溶胶凝胶法由细菌纤维素制备CuCe_(0.75)Zr_(0.25)O_x复合氧化物及其低温催化降解甲苯性能

Preparation of CuCe_(0.75)Zr_(0.25)O_x composite by bacterial cellulose promoted sol-gel method and its catalytic performance in the toluene degradation at low temperature

以绿色廉价的天然椰果细菌纤维素(BC)为造孔剂,采用溶胶凝胶法制备了CuCe_(0.75)Zr_(0.25)O_x复合氧化物催化剂,通过TG/DTG、N2低温物理吸脱附、XRD、H_2-TPR、O_2-TPD和Raman等手段对催化剂进行了表征,并对其在固定床上挥发性有机物(VOCs)降解的催化性能进行了研究。结果表明,利用BC精细的纤维网状结构和亲水性能与活性金属盐溶液形成凝胶,可有效制备介孔结构的复合氧化物催化剂。制备过程中,凝胶形式和成胶温度对催化剂降解甲苯的活性有较大影响;采用醇凝胶形式在70℃时制备的ACCZ-70催化剂完全降解甲苯的温度为205℃,明显低于已有文献报道的催化剂,这主要归因于该催化剂具有良好的低温还原性和高达0.81的氧空穴浓度。而采用水凝胶制备的催化剂降解甲苯时,在120-140℃存在吸附现象。

Mesoporous CuCe075Zr025Ox composite was prepared by a simple sol-gel method with environmentally benign bacterial cellulose(BC)as a pore former and characterized by TG/DTG,N2adsorption-desorption,XRD,H2-TPR,02-TPD and Raman;its catalytic activity in the degradation of toluene at low temperature was investigated in a fixed-reactor.The results indicated that BC with ultra fine three-dimensional networks and excellent compatibility is beneficial to the formation of gel with nitrate solution,to prepare the mesoporous catalyst.The catalyst performance of CuCe075Zr025Ox composite is significantly affected by the gel-form and gelling temperature during the preparation process.Over the ACCZ-70catalyst prepared by alcohol gelling at70°C,the temperature for a complete degradation of toluene(Tm)reaches205°C,much lower than those reported in open literature;the excellent activity of ACCZ-70is ascribed to its high reducibility at low temperature and high concentration of oxygen vacancies(0.81).In addition,adsorption phenomenon was observed in the range of120-140°C during the toluene degradation over WCCZ catalysts prepared by water gelling.