Comparison of the reactivities of H3PW12O40 and H4SiW12O40 and their K+, NH4+ and Cs+ salts in liquid phase isobutane/butene alkylation.

Activity in n-butane isomerization reaction of various alkaline salts of H3PW12O40 and H4SiW12O40 was shown to be strongly dependent on the strength and number of accessible protons whereas the stability with time on stream was correlated to the presence of mesoporosity. For the liquid iC(4)/C-4(=) continuous alkylation reaction, the strength and the number of acid sites appeared less important than the existence of mesoporosity indicating that the diffusion of the reactants and of the products plays an important role in this reaction.