Ferromagnetically modified zeolite catalysts for liquid-phase High–Throughput Experimentation

A novel method for the separation of heterogeneous catalysts from liquid-phase reactions in High–Throughput Experimentation (HTE) libraries was developed based on a magnetic recuperation procedure. Ferromagnetic iron nanoparticles were introduced in a set of zeolite structures by means of aqueous impregnation of an iron precursor, followed by reduction in H2. The obtained magnetic zeolites can be efficiently stirred in the catalytic reaction mixture using conventional magnetic stirring bars and they are automatically separated by depositing on the magnetic bar when the stirring is stopped. Characterization techniques demonstrated that the iron nanoparticles are distributed on the external surface of the zeolites, where the interference with the catalytic active sites is limited. Catalytic tests of a High-Throughput library of 10 wt. % Fe magnetic zeolites, performed using the liquid-phase benzylation of toluene with benzyl alcohol as test reaction, showed that the modified catalysts can be very easily and efficiently separated from the reaction mixture while they retain similar activity and selectivity to that of the unmodified samples.