Zhan Chao, Wang Qiuxiang, Zhou Lingyun, Han Xiao, Wanyan Yongyin, Chen Jiayu, Zheng Yanping, Wang Ye, Fu Gang, Xie Zhaoxiong, Tian Zhongqun
State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), National Engineering Laboratory for Green Chemical Productions of Alcohols, Ethers, and Esters, Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry and Department of Chemistry, Xiamen University, Xiamen 361005, China.
J Am Chem Soc. 2020 Aug 19;142(33):14134-14141. doi: 10.1021/jacs.0c03882. Epub 2020 Aug 4.
Direct epoxidation of propylene by molecular oxygen alone is one of the "dream reactions" in heterogeneous catalysis. Despite much effort, the yield of propylene epoxide is still too low to be commercially attractive due to the trade-off between conversion and selectivity. Here, we demonstrate that doping Cl into the lattice of CuO nanocrystals by the intergrowth method not only can enhance the catalytic selectivity and conversion of direct propylene epoxidation but also can solve the long-existing Cl loss problem. In particular, Cl-doped rhombic dodecahedral CuO with (110) exposing facets exhibited 63% PO selectivity with a 12.0 h turnover frequency at 200 °C, outperforming any other coinage metal-based catalysts under mild conditions. Comprehensive characterization and theoretical calculations revealed that the Cl-decorated Cu(I) facilitated formation of electrophilic oxygen species, thus boosting the production of propylene oxide. This work provides a general strategy to develop catalysts and explore the promoter effect by creating uniform isolated anion doping to activate a nearby metal center by virtue of well-defined nanocrystals.
仅用分子氧将丙烯直接环氧化是多相催化领域的“梦幻反应”之一。尽管付出了诸多努力，但由于转化率和选择性之间的权衡，环氧丙烷的产率仍然过低，缺乏商业吸引力。在此，我们证明通过共生法将氯掺杂到CuO纳米晶体晶格中，不仅可以提高丙烯直接环氧化的催化选择性和转化率，还能解决长期存在的氯流失问题。特别是，具有（110）暴露面的氯掺杂菱形十二面体CuO在200℃下表现出63%的环氧丙烷选择性和12.0 h的周转频率，在温和条件下优于任何其他基于硬币金属的催化剂。综合表征和理论计算表明，氯修饰的Cu（I）促进了亲电氧物种的形成，从而提高了环氧丙烷的产量。这项工作提供了一种通用策略，通过借助明确的纳米晶体创建均匀的孤立阴离子掺杂来活化附近的金属中心，从而开发催化剂并探索促进剂效应。
