均相沉淀水热法制备复合分子筛催化剂及其在甲烷制氢中的应用

Application of Composite Molecular Sieve Catalysts Prepared by Homogeneous Precipitation-hydrothermal Method to Hydrogen Production from Methane

针对沼气再利用,以甲烷制氢为目标反应,采用均相沉淀水热法直接合成了以镍为活性组分的铈基复合分子筛催化剂NiO/CZ-SX。借助在线测试,BET,H_2-TPR等技术对催化剂进行测试表征,结果表明,在前驱液配比TPAOH∶TEOS∶H_2O=25∶100∶15000的条件下制备的催化剂NiO/CZ-S15,其活性组分与载体的相互作用和表面及体相晶格氧的移动能力最强,能有效地提高催化剂的活性和高温水热稳定性;在常压、空速为3000 h^(-1)和水碳比为3的条件下,初始甲烷转化率为99.4%,在312 h的稳定性测试后,甲烷转化率仍维持在93.2%。此制备方法可以通过提高金属氧化物的分散度解决传统甲烷制氢催化剂高温水热稳定性较差的问题。

For biogas utilization,the catalysts NiO/CZ-SX were synthesized by the homogeneous precipitation-hydrothermal method and applied to methane steam reforming reaction.The catalysts were characterized by GC,BET and H 2-TPR and other technologies.In the paper,the catalyst NiO/CZ-S15 was prepared under the conditions of TPAOH∶TEOS∶H 2O=25∶10∶15000.It exhibited the most strong interaction between the active components and supporter.And it also enhanced the mobile ability of lattice oxygen of surface and body.These characters could effectively improve the activity of catalyst and hydrothermal stability at high temperature.The initial methane conversion on NiO/CZ-S15 was 99.4%at atmospheric pressure with GHSV of 3000 mL·g-1 h-1 and water/carbon molar ratio of 3.Furthermore,the methane conversion still maintained 93.2%after 312 h stability test.Therefore,homogeneous precipitation-hydrothermal method could be used to improve the dispersion of metal oxides and so obtain high hydrothermal stability at high temperature for hydrogen production catalysts.