碱金属碳酸盐改性对Au/TS-1催化剂的丙烯气相环氧化活性和稳定性的提升作用研究

制备了不同碱金属碳酸盐（Na₂CO₃、K₂CO₃、Rb₂CO₃和Cs₂CO₃）超声浸渍改性的Au/TS-1催化剂，采用XRD、ICP、XPS、UV-vis、NH₃-TPD、FT-IR和HAADF-STEM等手段对催化剂结构性质进行了表征，研究了碱金属碳酸盐改性对Au/TS-1催化剂的丙烯气相环氧化活性和稳定性的影响。结果表明，碱金属碳酸盐改性可以降低Au/TS-1催化剂的表面酸性，减缓环氧丙烷（PO）在催化剂表面吸附引起的积炭失活，抑制金颗粒粒径的增大；此外，Cs₂CO₃和Rb₂CO₃改性还可减少Au/TS-1催化剂上的骨架外Ti含量。碱金属碳酸盐改性后的Au/TS-1的催化活性和稳定性都得到明显的改善，其中，Cs₂CO₃改性的Au/TS-1表现出最佳的催化活性，丙烯转化率为6.2%，环氧丙烷选择性为86.2%，氢气利用效率为26.2%。相关研究为提高Au/TS-1催化剂的丙烯气相环氧化活性和稳定性提供了新的思路。

Enhancement of the activity and stability of Au/TS-1 catalyst in the gas-phase epoxidation of propene through alkali carbonate modification

A serious of robust Au/TS-1 catalysts were prepared by modifying with various alkali carbonates including Na₂CO₃, K₂CO₃, Rb₂CO₃ and Cs₂CO₃ via the ultrasonic impregnation. The alkali carbonate-modified Au/TS-1 catalysts were characterized by XRD, ICP, XPS, UV-vis, FT-IR, NH₃-TPD and HAADF-STEM and their catalytic activity and stability in the gas-phase epoxidation of propene were investigated in a fixed-bed reactor in the presence of H₂ and O₂. The results indicate that the modification with alkali carbonates can decrease the surface acidity and inhibit the aggregation of Au particles; moreover, Rb₂CO₃ and Cs₂CO₃ can even reduce the content of extra-framework Ti in Rb-Au/TS-1 and Ce-Au/TS-1. The catalytic activity and stability of Au/TS-1 in the gas-phase epoxidation of propene are significantly improved after the modification with alkali carbonates. In particular, Cs₂CO₃-modified Cs-Au/TS-1 catalyst exhibits the best performance, with a propene conversion of 6.2%, selectivity of 86.2% to propene oxide (PO) and H₂ utilization efficiency of 26.2%. The results suggest that alkali carbonate modification could be a novel strategy to enhance the catalytic activity and stability of Au/TS-1 in propene epoxidation.