Isobutane-ethylene alkylation process - with pyrolysis of by-product ethyl chloride to ethylene and hydrogen chloride

摘要

Process for alkylating isobutane (i-Bo) with ethylene over HCl - promoted AlCl3 catalyst to give effluent contg. i-Bu, alkylate, EtCl, n-Bu and 1-3c hydrocarbons is improved by (a) fractionating effluent into an i-Bu recycle stream) alkylate stream, 1-3C hydrocarbon stream and n-Bu-EtCl stream (I); (b) reacting (I) over bauxite in vapour phase at 400-1000, esp. 600-800 degrees F, and EtCl LHSV 0.1-5 to produce n-Bu, ethylene and HCl; (c) condensing out n-Bu; and (d) recycling ethylene and HCl to alkylation zone. Pref. >=95% Etce is pyrolysed, any remaining being recycled to pyrolysis zone. Alternatively catalyst is an AlCl3- hydrocarbon complex promoted with HCl and Etcl to give a C5+ stream and, after fractionation, an n-Bu-Etcl fraction which is treated as above. Alkylate is a motor fuel; HCl recovery is 90% of that required for catalysis and EtCl is removed without disposal problems.