Yang Liuqingqing, Pu Tiancheng, Tian Feixiang, He Yulian, Zhu Minghui
State Key Laboratory of Chemical Engineering, School of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China; University of Michigan - Shanghai Jiao Tong University Joint Institute, Shanghai Jiao Tong University, Shanghai 200240, China.
State Key Laboratory of Chemical Engineering, School of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China.
J Environ Sci (China). 2024 Jun;140:270-278. doi: 10.1016/j.jes.2023.08.028. Epub 2023 Sep 2.
The CO catalytic hydrogenation represents a promising approach for gas-phase CO utilization in a direct manner. Due to its excellent hydrogenation ability, nickel has been widely studied and has shown good activities in CO hydrogenation reactions, in addition to its high availability and low price. However, Ni-based catalysts are prone to sintering under elevated temperatures, leading to unstable catalytic performance. In the present study, various characterization techniques were employed to study the structural evolution of Ni/SiO during CO hydrogenation. An anti-sintering phenomenon is observed for both 9% Ni/SiO and 1% Ni/SiO during CO hydrogenation at 400°C. Results revealed that Ni species were re-dispersed into smaller-sized nanoparticles and formed Ni active species. While interestingly, this anti-sintering phenomenon leads to distinct outcomes for two catalysts, with a gradual increase in both reactivity and CH selectivity for 9% Ni/SiO presumably due to the formation of abundant surface Ni° from redispersion, while an apparent decreasing trend of CH selectivity for 1% Ni/SiO sample, presumably due to the formation of ultra-small nanoparticles that diffuse and partially filled the mesoporous pores of the silica support over time. Finally, the redispersion phenomenon was found relevant to the H gas in the reaction environment and enhanced as the H concentration increased. This finding is believed to provide in-depth insights into the structural evolution of Ni-based catalysts and product selectivity control in CO hydrogenation reactions.
CO催化加氢是一种直接利用气相CO的有前景的方法。由于其出色的加氢能力，镍除了具有高可用性和低价格外，还得到了广泛研究，并在CO加氢反应中表现出良好的活性。然而，镍基催化剂在高温下容易烧结，导致催化性能不稳定。在本研究中，采用了各种表征技术来研究CO加氢过程中Ni/SiO的结构演变。在400°C的CO加氢过程中，9%Ni/SiO和1%Ni/SiO均观察到抗烧结现象。结果表明，Ni物种重新分散成更小尺寸的纳米颗粒并形成Ni活性物种。有趣的是，这种抗烧结现象对两种催化剂产生了不同的结果，9%Ni/SiO的反应性和CH选择性逐渐增加，这可能是由于重新分散形成了大量表面Ni°，而1%Ni/SiO样品的CH选择性则呈现明显下降趋势，这可能是由于随着时间的推移形成了超小纳米颗粒，这些颗粒扩散并部分填充了二氧化硅载体的介孔。最后，发现重新分散现象与反应环境中的H气体有关，并且随着H浓度的增加而增强。这一发现被认为能为CO加氢反应中镍基催化剂的结构演变和产物选择性控制提供深入见解。
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