Microwave plasma assisted preparation of disperse chromium oxide supported catalysts Influence of the microwave plasma treatment on the properties of the supports

Microwave plasma technology has been used for the deposition of catalytic active chromia species on zirconia and lathanum-doped zirconia supports. The long time microwave (MW) plasma treatment causes a permanent decarboxylation as well as dehydroxylation of the surfaces of support particles. The dehydroxylation leads to a permanent decrease of the number of OH-groups available for anchoring of catalytic active species. This hydrophobization of the surface is also not reversible in humid air. At low or medium MW power and shorter treatment times, as used for microwave plasma enhanced chemical vapour deposition (MPECVD) mediated decomposition–precipitation of catalytic precursors, the surface chemical properties of supports are nearly unchanged. From this point of view, the microwave plasma and radiation should have no negative effect on the plasma chemical preparation of supported catalysts.