CuZnAl类水滑石制备过程pH值对其催化C_(2+)醇合成的影响

Effect of pH Value on the Catalytic Performance of CuZnAl-LDHs Catalysts in the Synthesis of C_(2+) Alcohols

采用沉淀水热法制备了具有类水滑石结构的CuZnAl催化剂前驱体,将其焙烧后制得CuZnAl催化剂用于合成气制取C_(2+)醇的反应,同时运用XRD、H2-TPR、BET、CO_2-TPD-MS和CO-TPD-MS分析方法对催化剂进行表征,考察了催化剂前驱体制备过程中pH值对催化剂结构和催化性能的影响。结果表明,pH值的改变对CuZnAl催化剂中可还原的Cu物种、比表面积、表面碱强度以及对CO的吸附能力均存在显著影响,进而影响催化剂的转化率及选择性。具有较高分散性的可还原Cu物种、较大的比表面积、适宜比例的中强碱和强碱量以及对CO有适当的解离和非解离能力的催化剂,均有利于C_(2+)醇的生成。

CuZnAl catalyst precursors were prepared by precipitation-hydrothermal method.The CuZnAl catalysts were obtained by calcination,and then used to synthesize C2＋ alcohols from syngas.The catalysts were characterized by XRD,H2-TPR,BET,CO2-TPD-MS and CO-TPDMS.The effect of pH value on the structure and performance was investigated.It is found that the pH value has a significant effect on the reduced Cu species,specific surface area,surface base strength and the adsorption capacity of CO.Therefore it affects the conversion and selectivity during catalytic reaction.The results show that high dispersion of Cu species,large specific surface area,appropriate ratio of the medium and strong base,as well as appropriate dissociation and nondissociation of CO are favorable of C2＋ alcohols synthesis.