热解条件对CuCe-O/γ-Al2O3催化性能的影响

Influence of pyrolysis conditions on catalytic performance of CuCe-O/γ-Al_2O_3

采用柠檬酸络合法制备了一系列的CuCe-O/γ-Al_2O_3催化剂,利用XRD,H_2-TPR,BET,SEM等手段对不同热解温度、热解气氛下制备的CuCe-O/γ-Al_2O_3催化剂进行表征,并在连续固定床微反装置上评价了CuCe-O/γ-Al_2O_3催化剂的CO氧化性能。实验结果表明,改变热解温度及热解气氛对CuCe-O/γ-Al_2O_3试样的比表面积及形貌特征影响较小,CuCe-O/γ-Al_2O_3试样中CuO在γ-Al_2O_3载体表面呈高度分散状态,弱氧气氛增强了CuO/CeO_2两相间的相互作用,加剧了Ce^(3+)从CuO中获取氧的趋势,提高了氧化铜的氧化还原能力,相应的H_2-TPR还原温度向低温区偏移;在15%(φ)空气+85%(φ)N_2热解气氛及230℃热解温度下制备的CuCe-O/γ-Al_2O_3试样具有优良的CO氧化活性,表明适宜的热解条件可以增强CuO/CeO_2两相的相互作用,进而提高CuCe-O/γ-Al_2O_3试样的氧化还原能力。

A series of CuCe-O/γ-Al2O3 catalysts were prepared by using amorphous citric precursor method,and characterized by XRD,H2-TPR,BET and SEM techniques.The CO oxidation performance of each CuCe-O/γ-Al2O3 catalyst was evaluated by a continuous fixed-bed microreactor.The results indicated that changing the pyrolysis temperature and atmosphere had little effect on the BET surface area and morphology of the CuCe-O/γ-Al2O3 catalyst,and CuO in the CuCe-O/γ-Al2O3 sample was highly dispersed on the surface of theγ-Al2O3 carrier.The poor oxygen atmosphere enhanced the interaction between CuO and CeO2,aggravated the tendency of Ce3+to acquire oxygen from CuO and increased the redox ability of the CuO,with the H2-TPR reduction temperature shifting to low temperature region accordingly.The CO oxidation results showed that the CuCe-O/γ-Al2O3 catalyst prepared in 15%(φ)air+85%(φ)N2 atmosphere at 230℃had excellent CO oxidation activity,indicating that the suitable pyrolysis conditions enhanced the interaction of CuO/CeO2,and then increased the redox ability of the CuCe-O/γ-Al2O3 catalyst.