Synthesis of high-surface area tungstated zirconia by atomic layer deposition on mesoporous silica

Abstract

Atomic layer deposition (ALD) was used to prepare ZrO 2 films on the surface of the mesoporous silica, SBA-15, and to modify the surface of these films with WO 3 in order to form tungstated zirconia. Adsorption-desorption isotherms, pore size distributions, and transmission electron microscopy demonstrated that the ALD synthesis produced zirconia films that were conformal to the SBA-15 pores. DRIFT spectroscopy of pyridine adsorbed on the tungstated-zirconia SBA-15 samples showed adsorbed pyridinium ions, confirming the presence of Brønsted-acid sites on this material, consistent with what has been reported for bulk tungstated zirconia. The ALD-synthesized, tungstated-zirconia SBA-15 was also shown to be active in the acid-catalyzed H-D exchange between toluene and D 2 O. • ALD growth of conformal films of zirconia and tungstated zirconia on SBA-15 was demonstrated. • Ultrathin ZrO 2 films significantly enhanced the thermal stability of the SBA-15. • ALD-grown tungstated zirconia on SBA-15 contained Brønsted acid sites similar to those on the corresponding bulk material.