GB1459044A - Concentrated copper -1- nitrate/propionitrile solutions as complexing agents for olefin separations - Google Patents

Abstract

1459044 Separating hydrocarbons using CuNO 3 -propionitrile solutions SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ BV 14 March 1974 [16 March 1973 (2)] 11447/74 Heading C5E A substantially anhydrous solution of CuNO 3 in propionitrile containing up to 26 wt. per cent Cu<SP>+</SP> and not more than 5 wt. per cent Cu<SP>++</SP> is used to separate an unsaturated hydrocarbon from less unsaturated and/or saturated hydrocarbons by selective complex formation of the unsaturated hydrocarbon with the copper (I) followed by decomposition of the complex. The solution is prepared by reacting Cu(NO 3 ) 2 and Cu in amounts to give on complete conversion not more than 4% by wt. Cu<SP>+</SP> in propionitrile solution at elevated temperature and then removing a proportion of the propionitrile solvent, e.g. by distillation under reduced pressure. Styrene may be separated from ethylbenzene; ethylene and/or propylene from methane, ethane, and/or propane; and butadiene and/or isoprene from C 4 -C 4 alkenes and alkanes. The hydrocarbon mixture may be contacted with the CuNO 3 -propionitrile solution at 30-80‹C., preferably countercurrently in an extractive distillation column. The separation of styrene may be carried out in the presence of a C 5 -C 18 paraffin counter-solvent in a rotating disc contactor, the styrene being recovered from the complex with Cu<SP>I</SP> by ligand exchange with an excess of a C 10 -C 14 olefinically unsaturated compound.