在室温下以太阳能替代传统的高温高压热反应条件,在固定床装置中实现连续动态光催化甲烷重整水气(PSRM)制氢反应:CH4+2H3O(g)→4H2+CO2.产物的主成分是H2和CO2,同时检测到微量或痕量的C2H6、C2H4和CO.重点考察了以光沉积法负载Pt的TiO2(p-Pt/TiO2)为光催化剂,该反应体系在不同CH4/H2O进料摩尔比、进料的总流速、光照波长、催化剂用量以及贵金属的负载方式等的实验条件对氢气产率的影响.最优化的反应条件为:CH4/H2O进料摩尔比为4;进料总流速为0.5mL min-1:光沉积负载要优于浸渍法:相同的负载方式Pd和NiOx为比较优异的助催化剂:最佳催化剂用量为20mg·cm-2.最后循环实验结果表明,p-Pt/TiO2及反应体系都具有比较高的稳定性.
Photocatalytic reaction of CH4 gas with H2O vapor over Pt/TiO2 at around room temperature (ca 323 K) was examined in a flow reactor. H2 and CO2 were the main products, and only trace amounts of C2H6, C2H4, and CO were observed. After an induction period, the molar ratio of H2 to CO2 in the outlet gas became close to 1.7. Thus, the main reaction is suggested to be: CH4+2H2O(g)→4H2+CO2, which can be referred to as photocatalytic steam reforming of methane (PSRM). The reaction would be promoted by photoexcited electrons and holes, which were generated by band gap photoexcitation of the TiO2 photocataiyst. In addition, the effects of reaction parameters, such as molar ratio of CH4 to H2O, total flow rate, noble-metal cocatalysts, wavelength of irradiating light, amounts of catalysts, and recycling efficiency of the p-Pt/TiO2 photocatalyst via light deposition of preformed Pt nanoparticles on P25, on the hydrogen evolution were investigated.