GB613926A - Improvements in or relating to alkylation process and products thereof - Google Patents

Abstract

Benzene compounds are alkylated with olefins of not more than 6 carbon atoms by reacting a mixture thereof with the benzene compound in molar excess, and free from other unsaturated hydrocarbons, in the presence of an absorbant gel comprising silica and not more than 10 per cent by weight of an oxide of a metal of Group 3B, including boron, or Group 4A. Suitable silica-alumina catalysts may be prepared as disclosed in U.S.A. Specifications 2,142,324 and 2,147,985. A hydrous silica gel is first made from alkali silicate and acid, washed, activated with a solution of a metal salt which is hydrolysable, and washed and dried to give hard granules. Alternatively, the metal salt may be added before gelation. Instead of alumina, oxides of boron, indium, thallium, titanium, zirconium and thorium may similarly be incorporated. The amount of metal oxide is preferably about 0.1-2 per cent by weight. Catalytic activity is increased by dehydration at about 200-300 DEG F. in a steam of inert gas prior to use. A benzene to olefin molar ratio between 1 : 1 and 1 : 10 is suitable. Multi-point injection of olefin and recirculation of the effluent may be used. Temperatures are generally about 200-700 DEG F. With propylene 250-450 DEG and with ethylene 450-550 DEG F. are preferred. Pressures to maintain a substantial amount of liquid phase, generally 50-2000 p.s.i., may be used. Temperature may be increased gradually as activity decreases. Flow rates are normally 0.1-10 liquid vols. per vol. per hr. Pure olefins or mixtures thereof or with paraffins may be treated. In addition to benzene and its homologues such as toluene, xylene and ethylbenzene compounds such as phenols and halogen derivatives may be used. In examples: (1) a silica-alumina gel containing 1.3 per cent alumina, made by adding sodium silicate to sulphuric acid, boiling the partially dried gel with aluminium sulphate solution, washing and drying is used to alkylate a 5 : 1 molar benzene-ethylene solution at 500 DEG F., 400 p.s.i., and reaction time of 46 mins.; (2) using aluminium and zirconium chlorides, a catalyst containing silica, alumina and zirconia in a weight ratio of 95 : 4 : 1 is obtained and used to produce ethylbenzene; (3) isopropylbenzene is prepared from propylene and benzene using the catalyst of (1) at 350-400 DEG F., reaction time 30 mins.; (4) the catalyst is first dehydrated in propane at 250 DEG F.; (5) benzene and propylene in molar ratio 8 : 1 are reacted at 300-330 DEG F. and 250 p.s.i.; (6) silica-zirconia made by mixed precipitation is used for a similar reaction; (7) a butane-butene fraction with benzene in 6 : 1 molar excess yields butyl benzenes; (8) a 3 : 1 benzene, ethylene mixture with the catalyst of (1) yields ethylbenzene; (9) a silica-zirconia catalyst is used for ethylating benzene.