US2426233A - Production of aviation base fuel - Google Patents

Description

Aug. 26, `1947. R. H. NEWTON PRODUCTION OF AVIATION BASE FUEL Filed March 2B, 1942 INVENTOF: ROGER Il /vEwr/v BY Qu l. num A'rroRNEf Patented Aug. 26, 1947 l I PRODUCTION-OF AVIATION FUEL Roger H; Newton, Bowling. Green, Pa., assignmto Houdry Process Corporation, Wilmington, Del., a corporation of Delaware Application March 28, 1942', Serial No. 436,547

6 Claims. (Cl. ISG-52) This invention relates to the production of desirable hydrocarbommaterials, including motor fuels and ,especially base material for l high quality, high octanev aviation gasoline of the fighting grade type. In certain respects it may be considered as an improvement upon or further development of the invention disclosed in my. copending applicationv Serial No.\427,409, led January 20, 1942.

One object of the invention is to produce high quality hydrocarbon materials having definite characteristics, Another object is to produce aviation base material which can be brought to an octane rating of 100 or better by the addition of tetraethyl lead alone. .Other objects will be apparent from the detailed description which follows.

In order to illustrate the invention one concrete embodiment thereof is indicated diagrammaticaily in the single figure of the accompanying drawing. i,

In the drawing fresh charge such as gas' oilis sent by line I, along with recycle material added by line 2 through vaporizing still 3, whence it passes at cracking temperature to a catalytic converter li containing high activity cracking catalyst. The cracked products pass by line 5 to suitable fractionating equipment such as tower 6 which divides the same in to: (1) a bottoms fraction, which is a clean stock higher ,boiling than motor gasoline,"su`ltable for use as Diesel oil or domestic fuel oil, which leaves the tower by line 1 to storage in tank 8; (2) a side stream fraction having an end point in the-range oi 325 to 475 F. which leaves tower 8 by line 9 to pass to aside stream stripper, preferably of the-reboiler type which feeds back into tower 6 at a higher. level byline ii; and (3) an overhead out having an end point in the range oi 180 to 260 F. which leaves tower 6 by line I2. The side stream fraction leaves stripper I by line |-3 which is branched to send a portion back to still 3 by line 2` as recycle while the remainder is added to the overhead cut in line I2 and passes with the same either vto condenser i4 and gas separator Ma., which are optional and utilized only when lighterpro'ducts of the ilrst stage of the operation are tile withdrawn, or by by-passing line i5 to further treatment in the second stage of the operatio'niwJr 2 The condensed hydrocarbons from gas separator 44a or by-pass line I5, or both, which comprise motor gasoline are now subjected to another catalytic treatment in vapor phase underl conditions as severe as in the first catalytic cracking zone 4 .and usually more severe, as higher temperatures, higher pressures, or both. To this end they are sent through vaporizing still i8 to catalytic converter I1 containing high activity cracking catalyst of the same or different type as in zone 4 and preferably of at least as high activity. The products pass to fractionating equipment such as tower I8 which divides the same according to the desires or requirements of the reflner. In the arrangement shown in they drawing three cuts aremade. Aviation base material, 300 F. end point, is taken overhead by line i9 to condenser 20 and thence to separator 2| where fixed gases are removed by line 22 and the aviation gasoline passes by line 23 to suitable stabilizing equipment (not indicated) and thence to storage tank '24. A side stream fraction of motor naphtha, boiling range 300 to 400 F., is removed by line 25 to storage tank 26. The remaining hydrocarbons boiling above 400 F. are removed by bottom line 21 and pass to storage tank 2B. The latterare highly aromatic, are highly'desirable as solvent, and have other uses of a specialized character.

Any known or suitable forms of catalytic equipment which give proper control of operating conditions may beutlized at 4 and i1. With stationary catalyst, which is preferred, there will be a battery oi converters' at each location to permit regeneration of the catalytic material in place and to provide for continuous operation. Known catalysts which are highly selective'and highly active in promoting cracking reactions are utilized for both zones. Siliciou's catalysts including silica-alumina blends or compounds, are suitable, preferably those of high purity and synthetically produced, with or without the inclusion of other active materials such as metals or metallic compounds. zirconium compounds with silica and with or without alumina are also effective catalysts. ity index of at least 35, which indicates ability to convert at least 35% of a standard reference stock, such as East Texas gas oil under standard operating conditions Ato lighter products in ac- They should have an activcordance with the procedure set forth in detail on page 2 of the specification of United States Patent No. 2,347,216, issued April 25, 1944, to Albert G. Peterkin.

The operating conditions in the first catalytic zone comprise cracking temperature above 750 F. with low or moderate pressures, but subatmospheric pressures may also be used. The combined charge to still 3, fresh and recycle, ranges from 1/211 to 3.5:1 (liquid volume of charge per hour per volume of catalyst) and the ratio of recycle to fresh charge may vary from A51 to 1:1 but is preferably 1/2:1 to %:1. While with certain charging stocks it is possible in the first y stage of the operation to take practically a full yaviation gasoline overhead in the first fractionating zone and to recycle a side stream cut from the two top trays of the tower, which side stream will overlap somewhat with the overhead cut, it is usually desirable that the recycled material have an initial boiling point of about 200 to 240 F. and an end boiling point of about 400 to 425 F.

As previously stated the operating conditions in the second catalytic zone are usually somewhat more severe than in the first catalytic zone. The temperature Will be above 775 F. and usually above 800 F. with superatmospheric pressures of at least 50 lbs. per square inchl gauge and usually 75 lbs. or above. The feed rate (liquid volume of charge per hour per volume of catalyst) is not over 1%:1 and is frequently asl'low as l/2:1 but is usually from 3/zl to 1:1.

Details of a typical operation are given below:

The fresh feed to the operation was an East Texas gas oil of 36 A. P. I. gravity and the fol- It was subjected to the action of a synthetic silica-alumina catalyst of high activity (40 index) maintained at a mean temperature of 820 F. under 30 lbs. per square inch gauge pressure for on-stream periods of ten minutes. The total feed rate to the catalyst was 21:20 (liquid volume of charge per hour per volume of catalyst) which was made up of fresh feed 14:20 and recycle stock 7:20, or at a recycle ratio of l/2:1. The recycle material was a naphtha of the following boiling range:

lowing boiling range:

. y F. Initial 432 10% 480 538 90% 640 F. Initial 230 10% 267 50% 318 90% 402 The material charged to the second catalytic zone was approximately 42% of the fresh charge to the lrst catalytic zone and had boiling range:

The second catalytic zone containing synthetic silica-alumina catalyst of the same type and acthe following tivity as the first zone and the operating conditions were; mean catalyst temperature 830 F.. pressure 75 lbs. per square inch gauge with 1:1 feed rate for on-stream periods of twenty minutes. The yields of both zones were taken for purposes of comparison and were es follows:

1 Solvent.

Inspection and tests of the aviation cut of gasoline from each zone revealed the following:

% Evaporation at 275 l- 262 F,

eid Vapor Pressure. 8.3 7.0. Acid Heat 2|v Less than 'i A. F. D.l-C Octane-+3 cc. 'I. 05.

+4 cc. 'l. E. L... J7.ti Ovcr 100 or iso- :ctaliiwI-k ec. Calculated A. F. D.l-C Octane at 7 00.8 Over 10U or iso- R. V. Pri-4 cc. T. E. L. nctnne-i-.Uz cc.

'l. ii. i..

In order to reach octane with the aviation gasoline from the first catalytic stage it was found necessary to add 20% alkylate in addition to the 4cc. T. E. L.

With gas oil charging stock of naphthenic Coastal types the aviation octanes obtainable in each stage will be somewhat higher than in the above example. Mid-Continent gas oils have been found to give approximately the same results as East 'lexas stocks.

It is preferable from an economical standpoint to send the entire motor gasoline cut from the rst catalytic stage to the second catalytic stage because of the increased yield of aviation gasoline but it is to be understood that if the aviation cut alone is charged to the second catalytic stage the resulting products will be of lik quality. It is particularly to be noted that with 4 ce. of tetraethyl lead the aviation base material from the second stage becomes a finished aviation gasoline having an octane rating considerably above 100, the measure of which is expressed accurate.- ly. as indicated in the above example, as isooctane tetraethyl lead (fractional cc.s of tetraethyl lead mean several octane points due to the high lead susceptibility of iso-octane).

I claim as my invention:

1. In the production of high grade fuels of the gasoline type including aviation fuels, the process comprising subjecting hydrocarbon charging stock to catalytic cracking in the presence of a body of highly active cracking catalyst, separating from products of said cracking a light normally liquiddistillate having an end point in the range oi F.'to 260 F. and a heavier distillate having a boiling range from approximately the end point of said light distillate to a temperature within the range of 325 F. to 475 F., returning a poi-tion only of said heavier distillate to said first body of catalyst with said hydrocarbon charging stock, subjecting said light distillate and the remainder of said heavier distillate to catalytic cracking in the presence of a second body of highly active cracking catalyst, and separating a product of the gasoline type from the products of the last named cracking the steps comprising subjecting hydrocarbon' charge heavier than gasoline to catalytic cracking in the presence of a body "of high activity cracking catalyst, separating from resulting cracked products a first liquid distillate fraction having an end point in the range of 180"4 F. to 260 F. and a heavier liquid distillate fraction having `a boiling range from approximately the end point of said first distillate fraction to a` temperature within the range of 325 F. to 475 F., returning a portion only 'of said Iheavier liquid distillate to said body of catalyst with said charge for conversion with the latter, combining said iirst distillate with the balance of said heavier distillate, subjecting the combined distillates to further catalytic cracking in a second separate catalytic cracking step at cracking conditions more severe than used in the iir'st mentioned catalytic cracking step, and separating from products of said second separate catalytic cracking step a high octane distillate of the gasoline type.

3. Inthe production of high grade fuels of the gasoline type including aviation fuels, the proc- V ess comprising subjecting hydrocarbon charging stock to catalytic cracking in the presenceof high activity cracking catalyst, separating from products of said cracking a relatively heavy gasoline type fraction comprising part only of the Vvcracked hydrocarbons boiling above about 180 F. and blow about 475 F., returning said fraction to said cracking catalyst with said hydrocarbon charging stock, subjecting to a second separate catalytic cracking stepV cracked gasoline type -distillate obtained from said first catalytic crackin g step, including relatively light gasoline hydrocarbons boiling below about 180 F; and relatively heavy gasoline hydrocarbons boiling within the range of an initial boiling point of approximately 180 F. to 260 F. and an end boiling point of approximately 325 F. to 475 F., and separating from the products of said second catalytic cracking step a high anti-knock liquid product of the gasoline type.

4. In the production of high grade fuels of the gasoline type including aviation fuels, the process comprising subjecting hydrocarbon charging stock to catalytic cracking in the presence of high activity cracking catalyst, separating from products of said cracking a relatively heavy gasostock to catalytic cracking in the presence of high activity cracking" catalyst, separating from products of said cracking a relatively heavy gasoline type fraction comprising part only of the cracked hydrocarbons boiling above about 180 F. and below about 475 F., returning said fraction to said cracking catalyst with said hydrocarbon charging stock, subjecting to a second separate catalytic cracking step effected at cracking conditions more severe than employed with said hydrocarbon charge cracked gasoline type distillate obtained from said first catalytic cracking step, including relatively light gasoline hydrocarbons boiling below about 180F. and relatively heavy gasoline hydrocarbons boiling withinithe range of an initial boiling point of approximately 180 F. to 260 F. and an end boiling point of approximately 325 F. to 475 F., and separating from the products of said second catalytic cracking step a high anti-knock liquid product of the gasoline type.

6. In theproduction of high grade fuels of the gasoline type including aviation fuels, the process comprising subjecting hydrocarbon charging stock to catalytic cracking in th'e presence of high activity cracking catalyst, separating from procli ucts of said cracking a relatively heavy gasoline type fraction comprising part only of the cracked hydrocarbons boiling above about 180 F. and below about 475-F., returning said fraction to said cracking catalyst with said hydrocarbon charging stock, subjecting to a second separate catalytic cracking step eected at higher temperatures and lower space rate than employed with said charging stock cracked gasoline type .distillate obtained from said first catalytic cracking step, including relatively light gasoline hydrocarbons boiling below about 180 F. and relatively heavy gasoline hydrocarbons boiling within the range of an initial boiling point of approximately 180 F. to 260 F. and an end boiling point of 4 approximately 325 F. to` 475 F., and separating line type fraction comprising part only of the lcracked hydrocarbons boiling above about 180 F. and below about 475 F., returning said fraction to said cracking c'at'alyst with said hydrocarbon charging stock in the ratio of one-fourth to one part of said fraction to each part of said hydrocarbon charging stock, subjecting to a second separate catalytic cracking step cracked gasoline type distillate obtained from said first catalytic cracking'step, including relatively light gasoline hydrocarbons boiling lb elow about 180F. and relatively heavy gasoline hydrocarbons boiling within the range of aninltial boiling point oi' approximately 180 F. to 260 F. and an end boiling point of approximately 325 to 475 F., and separating from the products of said second catalytic cracking step a high anti-knock liquid oi the gasoline type.

5. In the production of high grade fuels of the gasoline typek including aviation fuels, the process comprising subjecting hydrocarbon charging from'the products of said second catalytic cracking step a high anti-knock liquid product of the gasoline type.

ROGER H. NEWTON.

nEFEaENcEs crran The following references are of record in the iile of this patent:

AUNrrED s'rA'rEs PATENTS Number Name Date 2,224,840. Story Dec. 10. 1940 2,282,855 Egloi! May 12, 1942 2,293,759 Penisten Aug. 25, 1942 2,141,185 Houdry s Dec. 27, 1938 2,266,012 DOuville Dec.16, 1941 2,276,081 McGrew Mar. 10, 1942 l 2,283,854 Friedman etal May 19, 1942 2,287,940 McGrew June 30, 1942 2,304,183 Layng et al. Dec. 8, 1942 2,328,754 Thomas Sept.`7, 1943 2,310,327 Sweeney Feb.` 9, 1943 2,337,640 Burgin Dec. 28, 1939 2,339,918 Thomas Jan. 25, .1944 2,349,045 v Layng et ai. May 16, 1944 2,361,138 Voorhies, Jr. Oct. 24, 1944 2,361,611 DOuville et al. Oct. 31, 1944 FOREIGN PATENTS Number Country Date 829,582 French Apr. 5, 1938

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