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

  • 摘要: 采用水热还原法制备出具有金属Ni和K2MoO4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、N2物理吸附-脱附、H2-TPR、HR-TEM、SEM-EDS、XPS、H2-TPD、CO-TPD和CO2-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K2MoO4相,同时伴随NiMoO4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,K0.4-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C2+醇选择性为66.5%。

     

    Abstract: A series of non-sulfurized K-Ni-Mo-based catalysts with close contact between Ni and K2MoO4 were prepared by hydrothermal reduction for higher alcohol synthesis from syngas. The as-prepared catalysts were characterized by XRD, N2 adsorption-desorption, H2-TPR, HR-TEM, SEM-EDS, XPS, H2-TPD, CO-TPD and CO2-TPD techniques. The results indicate that the introduction of K facilitates the formation of the K2MoO4 phase while brings about a decrease of NiMoO4. 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 K0.4-Ni-Mo catalyst shows the best catalytic behavior with CO conversion of 19.6%, total alcohol selectivity of 57.8% and C2+ alcohol selectivity in the total alcohols of 66.5% at GHSV of 5000 h−1, 240 °C, and 5 MPa.

     

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