Pt/TiO_2纳米薄膜的制备及光催化气相甲醇制氢的研究

Preparation of Pt/TiO_2 nano-film and its photocatalytic activity of hydrogen production from methanol vapor

通过溶胶-凝胶法制备了Pt/TiO2纳米薄膜,并在气相连续流动装置中,对甲醇的光催化脱氢反应进行了研究。将Pt/TiO2薄膜催化剂与TiO2薄膜催化剂的光催化活性进行了比较,考察了产氢量甲醇浓度、光照时间的关系,以及空速、反应温度对甲醇转化率的影响。结果表明,经过还原后分散于TiO2薄膜表面的Pt是以Pt2+及Pt0价态存在的。Pt/TiO2纳米薄膜是未负载Pt的纳米薄膜光催化活性的28倍。增加甲醇蒸汽的浓度会使产氢速率增大;当甲醇浓度在29%时,产氢速率达到最大,为4.68mmol/h。醇的转化率随着空速的增加而减小。该反应在一定的浓度范围内是一级反应,其反应的活化能为26.19kJ/mol。

In the present work,Pt/TiO2nano-film was prepared by sol-gel method,and the photocatalytic decomposition of gaseous methanol on Pt/TiO2 nano-film was carried out in a continuous-flow reactor.The effect of various factors on the photocatalysis process was investigated,space velocity,illuminating time,methanol concentration,and also the photocatalytic activities of Pt/TiO2 nano-film was compared with TiO2 nano-film. The result shows that,Pt dispersed on TiO2 thin films are based on the existence of Pt2＋and Pt0valence.The photocatalytic activity of Pt/TiO2 nano film was as 28 times as that of TiO2 nano film under the same condition. The effect of methanol concentration showed the maximum value of hydrogen production is 4.68mmol/h when its concentration is 29%.The methanol conversion decreased with the increase of space velocity.The photocatalytic decomposition of methanol gas was first order reaction,and the activity energy is 26.19kJ/mol.The reaction mechanism was deduced according to the kinetic and GC/MS analytical results.