Preparation and characterization of porous alumina-based catalyst coatings in microchannels

Advances in the technology of micro-structured catalytic reactors depend crucially on the catalyst layer development. A detailed investigation on the influence of the different variables on the coating quality has lead to a procedure to coat commercial catalysts inside stainless steel microchannels with good adhesion and no loss of catalytic activity. A commercially available catalyst sample is directly slurry-coated inside the microchannels. These μμ-structured catalysts are tested for the water–gas shift reaction and compared to powder samples that underwent the same procedure. Adhesion of an alumina coating depends on both the initial particle size and the degree of macro-porosity. The latter is influenced by the nature of the binder. In the case of the commercial catalyst the particle size was difficult to control as milling was found to deteriorate its activity. Binders that can form metal complexes should be avoided in order to prevent redispersion of the active phase.