Catalytic membranes: alkene dimerisation by means of acidic porous thin-film composite membranes

Dimerisation of isobutene is of increasing interest to substitute oxygenated products such as MTBE or the like as fuel additives. Catalysts applied in commercial alkylation plants,e.g., hydrofluoric and sulfuric acid may be replaced by less harmful solid catalysts, for example by solid heteropolyacids ("super" acids) or polymeric sulfonic acids. To overcome decrease in catalyst performance by time and to increase product selectivity a membrane reactor approach is suggested and first successful results are presented.