杂多酸对Co-Pd/TiO2催化剂催化CH4-CO2两步梯阶转化合成乙醇和乙酸的影响

Synthesis of ethanol and acetic acid from CH_4 and CO_2 over heteropoly acid-modified Co-Pd/TiO_2 catalysts by a stepwise reaction technology

首先采用溶胶-凝胶法制备了Co-Pd/TiO_2催化剂,之后以磷钨酸为杂多酸,采用过量浸渍的方法制备了不同浓度磷钨酸改性的双金属催化剂。考察了改性催化剂对CH_4和CO_2两步梯阶转化直接合成乙醇和乙酸的催化性能,并通过XRD、NH3-TPD-MS、BET、FT-IR和XPS等技术手段对催化剂的结构、组成、比表面积和孔径分布等进行了表征。实验结果表明,以0.04mol/L磷钨酸改性的催化剂活性金属分散性好,催化剂比表面积大,这共同保障了该反应协同高效的进行。在常压、150℃的反应条件下其乙醇和乙酸的总时空速率达到10.54mg/(g·h),与未经磷钨酸改性的催化剂对比活性提高了2.55倍。

The Co-Pd/TiO2 catalysts were prepared by sol-gel method,which then were modified by impregnating them with excessive heteropoly acid of phosphotungstic acid in different concentrations.The catalytic performances of the modified catalysts for direct synthesis of ethanol and acetic acid from CH4 and CO2 by a stepwise conversion technology were investigated.XRD,NH3-TPD-MS,BET,FT-IR and XPS were used to characterize the structure,composition,specific surface area and pore diameter distribution of the catalysts.The results show that the catalyst modified by 0.04mol/L phosphotungstic acid display good dispersity of active metal and large specific surface area,which ensure the synergistic and efficient process of the reaction.Under atmospheric pressure and 150℃,over this catalyst,the total space-time yield of ethanol and acetic acid was up to 10.54mg·g^-1·h^-1,which was 2.55 times higher than that of the unmodified catalyst.