Oxidative dehydrogenation of isobutane over vanadia catalysts supported by titania nanoshapes

• TiO2 nanoshapes including truncated rhombi, spheres and rods were used to support vanadia.
• The structure of surface vanadia was found similar on the three TiO2 nanoshapes.
• The VOx/TiO2-nanoshapes were tested for oxidative dehydrogenation (ODH) of isobutane.
• The TiO2 shape does not show evident effect on the catalytic performance of vanadia in isobutane ODH.
• The insignificant support shape effect in isobutane ODH over VOx/TiO2 was tentatively explained.

Support plays a complex role in catalysis by supported metal oxides and the exact support effect still remains elusive. One of the approaches to gain fundamental insights into the support effect is to utilize model support systems. In this paper, we employed for the first time titania nanoshapes as the model supports and investigated how the variation of surface structure of the support (titania, TiO2) impacts the catalysis of supported oxide (vanadia, VOx). TiO2 truncated rhombi, spheres and rods were synthesized via hydrothermal method and characterized with XRD and TEM. These TiO2 nanoshapes represent different mixtures of surface facets including [1 0 1], [0 1 0] and [0 0 1] and were used to support vanadia. The structure of supported VOx species was characterized in detail with in situ Raman spectroscopy as a function of loading on the three TiO2 nanoshapes. Oxidative dehydrogenation (ODH) of isobutane to isobutene was used as a model reaction to test how the support shape influences the activity, selectivity and activation energy of the surface VOx species. It was shown that the shape of TiO2 support does not pose evident effect on either the structure of surface VOx species or the catalytic performance of surface VOx species in isobutane ODH reaction. This insignificant support shape effect was ascribed to the small difference in the surface oxygen vacancy formation energy among the different TiO2 surfaces and the multi-faceting nature of the TiO2 nanoshapes.

Figure optionsDownload high-quality image (234 K)Download as PowerPoint slide