Rational design of vanadia-based propane ODH catalysts: A multiple operando spectroscopic investigation of VOx/TiO2/CeO2

Abstract

The understanding of reaction mechanisms of supported metal oxide catalysts has significantly increased over the last years due to new methods being applied. This increased knowledge allows to develop approaches towards catalytic materials for reactions with low selectivities by rational design, such as the oxidative dehydrogenation (ODH) of propane, which is of great technical importance. Vanadia (VOx) supported on reducible oxides (TiO2, CeO2, etc.) has shown promising catalytic properties in propane ODH. In this study, we followed a rational-design approach employing atomic layer deposition (ALD) to synthesize a VOx/TiOx/CeO2 catalyst with superior selectivity, by combining favourable properties of the individual catalysts (VOx/TiO2, VOx/CeO2). By applying multiple spectroscopies, including multi-wavelength Raman, UV-Vis, DRIFT, and XP spectroscopy as well as XRD, we were able to identify the functions of each oxide and develop a mechanistic picture. The increased selectivity is the result of distinct interactions between the oxides that slow down the oxygen dynamics in the catalyst and favour reaction pathways beneficial to propylene formation. Our findings highlight the use of rational design to develop improved catalysts based on previously established mechanistic knowledge.