Dual effect of TiO2 vacancy on Pd catalyst in acetylene hydrogenation: Boosting performance and capturing reaction heat

Selective acetylene hydrogenation is a strongly exothermic process, easy to cause coking and metal agglomeration, and thus leads to deactivation. In this work, Pd/TiO2 with different oxygen vacancies (Vo) were synthesized by controlling reduction temperature in 300–700°C, in which Pd/TiO2‐HT300 (HT is reduction temperature) possessed the highest Vo content. It was found highly dispersed Pd nanoparticles adjacent to more Vo exhibited enhanced catalytic behavior (near 100% conversion at 55°C with 80% selectivity and turnover frequency of 0.12 s−1) due to hydrogen spillover generation and electron donation originating from Vo sites, confirmed by in situ x‐ray photoelectron spectroscopy, in situ Raman, and H2‐temperature programmed desorption. More importantly, the increasing Vo sites trap the released heat and devote to a decrease of heat accumulation over a single active Pd site, and consequently inhibit Pd agglomeration and polymerization, affirmed by high‐resolution transmission electron microscopy, CO chemisorption, and thermogravimetric analysis.