US2537283A - Isomerization of olefins - Google Patents

Description

Patented Jan. 9, 1951 UNITED" STATES PATENT OFFICE,

2,537,283 ISOMERIZATION or OLEFINS Raymond E. Schaad, Riverside, Ill., assignor to Universal Oil Products Company, Chicago, 111., a corporation of Delaware No Drawing. Application September 29, 1948, Serial No. 51,843

I Claims.

This application is a continuation-in-part of my co-pending application Serial Number 706,057 filed October 2-3, 1946.

This invention relates to a process for isomerizing olefinic hydrocarbons and particularly for isomerizing alkenes.

An object, of this invention is to isomerize an olefinic hydrocarbon.

Another object of this invention is to isomerize an alkene having at least four carbon atoms per molecule.

In one embodiment, this inventionrelates to a process for isomerizing olefinic hydrocarbons which comprises contacting an olefinic hydrocarbon having at least four carbon atoms per molecule at conversion conditions withan amprocess have at least four carbon atoms per molecule and include butylenes'pentenes, and higher molecular weight normally liquid olefins, the latter including various polymers of normally gaseous olefins. Cycloolefins such as cyclopentene, cyclohexene, and various cycloolefins may also be used but not necessarily under the same conditions of operation as employed with open chain olefins which may also be referred to as alkenes.

Catalysts useful in promoting an isomerization of olefinic hydrocarbons comprise ammonium salts of phosphoric acids. These ammonium salts include both neutral and acid salts of ortho-, pyro-, tri-, tetra-, and other polyphos phoric acids, as such, in admixture with one another and also supported on solid carriers, such as a siliceous carrier as silica, diatomaceous earth, fullers earth, crushed porcelain, etc., and also alumina, charcoal, and other packing materials Which do not interfere with the desired catalytic activity of an ammonium phosphate. Composites of an ammonium salt of an acid of phosphorus and a carrier, such as diatomaceous earth or some other siliceous material, are preferably calcined before being utilized as catalysts in conversion reactions of organic compounds and particularly of hydrocarbons. Such calcination is generally carried out at a temperature of about 200 to about 500 C.

According to the process of the present inven--' tion, an olefinic hydrocarbon may be-reacted in the presence of an ammonium phosphate catalyst at a temperature of from about C. to about 450 C. to produce isomeric olefins including branched chain and straight chain olefins. The isomerization of a straight chain olefinic in the presence of an ammonium phosphate yields a branched chain olefin as a result of so-called, skeletal isomerization of the charged olefinic .hy-

,drocarbons. The isomerization reaction .may

also involve the shifting of the position of the double bond along the carbon chain of the olefinic hydrocarbon. Thus a shift of the doublebond occurs when l-butylene is converted into 2- butylene whereas skeletal isomerization occurs;

during the conversion of either of the straight chain olefins, l-butylene and Z-butylene, into the branched chain olefin isobutylene, this being an example of the so-called skeletal isomerization- Olefin isomerization in the presence of acatalyst comprising an ammonium phosphate as its essential active ingredient, is carried out preferably at a temperature of from about 150 to about 350 0., particularly since the higher tem-- perature of the broader range, namely, from about 150 to about 450 C., sometimes result in certain amountsof decomposition, cracking, and.

hydrogen transfer reactions. The process is also carried out generally at atmospheric pressure,

although higher conversions may sometimes be obtained at subatmospheric pressure while increased capacity results when the process is effected at a slight superatmospheric pressure which is generally not more than about 5 atmospheres. At a superatmospheric pressure; a certain amount of olefin polymerization takes place with the result that the yield of isomerized olefin is decreased.

The process of the present invention is carried out in either batch or continuous types of operation. Thus in a simple batch type process, the olefin containing at least four carbon atoms per molecule is brought to a reaction temperature as specified above in the presence of an ammonium phosphate or of a solid composite of an ammonium phosphate and a suitable carrier 'or supporting material while the reaction mixture is stirred mechanically to eiiect intimate contact between the catalyst and the olefinic 56, hydrocarbon charging stock.

Claims (1)

1. A PROCESS FOR ISOMERIZING OLEFINIC HYDROCARBONS WHICH COMPRISES CONTACTING AN OLEFINIC HYDROCARBON HAVING AT LEAST FOUR CARBON ATOMS PER MOLECULE AT ISOMERIZING CONDITIONS WITH AN AMMONIUM PHOSPHATE.