US2326779A - High grade motor fuel from straight run and similar hydrocarbons - Google Patents

Description

Aug. 17, 1943. E. J. HOUDRY 2,326,779

HIGH GRADE MOTOR FUEL FROM STRAIGHT RUN AND SIMILAR HYDROCARBON$ Filed Feb. 1, 1940 no udwm INVENTOR I EugenedHnudr BY mQFS Q 5C ATTORNEY covery of 100% or more. The reaction also gives an increase of octane of some to 25 points by the production of such lighter material, which is mostly of the iso pa'raffin type, the average of the lighter material 50 produced being 60 to 80% iso paraffins. The products of the first reaction are then sent, at higher temperature, to a dehydrogenating catalyst which has little or no effect on the boiling range." The operating conditions of this reaction are adjusted to complete the increase in the octane number to the desired rating, and the octanerise here may range from 10 up to about 50 points. In this reaction there is a loss, which varies with the severity of the selected operating conditions, due to gas and coke formation and to the lowering of the A. P. I. gravity of the fuel by dehydrogenation The reaction is conducted between 850 and 925 F., as around 875 F. for example. The gas produced is 70 to 80% hydrogen and is directly useable when added to the charge to reduce coke formation on the catalyst, as taught in the aforesaid U. S. Patent No. 2,141,185, and is further useful to assist in the regeneration of the catalyst. Both operations reduce the sulphur content of the charge.

Hence, by combining the two operations, a solution of the problem of reforming naphthas, with high liquid recovery and without the expense and disadvantages of the use of addition agents, becomes a commercial reality.

It must be kept in mind that the charging material which is to be improved is already in the gasoline boiling range, and that it is, as a rule,

highly resistant to chemical transformation giving an increase of from 30 to 80 points of octane. Therefore, for greatest success, catalysts of extremely high activity are required. Also, for an economical operation, the catalysts must be kept at high activity through frequent regenerations, which should take place while the catalysts remain in place. These two requirements of high sustained activity and stability to frequent alternating reactions of reforming and regeneration impose a severe test upon catalytic materials to be used. Hence it is not merely sufficient to find a catalyst or a combination of catalysts which together will'improve the octane as well as other qualities of naphtha, or .to establish the best conditions of operation for the use of the catalysts. The activity and strength of the catalysts become of primary importance, because they must be capable of regeneration in situ, before the process can be of any value, and they must practically stable in yield and quality of products for a period of at least six months, if the process is to be economical. For proper operation, the catalyst must be in the form of bits, fragments, or molded pieces. It must not lose its shap change its size, or crumble into powder. Many gree of purity, with or without the addition or inclusion of smaliquantities ofother active materials, including metal oxides such as listed below, are suitable. The most active catalysts for this reaction so far developed have been synthetic materials-produced in the hydrous state, for example, by interreaction or coprecipitation of suitable substances, such as sodium silicate and an aluminum compound, as sodium aluminate or an aluminum salt, under controlled pH conditions and followed by suitable treatment to reduce the content of alkali metal to aminimum, as disclosed, for example, in the copending applications of John R. Bates, Serial Nos. 170,648 and 174,966, filed October 23, 1937 and November 17, 1937, respectively, now U. S. Patents 2,283,172 and 2,283,173.'

The catalysts for the second or dehydrogenating reaction may comprise any suitable materials for promoting such a reaction. Among the best materials for this purpose are vanadium, molybdenum, chromium and tungsten, although others,

such as iron,lead, copper, nickel and manganese, may also be utilized, or combinations of any of the above. The catalysts normally contain from 5 to 30% of such metals or metal compounds, and they may be prepared in any known or suitable manner, as under hydrous reaction conditions including the methods referred to above for the catalysts for the first zone. They may also be prepared by depositing the metals in and on previously prepared carriers which have the necessary strength and which may be either active or inert.

As indicated previously, the catalysts for both the reaction zones must have sufiicient strength to maintain their size and shape during continued and prolonged use. .When preformed carriers are utilized on which catalytic material is deposited, it is important to see that they have the proper strength and stability. When the carrier is inert or of low activity, the required strength is readily obtained through the use of heat. When the catalyst is formed synthetically by interreaction or coprecipitation from SOllltlOllS,

. difficulties are often encountered in preparing the contact material with suitable strength and.

No. 2,146,718, issued to G. R. Bond, Jr., on February 14, 1939, or by making dried gels fluid and casting the same in pellets, as disclosed in the vcopending application of H. A. Shabaker, Serial No. 209,070, filed May 20, 1938, now U. S. Patent 2,299,768, 0r,'in some instances, by adding to the mix a small amount of high swelling bentonite, as disclosed in the copending application of J. R. Bates andG. R. Bond, Jr., Serial No. 270,202, filed April 26, 1939, now U. S. Patent 2,283,174. Strength of at least 1800 grams applied to a 4 millimeter pellet through a knife edge is required, and the pellets must maintain such strength throughout the entire period of use.

Moderate pressures promote both reactions, as up to about 300 poundsper square inch. Since practical operation passesthe products of the first reaction directly to the second reaction zone, the same pressure is usually employed for the entire operation, a satisfactory pressure being of the order of pounds per square inch. Losses are reduced by mingling gaseous material with the charge to either or both of the zones, in the form of steam or refractory gases, such as mathane, ethane, propane, butane, hydrogen or mixtures of any of these, as taught in my previous PatentNo. 2,141,185, issued December 27, 1938, since such gases tend to inhibit secondary reactions and to keep down the deposit of contaminants upon the catalyst. The fixed gases from the dehydrogenating operation are entirely suit- \ing catalyst at least, the regeneration may. in-

able for this purpose, and they may be tapped back into the feed lines in any suitable or desired ratio producing a desirable and advantageous partial pressure efiect in either or both zones. The recycling of sufiicient gas to give approximately a moi to moi ratio or hydrogen to hydrocarbons, in the dehydrogenating zone. gives a good operation.

Rates of feed will depend upon the character of the charging stock and the degree of activity of the catalyst used, especially in the first or splitting zone. Since this zone is utilized to lighten the gravity of the charge and to increase the volatility of the same, with minimum production of gas or loss of liquid yield, the feed rates will be high, as of the order of 3 to 1 (three volumes of charge, measured as liquid, per hour per volume ofcatalyst) to 10 to l. The conditions in the second or dehydrogenating zone will, in most instances, be more severe, because here the refiner must impose operating conditions which will bring the products from the first zone up to the desired octane rating. Hence the feed rates will be lower, as from about 1 to l to about 2 to 1.

and raised to desired temper ture of from 600- to 800.F. and passed, by line 3, to converter 4i containing the catalyst for effecting the first or splitting reaction. The products leave converter a by line 5, pass preferably through'heater or heat exchanger 5, where the temperature is raised to from 850 to 950 F. (care being taken to avoid thermal reforming), and then sent, by line I, into converter 8, which is filled with a suitable dehydrogenating catalyst for effecting the second or dehydrogenating reaction. .The products leave converter 8 by valved line 9, which leads to a iractionating column 10 from which any products boiling outside the desired range may be withdrawn through bottom line H, while the desired products pass overhead by line 12 to condenser i3 and thence into separator It, from which the liquid products pass, by line 15, to storage in tank l6 or to other treatment or use. Fixed gases from separator M leave by line H, and any desired or required quantity of such gases may be sent through heater l8 and thence by branched lines 19 and 20 to be added to the products entering dehydrogenating zone 8 or to the charge entering the first splitting zone 4. When the products of the operation do not produce heavier hydrocarbons, or when their removal is not required, fractionatior l may be by-passed by means of valved line 2 clude a reducing step and the gases from separator may be utilized for this purpose. If necessary or desirable, a purifier (not, shown) may be provided in line l'l before or after heater 18, to render the gases suitable for use both to furnish an atmosphere of fixed gassduring on stream operaticn and for reduction du rin regeneration. The converters I and 8 may be ofiany suitable or desired type, either arranged for straight through flow of reactants or uniform distributoK of charge in and throughout the catalytic mass and uniform removal of products from all parts of the mass. Forbest operation, efiicient temperature control of the catalytic massis im-- portant, in order that it shall not fall below renow U. S. Patent 2,276,307, filed April 18, 1938.

' The following examples are given to indicate the use of the invention with various charging stocks. In all instances stable, highly active, syntheticaliy made silica-alumina catalysts of high purity with a silicato alumina ratio of about 12:1 were used in the first reaction zone, and molybdenum catalysts comprising at 1east7% molybdenum incorporated in 'a stable carrier in the second or dehydrogenatingzone. All the catalysts had the required degree of hardness. The operations were conducted under a pressure of 150 pounds per square inch, with hydrogen added to the charge to the second zone in substantially pool to mol ratio. Distillation data given in the examples are Engler according to the ASTM Each of the reaction zones may contain one or several converters, so that the operation may be I intermittent or continuous as desired. When it is from which valved branches lead to each of the converters. from the opposite end of the converter by suitable lines,.as indicated. For the dehydrogenat- Fumes of regeneration will leave method.

First example 5 A naphtha from East Texas crude with a boiling range of 244-410 F. (10% over at 274 F., 50% at 314 F. and at 377 R), an A. P. I. gravity of 50 and an octane rating of 40.8 C. F. R. motor method) was charged at reaction temperature and at a rate of about 6:1 (six volumes of charge, liquid measure, to one volume of catalyst) to the first catalytic reaction zone whichwas maintained at about 750 F., giving a very low formation of gas and of coke. The liquid recovery fromthis reaction was and the products had-an initial boiling point of 90 F., were 10% over at 184 F.,'50% over at 295 F. and 90% over at 379 F.; their A. P. I. gravity was 54.9" and their octane rating 56.7 (C. F. R.

motor method). They were charged without intermediate fractionation but with an increase in temperature to the second or dehydrogenating zone maintained at approximately 875 F., at a v Second example A naphtha from Coastal (grade B) crude with a boiling range of 198-410? I. (10% over at 238 F., 50% at 293 F., and 90% at 372 F.) an A. P. I. gravity of- 492 and an octane rating of 57 (C; F. R. motor method) was subjected to substantially the same two stage operation as in the first example. From the first reaction zone, the liquid recovery was 99.8%, and the products had an initial boilin point of 101 F., were over at 181 F., 50% over at 275 F., and 90% over at 392 F.; their A. P. I. gravity was 54.7 and their octane rating 67.9 (C. F. R. motor method) and 71.3 (C. F. R. research method). From the second or dehydrogenating zone, the liquid, recovery ,was 90.4% and the products had an A. P. I. gravity of 51 with an initial boiling point of 95 F., 10% over at 165 F., 50% over at 264 F., and. 90% over at 372 F. The octane number of such final product was 78.6 (C. F. R. motor method) and 85.2 (C. F. R. research method).

Third example A naphtha from Michigan crude having a, boiling range of 188-405 F. (10% over at 214 F., 50% over at 274 F., and 90% over at 354 F.). an A. P. I. gravity of 59.4, and an octane rating of 21 (c. F. R. motor method) was submitted to the two-stage reaction. It was charged to the first zone at arate of about 6:1, the catalyst being maintained at about 750 F. The liquid recovery from the first reaction was 99.6%. The products had an initial boiling point of 99 FL, with 10% over at 172 F., 50% over at 257 F., and 90% over at 353 F; the A. P. I. gravity was 62.5 and the octane was 32.7 (C. F. R. motor method). Without intermediate fractionation, they were charged to the second or dehydrogenating zone maintained at'a temperature of about 900 F., the charging rate being slightly in excess of one volume of hydrocarbons, measured as liquid, to one volume of catalyst. The liquid recovery was 85% and the final products had an A. P. I. gravity of 585, with an initial boiling point of 95 F., 10% over at 160 F., 50% over at 240 F., and 90% over at 351 F. The octane number was 74.8 (C. F. R. motor method).

Fourth example Another naphtha from Michigan crude, with a boiling range of 242-408 (10% over at 276 F., 50% over at 325 F., and 90% over at 383 F.), with an A. P. I. gravity of 54.9 and an octane rating ot 6 (C. F. R. motor method) was subjected to the two-stage reac ion under substantially the operating conditions set forth in the third example. The liquid recovery from the first reaction was 99.2% and the product had an initial boiling point of 90 F., with 10% over at 193 F., 50% over at 304 F., and 90% over at 387 F., with an A.- -P. I. gravity of 59.7 and an octane rating of 25.5 (C. F. R. motor method). The subsequentdehydrogenating reaction gave a liquid recovery of 80.6%, and the final product v had an A. P. I. gravity of 53.9, with an initial boiling point at 91 F., -10%'over at 161 F., 50% over at 283 F., and 90% over at 379 F. The octane number of this final product was 75- (C. F. R. motor method).

j Gas made in the dehydrogenating stage from the first-example is typical, and it analysison the mol percent basis is as follows:

From the above examples it will be apparent that high yields of high octane motor fuel can be prepared from any naphthas in the boiling range of 200 to 420 F., regardless of the octane rating of the original charge, and that the final product has substantially the A. P. I. gravity of the original charge. This accomplishment with relatively small loss is due to the fact that a substantial octane increase and proper adjustment of the volatility of the charge is produced in the first or splitting reaction with practically no loss of liquid, so that actual losses from the recoverable liquid standpoint are confined to the dehydrogenating zone, where operating conditions are adjusted to bring the final product to the octane rating desired. When the required octane increase is small, it will be apparent that only the first or splitting reaction need be used to make the improvement in the naphtha, and, at the same time, the volatility and the road performance of the product will be enhanced. All this is accomplished with little, if any, loss and often with a slight gain in liquid. In fact, this first reaction is most attractive from the operative as well as the economical aspect, because of low temperatures, practical absence of gas make and small deposit left on the catalyst. When the'operating conditions of the splitting operation are made severe to effect a greater octane incrase, gas and coke formation may be minimized through a partial pressure effect on the charge by adding to the latter a suitable amount of inert gas, suchas any of those specified in my aforementioned Patent No. 2,141, 85- By Combining the dehydrogenating step with the splitting step, it is clear that the two reactions complement each other in bringing any naphtha stock to desired octane rating. In practice, the same overall pressure will be utilized for both reaction stages of the operation, but even this lends itself to independent pressure control of each reaction through the addition of inert gas, such as the gas made in the dehydrogenating reaction,.to the charge to the second or to both reaction zones, through modification and adjustment of the partial pressure of the hydrocarbons. The operating conditions for any stock are readily determined by a few test runs in small laboratory apparatus. The primary factor to be established is the. rate,

whereupon final adjustment in operating conditions to give desired characteristics to the motor fuel may be made in temperature, rate or pressure.

I claim as my invention:

1. Process of making high grade motor fuel from naphthas in the boiling range of 200 to 420 F., which comprises subjecting the naphtha in vapor phase in the temperature range of 650 to 800 F. to a splitting reaction, adjusting the operating conditions to increaseJolatility and to give an octane increase of at least 10 points substantially without gas make or losshf liquid yield and then subjecting the products without intermediate fractionation and in the temperature range of 850 to 925 F. to a catalytic dehydrog'enating reaction to effect further increase in octane rating without any substantial change in the boiling range of said products, the'feed rate to each of said reactionsbeing maintained in excess of 1:1 and the rate to the first reaction higher than to the second reaction.

2. Process of making high. grade motor fuel from naphthas in the boiling range of 200- 420 F., which comprises subjecting the naphtha charge in vapor phase in the temperature range of 650 to 800 F. to the action of a splitting catalyst of high activity maintained withina re action zone, withdrawing products from said zone and directly subjecting them in the temperatixre range of 850 to 925 F, to the action of adehydrogenating catalyst in a second reaction zone, maintaining both reaction zones at sub stantially the same pressure up to 300 pounds per square inch while maintaining the feed rate to each zone in excess of 1:1 and the rate to the first zone higher than to the second zone, whereby a considerable octane increase is obtained in the products from the first zone with substantially no gas or liquid loss and the initial boiling point is lowered substantially while a further increase in octane is obtained in the second zone without any substantial change in the holiing range of the products 3. Process of making high grade'motor fuel from naphthas in the boiling range of eco- 420 F. which comprises subjecting the naphtha charge in vapor phase in the temperature range of 650 to 800 F. to the action of a splitting cataaction zone, withdrawing prociucts from sairi zone and directly subjecting them in the temperature range of sec to $25? F. to the action of a dehydrogenating catalyst in a second reaction acne, maintaining botlrreaction zones at substantially the same pressure up to 399 pounds per square inch while maintaining the feed; rate toeach zone in excess of 1:1 removing fixed gases from said second zone and supplying them at least to the first zone in order to provide a shorter vapor contact time therein than in the second zone whereby an increase in octane of at least to points is obtained in the products from the first zone with substantialiy'no gas or liquid loss and the initial boiling point is lowered substantially while a further increase in octane is obtained with substantially, no gas or liquid loss and the initial boiling point is lowered substantially while a further increase in octane is obtained in irnthe boiling range of the products.

5. Process for making high grade motor .fuels which compges subjecting a naphtha within the boiling rangaof 200 to 420 F. and with an octane rating of below approximately to (C. F,

w R. Motor Method) in vmphase at a tempera l gasoline boiling ,range feeding the charge to the zone at a rate hot-ween 3:1 and iilzi and main taining a pressure within the zone of up to 3636i pounds per square inch, correlating the pressure and the rate of feed'of the charge to provide a short time of contact of the charge in the re lyst of high activity maintained within a rean octane increase of at least it) points is 'clc- 4 action zone whereby the volatility of the prod ucts from the reaction is increased by producing of the order of 20 to 39 percent material hailing below the initial boiling point of the charge and tained with substantially no gas or liquid loss.

to Process oi making high grade motor fuel from naphthas in the boiling range of 260- sec F, which comprises subjecting the naplitha 3@ charge in vapor phase in the temperature range of 65pto 8iiil F. to the action of a splitting cata lyst oi high activity maintained within a re' action'zone, feeding the charge to the zone at a rate between'3zl and its]; and maintaining a pressure within the zone of up to coo pounds per in the second zone without any substantial change iii-boiling range of the products 4. Process of making high-grade motor fuel from naphthas in the boiling range of 200 to 420 F. which comprises subjecting the naphtha charge in vapor phase in the temperature range of 650 to 800 lit to the action of a splitting catalyst of high activity maintained within a reaction zone, withdrawing products from said zone and directly subjecting them at reaction temperature to a dehydrogenation catalyst in a second reaction zone, maintaining both reaction zones at substantially the same pressure up to 360 pounds per square inch while maintaining the feed rate to each zone in excess of 1:1 and the rate to the ilrstzone higher than to the second so octane increase is obtained with substantially no 1 gas or liquid loss while the A. P. I. gravity is square inch, correlating the pressure in accordance with the rate of feecl oi the charge to pro.- viole a short contact time of the charge in the.

reaction zone, whereby at least iii points of raised and the volatility of the products is improved than directly subjecting the products in the temperature range of 856 to 925 F to the action of a dehydrogenating catalyst in a second products in that zone over the contact time oi reaction zone, correlating the rate of iced vof the products-and the pressure in the second reaction zone to increase the contact time of the the charge in the first mentioned zone whereby a further increase in the octane rating of the \products is obtained without any substantial Zonawhereby at least 10 points octane increase I is obtained in the products from the first zone a change in the boiling range of said products.

- EUGENE J; HOUDRYQ the second zone without any substantial changewithin the

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