K-Ni-Mo基催化剂的水热还原法制备及用于合成气制低碳醇反应性能研究

Hydrothermal reduction synthesis of K-Ni-Mo-based catalyst and its catalytic performance for higher alcohol synthesis from syngas

采用水热还原法制备出具有金属Ni和K_(2)MoO_(4)紧密接触的合成低碳醇用非硫化态K-Ni-Mo基催化剂。通过XRD、N_(2)物理吸附-脱附、H_(2)-TPR、HR-TEM、SEM-EDS、XPS、H_(2)-TPD、CO-TPD和CO_(2)-TPD等手段对所合成催化剂进行了分析表征。研究结果显示,向Ni-Mo基催化剂中引入K可产生K_(2)MoO_(4)相,同时伴随NiMoO_(4)相含量的降低,显著提升了K-Ni-Mo基催化剂上CO非解离吸附活化能力,从而促进了CO转化和醇类产物的形成。此外,同时增加的催化剂表面碱性可提高催化剂上碱性羟基基团数量,进而有效降低烃类选择性,表现出优异的合成低碳醇性能。其中,K_(0.4)-Ni-Mo基催化剂具有最优的催化性能,在5 MPa、240℃、空速5000 h^(−1)的反应条件下,CO转化率达到19.6%,总醇选择性57.8%,其中,总醇中C_(2+)醇选择性为66.5%。

A series of non-sulfurized K-Ni-Mo-based catalysts with close contact between Ni and K_(2)MoO_(4) were prepared by hydrothermal reduction for higher alcohol synthesis from syngas.The as-prepared catalysts were characterized by XRD,N_(2) adsorption-desorption,H_(2)-TPR,HR-TEM,SEM-EDS,XPS,H_(2)-TPD,CO-TPD and CO_(2)-TPD techniques.The results indicate that the introduction of K facilitates the formation of the K_(2)MoO_(4) phase while brings about a decrease of NiMoO_(4).It can significantly assist the non-dissociative activation of CO for insertion and subsequently alcohol formation.Moreover,the addition of K increases the surface basicity,which leads to more amount of basic hydroxy groups on the catalytic surface.The catalytic basicity ameliorates the production of alcohols.In particular,the K_(0.4)-Ni-Mo catalyst shows the best catalytic behavior with CO conversion of 19.6%,total alcohol selectivity of 57.8%and C_(2+)alcohol selectivity in the total alcohols of 66.5%at GHSV of 5000 h^(−1),240℃,and 5 MPa.