硅源对蒸氨法制备Cu/SiO2催化剂催化甲醇裂解制氢的影响

采用蒸氨法制备Cu/SiO₂催化剂，分别考察气相二氧化硅（SiO₂-aer）、硅胶（SiO₂-gel）和碱性硅溶胶（SiO₂-sol）对Cu/SiO₂催化剂催化甲醇裂解制氢性能的影响，并采用N₂吸附-脱附、N₂O化学吸附、电感耦合等离子体原子发射光谱法（ICP-AES）、X射线衍射（XRD）、H₂程序升温还原（H₂-TPR）、透射电子显微镜（TEM）和X射线光电子能谱（XPS）等方法对催化剂进行表征。结果表明，硅源对Cu/SiO₂催化剂的活性具有较大影响。以碱性硅溶胶作为硅源制得的Cu/SiO₂-sol催化剂比表面积较大，活性中心粒径较小且分散均匀，这些使得其制氢性能优于其他两种硅源为载体所制备的催化剂。在反应温度280 ℃，反应压力1 MPa，甲醇质量空速0.6 h^-1的条件下，相较于Cu/SiO₂-aer和Cu/SiO₂-gel催化剂，Cu/SiO₂-sol催化剂的甲醇转化率分别提高10％和7％，气相副产物CH₄和CO₂浓度也有所降低，该催化剂上的甲醇转化率和气体收率分别达到98.4%和96.7%。

Catalytic performance of methanol decomposition on Cu/SiO2 catalyst with different silica sources prepared with ammonia evaporation method

Cu/SiO₂ catalysts were prepared via ammonia evaporation method, using fumed silica (SiO₂-aer), silica gel (SiO₂-gel) and alkaline silica sol (SiO₂-sol) as the silica sources and their catalytic performance in methanol decomposition were investigated. The catalysts were characterized by N₂ adsorption-desorption, N₂O chemisorption, inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray diffraction (XRD), H₂ temperature programmed reduction (H₂-TPR), transmission electron microscope (TEM) and X-ray photoelectron spectroscopy(XPS). The results indicate that silica source can affect the decomposition activity of Cu/SiO₂ catalysts. The Cu/SiO₂-sol catalyst prepared with alkaline silica sol exhibits larger surface area, smaller active site size and more uniform dispersion of Cu. Therefore, it gives Cu/SiO₂-sol a better decomposition performance than other catalysts. Methanol conversion on Cu/SiO₂-sol is 10% higher than that on Cu/SiO₂-aer, and 7% higher than that on Cu/SiO₂-gel. Additionally, byproducts concentration on Cu/SiO₂-sol is considerably lower than other catalysts. Under the reaction conditions of 280 ℃, 1 MPa and 0.6 h^-1 of WHSV, methanol conversion of 98.4% and gas yield of 96.7% can be achieved.