US2167602A

US2167602A - Treatment of hydrocarbon oils

Info

Publication number: US2167602A
Application number: US104306A
Authority: US
Inventors: Walter A Schulze
Original assignee: Phillips Petroleum Co
Current assignee: Phillips Petroleum Co
Priority date: 1936-10-06
Filing date: 1936-10-06
Publication date: 1939-07-25
Anticipated expiration: 1956-07-25

Description

July 25, 1939. w. A. scHuLzE TREATMENT OF' HYDROCARBON OILS Filed Oct. 6. 1936 2 Sheets-SheetI 1 A TTORNEYS.

Filed Oct. 6, 19256 2 Sheets-Sheet 2 INVENTOR W. A. SCHlTILZE By AM,MM\ N\ N .mi

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A TTORN E YS.

nanas July 2s, 1939 UNITED STATES PATENT OFFICE Walter A. Schulte. Bartlesville, kb., assigner to Phillips Petroleum Company, a corporation of Delaware Application October 8, 1988, Serial No. 105,306

ZClaIms.

This invention relates to the treatment of hydrocarbons and relates more particularly to catalytic methods of treating petroleum oils, such as straight run and cracked sasolines, pressure s distillates, naphthas. polymerized gasolines and natural gasolines. to produce an improved type of motor fuel.

Applicant's co-pending application Serial No. 104,303 diners from the present invention in l0 that it relates to a method of reducing poisoning oi adsorbent desulfurizatlon catalysts operating in a temperature range substantially lower than that specined in the present application, and Serial No. 104,304 relates to a process similar 16 in some respects to the present process but employing a diiierent catalyst.

In a more specific sense an object ci this invention is a process for treating such motor fuel components in the vapor form over certain cata- !0 lytic materials to increase their octane ratings and improve their antiknock qualites, to remove the organic sulfur compounds which are so deleterious to the octane number and lead susceptibility, and to produce other desirable rening 2l eilects.

Another object of the invention lies 1n the production of this enormous improvement in the characteristics oi' the petroleum oli with only a small decrease in volume of product boil- 80 ing within the same range as the untreated oli. This is in contradistinction to the large losses which occur in such conventional operations as thermal reforming ci the oils.

A further object of the invention is the pro- 86 duction of a petroleum oil with both a higher specinc gravity and a higher octane rating than the untreated oil, whereas cracking of oils in the established manner produces higher octane products but of lower specific gravity,

l A still further object of the invention is the production of a by-product gas relatively rich in hydrogen, such gas being quite useful in hydrogenation processes as well as i'or many other It is well known that motor fuel specifications call for much higher octane ratings today than formerly, and gasoline stocks are being subjected to extensive reforming operations in order to meet these specifications. Since the advent of 60 Q" gasoline several years ago. large quantities of tetraethyl lead. also, have been added to gasolines to raise them to 'l0 octane number, the rating of the average house-brand gasoline at the present time. All of these practices are quite Il expensive.

More recently certain results showing the deleterious eects of impurities of the sulfur type on the octane number and lead response of motor fuels were published in an article by Schulze and Bueil (Oil and Gas Journal, vol. 34, No. 21. p. 22 5 (1935) l. Organic sulfur compounds of different types exist in varying percentages in all petroleum distlllates and are present in unusually large amounts in those from West Texas and certain other regions. The form of combination of the sulfur also varies, e. g., mercaptans, alkyl suli'ldes. thiophenes and thiophanes. Some of these compounds are much more deleterious than others to the octane number and lead response of the motor fuels; hence the magnitude of the reduction in sulfur content may or may not be a criterion of the improvement in antiknock characteristics. Schulze and Buell in an application, Serial No, 756,142, led December 5, i934, describe catalytic processes for removing these 1m- 20 purites from sulfur-bearing petroleum oils. thereby obtaining marked improvement in octane number and lead response of such products as natural gasolines and refinery straight run, cracked and vapor recovery gasolines.

I have discovered that still greater improvement in antiknock characteristics can be obtained when the motor fuel stocks are treated under the conditions specied below. In addition to the decomposition and removal of the organic sulfur impurities which are so deleterious to the octane number and lead response of the motor fuel, certain reactions which involve still other deleterious impurities and/or low octane number compounds are made to take place; therefore, the treated product has an octane number considerably higher than that produced merely by the removal o! organic sulfur.

In one speciilc embodiment of the invention, the gasoline stock is passed in the vapor form over a catalyst such as well dehydrated bauxite at a temperature in the range oi 900 F. to 1200 F. and at a ilow rate of l to 100 liquid s volumes per hour per volume oi catalyst. For example. at a temperature of 1000 to 1025 F. the preferred flow rate is oi' the order of 2 to 10 liquid volumes per hour per volume of catalyst.

At higher temperatures shorter contact times are w suillcient; therefore, iiow rates as high as liquid volumes per hour per volume oi catalyst may be employed.

I have discovered that in treating gasoline stocks in the vapor state over bauxite catalyst that there are speclc temperature ranges for the reactions involving the decomposlton oi those compounds responsible i'or the low octane rating of the gasoline. At temperatures in the range oi 600 to 750 F. the organic sulfur compounds ot the mercaptan and sulde types are decomposed into hydrogen sulfide without any sul stantial decomposition of the hydrocarbon constituents, at temperatures in the range of 750 to 900 F. there is little or no additional improvement in octane number over that obtained in the simple desuliurization treatment. but at temperatures above 900 F. a second series of reactions takes place as evidenced by the formation of large quantities of hydrogen gas and by the marked increase in octane number of the treated oil.

The improvement which results from the treatment at temperatures above 900 F. ls not due to cracking" in the usual sense of the word, since in the absence of the bauxite catalyst and under otherwise similar conditions of temperature and contact time there is no appreciable change in the characteristics of the oil. For example. in the treatment of a pentane free-oil free natural gasoline oi' 59.9 octane number at a temperature of l,025 F. and a flow rate of 1.75 liquid volumes per hour over dehydrated bauxite catalyst the octane rating was increased by 5.1 octane numbers. At a temperature of 1,055I F. and a ow rate of 2.0 liquid volumes per hour the octane ating was raised 7.9 octane numbers. With the me gasoline at a temperature of 1,045 F. and i now rate of 1.6 liquid volumes per hour but .without the catalyst, the octane rating was increased only 0.3 of an octane number. At 1,0'15l F, and a flow rate of 1.5 liquid volumes per hour without the catalyst, the improvement was only 0.7 of an octane number.

Furthermore, the improvement which results from the treatment with bauxite under the conditions mentioned is not due to an accelerated reforming similar to that occasioned by the presence of adsorbent porous material sometimes referred to as material of the clay type. For example, the same stock of natural gasoline was passed over fullers earth and bauxite under identical conditions of temperature, pressure and contact time. The improvement in the bauxite test was 5.3 octane numbers while in the fullers earth the change was only 0.4 of an octane number.

In the operation of this process high pressures are not needed. extremely good results being obtained in the range of atmospheric to 100 pounds. Higher or lower pressures may, oi course. be employed. In practice it is usually desirable to use pressures somewhat above atmospheric so that the vapors can be conducted directly to a fractionator or to treating tanks for final processing.

Several typical examples of the operation of this process are given as illustrative of the results which have been obtained in the treatment of various gasoline stocks, but these examples are in no sense to be interpreted as limiting the in Vention,

Example 1 Renery low end-point straight run gasoline from Panhandle crude oil was contacted in the vapor form with dehydrated bauxite catalyst maintained at a temperature of 1.000 F. and a ow rate of about 1.4 volumes of liquid gasoline per hour volume of catalyst. After removal of alencon the decomposed impurities the following improvement was noted:

The response to 1 cc. tetraethyl lead per gallon was 10.6 octane numbers on the untreated and 10.8 octane numbers on the treated. When it is taken into consideration that the octane level is much higher on the treated gasoline, or that the octane numbers are converted into compression ratio, it is realized that an excellent improvement in lead response resulted.

The ilxed gas formed during the treatment o1 this gasoline amounted to 235 cu. it. per barrel ot gasoline charged. Most of this gas was hydrogen. There was only a small amount of methane. the hydrogen to methane ratio being greater than eight. The total loss in volume of product boiling within the gasoline range was about two per cent.

Example 2 Reilnery straight run gasoline from Michigan crude was passed in the vapor form over dehydrated bauxite at a temperature of 1,000 to 1,010 F. and a dow rate of 2.0 liquid volumes of gasoline per hour per volume ci catalyst. After removal of the decomposed impurities the following remarkable improvement was noted.

Before treatment A. E. T. M. octane number (0 cc. TELL.

With 1.0 ce. tetmethyl lead With 2.0 cc. tetraetllyl lead/gallon With 3.0 ec. tetmethyi lead/gallon Sulfur content, per cent... Specille mvity Reid vapor Unsaturation. mol per cent Engler distillation:

l0 evaporated.-

Low temperature fractional analyses of the gasoline before and after treatment showed only a minor change in composition. The two, three and four carbon atom compounds were increased by only 0.3 of one per cent.

The nxed gas formed during the treatment of this gasoline amounted to 260 cu. ft. (S. T. P.) per barrel of gasoline charged. The analysis of the gas was as follows: Hydrogen, 82.0 per cent; carbon monoxide. 0.9 per cent; methane, 6.5 per cent; ethylene, 2.4 per cent; ethane, 3.6 per cent; propylene, 1.9 per cent: propane, 2.7 per cent. 'I'he hydrogen amounted to 213 cubic feet per barrel ot gasoline and the methane to 17 cubic reet. a hydrogen to methane ratio oi' 12.6. The gas loss calculated as weight per cent o! the gasoline charged wasV only 1.98 per cent. 'Ihe total loss in volume of gasoline boiling within the same range as the untreated was about 3 per cent.

The treated gasoline was made into a 'l0 octane number motor fuel merely by adding 1.80 cc. tetraethyl lead per gallon whereas the untreated gasoline could not be raised to 70 octane number even with the addition of an excessive amount of tetraethyl lead.

anemona Example J 4. S. T. M Sulfur Unsaturaoctane content swg? tion mol number per cent m y per nent lntrcated gasoline. 61. 2 0. 0609 6754 Treated gasoline. 70. 6 0. 0033 6829 ll. 9

Example 4 Depentanized Mid-Contiinent natural gasoline was passed in the vapor form over a. bauxite catalyst at a temperature of 1,025" F. After removal of the decomposed impurities the following improvement was noted.

A ostgeM Specillo Unsaturation number gravity mol per cent llntrcated gasoline 50. 9 70% 0. 3 Treated gasoline 65. 0 7064 8. B

During this treatment 249 cubic feet (S. T. P.) of hydrogen and 24 cubic feet of methane were formed per barrel of gasoline charged, a hydrogen to methane ratio of l0.

Example. 5

Gasoline from pressure cracking of topped Panhandle crude was passed in the vapor form over a dehydrated bauxite catalyst at l.000 F. After removal of the decomposed impurities the iollowing improvement was noted.

The response to 1 cc. ot totraethyl lead per gallon was 7.2 octane numbers on the untreated and 7.4 octane numbers on the treated gasoline. When it is taken into consideration that the octane level is much higher on the treated gasoline, it is realized that a good improvement in lead response was obtained along with the large gain in original octane number.

During this treatment 'considerable hydrogen and a little methane were formed, the hydrogen to methane ratio being relatively high. The

total loss in volume of gasoline boiling within.

the same range as the original was about three per cent.

Example 8 Pure normal heptane tree oi water vapor was passed in the vapor form over thrwghly dehydrated bauxite catalyst at a temperature of 1,000 F. Under these conditions 170 cubic feet oi hydrogen was formed per barrel of normal heptane treated. The product, as determined by bromine titration, had an unsaturation of eight mol per cent. The following improvement in antiknock characteristics was obtained.

Before Alter treatment treatment A. S. T. M. octane number (0 cc. TEL) 0 16. 3 A. S. T. M. octane number with 1.0 cc.

TELfgalion 22. i 35. 2 A. E. T. M. octane number with 3.0 cc.

TEL/gallon 44. 3 56. 0

I have found that in the treatment of gasoline stocks in the vapor form over bauxite in the temperature range, that some dehydrogenation of the hydrocarbons occurs. There is only a very slight amount of cracking, as evidenced by the small proportion of methane in the gas, providing, oi' course, the temperature and contact time are properly chosen, since it is obvious that substantially long contact times at temperatures of 1,100 F. and above will produce cracking. With proper choice of the temperature and contact time, however, it is possible by means of this invention to substantially avoid the formation of methane and other products of cracking. In Example 2 the hydrogen to methane ratio was 12.8. At other times still higher hydrogen to methane ratios have been secured.

I have found that although dehydrcgenation of certain of the hydrocarbons occurs during the treatment according to this invention, this dehydrogenation is only one of several reactions taking place. It is evident from the results such as those given under Example 2 that the improvement of l5 to i6 octane numbers could not have resulted merely by the conversion of 'l per cent of saturated aliphatic hydrocarbons to simple unsaturated hydrocarbons of the olen type. Neither can it be accounted for on the basis of the amount oi' hydrogen formed. While I am not certain of the exact changes which occur during this treatment of gasoline stocks over a catalyst of the peculiar nature of bauxite, I believe the remarkable improvement in octane number results from several concurrent reactions, namely, (l) decomposition of deleterious organic sulfur compounds to hydrogen sulde and the subsequent removal of the hydrogen sulfide, (2) decomposition and removal of impurities other than the sulfur type. (3) dehydrogenation of hydrocarbons, and (4) changes in molecular structure of certain of the hydrocarbons. The extent of the improvement from each of these sources varies, of course, with the gasoline stock being treated.

Various catalysts have been used heretofore in connection with desulfurization processes and others in connection with dehydrogenation processes. Certain catalysts such as fullers earth and other clay like materials have been proposed also for accelerating reforming reactions, but as shown above fuller's earth does not give results similar to bauxite under the conditions specified herein. I believe that heretofore it has not been shown that the results enumerated above for my process could be obtained by means of either a single catalyst or a combination of catalytic steps.

In the practice of the present invention the bauxite or the bauxite like material is crushed to a suitable size, usually l0 to 30 mesh. If desired it may be diluted with diluents such as naturally associated active and/or inactive substances or substances which are suitable for diluting purposes although not naturally associated with the catalytic material.

Bauxite is essentially a hydrated aluminum oxide of highly porous and peculiar internal structure. 0n heating to elevated temperatures much water is given oi. This water of hydration is not driven olf gradually with increasing temperature, such as is the case with fullers earth and hydrosllicates in general. but very rapidly at a threshold temperature somewhere near 550 F. Therefore, since in practice of this invention the best results are obtained with thoroughly dehydrated bauxite, the rst step usually consists in dehydrating the bauxite, preferably in situ, by raising the temperature gradually to the temperature of operation while a slow stream of air or hydrocarbon gas is passed over it. 'I'his step of passing air or hydrocarbon gas over the bauxite can obviously be omitted, if desired, and the gasoline vapors started over the bauxite immediately. The improvement in the gasoline during the first few hours of operation will be lost, of course, by operating in this manner.

It has been found that the bauxite gradually loses its catalytic activity with use but it may be reactivated indenitely in the manner described in U. S. Patent 2,016,271 to Buell and Schulze.

Instead of bauxite catalyst, diaspore and other v bauxite like materials may be used in my process.

Likewise alumina prepared in various manners may be employed.

It has been found that the hydrogen-bearing gas which is formed during the treatment of gasoline stocks according to my invention may be re-cycled through the system by adding such gas or a portion of it to the gasoline vapors prior to passage over the catalyst. Such hydrogen gas should, of course. not be allowed to pyramid too much or the reaction may be unfavorabiy iniluenced. Also in processing gasolines containing appreciable quantities of sulfur compounds, the hydrogen sulfide should be removed from the gas prior to recycling.

Obviously the hydrogen gas produced as by a by-product in my process has considerable economic value. A gas containing up to 95 per cent hydrogen and the balance methane can be readily obtained by applying simple extraction methods for the removal of the small amount of hydrocarbons higher than methane. Concentrations of hydrogen higher than 95 per cent can be obtained by more elaborate extraction methods. tion and/or other purposes can be obtained in this treatment of gasoline stocks over bauxite at an extremely low cost. A very distinct advantage of my process is the formation of relatively large quantities of hydrogen with methane being the only impurity in appreciable amount. Obviously this gas can be utilized for many purposes where the more common mixture of hydrogen and carbon monoxide cannot be tolerated at any cost.

If desired, the gasoline stock vapors may be given two or more successive treatments with the catalytic material such as bauxite in a series of catalyst towers, or the vapors or any fraction thereof may be recycled with the fresh vapors through the catalyst tower. YSome additional' heat, also, may be supplied to the vapors prior In any event hydrogen for hydrogenato the second and/6r successive catalytic treatments.

Following the treatment of the vapors over the catalyst the decomposed impurities and light gas fraction are separated from the gasoline hydrocarbons by fractional condensation or any other conventional means. If desired. the uncondensed light gas fraction may be passed through a vapor recovery plant of the absorption or other conventional type whereby the hydrocarbons other than methane may be recovered and made useful for other purposes. Also, the decomposed impurities may be removed by chemical means in a step apart from that o! removal of the hydrogen and low boiling hydrocarbons from the gasoline hydrocarbons. f

The gasoline stock after treatment in the described manner usually requires a subsequent treatment to remove small amounts of colored and gum-forming constituents in order to make the stock suitable as motor fuel. This nal purllication step can be carried out in conventional manner such as clay treating in which case the vapors are generally cooled to about 400 F. prior to treatment.

In the accompanying drawings Figures 1-4 inclusive are diagrammatic illustrations oi apparatus for carrying out the invention.

Figure 1 represents schematically one type of apparatus in which my process may be used. This drawing shows the heated gasoline stock vapors entering the catalyst chamber i. Upon leaving the catalyst chamber the vapors may pass directly to the fractionating unit 2. or they may be passed through the cooler l and the clay tower l to improve color and gum stability and thence to the fractionating unit 2 where the gasoline is separated from the light gas. The light gas fraction passes from the fractionatlng unit to a vapor recovery plant I for the separation of hydrogen and methane from the ethane and heavier fraction.

Figure 2 represents apparatus for the recycling of part of the stream of hot treated vapors for a second pass through the catalyst tower. In this instance the stream of hot treated vapors leaving the catalyst tower I is split. one part going to the fractionating unit and the other through a compressor B (or its equivalent) wherein the pressure is raised just enough to force the recycled vapors into the stream of heated raw gasoline stock vapors prior to passage into the catalyst tower. Figure 3 illustrates an alternative method for giving gasoline stock vapors successive treatments in two catalyst towers in series with the alternative also of recycling a portion of the hot treated vapors. Figure 4 illustrates a method for supplying additional heat to the gasoline stock vapors prior to the second catalyst tower.

I'he foregoing specification and examples have disclosed and illustrated the invention, but since it is of generally wide application and the number of examples of results obtainable by its use might be multiplied greatly neither is to be construed as imposing limitations upon the scope of the invention. 'I'he term gasoline stock as used herein includes natural gasolines, refinery straight run, cracked and vapor recovery gasolines, polymerized gasolines, naphthas, pressure distillates and/or mixtures or blends of any two or more of these. Light gases associated with such stocks may, ii' desired, be treated along with the hydrocarbons boiling within the gasoline range.

I claim as my invention:

1. The method of improving the anti-knock characteristics of a gasoline stock and producing a gas with a hydrogen to methane ratio greater than one, which comprises containing the gasoline stock in the vapor form at a pressure between atmospheric and 100 pounds per square inch with a bauxite catalyst at a temperature in the range of 900 to 10.50 F. and a oW rate of about l. to 10 liquid volumes of gasoline stock per hour per volume of catalyst, cooling the vapors and separating by condensation the gasoline hydrocarbons from the uncondensed gas, and passing the uncondensed gas through a vapor recovery system whereby the hydrocarbons other than methane are substantially completely removed and a gas with a hydrogen to methane ratio greater than one is obtained.

2. The process of improving the antiknock CERTIFICATE OF Patent No. 2,167,602.

characteristics of a gasoline stock, comprising contacting said gasoline stock in the vapor form at a. pressure between atmospheric and 100 pounds per square inch with a bauxite catalyst at a temperature in the range of 900 to 1050* F. and a flow rate of about 1 to 10 liquid volumes oi gasoline stock per hour per volume of catalyst, splitting the treated vapors into two streams, recycling one of the streams without substantial cooling back into the heated raw vapors prior to the catalyst chamber, separating from the other stream of treated vapors the decomposed impurities and the light gas fraction containing a substantial proportion of hydrogen gas from the hydrocarbons boiling within the gasoline range. and thereby obtaining a gasoline stock which has greatly improved antiknock characteristics.

WALTER A. SCHULZE.

coRREcfrroN.

Jil/ly 25, 1959- WALTER A. SCHULZE.

vIt is hereby certified that error ap of the above numbered patent requiring column,

the said Letters pears in the printed specification correction as follows: Page 5, first line 5, claim l, for the word "containing" read contacting; and that Patent should pe read with this correction therein that the same may conform to the record of the case in the. Patent Office.

Signed and sealed this 10th day of October,

(Seal) 1 Henry Van Arsdale, Acting Commissioner of Patents.