热处理时间对CuZnAl催化剂合成C2+OH性能的影响

Effect of heat treatment time on the performance of CuZnAl catalysts in the synthesis of higher alcohols from syngas

  • 摘要: 采用完全液相法在不同热处理时间下制备了CuZnAl催化剂,利用X射线光电子能谱(XPS)、X射线衍射(XRD)、H2程序升温还原(H2-TPR)、NH3吸附-脱附(NH3-TPD-MS)和N2物理吸附-脱附等方法对其结构进行了表征分析,并在浆态床反应器上对其催化合成气制C2+OH的性能进行了研究。研究发现,延长热处理时间增强了催化剂中Cu和Al物种之间的相互作用力,改变了其中Cu+的量,从而影响Cu+-Cu0活性位的协同作用。同时,热处理时间的延长减少了催化剂的表面酸量,增大了孔容和孔径;催化剂表面较少的弱酸位及较大孔容和孔径均有利于C2+OH的生成。热处理时间为7 h时所制备的CuZnAl催化剂表现出了优良的低碳醇合成催化活性,CO转化率和总醇中C2+OH的质量分数分别达到了38.1%和65.9%。

     

    Abstract: A series of CuZnAl catalysts were prepared by the complete liquid-phase method with different heat treatment times and characterized by XPS, XRD, H2-TPR, NH3-TPD-MS and N2 adsorption-desorption; their catalytic performances in the synthesis of higher alcohols from syngas were investigated in a slurry bed reactor. The results indicate that an increase in the heat treatment time can enhance the interaction between the Cu and Al species and alter the amount of Cu+ species over the CuZnAl catalysts, influencing the synergistic effect of Cu+-Cu0 sites. In addition, with the increase of heat treatment time, the surface acidity of CuZnAl catalyst decreases, accompanying with an increase in the pore volume and pore size; small amount of surface weak acid sites, large pore volume and large pore size are beneficial to the formation of higher alcohols. The CuZnAl catalyst obtained by heat-treating for 7 h exhibits excellent performance in the synthesis of higher alcohols, with a CO conversion of 38.1% and a higher alcohols mass fraction of 65.9% in the total alcohols.

     

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