Olefin trimerization with titanium catalysts: MAO/silica-supported variants display higher productivities

Abstract

Treatment of dry silica with methylaluminoxane (MAO) followed by (FI)TiCl_3 (FI = (N-(5-methyl-3-(1- adamantyl)salicylidene)-2'-(2"-methoxyphenyl)anilinato), gives a heterogeneous supported ethylene trimerization catalyst, s(FI)Ti, which exhibits productivity more than an order of magnitude higher than its homogeneous analogs. This increase is attributed to a decreased rate of catalyst decompn. via comproportionation to an inactive Ti(III) species, which is retarded by immobilization. In addn., s(FI)Ti catalyzes trimerization α-olefins with high selectivity. Based on regioisomer distributions, catalysis by s(FI)Ti involves the same active species as the previously reported homogeneous systems (FI)TiR_2Me/B(C_6F_5)_3(R = Me, CH_2SiMe_3, CH_2CMe_3). Co-supporting the (FI)TiCl_3 catalyst with the ethylene polymn. catalyst (CpSiNR)TiCl_2 (CpSiNR = (C_5Me_4)SiMe_2NCMe_3), either on sep. or the same silica particles, affords a catalyst system for producing butyl-branched LLDPE from and ethylene-only feed.

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