Researchers in the UK and New Zealand have shown that using a membrane could help catalysts operating in the same system work more efficiently.

The team, led by Paul Taylor at the University of Warwick and Andrew Livingston at Imperial College London, used a membrane to keep catalysts in environments where they work best.

Taylor explained that in a process where two or more catalytic steps are combined in one operation, called a tandem catalytic process, the catalysts normally have to compromise on their performance. This is because the same operating conditions are imposed on both catalysts. 'We use technological tricks to avoid the compromise,' he said, 'and allow the catalysts to operate under their respective optimum conditions, while in terms of the process they are in the same synthetic operation.'

The team used the membrane in a tandem catalytic process called dynamic kinetic resolution, a process used to make enantiomerically enriched products. Jonathan Williams, professor of organic chemistry at the University of Bath, explained that, although there are many opportunities for using catalysts in tandem catalytic processes, there are practical problems associated with their use because of the different conditions they require. 'These researchers have provided an elegant solution to this problem by using a membrane to retain an enzyme catalyst in a lower temperature vessel whilst metal-catalysed racemisation occurs in a higher temperature vessel, leading to an effective dynamic kinetic resolution process,' he said.

The partnership involved collaboration between chemists interested in tandem catalysis and chemical engineers interested in membrane technology. Taylor explained that the collaboration resulted from effective networking with colleagues in industry interested in membrane separation.

Katherine Davies