Improvements in or relating to the production of valuable hydrocarbons by selective polymerisation of olefinic hydrocarbons

摘要

A hydrocarbon mixture containing substantial amounts of iso- and normal butylenes but substantially no olefines of more than 4 carbon atoms is passed over a phosphoric acid and a solid adsorbent at above 20 and below 121 DEG C. whereby the isobutylene is converted to mono-olefines of 8 carbon atoms which can be hydrogenated to iso-octanes. The selective polymerization of the butylenes may be effected in two stages, first in liquid phase at 20 to about 66 DEG C., e.g. about 38 DEG C., to polymerize a major portion of the isobutylene and, after separating unreacted butylenes by vaporization, polymerizing these in vapour phase, generally at a higher temperature, preferably at about 66 DEG C. If propylene is present, this is polymerized in a final stage at 121--260 DEG C., preferably 200--260 DEG C. The preferred catalysts are obtained by calcining a mixture of a phosphoric acid and a solid adsorbent under controlled temperature conditions to produce an acid usually between the pyro and meta acids in composition. The preparation of these catalysts is described in Specification 463,272, [Group III]. Steam or aqueous fluid may be added to the olefines in the proportion of 1--6 per cent by volume to prevent dehydration of the catalyst. The polymers are used as motor fuels or as blending agents for raising the anti-knock value of fuels. They may be stabilized and then hydrogenated. Fractions may be converted to the corresponding alcohols by forming mineral acid esters and hydrolyzing. In examples: (1) a mixture of normal and iso butylenes and normal butane is passed at 6,8 atm. through a catalyst containing a phosphoric acid approximating to the pyro acid and kieselguhr at 38 DEG C.; (2) reflux from the stabilizer of a cracking plant containing normal and iso butylenes and propylene is passed through three towers in series containing a catalyst made by calcining pyrophosphoric acid and kieselguhr, grinding, and sizing. In the first tower the isobutylene is polymerized at about 21 DEG C. and 13 atm., the liquid produced is stabilized by heating to 66 DEG C., the vapours passed through the second tower giving a mixture of octenes, and the residual gases treated at 232 DEG C. to give dimers and trimers of propylene. Specification 437,188 also is referred to.ALSO:Motor fuels or blending agents for raising the anti-knock value of fuels are made by passing a hydrocarbon mixture containing substantial amounts of iso- and normal butylenes but substantially no olefines of more than 4 carbon atoms over a phosphoric acid and a solid adsorbent at above 20 and below 121 DEG C. whereby the isobutylene is converted to mono-olefines of 8 carbon atoms which can be hydrogenated to iso-octanes. The selective polymerization of the butylenes may be effected in two stages, first in liquid phase at 20 to about 66 DEG C., e.g. about 38 DEG C. to polymerize a major portion of the isobutylene and, after separating unreacted butylenes by vaporization, polymerizing these in vapour phase, generally at a higher temperature, preferably at about 66 DEG C. If propylene is present, this is polymerized in a final stage at 121--260 DEG C., preferably 200--260 DEG C. The preferred catalysts are obtained by calcining a mixture of a phosphoric acid and a solid adsorbent under controlled temperature conditions to produce an acid usually between the pyro and meta acids in composition. The preparation of these catalysts is described in Specification 463,272. Steam or aqueous fluid may be added to the olefines in the proportion of 1--6 per cent by volume to prevent dehydration of the catalyst. The polymers may be stabilized and then hydrogenated. Specification 437,188 also is referred to.