Graphical We report an efficient and robust Cu-decorated Rh/TiO 2 catalyst that improves the styrene selectivity in selective hydrogenation of phenylacetylene. The appropriate Cu coverage is found to modulate the electronic states of surface Rh atoms and changes the Rh exposed active sites, thus mitigating the overhydrogenation and enhancing the selectivity. Phenylacetylene as an impurity in styrene is poisonous to catalysts for styrene polymerization in the production of polystyrene plastics. The selective hydrogenation of phenylacetylene to styrene is an industrially promising route to overcome this challenge yet lacks cost-effective catalysts to prevent the overhydrogenation of styrene to ethylbenzene. In this work, we report an efficient and robust copper-decorated Rh/TiO 2 catalyst for the selective hydrogenation of phenylacetylene to styrene. By optimizing the copper coverage on TiO 2 supported Rh nanoparticles, we achieved a selectivity of 83% towards styrene formation at a phenylacetylene conversion of 93%. The appropriate Cu coverage is found to modulate the electronic states of surface Rh atoms and changes the Rh exposed active sites, weakening the binding strength of alkene and hydrogen intermediates on Rh and thus mitigating the overhydrogenation and enhancing the selectivity for styrene generation. This work offers insights on the rational design of efficient Rh-based bimetallic catalysts for selective hydrogenation of phenylacetylene to styrene.
Zilin Wang,Dongbo Shu,Haijie Chen,Chuanmin Ding,Junwen Wang,Yan Lv,Qingqing Gu,Aiqin Wang,Bing Yang
The regulation of selectivity in CO2 hydrogenation is of great importance and has been intensively studied for the utilization of CO2. The particle size and metal–support interaction are proven to be key factors influencing the selectivity of CO2 hydrogenation. However, the dynamic structure evolution during real reaction conditions and their impact on the selectivity are still poorly understood. Here in this work, we reported the crystal-phase-mediated dynamic restructuring of the Rh/TiO2 catalyst during reaction that strongly modulates the mutual interaction of dynamic size stability and strong metal–support interaction (SMSI) encapsulation of the Rh catalyst and thus the selectivity of CO2 hydrogenation toward CO/CH4. By utilizing state-of-the-art characterizations, the interplay between dynamic size distribution and SMSI of the Rh catalyst on TiO2 was clearly elucidated. The selectivity of CO2 hydrogenation was prone to the particle size in the low reaction temperature range (225–275 °C) while highly depending on SMSI at high reaction temperatures (350–400 °C). Remarkably, anatase TiO2 promotes small Rh particles and strong SMSI at the low-temperature range, rutile TiO2 facilitates large particles but high-temperature SMSI encapsulation, while the P25 phase favors large Rh particles without encapsulation. The in situ DRIFTS experiments further reveal that all Rh/TiO2 catalysts follow the hydrogenation path via *HCOO as an intermediate, where the large Rh particle size facilitates deep hydrogenation of *HCOO to CH4, whereas the TiOx encapsulation favors the *HCOO decomposition to CO due to the suppressed H2 activation. Our results provide dynamic insight for the restructuring of the active sites in the Rh/TiO2 catalyst that tunes the selectivity of CO2 hydrogenation and opens up a route for the rational design of supported metal catalysts based on their dynamic structures.
危险品化学品经营许可证（带存储）