论文部分内容阅读
采用等体积共浸渍法制备了CuO-CeO2整体式催化剂,评价了催化剂对乙酸乙酯、异丙醇及甲苯的催化燃烧性能.采用N2吸附-脱附、X射线衍射(XRD)、氢气程序升温还原(H2-TPR)、氨气程序升温脱附(NH3-TPD)以及挥发性有机化合物脱附等手段对催化剂进行了表征.表征数据显示,氧化铜以高分散态均匀分散存在于载体表面,氧化铈则是小的纳米颗粒,氧化铈颗粒粒径随着Cu/Ce物质的量比的减小而增大.添加铈氧化物会显著增加总酸量,特别是路易斯酸酸位的量,同时增强了乙酸乙酯和异丙醇的吸附量,吸附量的增加提高了催化剂对乙酸乙酯和异丙醇的催化燃烧性能.从甲苯的催化燃烧实验可以看出,大量添加CeO2稍微增加了甲苯的吸附容量,减弱了催化剂的还原性、降低了活性氧的含量,最终导致甲苯的低转化率.催化行为由氧化铜、氧化铈以及载体三者之间的共同作用决定,这三者的协同作用不仅影响着表面氧的活性同时影响着催化剂对甲苯的吸附能力.“,”CuO-CeO2 monolithic catalysts supported on SiO2-Al2O3 modified glass-fiber honeycomb were prepared via co-impregnation method and their performance in the oxidation of volatile organic compounds (VOCs) such as ethyl acetate, isopropanol and toluene was evaluated.Various techniques such as N2 sorption, X-ray powder diffraction (XRD), hydrogen-temperature programmed reduction (H2-TPR), ammonia-temperature programmed desorption (NH3-TPD) and chemisorption of VOCs were employed to characterize the catalysts.The results show that the copper oxide species are highly dispersed on the CuO-CeO2 based catalysts;moreover, the size of CeO2 nanoparticles increases with the decrease of copper/ceria molar ratio.The addition of ceria oxide can evidently increase the amount of total acid sites, especially the Lewis ones, which can enhance the adsorption capacity of ethyl acetate and isopropanaol and promote the oxidation of ethyl acetate and isopropanaol.In the case of toluene combustion, the addition of large amount of CeO2 may decrease the reducibility and oxygen activation capability;as a result, it contributes little to the adsorption of toluene, resulting in a low activity in the oxidation of toluene.The catalytic activity is related both to the reactivity of surface oxygen and to the adsorption capacity of the catalyst towards VOC molecules, which are determined by the complex interactions among copper, cerium oxide and the support.