PROCESS FOR PARAFFIN-OLEFIN ALKYLATION

摘要

1,209,941. Alkylating isoparaffins; dehydrogenation; isomerization. SUN OIL CO. 22 Aug., 1967 [25 Aug., 1966], No. 38631/67. Heading C5E. C 4 -C 6 isoparaffins having a tertiary carbon atom are alkylated with a C 3 -C 6 mono-olefin at a temperature below the critical temperature of the lower boiling hydrocarbon and at a pressure such that the reactants are in the liquid phase in the presence of a substantially anhydrous crystalline alumino-silicate zeolite, and the reaction is stopped before the weight rate of production of unsaturated hydrocarbon becomes greater than the weight rate of production of saturated hydrocarbon. Preferably the rate of olefin addition is controlled so that the amount of unreacted olefin in the reaction mixture is less than 12 mole per cent based on the unreacted C 4 -C 6 isoparaffin. A halide promoter having a molecular cross-section of less than 9 €, selected from HF, HCl, HBr and saturated halohydrocarbons may be present in the reaction mixture in amount 10-5 to 10-1 moles per mole of isoparaffin reactant. Examples describe the alkylation of isobutane with isobutene, butane- 2, butane-1 and 2,3-dimethylbutene. Liquid mixtures of hydrocarbons are claimed per se which contain less than 1 % by wt.of unsaturates and which comprise at least 60 mole per cent of C 8 paraffin, the paraffin consisting of less than 1À5 mole per cent methylheptanes, 5-20 mole per cent dimethylhexanes and 80-95 mole per cent trimethylpentanes, the said trimethylpentanes comprising less than 30 mole per cent 2,2,4-trimethylpentane. Under the conditions of the alkylation it is found that butene-1, in the presence of n-butane, isomerizes to cis and trans butene-2. Lower paraffins such as C 5 and C 6 paraffins can be separated from the higher paraffins in the alkylate product and dehydrogenated using a fixed bed catalyst of Pt-Al 2 O 3 , Ni-SiO 2 , Ni- MgO, Ni-A1 2 O 3 , Cu-A1 2 O 3 or Cr 2 O 3 -A1 2 O 3 to give mono-olefins mixed with unreacted paraffins which may be used as a feed in the alkylation. The zeolite may have an atomic ratio Al/Si of 0À65 to 0À35 and contain at least one cation comprising a rare earth metal, preferably cerium.