浸渍溶剂对Pt/疏水陶瓷催化剂性能的影响

摘要

研究采用疏水陶瓷载体,分别使用水/乙醇(体积比2∶1)溶液、乙醇及丙酮作为浸渍溶剂,采用浸渍-气相还原法制备用于氢水催化交换的铂/疏水陶瓷催化剂.通过X射线衍射(XRD)、扫描电镜(SEM)、H2程序升温还原法(H2-TPR)、光电子能谱(XPS)及CO脉冲吸附对催化剂进行综合表征,采用气液并流方式测试催化剂催化活性,研究浸渍溶剂的选择对催化剂性能的影响.水/乙醇溶剂表面张力最高,浸润疏水载体能力小于乙醇及丙酮,使得氯铂酸在载体表面分布均匀度低,造成催化剂铂粒子分散度低,高价铂还原困难,催化活性远低于使用丙酮及乙醇作为溶剂制得的催化剂.丙酮的挥发速率最快,可减少氯铂酸在载体表面团聚,制得催化剂铂粒子分散度最高,高价铂更易被还原,催化活性优于使用乙醇作为溶剂制得的催化剂.%The inorganic hydrophobic catalyst used for H2-H2O liquid phase catalytic exchange were prepared by impregnation method with the solvent of water/ethanol (the volume ratio is 2 ∶ 1) solution,ethanol and acetone respectively.The influence of solvent on the performance of catalysts was studied,and the character of catalysts was tested by XRD,SEM,H2-TPR,XPS and CO adsorption.With the highest surface tension,the water/ethanol solvent can hardly infiltrate the hydrophobic carrier,which results in the low uniformity of chloroplatinic acid distribution,lead to the low platinum particle dispersion and the high reduction difficulties,the catalytic activity is far below the use of acetone and ethanol as the solvent.With the fastest evaporation,the acetone solvent can reduce the gathering of chloroplatinic acid on the carrier surface,and obtain the highest platinum particle dispersion.Then the platinum are more likely to be reduced,the catalytic activity of the catalyst is better than that of using ethanol as the solvent.