conduit 35 while hydrogen is removed from purification zone 30 through conduit 2.

The hydrocarbon product is removed from separation step 7 through conduit 9, is reduced in pressure and most of the dissolved gases are separated therefrom in flash drum 10. Flashed vapors are removed from flash drum 10 through conduit 31. Flash drum liquid is directed through conduit 36 to a fractionator 11 for separation into the desired products. Portions of the heavy fuel oil can be recycled and combined with fresh feed to the hydrocracking zone 4 if desired. In the hydrocracking zone 4, coke is deposited on the catalyst during reaction. The coked catalyst is removed from hydrocracking zone 4 by gravity through conduit 12 into heating zone 13. Catalyst heating is accomplished by injecting a free oxygen containing gas through conduit 32 to burn a controlled portion of the coke and further heated by indirect heat exchange with gases from line burner 33.

In heating zone 13, the coked catalyst is heated to a temperature sufficiently high to support subsequent steam reforming. The catalyst temperature at the outlet of zone 13 is between about 1100 F. to about 1600 F. The heated catalyst is removed through conduit 14 by gravity and is directed to steam reforming zone 15. Gaseous combustion products are separated from catalyst in heating zone 13 and removed therefrom through conduit 34.

In steam reforming zone 15, the coked catalyst is contacted with steam from conduit 37 under conditions to effect the water-gas reaction wherein coke is converted to mainly carbon oxides, and hydrogen gas. The gaseous products from steam reforming zone 15 are removed therefrom through conduit 16 and combined with the hydrogen rich gas from separation zone 7 in conduit 8. The combined hydrogen rich stream is purified in purification Zone 30 to substantially remove carbon oxides, hydrogen sulfide and ammonia. The purification step can best be performed under elevated pressures such as provided by the methanol wash process. A carbon monoxide conversion process can also be advantageously used to produce additional hydrogen. The relatively high hydrogen content gas is then directed through conduit 2, repressured and mixed with the oil charge from conduit 1. Additional hydrogen from other sources such as a conventional naphtha reformer can also be added to the process.

Catalyst is directed by gravity through transfer line 17 from steam reforming zone 15 to the lift pot 18. Steam or other gaseous streams, as for example the gaseous combustion products from heating zone 13 and directed through conduit 38 can be used to transport the catalyst from lift pot 18 through conduit 19 to surge separator 20. Lift gas is removed through line 21. Portions of deactivated catalyst can be removed through conduit 22 to permit addition of fresh catalyst to the process. The main portion of the catalyst is directed to reactor 4 from separator through conduit 27.

The catalysts employed in the process of this invention comprise one or more metal, metal oxide, or metal sulfide hydrogenation components, in combination with a base material containing crystalline aluminosilicate zeolite. The hydrogenation components which can be employed with the crystalline aluminosilicate base include the Group VIB and Group VIII metals of the Periodic Table as well as their oxides or their sulfides or mixtures thereof. The Group VIB metals which can be employed include chromium, molybdenum and tungsten while the Group VIII metals which can be employed include iron, nickel, cobalt, the platinum group metals and the palladium group metals. The preferred metal hydrogenation components are nickel, cobalt, platinum and iron. The crystalline aluminosilicate material and hydrogenation component can be combined on common catalyst particles or can be each associated alone on separate catalyst particles. As for example a hydrogenation metal on alumina can be mixed with discrete crystalline aluminosilicate particles either alone or on a matrix.

The crystalline aluminosilicate component is a structure having uniformly dimensioned pores formed by alumina and silica tetrahedra. There are available at the present time a number of crystalline aluminosilicates, each of which have their own characteristic pore size openings. For purposes of the present invention, it is desirable to employ a crystalline aluminosilicate having pore size openings between about 4 Angstroms and about 13 Angstroms, preferable from about 6 to about 13 Angstroms. The crystalline aluminosilicate employed herein can be derived from naturally occurring crystalline aluminosilicates or synthetic crystalline aluminosilicates. Among the crystalline aluminosilicates which can be used for purposes of the present invention are the naturally occurring crystalline aluminosilicates such as faujasite, mordenite, chabazite, stilbite, ferrionite, heulandite, dachiaridite, clinoptilolite, and erionite and the synthetic zeolites such as zeolites X, Y, B, L, A, T and ZKlS. These synthetic crystalline aluminosilicates are usually prepared in the sodium form. In some cases it is desirable to alter the crystalline aluminosilicate to remove sodium by employing known base exchange techniques. However, it is within the scope of the present invention to employ a crystalline aluminosilicate which has not been base exchanged to remove sodium so long as the requisite stability and performance is obtained. The crystalline aluminosilicate or hydrogenation component may also be dispersed in an inorganic oxide matrix. Preferred matrices comprise hydrous oxides such as those rich in silica, alumina and materials thereof such as clays, gels and the like.

The synthetic crystalline aluminosilicates are usually prepared in the sodium form while the naturally occurring crystalline aluminosilicates usually contain sodium ions and other metal ions such as calcium. It has been found that the cracking activity and the stability of these crystalline aluminosilicates can be very materially increased by replacing the great majority of the sodium ions therein with other metal ions or hydrogen ions. In particular, it has been found that sodium in the presence of steam tends to act as a flux and results in catalyst surface area reduction and crystallinity reduction. Typically, a fluid containing metal ions which are exchangeable with sodium in a manner such as described in US. Patents 3,140,249 and 3,140,253 to Plank et al. Metallic cations which can be exchanged with the sodium ions in the crystalline aluminosilicate are those in tne Groups I-B through VIII of the Periodic Table as well as the rare earths. In addition, the sodium can be removed from the crystalline aluminosilicate by base exchanging with a hydrogen precursor cation such as the ammonium ion to obtain the crystalline aluminosilicate in hydrogen form. Further, the crystalline aluminosilicate can be base exchanged in a manner to replace the sodium cation with a mixture of the above metal cations or a mixture of the above metal cations with a hydrogen containing ion. The preferred forms of the crystalline aluminosilicate are those containing divalent or multivalent cations. Thus, it is seen that the hydrogenating metal can be employed to function as a means for removing sodium from the crystalline aluminosilicate as well as providing hydrogenating activity for the catalyst.

The metal hydrogenation component of the crystalline aluminosilicate containing catalyst is present in amounts of from about 0.5 to about 50 weight percent and preferable from about 1 to about 25 weight percent. The hydrogenation component is introduced into the crystalline aluminosilicate by ion exchange and/or impregnation. Introduction of the hydrogenation component by ion exchange can be accomplished before, during or after base exchange with cations capable of removing sodium from the aluminosilicate, such as the hydrogen ions, ammonium ions or cations of trivalent metals such as rare earths or mixtures thereof. In the process of the present invention, the preferred catalysts comprise rare earth, hydrogen, or aluminum base exchanged zeolite X, zeolite Y or mordenite having as a hydrogenation component nickel, cobalt, platinum or iron. Acid or hydrogen base exchanged mordenite exhibits excellent steam and thermal stability which affords its use in the present process.

The methods for ion exchanging aluminosilicates to introduce thereto desired ions are well known. One method comprises contacting the aluminosilicate with an aqueous solution of a salt of the ion desired. The concentration of metal salts in the aqueous solution can range from about 0.1 N to above 2.0 N, although about 1.0 N solutions are preferred for ease of operation. In addition, the ion exchange treatment can be carried out with metal cations in the form of molten material, vapor or non-aqueous solution and can be passed slowly through a fixed bed of aluminosilicate. The salt should be of a molecular size sufficiently small to enter and exit the pores of the aluminosilicate. Representative of the metal salts which can be employed to base exchange aluminosilicates include chlorides, bromides, iodides, carbonates, bicarbonates, sulfates, sulfides, thiocyanates, dithiocarbona'tes, peroxysulfates, acetates, benzoates, citrates, nitrates, nitrites, formates and the like. The particular salt employed must be sufficiently soluble in the solutizing medium employed to give the necessary ion transfer. The preferred salts are chlorides, nitrates, sulfates and acetates.

Following the base exchange treatment with the salt, the aluminosilicate may be washed with water, preferably distilled water, and genera-11y thereafter dried between 150 F. and 600 F. The aluminosilicate can thereafter be calcined in air or an inert atmosphere or nitrogen, hydrogen, helium, fiue gas or other inert gas at temperatures ranging from about 500 F. to 1500 F. for periods of time ranging from 1 to 48 hours or more.

It is preferred that at least some of the hydrogenation component be introduced into the crystalline aluminosilicate by base exchange rather than by impregnation. Metal incorporated by exchange has less tendency to migrate to the catalyst surface and form agglomerates thereon. Such migration, in effect, reduces the effective catalyst surface area by closing the pores and results in an inefiicient catalyst. Incorporating at least some of the hydrogenation compound by well known impregnation processes also produces superior catalysts. Again, the hydrogenation component may be incorporated before, during or after ion exchanging the aluminosilicate to reduce its sodium content.

It is preferred to employ the process of this invention in a continuous cyclic system. Thus, either a moving bed system or a fluid bed system can be employed. In a moving bed system particulate catalyst material usually in bead form of a size from about /3 inch to about inch in diameter is passed downwardly by gravity through the hydrocracking zone and subsequently through the catalyst heating zone and the steam-reforming catalyst regeneration zone. It is within the scope of the present invention in a moving bed system to locate the steam reforming zone above the catalytic hydrocracking zone. In either case, the catalyst is moved from the bottommost conversion zone to the uppermost conversion zone usually by a gas lift. Where large amounts of coke are expected to be produced, regeneration can be staged by using a second oxidation and reforming step to keep temperatures in the proper ranges for each of the reactions. In the fluid bed system the catalyst employed is usually of the size of from about 20 microns to about 130 microns. Each of the conversion zones is maintained as dense fiuid beds of catalysts.

In the hydrocracking zone, hydrocracking conditions are maintained at a temperature of between about 550 F. and about 950 F., preferably between about 700 F. and about 900 F.; a pressure of between p.s.i.g. and about 500 p.s.i.g., preferably between about 200 p.s.i.g. and about 400 p.s.i.g.; a liquid hourly space velocity of between about 0.5 v./hr./v. and about 10 v./hr./v., preferably between about 1 v./hr./v. and about 5 v./hr./v.

In the process of this invention, it is preferred to conduct the steam reforming steps under conditions to substantially remove all coke from the catalyst. In this manner, catalyst activity is maintained in the subsequent hydrocracking step. The concentration of coke on the catalyst from the hydrocracking zone is dependent upon the type of feed and the reaction conditions employed. Catalyst circulation rate is an important parameter. Increased catalyst circulation rates decrease coke 0n catalyst. The coke concentration on catalyst also decreases with an increased hydrogen partial pressure and with use of a lesser refractory feed. The yoke concentration on catalyst from the hydrocracking zone usually ranges from about 0.5 weight percent to about 12 weight percent based upon the weight of catalyst. Especially at the higher coke on catalyst levels it is desirable to remove some of the coke by burning which is an eflicient way to help achieve the higher catalyst temperatures required for the reforming step and, furthermore, reacting high amounts of coke with steam would reduce catalyst temperatures below that required for the hydrocracking step. Therefore, a balance is maintained between heat input (by oxidatively burning some of the coke and by heat exchange with hot gases) and heat consumption (by the endothermic steam-coke reaction). In the steam reforming zone the steam to actual coke ratio is between about 1.5 and 4, i.e., a steam rate of 3 pounds per unit of time per pound of carbon entering the regenerator per unit of time. The pressure in the steam reforming zone is maintained between about 100 p.s.i.g. and about 500 p.s.i.g., preferably from about 200 p.s.i.g. to about 400 p.s.i.g.

The hydrocarbon feeds which can be employed in the process of this invention have initial boiling points above about 650 F. Illustrative of such hydrocarbon feeds are heavy gas oils, vacuum or atmospheric residual oils, heavy coker bottoms, tars, and refractory streams from catalytic cracking units.

The hydrogen purifying step is conducted to separate hydrogen from the carbon oxides-low boiling hydrocarbon gaseous mixture, Thus, for example, this hydrogen gas can be separated by cryogenic means or by a methanol solvent wash process. The separated carbon monoxide can be further reacted with steam via the water gas shift reaction to produce additional hydrogen.

Having fully described the invention, I claim:

1. A method for utilizing a crystalline aluminosilicate containing catalytic composition having acidic catalytic functions in association with hydrogenating-dehydrogenating catalytic functions which comprises:

(a) employing a crystalline aluminosilicate containing catalytic composition comprising acidic catalytic functions in association with hydrogenating-dehydrogenating catalytic functions in a moving bed process to effect the conversion of a hydrocarbon feed material to lower boiling products in the presence of hydrogen at a temperature in the range of from about 550 F. to about 950 F. and a pressure below about 500 p.s.i.g. thereby depositing carbonaceous materials on said catalytic composition,

(b) withdrawing said lower boiling products and crystalline aluminosilicate catalytic composition from the conversion zone,

() removing a portion of the thus formed carbonaceous material from said withdrawn crystalline aluminosilicate catalytic composition by burning with only a sufficient amount of oxygen containing gaseous material to thereby heat said catalytic composition to an elevated temperature in the range of from about 1000 to about 1600" F.,

(d) etfecting a further removal of deposited carbonaceous material from the crystalline aluminosilicate catalyst heated with oxygen Containing gas by further contact thereof with steam under steam reforming conditions selected to produce hydrogen and carbon oxides,

(e) employing the crystalline aluminosilicate catalytic composition thus freed of carbonaceous material in said hydrocarbon conversion step (a) and (f) passing a portion of the hydrogen produced in step (d) above to step (a).

2. The method of claim 1 wherein the steam reforming step (d) is effected at a pressure in the range of 100 to 500 p.s.i.g. and the endothermic heat requirements thereof are supplied essentially by the partial removal of carbonaceous material from the catalytic composition by burn- 3. The method of claim 1 wherein the crystalline aluminosilicate is zeolite Y.

4. The method of claim 1 wherein the crystalline aluminosilicate is zeolite X.

5. The method of claim 1 wherein the crystalline aluminosilicate is acid mordenite.

6. The method of claim 1 wherein at least part of the ions of the crystalline aluminosilicate are exchanged with rare earth ions.

7. The method of claim 1 wherein the hydrogenationdehydrogenation component is nickel.

8. The method of claim 1 wherein the hydrogenationdehydrogenation component is a noble metal.

9. The method of claim 1 wherein the hydrogenationdehydrogenation component is a Group VIII metal.

10. The method of claim 1 wherein the crystalline aluminosilicate and the hydrogenation-dehydrogenation component are each separately associated with separate catalyst particles.

11. The method of claim 1 wherein said acidic functions and said hydrogenating-dehydrogenating functions of said catalytic composition are distributed in an inorganic oxide matrix.

References Cited UNITED STATES PATENTS 2,284,603 5/1942 Belchetz et a]. 208153 3,140,253 7/1964 Plank et al 208 3,210,265 10/ 1965 Garwood 208 1 11 DELBERT E. GANTZ, Primary Examiner.

G. E. SCHMITKONS, Assistant Examiner.

US. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,433,732 March 18, 1969 Wi lbur K Leaman It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 4, line 57, after "Typically," insert the crystalline aluminosilicates are base exchanged with Signed and sealed this 31st day of March 1970.

(SEAL) Attest:

WILLIAM E. SCHUYLER, JR.

Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer

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