Chlorogallate(III) ionic liquids: Synthesis, acidity determination and their catalytic performances for isobutane alkylation

A series of triethylammonium-based chlorogallate(III) ionic liquids with varied Lewis acidity was synthesized, characterized, and firstly applied to isobutane alkylation. The Et₃NHCl]-GaCl₃ with $\chi _{GaCl_3 } $ = 0.65 displayed a potential catalytic activity for the alkylation. The addition of copper halide into the chlorogallate(III) ionic liquids dramatically enhanced the alkylation reaction. Up to 70.1% C₈ selectivity and 91.3 RON were achieved with the Et₃NHCl]-GaCl₃-CuCl ( $\chi _{GaCl_3 } $ = 0.65, CuCl = 5% mol) under 0.5 MPa, 900 r/min, 15 min, 288 K using the industrial C₄ cut (isobutane/butene = 10). These results indicate that the chlorogallate(III) system may be used as a promising catalyst for the C₄ alkylation.