Ce-Cu-Co/CNTs催化剂催化合成气制低碳醇及乙醇的研究

采用共浸渍法制备了不同Ce含量的Ce-Cu-Co/CNTs 催化剂, 考察了其在合成气制低碳醇反应中的催化性能, 借助X射线衍射(XRD)、程序升温还原(H₂-TPR)、N₂吸脱附实验(BET)、透射电镜(TEM)和CO程序升温脱附(CO-TPD)对这些催化剂进行了表征. 结果表明, 当Ce的质量分数为3%时, 低碳醇的时空收率和选择性达到最高, 分别为696.4 mg·g^-1·h^-1和59.7%, 其中乙醇占总醇的46.8%, 适量Ce的添加能提高Cu物种在催化剂上的分散度和催化剂的还原性能, 能显著地增加催化剂吸附CO的能力, 促进合成醇活性位的形成, 进而明显提高催化剂的活性和总醇的选择性. 研究表明, 将具有高活性和高碳链增长能力的CuCo基催化剂与碳纳米管的限域效应结合, 可实现缩窄产物分布、大幅度提高乙醇选择性的目的.

Study of Ce-Cu-Co/CNTs Catalysts for the Synthesis of Higher Alcohols and Ethanol from Syngas

A series of Ce-Cu-Co/carbon nanotubes (CNTs) catalysts with different Ce contents were prepared by co-impregnation, and the catalytic performance was investigated for the synthesis of higher alcohols from syngas. The catalysts were characterized by X-ray diffraction (XRD), temperature-programmed reduction of H₂ (H₂-TPR), N₂ adsorption-desorption isotherms (BET), transmission electron microscopy (TEM), and temperature-programmed desorption of CO (CO-TPD). The results showed that at a Ce content of 3% the catalyst had the highest catalytic activity. The formation rate and selectivity of alcohol reached 696.4 mg·g^-1· h^-1 and 59.7%, where the mass fraction of ethanol was 46.8% of the total amount of alcohols. The addition of an appropriate amount of Ce facilitated the dispersion of Cu and promoted reduction of the catalysts. It also markedly increased the adsorption capacity for CO, and significantly improved the formation of active sites for alcohols, which is favorable for the catalytic activity and to improve the selectivity of alcohols. Research showed that combining the CuCo-based catalyst, which has high activity and a high ability of carbon chain growth, with the confinement effect of CNTs can result in a narrow distribution of alcohols and significantly improve the selectivity of ethanol.