Assembly of ordered mesoporous alumina-supported nickel nanoparticles with high temperature stability for CO methanation
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- Tian, H., Li, S., Zeng, L. et al. Sci. China Mater. (2015) 58: 9. doi:10.1007/s40843-014-0014-1
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The high-temperature methanation of CO is an important reaction in the processes used to produce substitute natural gas, while the Ni-based catalysts prepared using the conventional impregnation method tend to deactivate under high-temperature reaction conditions. This paper describes the design and assembly of ordered mesoporous alumina (OMA) using highly disperse ∼5 nm nickel nanoparticles (Ni NPs), via a one-pot, evaporation-induced self-assembly (EISA) method. Small-angle X-ray diffraction (XRD), transmission electron microscope (TEM), and N2 adsorption and desorption results revealed that this catalytic material had highly ordered mesopores, which were retained even after long-term stability tests. The catalyst exhibited excellent sintering-resistant and anti-coking properties in high-temperature CO methanation reactions (60% CO conversion after 50 hours of accelerated deactivation at 700°C). The improved catalytic performance was attributed to the matrix of the OMA, which effectively improved the dispersion of the nickel particles, and prevented the Ni NPs from sintering, via a particle migration and coalescence mechanism. The Ni-OMA catalyst demonstrated here shows promise for high-temperature methanation.
CO高温甲烷化反应是工业上生产合成天然气的重要反应, 采用传统的浸渍方法合成的镍基催化剂在高温的反应条件下容易发生烧结和积碳现象而导致失活. 本文以蒸发引导的自组装方法为原理, 通过“一锅法”设计并合成了有序介孔氧化铝负载高分散镍纳米颗粒(粒径在5 nm左右)的催化剂. 通过小角XRD、 TEM和N2物理吸附等表征验证了有序介孔结构的存在, 并且这种结构在长时间的高温稳定性测试后仍能保持. 该催化剂在CO高温甲烷化反应中表现出良 好的抗烧结、 抗积碳的性能. 载体氧化铝的有序介孔结构是这种催化剂性能提升的关键, 因为有序介孔结构有利于改善活性组分镍颗粒的分散情况, 同时纳米级的介孔孔道可以限制镍颗粒在高温下通过颗粒迁移和聚集而烧结长大.