论文部分内容阅读
采用浸渍法、溶胶 凝胶过程与普通干燥、超临界干燥过程相结合的方法制备了三种 82 3K焙烧的NiO CeO2 Al2 O3 体系催化剂 ,分别为浸渍型催化剂 (iNCA5 5 0 )、干凝胶催化剂 (xNCA5 5 0 )和气凝胶催化剂 (aNCA5 5 0 ) ,考察了它们在CH4 CO2 重整反应中的催化性能及反应的稳定性 ,采用TG、TEM、XPS等手段研究了反应前后催化剂的结构性质。研究结果表明 ,在 10 73K、CH4 CO2 =1∶1、180 0 0mL h·g的反应条件下 ,三种催化剂中aNCA5 5 0在CH4 CO2 重整反应过程中的积碳量较大 ,但却具有最好的反应稳定性 ;aNCA5 5 0具有较大积碳量与其表面酸量较大、酸性较强及较大镍分散度有关 ,然而由于它具有较大的积碳容量和很强的金属抗烧结能力 ,因此保持了较好的反应稳定性。催化剂积碳和金属镍烧结导致催化剂表面活性中心数目减少是催化剂失活的主要原因。
Three types of 82 3K calcined NiO CeO2 Al2 O3 catalysts were prepared by a combination of impregnation method, sol-gel process, and ordinary drying and supercritical drying processes. They were impregnated catalyst (iNCA550), xerogel catalyst (xNCA550) and aerogels (aNCA550) were used to investigate their catalytic performance and reaction stability in the CH4 CO2 reforming reaction. The structures of the catalysts before and after the reaction were investigated by means of TG, TEM and XPS. . The results showed that aNCA550 had a larger amount of carbon deposition during the CH4 CO2 reforming reaction at 1073K, CH4 CO2 = 1: 1, 180O0mL h · g Has the best reaction stability; aNCA550 has a larger amount of carbon deposition and the surface acidity is larger, more acidic and larger nickel dispersion, but because of its larger carbon deposition capacity and strong metal Anti-sintering ability, thus maintaining a good reaction stability. Decrease in the number of catalyst surface active sites caused by catalyst carbon deposition and nickel metal sintering is the main reason for catalyst deactivation.