摘要
利用XRD、XPS和TPD等谱学方法对合成气制混合醇硫化钼基催化剂活性相作了表征研究。实验结果表明,碱助的MoS_x-K^+/SiO_2催化剂工作表面生成了Mo-S-K新相,很可能是催化活性相;表面钼物种主要是Mo^(4+),硫除了以S^(2-)作为主要硫物种之外,还观测到低价硫阴离子物种S^-或[s—s]^(2-)。随着碱性钾盐助剂添加量的增加,[s—s]^(2-)物种的浓度下降,H_2吸附量相应减少,这同催化剂的选择性由烃向醇的转变有着密切的联系。
Spectroscopic characterization, by means of XRD, XPS, and TPD methods, of the MoSx-K+/ SiO2 catalysts for the synthesis of mixed alcohols from syngas has been carried out. The results of XRD investigation show that a strong interaction takes place between the MoSx-component and the promoter K2CO3, leading to the formation of a new, probably catalytically active, Mo-S-K phase. The XPS investigation of the functioning catalysts indicated that the Mo-species are mainly in single valence state, Mo4+, and sulfur in several oxidation states: S2-(as sulfide), S- or (S-S)2- (as disulfide), and S6+(as sulfate). TPD spectra of H2, CO, and CO-H2mixtrure on these catalysts were taken. Two to four peaks(473, 513, 593, and 623 K) for hydrogen, three peaks(373, 523, and 623 K ) for CO, and three peaks(373, 513,and 623 K) for CO-H2, were observed. With addition of alkaline potassium salt(s) , the concentration of the (S-S)2- species at the surface of the functioning catalysts decreased and so did the hydrogen adsorption on the catalysts, which is closely correlated with shifting the selectivity from hydrocarbon (over MoS2) towards alcohols (over MoSx-K+catalysts).
出处
《分子催化》
EI
CAS
CSCD
1992年第5期321-327,共7页
Journal of Molecular Catalysis(China)
基金
国家自然科学基金资助课题
关键词
合成
混合醇
钼硫基
催化剂
制备
Syngas conversion, Mixed alcohol, MoSx-based catalyst, Spectroscopic characterization.
