1660320254200 1103 Inprocess Toulene Catalyst Ts

Toluene Offers Golden Opportunity

Feb. 23, 2011

A new catalyst enables solvent-free low-temperature selective oxidation of toluene to benzyl benzoate at high yield.

A new catalyst enables solvent-free low-temperature selective oxidation of toluene to benzyl benzoate at high yield, report researchers at Cardiff University, Cardiff, U.K., and Lehigh University, Bethlehem, Pa. The catalyst -- gold/palladium nanoparticles on a carbon support -- boasts turnover numbers around 30 times higher than other heterogeneous catalysts for the reaction. "This opens up the possibility of using hydrocarbon feedstocks in a new way to form intermediates and final products for use in the chemical, pharmaceutical and agricultural business sectors," notes Graham Hutchings, a professor in the Cardiff School of Chemistry who was on the research team.

Catalyst Researcher

Figure 1. Prof. Graham Hutchings of the Cardiff School of Chemistry was part of the research team. Source: University of Cardiff.

The catalyzed reaction at 160°C produces benzyl alcohol, benzaldehyde, benzoic acid and benzyl benzoate but no carbon dioxide. Selectivity to the benzoate exceeds 94%. "Catalyst activity could be higher, but it is usable," notes Hutchings, who adds that the next step in the development is to increase catalyst activity.

The nanoparticles are 2--5 nm in size and were prepared by sol immobilization. They contain gold and palladium at about a 1:1 ratio by weight -- the addition of palladium significantly enhances the conversion -- and are stable and reusable, the researchers say. More details appear in a report in Science.

The catalyst currently is in the form of a powder but could be made into pellets, adds Hutchings, who foresees use in either a stirred-pot or continuous flow reactor.

The work was funded by a grant from the Dow Chemical Co., as part of the Dow Methane Challenge, www.chemicalprocessing.com/articles/2007/069.html.