Nanosystems for heterogeneous catalysis

Johan A. Martens, Centre for Surface Chemistry and Catalysis, KU Leuven, Belgium

Heterogeneous catalysis is the bringing together and activation of chemical reactants on active sites on a solid material such that the desired reaction is accelerated and undesired side reactions suppressed. It enables clean, waste-free and energy efficient manufacturing of fuels, chemicals, polymers and pharmaceuticals. Continuously new challenges for catalyst development arise such as e.g. in the area of pollution control, in the interconversion of energy vectors and in the utilization of renewable feedstocks.

The traditional approach of catalysis R&D involves high-throughput and pilot scale testing of candidate catalyst materials in appropriate reactors. Such traditional catalyst testing provides activity and selectivity data that are averaged over all active sites in a catalyst bed. Since properties of individual catalytic sites in a catalyst can vary substantially, the traditional approach leads to fragmentary understanding of structure-activity relationships and, unfortunately, to relatively slow scientific progress.

In the lecture a new catalysis research concept will be presented, viz. the design of heterogeneous catalysts by assembly of single active sites. In the new approach individual active sites are molecularly engineered. Multidiagnostic tools with nanoresolution such as fluorescence microscopy are excellent tools for identification and characterization of these individual active sites. In a next step optimized active sites are assembled into nanoparticles to provide superior activity and selectivity. Next, engineered nanoparticles are integrated in meso- and macro-structured catalyst bodies via concepts of supra-molecular assembly. The new catalyst finally is operated in an optimized reactor concept.

This innovation in catalysis research will be demonstrated with timely examples in the area of acid catalysis with zeolites and metal organic frameworks. With both types of catalyst materials the different links of the catalysis innovation chain have already been developed.