溶液燃烧法制备Ni-Al2O3催化剂用于CO2-CH4重整研究

采用溶液燃烧法制备了Ni含量为2wt%、4wt%、6wt%、8wt%和10wt%系列催化剂, 并对反应前后催化剂进行N₂吸附-脱附、XRD、H₂-TPR、TPH、Raman、TEM和TG-DTG等表征。与等体积浸渍法(以溶液燃烧法制备的Al₂O₃为载体)制备的催化剂相比, 溶液燃烧法制备的催化剂具有较大的比表面积, 孔径分布可分为2~4.5 nm和4.5~10 nm两段, 属典型的多级孔结构; NiO高度分散在载体上, 与载体具有较强的相互作用, 这种相互作用有利于提高催化剂的稳定性。催化剂210 h稳定性试验表明, 溶液燃烧法制备的Ni含量为8wt%试样的CH₄转化率维持在90%左右, 失活速率仅为0.035%/h, 优于浸渍法制备的相同Ni含量催化剂。

Preparation of Ni-Al2O3 Catalysts by Solution Combustion Method for CO2 Reforming of CH4

Ni-Al₂O₃ catalysts with Ni loading of 2wt%, 4wt%, 6wt%, 8wt%, and 10wt% were prepared by solution combustion method for carbon dioxide reforming of methane to produce syngas, and characterized by N₂ adsorption-desorption method, XRD, H₂-TPR, TPH, Raman, TEM, and TG-DTG techniques. Results showed that all the catalysts preserved large specific surface areas and hierarchical pore size distributions (2-4.5 nm as one part and 4.5-10 nm as another part) as compared to 8IMNi-Al catalyst prepared by impregnation method (Al₂O₃ as support prepared by solution combustion method). NiO was highly dispersed in the Ni-Al₂O₃ catalysts, which combined with support with strong metal-support interaction (SMSI), improving the stability performance. The 210 h stability test of 8Ni-Al catalyst showed that conversion rate of CH₄ was around 90% with the deactivation rate of only 0.035%/h, lower than that of 8IMNi-Al catalyst within the 182 h endurance test. TG-DTG result demonstrated that carbon deposition rate of 8Ni-Al catalyst was only 0.34 mg/(h·g_cat), which was lower than that of 8IMNi-Al catalyst (0.80 mg/(h·g_cat)). Therefore, the Ni-Al₂O₃ catalyst prepared by solution combustion method presented well stability.