Ni/白云石催化剂CO_(2)吸收及甲烷化性能研究

Performance of Ni/dolomite catalyst for CO_(2) sorption and methanation

针对甲烷化耦合焦油重整工艺的要求,设计并制备了铝酸钙水泥混合的白云石复合物负载Ni催化剂,在热重分析仪上测试了该催化剂的CO_(2)吸收量和循环稳定性,在固定床反应器中考察了不同温度和Ni负载量下催化剂的甲烷化反应性能,并采用XRD、低温氮吸附等表征手段分析了催化剂的结构特性。结果表明,Ni负载量为8%的Ni/白云石催化剂具有良好的CO_(2)吸收循环稳定性;在甲烷化反应温度为500°C,其CO_(2)转化率和CH4选择性分别为66.7%和85.9%;铝酸钙水泥的引入使得催化剂具有良好的CO_(2)吸收循环稳定性;白云石中的MgO与活性组分Ni以较稳定的NiO-MgO固溶体形式存在,有助于Ni在反应过程中保持分散性。

According to the requirement of methanation coupled tar reforming process,a Ni catalyst supported on the composite of dolomite mixed with calcium aluminate cement was designed and prepared.The CO_(2) sorption capacity and cyclic stability of the catalyst were tested by thermogravimetric analyzer.The methanation performances of the catalyst under different temperatures and Ni loadings were investigated in a fixed bed reactor.The structures of the catalyst were characterized by XRD and low temperature N2 adsorption.The results show that the Ni/dolomite catalyst with 8%Ni loading has good cyclic stability of CO_(2) sorption.Under the methanation reaction temperature of 500℃,the CO_(2) conversion and CH4 selectivity are 66.7%and 85.9%,respectively.The introduction of calcium aluminate cement contributes to high CO_(2) sorption stability of the catalyst in multiple cycles.The MgO from dolomite combines with Ni to form a stable Ni O-MgO solid solution,which helps maintain the dispersion of Ni in the reaction process.