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作为煤制天然气的核心技术之一,CO甲烷化工艺的开发基础便是高效催化剂的研制.目前,CO甲烷化催化剂主要采用Ni作为活性组分,但如何保持其具有较高的催化活性和优异的高温稳定性,仍为当今不得不面临的棘手问题.本文以乙二醇改性的三维介孔KIT-6为载体,利用其较高的比表面积、可调孔径、独特的双螺旋三维孔道结构等特点,通过湿式浸渍法成功制备了由助剂改性的Ni基催化剂,探讨了V,Ce,La,Mn等不同助剂对Ni基催化剂CO甲烷化催化性能的影响.分别采用X射线衍射、氢气程序升温还原、氢气程序升温脱附、傅里叶变换红外光谱、透射电子显微镜、能量色散X射线光谱、激光拉曼光谱和热重分析等手段对催化剂特性进行了表征.结果显示,Ni-V/KIT-6具有最高的Ni纳米粒子分散性(26.5%)和催化还原性,产生了最多的活性位,同时,Si–O–V的形成增强了金属-载体间相互作用,并因载体的三维介孔限制效应而形成较小Ni纳米粒子,这些均有助于提升Ni基催化剂CO甲烷化的催化性能和稳定性.在常压、250–400 ℃和60000mL/(g?h)空速的实验条件下对催化剂进行了催化活性评价测试.结果表明,助剂提高了CO甲烷化低温催化活性,其中,Ni-V/KIT-6在350 ℃的条件下实现了CO的完全转化,CH_4产率也高达85%;其在常压、500 ℃和60000 mL/(g?h)空速的操作条件下所进行的稳定性测试结果还显示,Ni-V/KIT-6也具有优异的抗烧结和抗积碳能力,展示了良好的高温稳定性.因此,Ni-V/KIT-6是一种具有广阔应用前景的CO甲烷化催化剂.
As one of the core technologies of coal-to-gas, the development of CO methanation is based on the development of highly efficient catalysts. Currently, CO methanation catalysts mainly use Ni as the active component, but how to maintain their high catalytic activity and excellent Is still a thorny issue that must be confronted with today.In this paper, ethylene glycol-modified three-dimensional mesoporous KIT-6 was used as carrier, and its high specific surface area, adjustable pore size, unique double helix three- Structure and other characteristics, Ni-based catalysts modified by aids were successfully prepared by wet impregnation method, and the effects of different promoters such as V, Ce, La, Mn on the catalytic activity of CO methanation of Ni-based catalysts were discussed. The characteristics of the catalysts were characterized by means of X-ray diffraction, diffraction of hydrogen, temperature-programmed desorption of hydrogen, Fourier transform infrared spectroscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, laser Raman spectroscopy and thermogravimetric analysis. Ni-V / KIT-6 has the highest Ni nanoparticle dispersion (26.5%) and catalytic reducibility, resulting in the most active sites, while the formation of Si-O-V enhances the metal-support interaction , And the formation of smaller Ni nanoparticles due to the three-dimensional mesoporous limiting effect of the support all contribute to improving the catalytic performance and stability of CO methanation of the Ni-based catalyst at atmospheric pressure, 250-400 ° C. and 60000 mL / (g ? h) space velocity experiment was carried out to evaluate the catalytic activity of the catalyst. The results show that the promoter enhances the catalytic activity of CO methanation at low temperature, in which Ni-V / KIT-6 achieves CO , The yield of CH_4 was as high as 85%. The results of the stability test under operating conditions of atmospheric pressure, 500 ℃ and 60 000 mL / (g · h) space velocity also showed that Ni-V / KIT- 6 also has excellent resistance to sintering and carbon deposition, showing good high temperature stability.Therefore, Ni-V / KIT-6 is a promising CO methanation catalyst.