Zr-Doped TiO 2– x Nano-Oxide with Coordinatively Unsaturated Ti(Zr)–O Acid–Base Pairs for Efficient Propane Dehydrogenation

Recently, some traditional oxide supports, such as nano TiO 2 and ZrO 2 with high surface energy, have been found to be partially reduced to generate oxygen vacancies and coordinatively unsaturated metal (M cu ) cations as efficient active sites for nonoxidative propane dehydrogenation (PDH). However, the primary challenge in their industrial applications is rapid deactivation because of coke, over-reduction, and aggregation under the reaction conditions of high temperature and reducible atmosphere. Herein, we reported that cost-effective and environmentally friendly Zr-doped TiO 2 (Ti x Zr 1 ) prepared by a simple coprecipitation method can be used as a highly efficient and stable catalyst for PDH. Ti 3 Zr 1 exhibited the C 3 H 6 formation rate [ r (C 3 H 6 )] of 0.6 mmol g –1 min –1 at 550 °C, which was 17 times that of pure TiO 2, and a deactivation constant ( K d ) 2.8 times lower than that of commercial TiO 2 . Moderate Zr doping promotes the generation of surface active lattice oxygen, which can be reduced at a relatively low temperature to form oxygen vacancies and Ti(Zr) cu –O acid–base pairs as the active sites for PDH, and their number is in line with r (C 3 H 6 ) of Ti x Zr 1 catalysts. With the increase of the Zr doping amount, the bulk crystal phase of Ti x Zr gradually transforms from Zr-doped anatase TiO 2 to TiZrO 4 via Ti 2 ZrO 6 with enhanced thermostability, which can inhibit over-reduction and aggregation of the nano-oxide.