Y修饰CuO/ZrO_2催化剂高效催化水煤气变换反应制氢

采用水热法制备了具有不同Y掺杂量的单分散ZrO_2纳米粒子(n(Y)/n(Y+Zr)=0-5%),并以其为载体采用沉积-沉淀法制得CuO/ZrO_2催化剂;考察了富氢气氛下上述催化剂的水煤气变换反应(WGS)催化性能。结果表明,掺杂Y后催化剂的活性明显提高,其中,载体掺杂2%Y的催化剂具有最佳的催化活性,在270℃时的CO转化率高达91.4%,明显高于研究较多的CuO/ZnO和CuO/CeO_2催化剂。X射线粉末衍射、N_2物理吸附-脱附、N_2O滴定、扫描电镜和CO程序升温还原等表征结果表明,Y~(3+)掺入了ZrO_2的晶格并对催化剂的结构和还原性能产生直接影响。Y助剂的引入一方面促进了CuO在ZrO_2表面的分散,提高了催化剂表面活性Cu-O]-Zr物种的含量;另一方面,改善了催化剂的颗粒单分散性和织构性能。载体掺杂2%Y助剂的样品具有较高的Cu-O]-Zr物种含量、较佳的颗粒单分散性和织构性能,且其表面的Cu-O]-Zr物种和活性羟基具有较佳的还原性能,因而表现出较高的催化活性

Highly active Y-promoted CuO/ZrO2 catalysts for the production of hydrogen through water-gas shift reaction

ZrO₂ doped with various concentrations of yttrium(0-5%) was prepared by a hydrothermal homogeneous co-precipitation method and CuO was then deposited on ZrO₂ by a deposition-precipitation method to get the yttrium promoted CuO/ZrO₂ catalyst; its performance in the water-gas shift reaction for producing hydrogen was then investigated. The results indicate that the catalytic activity of CuO/ZrO₂ can be effectively improved by yttrium modification; over the yttrium promoted CuO/ZrO₂ catalyst with an yttrium concentration of 2%, the CO conversion reaches 91.4% at 270℃, much higher than those over the conventional CuO/ZnO and CuO/CeO₂ catalysts. The XRD, N₂-physisorption, N₂O titration, SEM and CO-TPR characterization results reveal that Y³⁺ is successfully incorporated into the lattice of ZrO₂, which has a great influence on the structure and reducibility of the CuO/ZrO₂ catalysts. Y³⁺ doping into ZrO₂ introduces oxygen vacancies, improving the dispersion of CuO and increasing the proportion of catalytically active Cu-O]-Zr species. In addition, the introduction of yttrium improves the monodispersity and modifies the texture properties of the CuO/ZrO₂ catalysts. As a result, the superior activity of 2% yttrium promoted CuO/ZrO₂ catalyst is probably attributed to the abundance of Cu-O]-Zr species, high reducibility of Cu-O]-Zr species and surface hydroxyl groups, high monodispersity and proper textural properties.