材料期刊网

分别采用硝酸钴、醋酸钴、硫酸钴和氯化钴为前驱体制备了Co/SiO2催化剂,用XRD,TPR,SEM和H2-TPD等实验技术考察了钴盐前驱体对催化剂结构和二氧化碳重整甲烷反应性能的影响,重点考察了硝酸钴和醋酸钴的作用.结果表明,由醋酸钴制备的Co/SiO2催化剂有最佳的催化活性和稳定性,它在钴物种的存在状态、金属-载体相互作用、钴金属晶粒度及抗烧结、抗积炭能力等方面,均与由硝酸钴制备的Co/SiO2催化剂存在显著的差别.Co/SiO2催化剂的反应活性和稳定性分别与其金属分散度和抗烧结、抗积炭能力密切相关.

Co/SiO2 catalysts are prepared by impregnation method fromdifferent cobalt sa lt precursors, such as Co(NO3)2, Co(CH3COO)2, CoSO4 and CoCl2, respe ctively. The effects of cobalt salts, especially Co(NO3)2 and Co(CH3COO)2, on catalyst structure and performance in CO2/CH4 reforming are studied using activity evaluation as well as XRD, TPR, SEM and H2-TPD techniques. A mong the catalysts investigated, Co/SiO2 starting from Co(CH3COO)2 exhibit s the highest activity and stability. It maintains its high activity during 10 h of reaction at 973 or 1 073 K, while the catalyst from Co(NO3)2 shows nota ble deactivation after reaction at the same temperatures for only 6h. The highe r the cobalt loading or the lower the temperature, the greater the activity diff erence between the two catalysts. The results of characterization show that Co/S iO2 catalysts prepared from Co(CH3COO)2 and Co(NO3)2 are greatly diffe rent in many ways, such as existence of Co species, metal-support interaction, Co0 particle size and resistance to sintering and coking. Combining the result s of the reaction with the characterization of catalysts, it is established that CO2/CH4 reforming over Co/SiO2 catalyst is of structure sensitivity, and the activity and stability of the catalyst are close related to the degree of dispersion of metallic cobalt and resistance to sintering and coking, respectively.