Mesoporous silica stabilized MOF nanoreactor for highly selective semi-hydrogenation of phenylacetylene via synergistic effect of Pd and Ru single site
Zhenxing Li, Mingliang Hu, Jiahao Liu, Weiwei Wang, Yanjie Li, Wenbin Fan, Yixuan Gong, Jiasai Yao, Ping Wang, Miao He, Yongle Li
Abstract
Selective semi-hydrogenation of phenylacetylene to styrene is a crucial step in the polystyrene industry. Although Pd-based catalysts are widely used in this reaction due to their excellent hydrogenation activity, the selectivity for styrene remains a great challenge. Herein, we designed a mesoporous silica stabilized Pd-Ru@ZIF-8 (MS Pd-Ru@ZIF-8) nanoreactor with novel Pd and Ru single site synergistic catalytical system for semi-hydrogenation of phenylacetylene. The nanoreactor exhibited a superior performance, achieving 98% conversion of phenylacetylene and 96% selectivity to styrene. Turnover frequency (TOF) of nanoreactor was up to as high as 2,188 h−1, which was 25 times and 5 times more than the single metal species catalysts, mesoporous silica stabilized Pd@ZIF-8 nanoreactor (MS Pd@ZIF-8), and mesoporous silica stabilized Ru@ZIF-8 nanoreactor (MS Ru@ZIF-8). This catalytic activity was attributed to the synergistic effect of Pd and Ru single site anchored strongly into the framework of ZIF-8, which reduced the desorption energy of styrene and increased the hydrogenation energy barrier of styrene. Importantly, since the ordered mesoporous silica was introduced into the nanoreactor shell to stabilize ZIF-8, MS Pd-Ru@ZIF-8 showed excellent reusability and stability. After the five cycles, the catalytical activity and selectivity still remained. This work provides insights for a synergistic catalytic system based on single-site active sites for selective hydrogenation reactions.