Processing of catalysts by atomic layer epitaxy: modification of supports

Different supports were modified with titania, zirconia and chromia by the atomic layer epitaxy technique (ALE). In ALE, a metal precursor is bound to the support in saturating gas-solid reactions. Surface oxides are grown by alternating reactions of the metal precursor and an oxidizing agent. Growth mechanisms differ depending on the precursor-support pair and the processing conditions. In this work, the influences of the support, precursor and reaction temperature were investigated by comparing the growth of titania from Ti(OCH(CH3)2)4 on silica and alumina, titania from TiCl4 and Ti(OCH(CH3)2)4 on silica, and zirconia from ZrCl4 on silica and alumina. The modification of porous oxides supported on metal substrates (monoliths) was demonstrated for the growth of chromia from Cr(acac)3.