US3105811A

US3105811A - Combined desulfurization, hydrocracking, and reforming operation

Info

Publication number: US3105811A
Application number: US55352A
Authority: US
Inventors: John H Engel
Original assignee: Phillips Petroleum Co
Current assignee: Phillips Petroleum Co
Priority date: 1960-09-12
Filing date: 1960-09-12
Publication date: 1963-10-01
Anticipated expiration: 1980-10-01

Description

operation. In this manner United States Patent Ofi ice 3,105,81 l Patented Get. 1, 1963 This invention relates to upgrading of motor fuel stocks. In one aspect it relates to upgrading of motor fuel stocks as regards yields and antiknock value. In another aspect it relates to an operation utilizing less costly equipment and therefore a lower capital investment than required by known processes.

Catalytic and noncatalytic conversion processes have been devised in attempts to increase motor fuel yields and to improve such other properties as antiknock value. In one prior art process, over which the present invention is an improvement, an entire hydrodesulfurization efliuent liquid, along with the high boiling end fraction of a hydrocracking operation, is charged to the hydrocracking operation for conversion. The present invention is a marked improvement over this prior art process because in place of hydrocracking a hydrodesulfurized naphtha of full boiling range, only the high boiling end fraction of the naphtha, along with the high boiling end fraction of a hydrocracking operation, is charged to the hydrocracking the more or less free-riding, gasoline boiling range portion of the naphtha, which is usually not markedly improved in antiknock value, is not passed through the hydrocracking portion of the operation. Thus, by eliminating the portion of the feed stock which is improved slightly or even not at all, I am able to employ a hydrocracking unit of markedly reduced capacity and therefore much less costly than larger units.

An object of this invention is to devise a process for upgrading motor fuel stocks as regards antiknock values. Another object of this invention is to provide an operation which can produce increased yield of motor fuel stocks of at least equal or greater antiknock values than prior art processes. Still another object of this invention is to provide an operation which can be carried out in less costly apparatus and equipment than conventional. Still other objects and advantages of this invention will be realized upon reading the following description which, taken with the attached drawing, forms a part of this specification.

Specifically, this invention comprises a process for increasing the production of valuable hydrocarbons comprising mixing a hydrocarbon naphtha and a cycle oil with an efiluent of a hydrocracking operation as subsequently produced, separating the mixture into a gas phase and a first liquid phase, from this liquid phase separating by distillation a bottoms material, hydrocracking this bottoms material in the presence of added hydrogen, separating the efliuent of the hydrocracking operation into a hydrogen gas rich phase and a second liquid phase, said second liquid phase being the aforementioned eflluent of a hydrocracking operation as subsequently produced, and from the aforesaid distillation separating an intermediate boiling range product of increased yield as a product of the process.

The drawing illustrates in diagrammatic form one arrangement of apparatus parts for carrying out the process of this invention.

In the drawing, feed material which is a full boiling range naphtha, a light cycle oil, or a mixture of these two materials, is introduced from a source, not shown, through a conduit 1 into a hydrodesulfurization zone 2. The catalyst vessel of the hydrodesulfurization zone is provided with a cobalt-molybdena containing catalyst alone or supported on suitable carriers. A suitable cobalt-molybdena catalyst is prepared by adding two parts of ammonium hydroxide to one molar part of ethylenediamine tetraacetic acid slurried in water. One molar part of cobaltous hydroxide or cobaltous carbonate is added to the mixture just prepared with gentle warming to speed the chelation reaction. Upon concentration of this solution, a salt is obtained having the formula (NH4)2C0(Y) "411 0 in which the symbol Y is used to designate the completely ionized form of ethylenediamine tetraacetic acid with the formula as follows:

CH COO NCH CH N( CI-I CO O") +4H+ White beads of a commercial silica-alumina cracking catalyst containing 10 percent by weight of alumina, and 8 to 14 mesh, are used as a support for the above-produced cobalt-containing material. The cobalt-chelate solution concentration is adjusted so that the volume of chelate solution absorbed by the support material contains a quantity of dissolved cobalt metal equal to 0.5 percent by weight of the finished catalyst. Sufiicient ammonium molybdate [(NH4)6M07O244H2O] is then dissolved in the cobalt-chelate solution so that the volume of the solution absorbed by the support material contains a quantity of molybdenum metal equal to 2 percent of the finished catalyst by weight. Since the cobalt has been prepared as a chelate compound, it is not necessary to add ammonia in great excess, as is required to maintain cobalt and molybdenum in the conventional impregnating solution where the cobalt is not chelated. The support is covered with the cobalt-molybdenum solution and allowed to stand for 24 hours to assure thorough impregnation. The support material is then removed from the solution and kept at 250 F. until dry. It is then calcined for two hours at 830 F., two hours at 930 F. and for twelve hours at l030 F.

Full details of the preparation of this cobalt-molybdenum catalyst are given in US. Patent 2,889,287.

However, if desired, the hydrodesulfurization vessel can employ a platinum containing catalyst in place of the cobalt-molybdenum catalyst described above. If platinum supported catalyst is desired, it may be prepared by adding, for example, ammonium hydroxide to a salt of aluminum, as, for example, aluminum chloride, aluminum sulfate, aluminum nitrate, or other suitable, soluble aluminum salt in an amount to form aluminum hydroxide. Upon drying this so-formed aluminum hydroxide, it is converted to alumina, this term being intended to be sufficiently broad to include aluminum hydroxide as produced by the ammonium hydroxide reaction. Thus, after this alumina has been formed, it is washed to remove such soluble impurities as chloride. Washing is usually carried out with water either by filtration or by decantation. Washing is expedited in case the wash water is made alkaline with ammonium hydroxide. After the alumina is free from soluble impurities halogen ion such as fluoride, preferably, or chloride is added in the form of, for example, the corresponding acid. Suflicient concentration of halogen ion in the finished catalyst will be Within the range of from about 0.1 percent to about 8 percent by weight of the alumina on a dry basis. 'In case fluoride is added, the concentration of the fluoride is generally within the range of about 0.1 to about 3 percent by weight of the alumina on a dry basis. In case the halogen ion is chloride, it will be added to the alumina in an amount to provide chloride from about 0.2 percent to about 8 percent and preferably from about 0.5 percent to about 5 percent by weight of the alumina on a dry basis.

After halogenating the alumina catalyst, as just described, a separate solution of chloroplatinic acid in water is saturated with hydrogen sulfide at room temperature 3 until the solution reaches a constant dark coloration. It is preferable to add the hydrogen sulfide to the chloroplatinic acid solution at room temperature. The platinum is added in an amount to produce a final catalyst containing from about 0.01 percent to about 1 percent by weight of irregular size and shape.

After pilling, extruding, or forming as a powder or granules, the catalyst is calcined at a temperature of from about 800 to about 1200 F. for a period of from about 2 to 8 hours or more Full details of the preparation of such a platinum catalyst are given in US. Patent 2,479,110.

The boiling range of the combined naphtha (100 to 500 F.) and light cycle oil (460 to 660 F.) fed through conduit 1 to the hydrodesulfurization zone 2, when employing a cobalt-molybdenum catalyst prepared as mentioned hereinabove, is from about 100 to about 700 F. The feed material is heated to a temperature within the range of about 500 to about 900 F. and passed at this temperature into the cobalt-molybdenum catalyst at a space velocity of about 0.5 to 4 volumes of feed material per volume of catalyst per hour. At a space velocity of '3 the catalyst is maintained at a temperature of about 700 F. under a pressure of about 425 p.s.i.g. (pounds per square inch gauge). Hydrogen, from a source, not shown, is passed through a conduit 3 into the hydrodesulfurization zone 2 at a rate of about 5 -5 000 =s.c.f. per b arrel of hydrocarbon feed. Pressure in the zone can be varied between approximately 350 and 1000 p.s.i.g. (S.c.f. is standard cubic feet.)

Efiluent from the hydrodesulfurization zone is removed therefrom and passed through a conduit 4 and is cooled-to a heat exchanger 31. After cooling in exchanger 31 a liquid hydrocarbon hydrocracking effluent, subsequently produced, is passed through a conduit 5 and added thereto and the combined feed material is passed into a phase separator 6. In this phase separator maintained at a temperature within the range of about 95 to about 115 F., and at a pressure of about 275 to 325 p.s.i.g., the gaseous material is withdrawn through a conduit 7 for such disposal as desired. This gaseous material is rich in hydrogen and contains hydrogen sulfide in proportion to the sulfur content of the naphtha in the feed in conduit 1. The liquid phase separated in separator 6 is withdrawn therefrom and is passed through a conduit 8, and is heated in a heat exchanger 32 and introduced into a fractionator 9. This fractionator is operated under such fractional distillation conditions as to produce a light hydrocarbon overhead product, and a difiicultly condensible overhead gas. Also, an intermediate boiling range sidestream is withdrawn through a. conduit 17 while a bottoms liquid material is withdrawn through a conduit 21. The overhead vapors from fractionator 9 are withdrawn therefrom by way of a conduit 10, condensate is produced in condenser 11 and phase separation takes place in an accumulator vessel 12. Uncondensed gases are removed through a conduit 13 for such disposal as desired. Condensate passes through a conduit 14 and that portion thereof required for refluxing the fractionator is passed through a conduit 15 to the upper portion of the vessel. The portion of condensate, not required for refluxing is withdrawn from the system through a conduit 16 for such disposal as desired.

The sidestrearn taken through conduit 17 boiling in the range of about ISO-400 F. can, if desired, be improved in antiknock value by conversion in a reforming operation. For reforming the sidestream from conduit 17 is.

heated in a heat exchanger 33, which can be a furnace, to such a temperature as required for conversion in a reforming unit 18. In the reforming unit 18 a platinumcontaining catalyst such as that mentioned hereinbefore can, if desired, be used. Gaseous hydrogen, froma source not shown, is introduced into the reforming unit 18 through a conduit 35.

In general, a reforming operation employing the platinum catalyst involves subjecting the sidestrea-m from conduit 17 in the reforming unit to contact with the catalyst at a temperature of from about 800 to about 1000 F., at a pressure from about 200 to about 800 p.s.i.g., at a weight hourly space velocity of from about 0.5 to about 10, in the presence of from about 0.5 to about 10 mols of hydrogen per mol of hydrocarbon. The catalyst in this particular case comprises support alumina containing from about 0.01 percent to about 1 percent of platinum by weight of the catalyst and halogen ions in an amount of from about 0.1 percent to about 8 percent by weight of the catalyst. a

This reformer 18 includes the actual catalyst-contain ing vessels with furnaces for reheating in between the vessels, reformer eilluent condensing means and liquid-gas separator. The reformed liquid hydrocarbon is withdrawn through a conduit 19 for such disposal as desired while the gas from the separator is withdrawn through a conduit 20. In such a reforming operation the gas in conduit 20 is largely hydrogen. is produced in the reforming operation than is required in the reforming operation and in a subsequent operation, to be hereinafter described, the net hydrogen produced is withdrawn from the system through a conduit 36 for such disposal as desired. A portion of the hydrogen from the reformed can be recycled from the conduit 20 to conduit 35, and the remainder used for other purposes, as herein disclosed.

The liquid bottoms fraction passing through conduit 21 from fractionator 9 has a boiling range in general higher than the end boiling point of the desired gasoline fraction. This material, I find, is susceptible to further improve ment as regards production of gasoline boiling range bydrocarbons of improved octane number or antiknock value. Thus, I pass this high boiling bottoms fraction through conduit 21 by pump 22, through a conduit 23 to a heater or heat exchanger 34. This heat exchanger heats this material to a temperature within the range of about 400 to about 900 F. After passing through heat exchanger 34 the heated material is passed into a hydrocracking zone 25 maintained at a pressure within the limits of about 500 to 2000 p.s.i.g., and which is provided preferably with a cobalt-molybdenum-containing catalyst hereinabove described. Along with the bottoms from fractionator 9 free hydrogen gas is also heated in heater 34 and passed into the hydrocracking zone. At least a portion of the hydrogen entering conduit 23 can, if desired, originate in the reforming unit 18 and, after being separated from the reformed liquid hydrocarbon in zone 18, is passed through conduit 20, compressor 24, for addition to the hydrocarbon in conduit 23. The hydro- -cracked eflluent material is passed from zone 25 through a conduit 26 and is cooled in a heat exchanger 27.

From the cooler or heat exchanger 27 the hydrocracked material is passed on into a separator vessel 28 in which difiicultly condensible gases are separated from a liquid phase. The difiicultly condensible gases separated in separator 28 comprise largely unused or newly produced free hydrogen gas. This gas is passed through a conduit 29 by a compressor 30 and is added to the charge liquid passing through conduit 23. Liquid separated in separator 28 is passed through a conduit 5 and is added to the hydrodesulfurization zone effluent flowing through conduit 4 prior to its entry into the phase separator 6. The separator 2.8 is maintained at a temperature within the' range of about to about F. at a pressure with-- in the range of about 500 to about 2.000 p.s.i.g. Thev In casemore hydrogen.

pressure in this separator is usually about p.s.i.g. less than in the conversion zone 25.

As mentioned hereinabove, a preferable catalyst for use in the hydrocracking operation in zone is a cobalt-molybdena catalyst as previously described. New hydrogen for introduction into the hydrocracking zone and originating from the reforming operation comprises about 2 to 9 pounds per barrel of charge, While the total recycle hydrogen, that is, that hydrogen separated in separator 28 and passed through conduit 29, comprises from about 4 to pounds per barrel of charge to zone 25. The space velocity of the charge liquid entering the hydrocracking Zone 25 is from 3 to 4 volumes of hydro carbon per volume of catalyst per hour.

The fractionator 9 is provided with efiicient vapor liquid contact promoting apparatus such as bubble cap trays which are conventional in the fractional distillation art. Reboiling heat is provided as required.

In the following tabulation are given the broad operating conditions of the several process steps of this invention.

Range Specific Example (11) Hydrodesuliurization Zone:

Pressure, p.s.i.g

Temperature, F-- Catalyst Used- Hydrogen, s.e.t'./bbl

Feed b. Naphtha 600; 51.1 Ih API. Light cycle oil 200; 28 API. (Light Cycle Oil) API at 60/60" F-.- 24 to 32 28. Boiling Range 350 F. to 700 F. 460 F. to 660 F.

(ASTM). Aniline No 100-120" F 110 F.

Space Velocity, Vol./Hr./

o Hydrocracking Separator iquid: Quantity to HDS Separar, API at [SO/60 F Boiling Range (c) HDS Separator Zone:

Temperature, F Pressure, p.s.i.g- H1 (foul) removed, Lbs./

Liguid to Fractionator,

in at e0/eo F 44-55 Boiling Range 100 F. to 700 F. 160 to 656 F (ASTM). (ASTM).

Fractionation Zone:

Top pressure, p.s.i.g Top temperature, F Bottom pressure, p.s.i.g Bottom temperature, F Yields:

Vapofr (composition),

5.0. Light H/C, b./h

133. APT at (SO/60 F--- 87.3. 0 Boiling Range -44 F. to 190 F.

lBP l Distillatron. To Reformer, b./h

API at (EU/60 F- Boiling Range (e) Hydrocraclring Zone:

Pressure, p.s.i.g Temperature, F 9 Hi from Reforming, #lbarrel of charge. Rigycle H2, #/barrel of arge. Space Velocity, Vol./Hr./

1 True boiling point. 2 Research Octane Number with 3 cc. tctraethyl lead.

Range Specific Example (I) Hydrocracking Zone Separator: Pressure, p.s.i.g 5002,000 1,500. Temperature, F -125 115.

While certain embodiments of the invention have been described for illustrative purposes, the invention obviously is not limited thereto.

That which is claimed is:

1. A process for increasing the production of valuble hydrocarbons comprising hydrodesulfurizing a hydrocarbon feed liquid comprising a full boiling range naphtha and a light cycle gas oil, said feed liquid boiling within the range of about 100 to about 700 F. at a temperature Within the range of about 500 to about 900 F. at a pressure Within the range of about 350 to 1000 p.s.i.g. in the presence of a hydrogenation catalyst and from about 2.5 to about 27 pounds free hydrogen per barrel of said feed liquid, mixing with the effluent of the hydrodesulfurizing operation an entire liquid phase efiluent of a hydrocracking operation as subsequently produced, separating the mixture into a gas phase and a first liquid phase at a temperature within the range of about 90 to F. and at a pressure Within the range of about 200 p.s.i.g. to about 500 p.s.i.g., from this first liquid phase separating by distillation a bottoms material boiling Within the range of about 350 and about 700 F., hydrocracking only this bottoms material at a temperature Within the range of about 400 to about 900 F. at a pressure of within the range of about 5 00 to 20-00 psi-g. in the presence of added hydrogen Within the range of about 2 mols to about 10 mols .per mol of bottoms hydrocarbon and in the presence of a hydrogenation catalyst comprising cobalt oxide and molybdenum oxide on an alumina containing catalyst, cooling the effluent of the hydrocracking operation and separating therefrom a hydrogen gas rich phase and a second liquid phase at a temperature Within the range of about 105 to F. at a pressure within the range of about 500 to 2000 p.s.i.g., said second liquid phase being said entire liquid phase cflluent of a hydrocracking operation as subsequently produced, said hydrogen gas rich phase being at least a portion of said added hydrogen, and from the aforesaid distillation separating an intermediate boiling range product of increased yield and suitable as a charge stock for a reforming operation.

2. In the process or" claim 1, reforming said intermediate :boiling range product thereby producing a final product of improved antiknock value and of increased yield.

References Cited in the file of this patent UNITED STATES PATENTS 2,334,159 Friedman Nov. 9, 1943 2,380,279 Welty July 10, 1945 2,703,308 'Oblad et al. Mar. 1, 1955 2,736,685 Wilson et al. Feb. 28, 1956 2,911,352 Goretta et *al. Nov. 3, 1959 2,917,456 Ashley -Dec. 15, 1959 2,982,717 Waddil May 2, 1961 FOREIGN PATENTS 791,072 Great Britain Feb. 26, 1958

Claims

1. A PROCESS FOR INCREASING THE PRODUCTION OF VALUBLE HYDROCARBONS COMPRISING HYDRODESULFURIZZING A HYDROCARBON FEED LIQUID COMPRISING A FULL BOILING RANGE NAPHTHA AND A LIGHT CYCLE GAS OIL, SAID FEED LIQUID BOILING WITHIN THE RANGE OF ABOUT 100* TO ABOUT 700*F. AT A TEMPERATURE WITHIN THE RANGE OF ABOUT 500* TO ABOUT 900*F. AT A PRESSURE WITHIN THE RANGE OF ABOUT 350 TO 1000 P.S.I.G. IN THE PRESENCE OF A HYDROGENATION CATALYST AND FROM ABOUT 2.5 TO ABOUT 27 POUNDS FREE HYDROGEN PER BARREL OF SAID FEED LIQUID, MIXING WITH THE EFFLUENT OF THE HYDRODESULFURIZING OPERATION AN ENTIRE LIQUID EFFLUENT OF A HYDROCRACKING OPERATION AS SUBSEQUENTLY PRODUCED, SEPARATING THE MIXTURE INTO A GAS PHASE AND A FIRST LIQUID PHASE AT A TEMPERATURE WITHIN THE RANGE OF ABOUT 90* TO 120*F. AND AT A PRESSURE WITHIN THE RANGE OF ABOUT 200 P.S.I.G. TO ABOUT 500 P.S.I.G., FROM THIS FIRST LIQUID PHASE SEPARATING BY DISTILLATION A BOTTOMS MATERIAL BOILING WITHIN THE RANGE OF ABOUT 350* AND ABOUT 700*F., HYDROCRACKING ONLY THIS BOTTOMS MATERIAL AT A TEMPERATURE WITHIN THE RANGE OF ABOUT 400* TO ABOUT 900*F. AT A PRESSURE OF WITHIN THE RANGE OF ABOUT 500 TO 2000 P.S.I.G. IN THE PRESENCE OF ADDED HYDROGEN WITHIN THE RANGE OF ABOUT 2 MOLS TO ABOUT 10 MOLS PER MOL OF BOTTOMS HYDROCARBON AND IN THE PRESENCE OF A HYDROGENATION CATALYST