GB501776A - Process for producing valuable liquid hydrocarbons from normally gaseous olefinic hydrocarbons - Google Patents

Abstract

501,776. Polymerizing olefins. MOND, A. L., and UNIVERSAL OIL PRODUCTS CO. Nov. 9, 1937, No. 30784. Addition to 464,671. [Class 2 (iii)] In a process for producing normally liquid hydrocarbons from a normally gaseous hydrocarbon mixture containing iso-butylenes and n-butylenes, e.g. mixtures produced in oil cracking operations, such as stabilizer refluxes, or B-B fractions, the mixture is subjected to selective polymerization by contact with solid phosphoric acid catalysts at a temperature of 20-66‹ C. in a first stage to polymerize substantially only iso-butylenes and of 66-121‹ C. in a second stage to polymerize n-butylenes, sufficient pressure being maintained in each stage. to retain the butylenes in liquid phase. The pressure in the first stage is preferably 3À4-10 atmospheres and in the second 10-24 atmospheres. Some mixed polymerization between the iso and n butylenes may take place. If the initial gases contain propylene this may be polymerized in a third stage at higher temperature, preferably 205- 260‹ C. and at superatmospheric pressure, e.g. 6À5-20 atmcspheres. Hydrogen sulphide, low boiling mercaptans, dienes and other gases which may interfere with the catalyst may be removed from the gas mixture before treatment. The liquid polymer products may be subjected to ordinary chemical treatments e.g. with sulphuric acid, caustic soda or sweeteners, or small amounts of inhibitors may be added. The iso-octenes produced in the first stage and the octenes of the second stage may be hydrogenated in known manner to octanes, useful as fuels or as anti-knock blending fluids. Details are givan of the preparation and regeneration of the catalysts. In examples : (1) a mixture of 16À8 per cent isobutylenes, 36À0 per cent n-butylenes and 47À2 per cent nbutane was passed at 38‹ C. and 6À8 atmospheres pressure through a bed of catalyst comprising 72 per cent of phosphoric acid (approximating the pyro acid in composition) and 28 per cent kieselguhr. After removal of iso-butylene polymers, the residual mixture was passed at 93‹ C. and 17 atmospheres pressure through the catalyst to polymerize the n-butenes ; (2) a stabilizer, reflux from a cracking plant containing 5 per cent isobutylene, 10 per cent nbutylenes and 25 per cent propylene was passed at 21‹ C. and 13 atmospheres downwardly through a tower containing catalyst granules formed by adding 65 per cent of pyrophosphoric acid to kieselguhr and mixing at 160‹ C. The resulting liquid was stabilized by heating to 66‹ C. to vaporize the unpolymerized three and four carbon atom olefines, which were then condensed and passed to a second tower at 93‹ C. and 17 atmospheres pressure. The resulting liquid polymers were separated and residual propylene passed to a third tower at 232‹ C, and 6À8 atmospheres pressure.