【摘要】 采用沉积沉淀法制得Au/TiO2负载型催化剂,研究了该催化剂的丙烯气相直接环氧化合成环氧丙烷的反应性能,对新鲜、失活和再生后的催化剂进行TG-DTA、FT-IR、吡啶-IR、TEM以及活性评价等表征.研究结果表明,催化剂的失活是由于吸附在催化剂表面酸性Ti位上的环氧丙烷产物发生副反应生成了大分子沉积物.该沉积物存在着两种类型,其含有长碳烷基和酯基.催化剂再生实验表明在空气和H2中再生时活性恢复良好,而在N2中的再生效果则很差.更多还原

【Abstract】 Direct gas-phase epoxidation of propylene to PO in the presence of oxygen and hydrogen over the gold catalyst is an environmentally friendly process. In this paper, Au/TiO₂ catalysts were prepared by the deposition-precipitation method. Fresh, deactivated and regenerated catalysts were characterized by HRTEM, FT-IR and DTA-TG. Results show that the fast deactivation of Au/TiO₂ can be attributed to the deposition of some organic by-products on the catalyst. The deposit contains long-chain alkyl and ester groups. The activity of the catalysts can be fully restored after regeneration in air at 300 ℃; Regeneration in H₂-N\-2 also can restore more than 95% of activity, indicating that H₂ contributes to the desorption of the deposit; However, it was found that pure N₂ plays poor role in the regenertion of deactivated catalysts, and only less than 50% of activity can be restored even under a high temperature of 500 ℃.更多还原