课题组近期研究发现,水热辅助CTAB(十六烷基三甲基溴化铵)软模板法制得的多孔CoCex复合催化剂具有优异的CH4/CO2重整催化活性。过渡金属Co作为CH4/CO2重整反应的主要活性中心,易在反应中失去电子,促进反应物分子CH4和CO2的活化。Ce物种的引入能促进高分散度金属Co物种和催化活性中心的形成,促进催化剂对CO2分子的吸附与活化。Ce物种与Co物种间产生强电子效应,形成缺电子的CeO2-δ和富电子的Coδ-物种。CeO2-δ物种的形成有利于CH4分子的吸附活化形成CH4-x(x = 0-4)活性物种;Coδ-的形成有利于CO2和CH4分子的活化,从而促进DRM反应。Co/Ce摩尔比对CoCex催化剂的物理化学性质具有显著影响,Co/Ce摩尔比为2时制得的CoCe2催化剂具有最佳的CH4/CO2重整催化性能和稳定性。在反应温度为700 °C时,CH4和CO2转化率分别达88.6%和52.1%,且能保持较高循环使用稳定性。
该研究提供了关于Co与CeO2间相互作用的重要信息,为开发高性能CH4/CO2干重整催化剂提供了理论基础和可行的思路。
Dong Zhang (张栋), Hongmei Xie, Shuang Chen, Guilin Zhou∗. Porous CoCe composite catalyst prepared by hydrothermal assisted soft template method for CH4/CO2 dry reforming [J]. Fuel, 2022, 327: 125105. https://doi.org/10.1016/j.fuel.2022.125105
The CoCex composite catalysts prepared by hydrothermal assisted template agent CTAB, have superior catalytic performances for CH4/CO2 dry reforming (DRM). The physicochemical properties of the catalysts were investigated in depth with the help of XRD, H2-TPR, CO2-TPD, ICP, Quasi in-situ XPS and N2 adsorption-desorption measurements. The transition metal Co is the main active center in the DRM reaction, which can easily release the outer electrons in the reaction to activate the reactant molecules. The introduction of Ce species can promote the highly dispersed metal Co species and catalytic active centers to be formed, as well as the adsorption and activation of CO2 molecules by the catalyst. Ce species can produce strong electronic effects with Co species, which can promote the electron-deficient CeO2-δ and electron-rich Coδ- species to be formed. The formation of CeO2-δ species facilitates the adsorption and activation of CO2 molecules, and the active oxygen species on the CeO2-δ surface facilitates the oxidative activation for CH4 molecules. The CH4 and CO2 reactant molecules can be adsorbed and activated by the formed Coδ- species to form CH4-x (x = 0-4) and CO2δ- reactive species, which can promote the DRM reaction. The Co/Ce molar ratio has an important effect on the physicochemical properties and CO2 adsorption performance of CoCex catalysts. And the CoCe2 catalyst prepared at a 2.0 Co/Ce molar ratio exhibited superior catalytic performance and high stability for the DRM reaction. The CH4 and CO2 conversion of the CoCe2 catalyst reached 88.6%, and 52.1% at 700 °C, respectively. In addition, the CoCe2 catalyst can maintain high cycle stability for CH4/CO2 dry reforming.