US2242960A - Production of motor fuel - Google Patents

Description

. alkylated benzenes by lar unsaturated material, either from the prod- Patented May 20, 1941 PRODUCTION OF MOTOR. FUEL Alexander N. Sachanen and Arlie A. OKelly, Woodbury, N. J., assignors to Socony-Vacuum Oil Company, Incorporated, New York, N. Y., a I

corporation of New York Nb Drawing. Application August 27,

Serial No. 227,106

4 Claims. (01. 260-671) This invention relates to the production of alkyl aromatic'compounds by reacting aromatic and oleflnic hydrocarbons. J More particularly,

the invention relates to a process for the production of alkyl aromatic hydrocarbons of high anti-knock value which are of suitable boiling range for use as motor fuels.

Processes for the cracking lar petroleum fractions to gasoline result in the production of hydrocarbons boiling within the gasoline range, and also result .in the production of a considerable amount of lighter, normally of gas oil and simi- I gaseous hydrocarbon products. Appreciable quantitles of these lighter gaseous products are olefinic and unsaturated in nature. Appreciable quantities of thegasoline-like condensate are also oleflnic in nature. Processes of this nature result in the production of gasolines of varying qualities with respect to anti-knock characteristics, dependent upon both the charging stock process of cracking through which it has been passed.

Many of the liquid gasoline-like products of such cracking processes are relatively high in anti-knock characteristics when judged from the standpoint of the requirements of an automobile motor. Few of them, however, even approach the possession or sufliciently high anti-knockcharacteristics to permit of their use, as produced, in

more advanced high compression type of engines, as for example the engines designed for use in aviation.

originally processed and upon the nature of the Alkylated benzenes boiling within the boiling 7 range of commercial gasoline are known to be capable, when mixed with gasoline, of imparting to the mixture 2. high degree ofanti-knock capability. Various methods for the production of combining olefinic O'r simiuctsof. a conventional cracking process or from other sources, with aromatic-compounds of the benzene or its homologues have'been nature of proposed.

The proposed prior processes, in general, take produced during cracking; together with benzene, through condensing catalysts of the nature of iullers earth, at these low temperatures. However, at such low temperatures clay-like catalysts do not appear to exert much, it any, catalytic action, and, as the reaction does not proceed appreciably at these low temperatures without the use of a catalyst, other catalysts, such as sulfuric acid; etc. are'generally used. s

In general, the catalytic processes conducted at low temperatures are open to many objections. One of the principal disadvantages of such processes when employing the usual low-temperature reactive catalysts, such as metal chlorides, sulfuric acid and phosphoric acid, is that the consumption of catalytic material is relatively high, and, if not entirely consumed, a complicated and costly process of regeneration is required. 'Many of these catalytic materials are corrosive to the materials of construction normally used, and introduce this, as well as other operating difilculties.

A more serious objection, however, to processes carried out at low temperatures for the alkylation of aromatic compounds to form compounds to be added to gasoline, isthat of low yield of products distilling in the boiling range of gasolines.- The low yield is caused-in the main, by a considerable amount-of the raw materials forming compounds of higher boiling range which are not usable in gasoline, and'are particularly unsuitable for'usejn gasolines of the lower boilingpoint type, such'as gasolines of aviation grade and the like. Since any condensation catalyst will not only bring about the joining of a single alkyl radical with an aromatic radicaL'but will also, more or less, efiect-polymerization reactions among the alkyl radicals themselves, aswell as the condensation of several alkyl radicals with a single aromatic radical, it may be seen that the possibilities of loss of yield from this source-may be quite high.

the nature of catalytic condensation reactions.

carried out at'comparativ ely. low temperatures in the presence of condensation catalysts. For example, such catalysts as aluminum chloride, various other metallic chlorides,sulfuric acid, phosphoric acid, and the like, peratures, i. e. temperatures or the nature of 30 to 350 F. (about --1' O. to +1'7'7 0.). It has also been proposed to pass cracked gasoline in company with the normally gaseous materials 0 are'used at low tem- It is. an object of this invention to provide a highly efllcient process for the production of alkyl aromatic compounds. a

Another object otthis invention is to provide a highly eflicientprocessfor. the production of alkylated aromatic compounds whichpossess a high anti-knock value and are of suitable boiling range to be used in motor fuels.

A further object of this invention is to provide a highly efficient process-fol the production of alkylated aromatic compounds which afiords op-- timumconditions for the-formation of alkylated aromatic compounds of a desired boiling range and minimizes the formation of alkylated benzenes without the desired boiling rangeand, furthermore, acts to reduce compounds of undesired boiling range, if formed, to compounds the desired boiling range. I Still another'object of this invention is to provide a process for the production of alkylated aromatic compounds wherein such catalysts as various clays and the like may be used with a high degree of success. This invention is based upon the discover that the reactions between unsaturated or olefinic materials and aromatic materials to produce compounds of the alkylfbenzene type which are within the gasoline boiling range are remarkably improved and, moreover, give commercially feasible yields even in cases where no perceivable reaction .occurs under more moderate conditions of operation, when the reactions are-carried out at high temperatures of the nature herein disclosed and under suitable conditions tending to promote the condensation reaction. For v.instance, we have discovered that when the reaction is carried out at temperatures upwards of about 400 C., catalytic materials promote the reaction to an unusual degree and under optimum conditions as when elevated pressures are also used, practically a theoretical yield of aralkyl compounds within the gasoline boiling range. may be obtained.

It is believed that the remarkably improved results derived from our invention are attributable to the fact, that at the elevated temperatures of .our process combined with the action of a suitable catalyst, not only will olefinic or similar compounds combine with aromatic materials to form alkylated aromatic compounds within the gasoline boiling range to an optimum degree, but

that also under these conditions the formation 'of polymers of olefinic materials and of polyalkyl benzenes not within the gasoline boiling range is minimized and that such compounds, if formed, are immediately broken down into lower boiling compounds of an-alkylated benzene nature which are within the gasoline boiling range,

The aromatic compounds with which our invention is concerned are of the nature of henzene', its homologues or compounds containing benzene nuclei. The aromatic compound (or mixture of aromatic compounds) maybe employed in a relatively pure condition or they may be supplied by the use of products which are -known to contain asubstantial portion of these aromatic ingredients. Likewise the olefinic materials may be supplied as a relatively pure product or may be derived from the use of a product containing a substantial amount thereof. For

instance tthe olefinic material may be propylene, butylene, amylene, mixtures thereof, normally gaseous products of cracking, cracked gasolines or fractions .of cracked gasolines containing ole- The catalyst employed should be highly selective in that it promotes alkylation reactions but is either a non-catalyst or a negative catalyst for other reactions. Catalysts usually, do not act with perfect selectivity, hence normally one must choose a catalyst which acts predominantly in the desired manner. The catalysts which we prefer to use are of the clay type. In addition to the various clays themselves and the various activated clays, there are numerous other porous,

refractory, adsorptive materials of similar nature which may be used and come under the common designation of clay type catalyst, for example,

earth. Furthermore, it is to be understoodthat these various clay-type catalysts which have other catalytic materials impregnated therein or thereon or otherwise conjoined for use maybe employed. In general, any alkylation catalyst which is active at the temperature of our reaction may be used. However, it is to benoted that the normally used catalysts of low temperature processes, such as aluminum chloride, sulfuric acid, etc. cannot be used in our high temperature process. 1

Since the alkylation reaction, together with the attendant cracking reactions which are present at the temperatures herein disclosed, bring about a gradual poisoning or deterioration of the catalyst by the deposit of carbon and carbonaceous impurities thereon, it is well to use a clay which I is possessed of a sufficiently refractory nature so that it may be regenerated in situ by burning; in fact, some of the clay catalysts used by us have been regenerated as manyas 8000 times and are still quite satisfactory. Because of the ease with which the clay-type catalysts may be regenerated, they afford a substantial advantage in their use. It is also well to use clay particles of such physical nature with respect to size and dimension that they may be effectively packed together in a catalytic mass and yet, at the same time, present a suflicient cross-sectional area of flow that the reactants may have a ready passage therethrough as well as a suitable exposure of catalytic material to reactants. A convenient and efficient form for the catalyst is small granules, rods or cylinders.

. The use of clay-type catalysts has many distinct advantages in addition to those already named. For instance, the clay is not corrosive to the normal apparatus as are the usual-alkylation catalysts and, furthermore, there is a relatively small consumption of the clay catalyst during operation as contrasted to the relatively high consumption of catalyst which is usually encountered. It is to be noted that our process alone appears to afford suitable conditions for thesat isfactory use of clay catalyst since under more moderate conditions of operation the clay' appears to be relatively ineffective as a catalyst.

The temperatures employed in our process should be-sufiiciently high to be capable'of pro ducing at least a partial cracking of the hydrocarbons having boiling points higher than thegasoline boiling range, as, for instance, temperatures upwards of about 400 C., and it is desirable to maintain the temperature between about 400 C. and 600 C., since above 600 C. the reof pressures between about 50 and about atmospheres. It is to be'understo'od, however, that pressures above 100 atmospheres and up to about 250 atmospheresmay likewise be used with good results; Above 250 atmospheres the results become less favorable as there is an increase in the production of heavy molecules above the at a reaction" temperature of 890 F. (about 470 C.) for a time of fifteen minutes.

At atmospheric pressure and in the absence or a catalyst, no reaction products of the nature of alkylated benzenes were detectable in the eflluent.

At atmospheric pressure in the presence of a highly activated porous ad'sorptive catalyst or the clay type, reaction products'indicated that 45% of the theoretical yield of alkylated benzene products could be obtained. I

At a pressure of 1500 pounds per square inch with the catalyst, a reaction yield of 58% of the theoretical was obtained.

At a lower temperature'range of 400-to 600 F. (about 205 to 315 'C. which is much higher than the customary alkylating temperature) even in the presence of a highly active catalyst of the clap type, no measurable rate of reaction was found.

To further point out the diflerences between the prior art and the present invention, we may discuss the reactions involved. For example, when benzol is condensed with amylene, the fol lowing reaction takes place:

cerreq-campc rn-csmr and with butylene: v

CeHc-FC4Ha=CeH5'-C4H9 These are the simplest reactions possible under these circumstances, and, as may be observed, result in each case in the alteration of benzol.

' which has a boiling point of 194 F. (within the kylated aromatics of considerably higher boiling ranges nottcapable of being used in any type of gasoline.

In contrast,. the reaction of benzene with .amylene and butylene at the high temperatures of our process hereindescribed are-mainly of the following nature: I--With amylene:

These two compounds formed, namely propyland ethyl-benzene, boil respectively at 310 F. and 284 F. and both may be used even in the low-boiling typesof gasoline, such as aviation gasoline. These differences in the type of reaction encountered are especially striking when the material from which the alkylaiting compounds are derived is gasoline or a mixture of gasoline and cracking vapors, because many of the oleflnes present, particularly those derived from the gasoline, are high molecular weight olefines, and many of them are oleflnes of a complicated-nature quite prone to-polymerization, as is evidenced by their /capability of gum formation, and the like, and by their ability to polymerize to materials of boiling point higher than gasoline under the relatively simple treatment encountered in the vapor phase degummingprocesses in contact with fullers earth.

With increases in temperature this difference in the type of reaction becomes more striking,

since with increases in temperature. there is a rapidly increasing tendency to' break up the aliphatic radical, resulting in the production of alkylated benzenes containing very short and simple alkyl radicals, such as toluene, ethyl benzenes and propyl benzene and, consequently, re-

sulting not only in the production of a greater amount of alkylated benzenes within the boiling range of aviation gasoline, but also in a much more eflicient utilization of the aromatic radicals present.

The-1 process may be carried out either asa batch operation or the process may be made continuous by employing a pipe still and a reaction chamber.

The effectiveness of this method of operation, and the eifect of the .several variables, may be seen from a consideration of the following examples, in each of which one or more of the operating principles herein disclosed is applied. It is to be understood that these examples are merely for purposes of illustration and notto be.

construed as limiting the invention in any sense.

Example I I Example II Toluene is alkylated wRh amylene by passing the mixture over a, similar-activated clay catal st at a temperature of 885 F. (about- 474 C.) a d at a pressure which is substantially atmospheric (batch operation). The total yield of alkylated toluenes is 57% of that which might theoretically be expected, and of these alkylated toluenes are within the gasoline boiling range.

Example III Benzene is alkylated with butylene in the presence of a similar activated clay catalyst ata temperature of 850 F..(ab out 454 C.) at a pressure of 1500 pounds per square inch gauge (100 atmos.) fora period of fifteen minutes (batch operation). The total yield of alkylated benzenes is 74% of that which might be expected, and of these alkylated benzenes over arewithin the gasoline boiling range.

Example IV ene and 17% butylenes in the presence of a clay The above mixture of lihuefled gases' and an excess of benzene is charged to the pipe catalyst.

still at 975 F. under a pressure of 1500 lbs. per square inch gauge in aonce-through process. The total yield of alkylated benzenes is 96% of that which might be expected, and of these pounds inthe gasoline boiling range which comprises alkylating aromatic hydrocarbons with .olefine hydrocarbons at a, temperature, between about 400 C. and about 600 C. in the presence of a catalyst comprising an association oi. silicon oxide and aluminum oxide and under 'a superatmospheric pressure. e

2. A process of preparing alkyl aromatic compounds in the gasoline boiling range which comprises alkylating aromatics with olefines' at a temperature between about 400 C. and about 600 C. in the presence of a clay catalyst.

3. A proces of preparing alkyl aromatic compounds in the gasoline boiling range which comprises alkylating aromatics with oleflnes at a temperature between about 400 C. and about 60050. in the presence of a clay catalyst and under a pressure between about and about 250 atmospheres. v

4. A process of preparing alkyl aromatic compounds in the gasoline boiling range which comprises alkylating aromatics with olefines 'at a temperature between about 400 C. and about 500 C. in the presence of a clay catalyst and under a pressure betweenabout 50 and about atmospheres.

r1. SACHAN'EN. ARLIE A. o'KEL r.