CeO2-Y2O3涂层和负载型Pd催化剂催化燃烧VOCs

制备了一种粘附在堇青石蜂窝陶瓷载体上的CeO_2-Y_2O_3(CeY)复合氧化物新涂层.以二氧化铈和柠檬酸钇为前驱体,制备过程中无有害物质产生,对环境友好.CeY涂层和Pd/CeY催化剂通过SEM、EDX、XRF和Raman光谱等表征.结果表明,此涂层的粘结强度高,对活性组分的吸附性能好,适合用来负载钯催化剂.Y_2O_3大部分进入了峰窝陶瓷的孔道内,CeO_2和Pd物种则富集在载体的表面.以CO、甲苯和乙酸乙酯的催化燃烧来评价Pd/CeY催化剂的性能,此催化剂具有较好的催化活性和热稳定性.500℃焙烧的催化剂,CO、甲苯和乙酸乙酯的T_(99)(转化率99%以上所需的最低反应温度)分别为150、220和310℃;1050℃焙烧的催化剂,它们的T_(99)分别为180、250和330℃.高温焙烧的催化剂,活性物种PdO的晶粒增大,这可能导致催化剂的活性下降.

CeO2-Y2O3 Washcoat and Supported Pd Catalysts for the Combustion of Volatile Organic Compounds (VOCs)

A novel CeO2-Y2O3 (denoted as CeY) washcoat adhered to the cordierite honeycomb was prepared. The preparation technique, using nano-sized CeO2 and yttrium citrate as precursors, was friendly to environment because no deleterious products were formed during the operation. The CeY washcoat support and Pd/CeY catalysts were characterized using scanning electron microscope (SEM), energy dispersive X-ray (EDX), X-ray fluorescence (XRF) spectrometer, and Raman spectroscopy. The results showed that the washcoat had sufficient adhesion and high adsorption efficiency for active species and was suitable for supporting Pd catalysts. For the catalysts, most of Y2O3 entered into the channel of the cordierite honeycomb, whereas CeO2 and Pd enriched on the surface. Furthermore,model reactions for the catalytic combustion of CO, toluene, and ethyl acetate were carried out to evaluate the performance of the Pd/CeY catalyst. It exhibited fairly good catalytic activity and thermal stability. For those catalysts calcined at 500 ℃, the T99 (the lowest reaction temperature when the conversion is 99%) of CO, toluene, and ethyl acetate was 150, 220, and 310 ℃, respectively, whereas for those catalysts calcined at 1050 ℃, the T99 of CO, toluene, and ethyl acetate was 180, 250, and 330 ℃, respectively. Catalysts calcined at higher temperature, the crystallite size of active species (PdO) increases, which possibly results in a decline in the catalytic activity.