Lithium Cation Modification Markedly Enhances Ru Dispersion and CO2 Methanation Activity on Ru/SiO2 Catalysts

IF 13.1 1区化学 Q1 CHEMISTRY, PHYSICAL ACS Catalysis Pub Date : 2025-04-24 DOI:10.1021/acscatal.5c00176

Shaorong Deng, Chenji Zhu, Xiuzhong Fang, Xianglan Xu, Xiang Wang

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Abstract

A series of Ru-x%Li⁺/SiO₂ catalysts (x = 0.05–0.2), modified with varying amounts of lithium cation (Li⁺), were prepared via coimpregnation and evaluated for CO₂ methanation to explore Li⁺ modification on Ru/SiO₂. Introducing trace Li⁺ markedly boosts reaction activity, with the optimal Ru-0.1%Li⁺/SiO₂ exhibiting 38.4 and 12.3 times higher overall reaction rate and turnover frequency at 200 °C, respectively, compared to Ru/SiO₂. Structural characterization confirmed that Li⁺ incorporation effectively suppresses RuO₂ crystallization, thereby improving Ru dispersion from 9.1% to 31.5%, enhancing the active surface area from 33 to 115 m² g^–1, while simultaneously reducing Ru particle size from 18.4 to 3.2 nm. In situ spectroscopy and surface reaction experiments revealed that the CO* pathway occurs for CO₂ methanation on both catalysts, which involves CO₂ dissociation and subsequent CO* hydrogenation. The smaller Ru nanoparticles on Ru-0.1%Li⁺/SiO₂ exhibit superior intrinsic activity for both steps compared to the larger nanoparticles on Ru/SiO₂. The additional alkaline sites introduced by Li⁺ additives also promote CO₂ dissociation. The exceptional activity of Ru-0.1%Li⁺/SiO₂ for CO₂ methanation is governed by the synergistic effect between the Ru particle size effect and Li⁺-induced basicity, with the former being predominant.

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锂离子改性显著提高Ru/SiO2催化剂上Ru的分散性和CO2甲烷化活性

采用共浸渍法制备了不同量Li+改性的Ru-x%Li+/SiO2催化剂（x = 0.05 ~ 0.2），并进行了CO2甲烷化评价，探索Li+在Ru/SiO2上的改性作用。微量Li+的引入显著提高了反应活性，在200℃下，Ru-0.1%Li+/SiO2的最佳反应速率和周转率分别是Ru/SiO2的38.4倍和12.3倍。结构表征证实Li+的掺入有效抑制了RuO2的结晶，从而使Ru的分散度从9.1%提高到31.5%，使活性表面积从33 m2 g-1提高到115 m2 g-1，同时使Ru的粒径从18.4 nm减小到3.2 nm。原位光谱和表面反应实验表明，两种催化剂上的CO2甲烷化都发生了CO*途径，即CO2解离和随后的CO*加氢。Ru-0.1% li +/SiO2表面较小的Ru纳米颗粒比Ru/SiO2表面较大的Ru纳米颗粒表现出更强的本征活性。Li+添加剂引入的额外碱性位点也促进了CO2的解离。Ru-0.1%Li+/SiO2对CO2甲烷化的特殊活性是由Ru粒度效应和Li+碱度的协同作用决定的，前者占主导地位。

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来源期刊

ACS Catalysis CHEMISTRY, PHYSICAL-

CiteScore

20.80

自引率

6.20%

发文量

1253

审稿时长

1.5 months

期刊介绍： ACS Catalysis is an esteemed journal that publishes original research in the fields of heterogeneous catalysis, molecular catalysis, and biocatalysis. It offers broad coverage across diverse areas such as life sciences, organometallics and synthesis, photochemistry and electrochemistry, drug discovery and synthesis, materials science, environmental protection, polymer discovery and synthesis, and energy and fuels. The scope of the journal is to showcase innovative work in various aspects of catalysis. This includes new reactions and novel synthetic approaches utilizing known catalysts, the discovery or modification of new catalysts, elucidation of catalytic mechanisms through cutting-edge investigations, practical enhancements of existing processes, as well as conceptual advances in the field. Contributions to ACS Catalysis can encompass both experimental and theoretical research focused on catalytic molecules, macromolecules, and materials that exhibit catalytic turnover.