碳纳米管促进Cu-基高效甲醇合成催化剂

用自行制备的碳纳米管（CNTs）作为促进剂，研制出一类高效甲醇合成催化剂CuiZnjAlk-Ox-wt%CNTs，评价它们对CO／CO加氢成甲醇的催化活性，并与非CNTs促进的相应体系作对比研究。实现发现，碳纳米管能显著地促进甲醇合成反应活性的提高。在493K，5．0MPa,H2/CO/CO2/N2=62/30/5/3(V/V),GHSV=8000h^-1的反应条件下, Cu6Zn3Al1-Ox-12.5wt%CNTs催化剂上，甲醇的时空产率达1064mgh^-1(g-catal)^-1；产物中甲醇的选择性达98％以上；而在相同的制备和反应条件下、在非促进相应催化剂Cu6Zn3Al1-Ox上，甲醇的时空产率只达729mgh^-1（g-catal)-1.H2-TDP观测揭示，常压下在CNTs材料、以及CNTs促进催化剂CuiZnjAlk-Ox-wt%CNTs上，可以吸附存储着数量相当可观、在423－573K温度范围处于可逆吸、脱附的吸附氢物种。这一特性将有助于在甲醇合成反应条件下，营造较高氢稳态的表面氛围，以有利于提高表面加氢反应的速率；与此同时，很可能由于加氢活性的提高，使得碳纳米管促进催化剂上甲醇合成反应所需温度比非促进的相应体系下降15－25K，这在相当大程度上将有利于提高CO的平衡转化率和甲醇合的平衡产率。本文结果表明，碳纳米管对H2优异的吸附、活化及存储性能对于促进其所改进催化剂上甲醇合成反应活性的显著提高，起着关键作用。

Highly Active CNTs-Promoted Cu-based Catalyst forHydrogenation of CO/CO2 to CH3OH

With a kind of multi-walled carbon nanotubes (CNTs) synthesized catalytically in-house and the nitrates of the corresponding metallic components, highly active CNTs-promoted catalysts, Cu iZn jAl k-O X-wt%CNTs, were prepared by co-precipitation method, and their catalytic performance for synthesis of methanol from H 2/CO/CO 2 was investigated and compared with the corresponding CNTs-free catalyst. It is experimentally found that incorporation of the CNTs into the Cu iZn jAl k-O X can significantly advance the catalyst activity for methanol synthesis. Over a Cu 6Zn 3Al 1-O X-12.5wt%CNTs catalyst and under reaction conditions of 493 K, 5.0 MPa, feed-gas H 2/CO/CO 2/N 2= 62/30/5/3 (V/V), GHSV= 8 000 h -1, conversion of CO reached 31%, with the corresponding methanol-STY at 1 064 mg-CH 3OH h -1 (g-catal.) -1, which was about 1.46 times as high as that (729 mg h -1 (g-catal.) -1) over the corresponding CNTs-free catalyst Cu 6Zn 3Al 1-O X. The H 2-TPD measurement demonstrated that the CNTs material and prereduced Cu iZn jAl k-O X-wt%CNTs system could reversibly adsorb and storage a considerable quantity of hydrogen under atmospheric pressure in temperature region from room temperature to ca. 573 K. This peculiarity would be conducive to generating surface circumstances with higher stationary-state concentration of hydrogen-adspecies on the functioning catalyst, and in turn favourable to enhancement of speed of the surface hydrogenation reactions. Meanwhile, the operation temperature for methanol synthesis over the CNTs-promoted catalyst can be 15~25 K lower than that over the corresponding CNTs-free catalyst, which would considerably contribute to an increase in equilibrium CO-conversion and CH 3OH-yield. The results of the present work indicated that the carbon nanotubes could served as an excellent promoter, and that its peculiarity of adsorbing and storing H 2 played an important role in promoting enhancement of reactivity of methanol synthesis over the CNTs-promoted Cu iZn jAl k-O X catalysts.