Zr-Doped TiO<sub>2–<i>x</i></sub> Nano-Oxide with Coordinatively Unsaturated Ti(Zr)–O Acid–Base Pairs for Efficient Propane Dehydrogenation
Zean Xie, Kemeng Song, Yu Ren, Liyu Hou, Rongrong Hu, Jianmei Li, Qi Shi, Dong Li, Wen‐Cui Li, Xiaoqiang Fan, Lian Kong, Xia Xiao, Zhen Zhao
Abstract
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.