US3642611A

US3642611A - Production of motor and jet fuels

Info

Publication number: US3642611A
Application number: US887720A
Authority: US
Inventors: Odes B Robertson; Thomas A Cooper; Henry D Moorer
Original assignee: Texaco Inc
Current assignee: Texaco Inc
Priority date: 1969-12-23
Filing date: 1969-12-23
Publication date: 1972-02-15
Anticipated expiration: 1989-02-15

Abstract

Good yields of high-quality motor fuel and jet fuel are obtained by solvent extracting a gas oil to produce a paraffin-rich raffinate and an aromatic-rich extract, hydrocracking the raffinate using a catalyst having an amorphous support, separately hydrocracking the extract using a catalyst containing a crystalline zeolitic support and recovering jet and motor fuels from the respective hydrocracker effluents.

Description

United States Patent Robertson et al.

[151 3,642,611 [451 Feb. 15,1972

154] PRODUCTION OF MOTOR AND JET FUELS [72] Inventors: Odes B. Robertson, Groves; Thomas A. Cooper, Port Arthur, both of Tex.; Henry D. Moorer, Richmond, Va.

[73] Assignee: Texaco Inc., New York, NY.

[22] Filed: Dec. 23, 1969 211 Appl. No.: 887,720

[52] US. Cl ..208/87, 208/15, 208/78,

[51] Int. Cl ..Cl0g 13/02 [58] Field ofSearch ..208/15,78, 80, 87, 111

[56] References Cited UNITED STATES PATENTS 2,627,495 2/1953 Lanning ..208/80 Primary Examiner-l-lerbert Levine AttorneyThomas H. Whaley, Carl G. Ries and Robert Knox, Jr.

[57] ABSTRACT Good yields of high-quality motor fuel and jet fuel are ob- 9 Claims, No Drawings PRODUCTION OF MOTOR AND JET FUELS This invention is concerned with the production of gasoline and jet fuel. More particularly it relates to a method for the simultaneous production of jet fuel and gasoline.

Up until recently gasoline or motor fuel was by far the greatest demand product of the petroleum industry and accordingly it was desirable to get the maximum yield of gasoline per barrel of crude oil. To this end, most refineries were designed to convert those fractions boiling between about 450 F. and the lube oil range, i.e., the gas oil fractions, into gasoline and this was accomplished, for the most part, by fluid catalytic cracking. in the cracking of petroleum fractions, it is customary to recycle unconverted material to the cracking unit but eventually this recycled fraction, known as cycle gas oil, becomes so refractory and difficult to crack that a portion of it is withdrawn and sold as distillate fuel. However, with-the advent of jet engines, fractions having an initial boiling point of from 350-400 F. and an end point of about 525 F. have come into great demand as jet fuels. It has therefore now become customary to charge virgin gas oils to fluid catalytical cracking units and recover from the cracking unit as product bath gasoline and jet fuel and to recycle to the cracking unit that fraction of the effluent boiling above the jet fuel range. However, for the most part this process is unsatisfactory in that to meet the ever increasing jet fuel demands the gasoline end point must be compromised with jet fuel quality and/or product demands. This generally results in a gasoline having an end point of about350 F. which means an overall reduction in the amount of gasoline produced. Moreover, because of its low lurninometer number, the jet fuel fraction of the cycle gas oil is not completely satisfactory for use in jet aircraft engines.

It is an object of the present invention to provide a process for the production of motor fuel and jet fuel which comprises subjecting a petroleum hydrocarbon liquid having an initial boiling point of at least about 5,000 F. to solvent extraction to produce a paraffin-rich raffinate and an aromatic rich extract, hydrocracking the raftinate using a catalyst comprising a hydrogenating component on a noncrystalline amorphous support, recovering ajet fuel from the hydrocracked raffinate, separately hydrocracking the aromatic-rich extract using a catalyst comprising a hydrogenating component on a support comprising a crystalline zeolite and recovering a motor fuel from the hydrocracked extract.

The charge stocks used in the process of our invention include any hydrocarbon oil boiling above about 500 for example atmospheric gas oils, vacuum gas oils, atmospheric residua and the like. The preferred starting materials are virgin atmospheric gas oils and cycle gas oils obtained-from the fluid catalytic cracking units.

The charge is subjected to solvent refining using a solvent having an affinity for aromatics such as S0,, furfural, N- methyl pyrrolidone and the like. solvent dosages may range from 75-600 percent depending on the solvent and the charge stock. Temperatures of 50-250 F. may be used also depending on the solvent and charge stocks. Preferred solvents are furfural of N-methyl pyrrolidone used at dosages of 75-300 percent and temperature of about 75-l 50 F.

The rafiinate after being stripped of residual solvent is hydrocracked by being brought into contact with a hydrocracking catalyst at a temperature between about 450 and 900 F., a pressure between about 500 and 5,000 p.s.i.g., a space velocity between 0.2 and and a hydrogen rate of 2,000-30,000 SCFB. Preferred conditions are temperatures between 550 and 850 F., pressure of l,00O-2,500 p.s.i.g., space velocities between 0.5 and 3 and hydrogen rates between 4,000 and 20,000 SCFB.

The catalyst used for the hydrocracking of the raffinate comprises a hydrogenating component on an amorphous support. The hydrogenating component may comprise a Group Vll metal or compound thereof either alone or in conjunction with a Group Vl metal or compound thereof. When the hydrogenating component is a noble metal such as platinum,

palladium, sodium and the like, it is used in amounts between 0.1 and 5 percent, preferably between 0.2 and l percent based on the weight of the catalyst composite. When the hydrogenating component comprises an iron group metal or compound thereof, it may be used alone but preferably it is used in conjunction with a Group Vl metal such as molybdenum or tungsten or compounds thereof. In such event, the iron group metal may be present in an amount between about 2-20 percent, preferably 5-l0 percent by weight based on the catalyst composite and the Group V] metal may be present in an amount between about 5 and 35 percent, preferably between 6 and 25 percent by weight. Examples of combinations of Group V] and Group Vlll metals are cobalt-molybdenum, nickel-molybdenum and nickel-tungsten. Advantageously the catalyst contains a minor amount of halogen such as 0.1-5 percent fluorine or chlorine.

The support for the catalyst used in the hydrocracking of the raffinate is composed of one or more amorphous inorganic oxides such as silica, alumina, zirconia, magnesiaandthe like. The preferred support is a mixture of silica and alumina containing from about 50-80 percent silica and 50-20 percent alumina by weight. A preferred catalyst contains 6 percent nickel and 19 percent tungsten on a support composed of 73 percent silica and 27 percent alumina. Advantageously, the catalyst is sulfided prior to use.

After the solvent has been removed from the extract as for example by distillation and stripping,'the extract is subjected to hydrocracking. The conditions used for the hydrocracking of the extract such as temperature, pressure, space velocity and hydrogen rate are substantially the same as those used for the hydrocracking of the raffinate. However, the catalyst which contains a hydrogenating component such as (and which may be the same as) that of the catalyst used for the hydrocracking of the raffmate also contains a support which includes about 8-60 percent by weight of the support of a crystalline zeolitic alumino silicate. The crystalline portion of the support has substantially uniform pore openings of from 6-l 5 Angstroms and has an alkali metal content of less than 5' percent and preferably less than 1 percent. Suitably the crystalline portion of the support may be prepared by subjecting zeolite Y to ion exchange treatment with a solution of an ammonium salt to reduce the alkali metal content to about 3 percent. The zeolite is then washed, dried and calcined at a temperature of about l,200 F. for several hours the calcined zeolite is then subjected to a second .ion exchange treatment with a solution of an ammonium salt to reduce the alkali metal content to less than 1.0 percent, washed, dried and again calcined at a temperature of at least about l,000 F. for several,

hours. The zeolite is then mixed with an amorphous inorganic oxide to provide the support for the hydrogenating component. Preferably, the balance of the support comprises a mixture of silica and alumina containing from 50-80 silica and 50-20 percent alumina. A preferred catalyst contains 6-8 percent nickel and 22 percent tungsten on a support containing 24 percent decationized zeolite Y, 57 percent silica and I9 percent alumina.

The effluents from the two hydrocracking units may be combined and fractionated to recover a motor fuel fraction and a jet fuel fraction, that portion of the effluent boiling above the jet fuel range being recycled to a fluidized catalytic cracking unit. Alternatively the effluents may be fractionated separately to recover motor and jet fuels with recycle of the unconverted material. In a preferred embodiment the hydrocracked product boiling above the jet fuel range, whether obtained from the rafilnate or the extract is recycled to the solvent extraction zone.

When the charge to the system has a relatively high basic nitrogen content e.g., above about ppm. nitrogen, it may be subjectedto a denitrogenation treatment such as by contacting the charge with a catalyst such as nickel molybdate on alumina, in a manner well known to the art, to convert the nitrogen therein to ammonia which is removed prior to the solvent extraction step. However when the catalyst used for the hydrocracking of the extract is composed of nickel and TABLE 111 tungsten on a zeolite containing base as described above, then Ramnate Emmi; it is not necessary to subject the entire charge to a g denitrogenation and it is sufficient to subject only the raffinate Isobutene 4. 06 4. 78 2. 36 3. 88 to nitrogen removal prior to hydrocracking. The nickel tung Butane 2 09 L 54 0 60 Q 97 sten sulfide zeolite-based catalyst 18 particularly resistant to Isommanes 4 29 gig 3,4 n-Pentane 0.93 0.60 6 nitrogen poisoning and therefore the extract need not be given H35, F. gasoline 1M5 13. 42 5. 77 9. M this addltlonaltreatment- 235-325 F. gasoline 19.42 1.23 16.37 '26. 1a 325525" F.1etiuel 44. 55 9 The hydrogen used m our process need not be pure. Total 04+ 9Q 09 76 62 63 44. 62 Hydrogen of 70 percent purity may be used but a hydrogen purity of at least 85 percent is preferred. 2354017 Easmine- The following examples are given for illustrative purposes For comparative purposes harge stocks A and B are ub. yjected to hydrocracking using both the amorphous and Charge A i an atmospheric g il in fro South zeolite-based catalysts specified above under comparable Louisiana Light Regular Crude and Charge 3 cycle gas oil operating conditions. Yield date are shown in Table IV.

' TABLE IV Zeolite Amorphous Zeollte Amorphous H consumption, s.c.l.b 1,500 1,090 1,734 1,015 Isobutane, volume percen 15.88 5.10 6.72 7.57 n-Butane, volume percent. 8. 44 2. 68 5. 66 2. 46 Isopetanes, volume percent 19. 5. 48 8. 62 ti. .14 n-Pentenes, volume percent 2.00 1.10 2. 47 1. 43 115-235 F. gasoline, volume percent.. 34. 36 10.32 18. 88 15.82 235-325 F. gasoline, volume percent. 26. 54 24. 31. 26 30. 411 Total gasoline 60. 81 43. 77 50.14 46. 31 325525 F. jet fuel, volume percent... 16.16 57.07 45. 42 54. 84 Total 115-525 F., volume percent... 76.97 100.84 15. 56 101.15 Total 04+, volume percent 122. 115. 38 110.03 110.

obtained from a fluid catalytic cracking unit. The characteristics l e r es ersseliertli sle leblsl.

TABLE I Gravity, API 30. 6 2s. 3 ASTM distillation, F.: 35 IBP-5 513-539 392-466 10-20. 556-580 508-553 30-40. 600-622 578-604 50 640 626 60-70. 662-684 646-665 -90. 714-754 686-718 595-111. 760+ 750-760-l- 40 Sulfur, X-ray, wt percen 0. 15 0.18 Basic nitrogen, p.p.m 61 26 Total nitrogen, p.p.m 111 98 Total aromatics, wt. percen 23. 5 38. 1 Polycyclic aromatics, wt. percen 8. 66 29. 3

Charge A is subjected to solvent extraction with furfural 45 (containing 5 percent water) at a dosage of 75 volume percent and a temperature of F. to obtain a yield of 79.5 volume percent of a raffinate containing 8.8 volume percent aromatics and 20.5 volume percent of an extract containing 80.0 volume percent aromatics. Solvent extraction of Charge B 50 with furfural (5 percent water) at a dosage of volume percent and a temperature of 90 F. yields 66.7 volume percent of raffinate containing 17.1 percent aromatics and 33.3 volume percent of extract containing 80.0 volume percent aromatics.

Hydrocracking conditions for the extracts and raffinates appear below in Table II. In each case for the hydrocracking of the extract the catalyst contains 7.9 weight percent nickel oxide and 24.7 weight percent tungsten oxide on a support containing 24 percent decationized zeolite Y, 57 percent silica and 19 percent alumina whereas the catalyst for the hydrocracking of the raftinate contains 6.5 percent nickel, 21 percent tungsten, 51 percent silica, 18 percent alumina and 1.5 percent fluorine. Also, in each case, the catalyst is sulfided A comparison of the gasoline produced by the various 7 30 procedures exemplified above appears in Table V. Column 1 represents the process of our invention in which the charge is solvent extracted and the raffinate and extract hydrocracked separately using amorphous and zeolite based catalysts respectively. Column 2 represents the process in which'the total charge is hydrocracked over the zeolite-based catalyst and Column 3 in which the total charge is hydrocracked over t e v eessslely t TABLE V Charge stock 1 2 Z1 -235 F. fraction:

Gravity, API. 70. 6 73. 5 68. 5 Research octane ar.-. 74.0 72.0 70.5 Plus 3 c 91. 5 .11. 0 811. 0 235-325 F. fraction:

Gravity, API 56. 5 56. 5 55.11 Research octanes:

Clear 50. 0 (12. 5 50. 0 Plus 3 cc. TEL 70. 0 81. 5 70. 5 235400 F. fraction:

Gravity, API 4855 Research octanes:

Clear 72.0 Plus 3 cc. TEL 88.0 Octane barrels at 3 cc.: TEL basis 100 bbls.

charge 5, 765 4, 265 3, 832

Table VI below shows the jet fuel quality comparison between jet fuels prepared by our process and those prepared by hydrocracking the charge. in Table VI Columns 1 and 3 show the characteristics of the product when the total charge is hydrocracked using a sulfided nickel tungsten silica alumina catalyst and Columns 2 and 4 when the rafflnate is hydrocracked using a sulfided nickel tungsten on silica-aluprior to use. mina catalyst (Table 111). WW W 7 TABLE II Rulllne to Extract Ruillnute Extract 'lcmpumturo, l" 075 715 700 725 l'russurv, p.s.i.g 1. 500 1,500 1,500 1,500 He luto s.r.l./l1l1l. l'vcCL 0, 000 (l, 000 0, 000 (l, 000 IIISV, 'o/llix/Vr U 1.0 l. 1.0 1.0 l'ur puss conversion, volumn pcrccnt 30.0 70.0 30. 0 70.0

Yields from the hydrocracking of the raffinates and extracts in terms of volume percent based on the total charge appear in Table III.

From the foregoing it can be seen that the process of our invention produces motor fuel and jet fuel in greater yields and of better quality than conventional processes.

mam vi Charge stock 1 2 3 4 Gravity API...-.- 45.6 48 43.7 47 AS'IM distillation, a

348 350 347 350 95%- 488 490 498 490 EP 503 510 529 510 Freeze point, F --64 65 52 -65 Flash point, F.- 113 120 120 120 Smoke point, mim 30 40 28 38 Lumlnometer number 64 86 61 83 FIA analysis, volume percent:

romatics 5. 4 2. 0 5. 8 2. 6 Olefins 1. 4 Trace 0.8 Trace Dlnuclear aromatics, wt. percent 0. 06 Trace 0. 24 Trace It is also possible to recycle unconverted material into the system. For example that portion of the hydrocracked raffinate boiling above the jet fuel range may be recycled to the catalytic cracking zone, to the solvent extraction zone or to the raffmate hydrocracking zone. Similarly that portion of the extract boiling above the motor fuel range may be recycled to the catalytic cracking zone, the solvent extraction zone or to the extract hydrocracking zone. Various other modifications of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof and therefore only such limitations should be imposed as are indicated the support in an amount between 8 and 60 percent by weight .of the support.

4. The process of claim 1 in which each hydrogenating component comprises a Group VIII metal or compound thereof.

5. The process of claim 4 in which the catalyst used for the ihydrocracking of the rafi'mate comprises nickel and tungsten.

6. The process of claim 4 in which the catalyst used for the hydrocracking of the extract comprises nickel and tungsten.

7. The process of claim 1 in which the gas oil is derived from a catalytic cracking reaction and that portion of the ihydrocracked raffinate boiling above the jet fuel range is retumed to the catalytic cracking zone.

8. The process of claim 1 in which that portion of the hydrocracked extract boiling above the gasoline range is returned to the solvent extraction zone.

9. The process of claim 2 in which the crystalline zeolite has been prepared by subjecting zeolite Y to a treatment comprising ion exchange with a solution of an ammonium compound, calcination, a second ion exchange with a solution of an ammonium compound and a second calcination.

Claims

2. The process of claim 1 in which the crystaline zeolite has an alkali metal content of less than 1 percent by weight.
3. The process of claim 1 in which the zeolite is present in the support in an amount between 8 and 60 percent by weight of the support.
4. The process of claim 1 in which each hydrogenating component comprises a Group VIII metal or compound thereof.
5. The process of claim 4 in which the catalyst used for the hydrocracking of the raffinate comprises nickel and tungsten.
6. The process of claim 4 in which the catalyst used for the hydrocracking of the extract comprises nickel and tungsten.
7. The process of claim 1 in which the gas oil is derived from a catalytic cracking reaction and that portion of the hydrocracked raffInate boiling above the jet fuel range is returned to the catalytic cracking zone.
8. The process of claim 1 in which that portion of the hydrocracked extract boiling above the gasoline range is returned to the solvent extraction zone.
9. The process of claim 2 in which the crystalline zeolite has been prepared by subjecting zeolite Y to a treatment comprising ion exchange with a solution of an ammonium compound, calcination, a second ion exchange with a solution of an ammonium compound and a second calcination.