The formation of a heterogeneous-homogeneous catalytic system for the benzene alkylation with ethylene upon interaction of aluminum and carbon tetrachloride alloys

Abstract

The in situ formation of the catalytic heterogeneous-homogeneous system including the Al-M (M = Ni, Co, Cu) alloy and the Al(M)/Cl complex in a benzene-ethylene medium at a temperature of 80 °C and pressure 0.2–0.3 MPa was studied. Regularities were found in the interaction of Al-M alloys activated by the liquid-metal Ga-In eutectic with a chlorinating agent (CCl4), which led to the formation of catalytically active Al(M)/Cl metal-aluminum chloride complexes. Spectrokinetic measurements showed that reactivity of the activated alloys toward an excess of CCl4 can form the following series: Al-Cu ≈ Al-Ni > Al > Al-Co. The highest catalytic activity was observed for the nickel-aluminum chloride complexes; their selectivity to ethyl benzene was up to 48 %. According to IR and UV-vis spectroscopy data, the structure and composition of the metal-chloride complexes formed in situ in the aromatic reaction medium are determined by a combination of the coupled ion pairs [AlCl4]–tetrahed./[NiCl6]4–octahed. and [AlCl4]–tetrahed./[CuCl2]–lin. stabilized by the (C6H5)3C+ carbocation.