US2361600A - Conversion of hydrocarbons - Google Patents

Description

- alhylation reactions the molar ratio of isopr iii Tl.

"Poientedoct. 31,

UNITED s urs s PATENT OFFICE commiss on on mnocnnnons non n." Carmody. ond, Incl, asslxnor to Standard Oil Company, Chicago, 111., a oorporation of Indiana No Application March 28,

Serial No. 326,468

' I 2 Claims. This invention relates to a-process for the procarbons from hydrocarbons of lower, molecular weight and relatesz'nore particularly to a process for the lntcsaction of paramnic hydrocarbons for ductionof high octane number liquid hydro-.

the production of normallyliquid hydrocarbons suitable for aviation gasoline.

It is an object of this invention to provide a process wherein param nic hydrocarbons, and particularly is'oparafinic hydrocarbons, are reacted to form isopar ii c hydrocarbons othlgher molecular weight. Another object of this invention is to provide a process wherein isoparafhnlc hydrocarbons of low' molecular weight are reacted in the presence of an alcohol. It it a further object of invention to provide a.

process for the production of hieh oce numher-gasoline by the condensation of isopar r hydrocarbons having at least four carbon atoms per molecule in the presence of a promoter such as an alcohol. *l: objects and advantages will become appent as the description oi my process proceeds. v

The almlation of hydrocarbons, particularly isobutane and isopentane with olefins'in the presence of sulfuric acid for the production of high octane number hydrocarbons on within the gasoline boiling range is well r in to olefin reacting is always 1:1 or less. This is obvious when it is remembered that onemol oi isoparac hydrocarbon reacts with on moi of olefinic hydrocarbon to form 'onem'ol or isoparatflnic hydrocarbon of higher molecular weight. In the event that the higher lsoparal finic hydrocarbon formed is further alkylated under certain circumstances with an additional moi of olefihic hydrocarbon, themolar ratio of original isoparac hydrocarbonto olefinlc hydrocarhon is reduced to less than 1:1. I have discovered, however, that by carrying out the the absence'of an icon the above example.

. will be noted that the primary products from process under similar conditions in the absence- .oi ole but with-the addition of an alcohol tion can be made to react in suchmanmore than one mol of isoparaflinic hydrocarbon reacts per mole! alcohol with the formation of higher boiling-liquid hydrocarbons characterized by high octane number. the process the alcohol is simultaneously con-' During- .1. hydrocarbons having an isomeric-- verted to a pee hydrocarbon which can j be separated from'the product or can be left blended therewith if desired, in order to provide a balanced iuel suitable. both in boiling range and octane number for in aviation engines.

a y particular theory a v t0 the mechanism by which this reectiontakes place, it is, my sus- As an example 01' my process, 280 parts by weight of isobutane wasi'nixed by violent agitation with 423 parts by weight or 98.6% sulfuric acid to form an emulsion at a temperature or about to F. An inert diluent, normal heptane, was added to lower'the vapor pressure of the isobutane. To the emulsion thus' formed was added 101 parts by weight of tertiary amyl alcohol, the addition being made over a period.

of approximately 3*hours. The reaction was carried out over a total periodof 6.25 hours.. A

- total of 161 parts by weight'oi product boiling above .pentanes was produced. The weight percent yield of product, exclusive oi unreacted feed stock, was 200% based on the potential olefin in the alcohol which was distributed as iollows:

' Fractionation of product:

that added as inert diluent was recovered from the C1 out. The data have been corrected for this. A parallel run was made with the same amount of tertiary amyl alcohol and normal 'heptane at'the same operatingconditions but in :ii c hydrocarbon. The normal heptane was recovered quantitative- 1y. thus indicating that thisdiluent is inert in etely tltiiiata. It

All products were compl the reaction are pentanes and octanes. Ordinarily it would be expected that "alwlation" would take place between the isobutane and the tertiary amyl alcohol with the formation of an isononane and the elimination of In'. placeot this it appears from the distribution of v the products that the isobutane has reacted with itself with the formation of isooctane and that the tertiary amyl alcohol has been convertedtc isopentane, This is further emphasized by the fact that in this example 3 mols o! isoparamn per mol of alcohol reactednnd that a corresponding amount of isopentane was produced.

Although I do not intend-to be restrictcdto section that underth: set forth hydrogen or a hydrogen radical, or a proton is removed from the isobutane, and used for the hydrogenation of the tertiary, amyl alcohol with the accompanying production of water therefrom. The dehydrogenated isobutane either simultaneously or subsequently interacts to form an isooctane.

A similar experiment was carried out employing 319 parts by Weight of isopentane and 580 parts by weight of 98.6% sulfuric acid. In this case no inert diluent was used. Over a period of 5.3 hours '75 parts by weight of tertiary butyl alcohol was added at a'temperature of 70 to 80 F. and the reaction continued for a total period of 6 hours. Product equivalent to 237 parts by weight, exclusive of unreactedfeed stock, was obtained giving a weight yield of 423% based on the the potential olefin in the alcohol. In this case 2.7 mols of isopentane per mol of alcohol reacted.

The product consisted of 65 parts by weight of isobutane and 172 parts by weight of hydrocarbons (exclusive of the unreacted isopentane) boiling in the gasoline range. The higher boil- All products were completely saturated.

In this case it will be noted that there is a more even distribution of products between the hexanes, octanes, nonanes and decanes which is believed tobe due to the tendency of the decanes which would be formed by the interaction of the isopentane to break down under the-conditions employed here into Cs and C4 hydrocarbons. The isobutane produced from the butanol or from the disproportionation of the decane may then react to produce Cs.

A run employing secondary butyl alcohol and isopentane was carried out as follows:

424 parts by weight of 98.6% sulfuric acid, 314 parts by weight of isopentane and 73.5 parts by weight of secondary butyl alcohol were reacted as described above at '70-'78 F. for 6.25 hours to yield 42 parts by weight of isobutane and 144 parts by weight of hydrocarbons boiling in the gasoline range exclusive of unreacted isopentane. This represents a yield of 334% by weight based on the potential butylene in the alcohol, and corresponds to 2.2 mols of isoparaffin per mol of alcohol reacting. The gasoline hydrocarbons had the following distribution:

. Vol. Cs 22.7 C7 Ca 0 C9 I 50.0 C1o+ 27.3

ucts such as aviation .safetyfuel, a feed material consisting of isoparafllnic hydrocarbons having a molecular weight of 86 or higher should be used.

Broadly speaking, my process may be carried out at temperatures limited only by freezing temperature of the sulfuric acid as the lower limit, and the oxidation of the hydrocarbons by the sulfuric acid as the upper limit. A range from about 10 F. to 110 F. is permissible, and, preferably, I may use a temperature of from about 30 to about 80 F. Sulfuric acid having an acidity of from 85% to 101%, preferably about 96%, is a suitable catalyst for my process. It is desirable in all cases that sufficiently violent agitation be used to insure intimate contact between there- I'his may be accomactants and the catalyst. plished by stirring mechanisms, by jet injectors,

or by any other suitable mechanical means. |An

inert diluent may be employed to reduce the vapor pressure of the reactants or the reactants may be maintained in the liquid phase by superatmospheric pressure. The presence of inert gases,

lsuch as normal parafflns which are ordinarily found mixed with isoparaffins in hydrocarbons from such sources as the crack ng of petroleum and in natural gas or casinghead, is not objectionable, altho, since they do not enter into the reaction, they are not desirable. I prefer to, carry out the reaction using an excess of isoparaflinic hydrocarbons above that theoretically necessary to react with the alcohol. There should be present at least two mols or isoparafiln for every mol of alcohol, and preferably more than two mols of isoparafiin for every mol of alcohol. a

It has been found that 'isopropyl alcohol is not effective for my process, which I have designated dehydroalkylation. When using isopropyl alcohol a direct reaction between the alcohol and the. isoparafiin is obtained with the formation, forexample; of isoheptane, when using isobutane with isopropyl alcohol.

When employing a butyl alcohol in my process one of the primary products is isobutane which can be utilized in a corresponding dehydroalkylation reaction employing an alcohol of four or more carbon atoms or it may be fittingly employed in an alkylation reaction using isopropanol and an isoparaflin as the feed. When using tertiary amyl alcohol in my process, the isopentane formed can be retained in or' suitably blended with the dehydroalkylation product since generally it is desirable to increase the volatility of the aviation fuel, and isopentane has a sufflciently high octane number to render its presence valuable in the production of an aviation gasoconcentration or by fortification with sulfur trioxide or fuming sulfuric acid. The diluted acid can also well be employed in a polymerizationrecess in which oleflnic gases are converted to liand tri-oleflns in the presence dilute suluric acid or if sufllciently diluted, the acid can )8 directed to an alcohol-producing unit for absorption of olefins and the formation of alcohol suitable for use in my process. Further modification and extrapolations of my process will readlly occur to one skilled in the art.

My process is notable in that it is' ordinarily considered, thermodynamically, that twoparaflin molecules cannot form a higher paraflin by the elimination of a. molecule of hydrogen. By my process, however, a hydrogen acceptor" is provided, which furnished a means whereby the hydrogen apparently can be withdrawn from the reaction, leaving the dehydrogenated parafllns available for reaction. In spite of this hypothesis, however, it is indeed surprising that more than one mol of isoparaflinlc hydrocarbon reacts per mol of alcohol rather than one mol or less of. the isoparaflln feed stock reacting with each mol of olefin as in the case of the well-known alkylation processes. I

It should also be pointed out that by my process hydrocarbons of gasoline-like properties characterized by high octane numbers are produced with greater yields than the usual commercial synthesis, and without the necessity for involved recycling in order to utilize as far as possible the available paraiiinic feed stock.

, I- claim: g

1. In a process of producing a saturated hydrocarbon from isoparaflinic and oleflnic hydrocarbons, the steps of absorbing olefin-containing gases in dilute sulfuric acid, diluting the sulfuric acid further to separate out the alcohols, con tactingthe resulting alcohols with said isoparaffinichydrocarbons in the presence of concentrated sulfuric acid at a temperature whereby a higher molecular weight saturated hydrocarbon and water are produced thereby diluting the sul furic acid and supplying the diluted sulfuric acid to the first-mentioned absorption step.

2. In a process of producing a saturated hydrocarbon boiling in the gasoline range from isoparaflinic and olefinic hydrocarbons having mor than three and less than six carbon atoms per molecule, the steps of absorbing the oleflnic h: drocarbons in dilute sulfuric acid, diluting the combined stream of, absorbed oleflns and sulfuric acid to recover the coresponding alcohols, contacting the isoparafiinic hydrocarbons and said alcohols in the presence of sulfuric acid having 'an acidity of between about 85 and about 101% at a temperature of between about and F. to produce'isoparafllnic hydrocarbons boiling in the gasoline range, a saturated hydrocarbon corresponding to the alcohol and water, recovering the resultant diluted sulfuric acid and supplying the diluted acid to the first mentioned olefin absorption step.

DON a. cARMo'DY.