湿式氧化工艺中颗粒Ru催化剂的活性和稳定性

Activity and Stability of Pelletized Ruthenium Catalysts in Wet Air Oxidation

分别采用传统成型法和新的成型法制备了一系列以CeO2为主要成分的载体,将贵金属Ru浸渍在这些载体上制备了不同的催化剂.对催化剂的比表面积和机械强度进行了表征,并通过湿式氧化乙酸的静态实验和湿式氧化苯酚的动态实验分别考察了催化剂的活性和稳定性.结果表明,Ru负载在采用新方法成型的载体上制得的催化剂具有更大的比表面积.向CeO2中掺杂Zr能增大载体的比表面积.新方法制备的催化剂Ru/ZrO2-CeO2催化湿式氧化乙酸具有良好的活性,化学需氧量(COD)去除率为98%.在110h的催化湿式氧化苯酚反应中,苯酚和COD的去除率维持在96%左右,反应过程中活性组分的溶出浓度很小,催化剂表面有少量的积炭,但积炭在300℃能够被完全氧化.因而催化剂具有较好的稳定性和工业应用可能性.

A series of pelletized supports mainly consisting of CeO2 were developed by the traditional molding method and new molding method. Ruthenium catalysts loaded on these supports were prepared by impregnation. The analysis of BET surface area and mechanical strength of the catalysts were carried out. Their activity in wet air oxidation of acetic acid and the stability of Ru/ZrO2-CeO2 in wet air oxidation of phenol were investigated. Ruthenium catalysts prepared by the new method possess larger surface area than that prepared by the traditional method. Introduction of Zr into Ru/CeO2 can increase surface area of the catalyst. In a batch experiment of wet air oxidation of acetic acid with pelletized Ru/ZrO2-CeO2, chemical oxygen demand （COD） removal was 98 %. In the dynamic experiment of wet air oxidation of phenol with pelletized Ru/ZrO2-CeO2, phenol and COD reduction was maintained at 96 % during 110 h of reaction. The concentration of the main intermediates was small. In the experiment of catalytic wet air oxidation of phenol, the leaching concentration of active species was small. There were small amounts of carbonaceous deposits on the surface of the used catalysts, and the carbonaceous deposits can be completely oxidized at 300 ℃. Pelletized Ru/ZrO2-CeO2 possesses good stability and possibility of use in practical processes.