Heteropolyanions based catalysts for paraffins isomerization

Abstract n -Hexane isomerization was carried over Cs x H 3− x PW 12 O 40 catalysts promoted with Pt by mechanical mixing with a Pt on alumina catalyst. Different parameters as caesium and platinum content in the catalyst, temperature and atmosphere of heteropolyacids pre-treatment were optimized. The catalytic performances of the best catalyst were compared with those of industrial Pt promoted mordenite. 0.3 wt.% Pt-promoted Cs 2 H 1 PW 12 O 40 pre-treated under hydrogen flow at 473 K showed the highest conversion and selectivity. Its performances are very close to those of the industrial zeolitic catalyst in the same reaction conditions. The gain in dibranched isomers selectivity is really promising for the future. With this catalyst, the reaction proceeds by a non-ideal bifunctional mechanism resulting from the superposition of a monofunctional acid and a bifunctional metal–acid mechanism.