{"title":"Boosting Low-Temperature CO2 Methanation Activity on Ru/Anatase-TiO2 Via Mn Doping: Revealing the Crucial Role of CO2 Dissociation","authors":"Shaorong Deng, Zijian Qian, Chenji Zhu, Boxing Cheng, Xiaowei Wang, Xiuzhong Fang, Xianglan Xu* and Xiang Wang, ","doi":"10.1021/acscatal.4c0380110.1021/acscatal.4c03801","DOIUrl":null,"url":null,"abstract":"<p >A series of Ru/Ti<sub>1–<i>x</i></sub>Mn<sub><i>x</i></sub>O<sub>2</sub> catalysts with varying Mn/(Ti + Mn) molar ratios (<i>x</i> = 0.10–0.25) were synthesized to investigate the CO<sub>2</sub> methanation mechanism on anatase TiO<sub>2</sub>-supported Ru catalysts (Ru/a-TiO<sub>2</sub>) and develop high-performance catalysts at low temperatures. Among these catalysts, the Ru/Ti<sub>0.8</sub>Mn<sub>0.2</sub>O<sub>2</sub> exhibited the highest activity, achieving approximately 65% CO<sub>2</sub> conversion at 230 °C, which is markedly superior to the unmodified Ru/a-TiO<sub>2</sub> catalyst yielding only about 15% CO<sub>2</sub> conversion. The majority of Mn cations were incorporated into the lattice of a-TiO<sub>2</sub> as Mn<sup>3+</sup> cations, forming a solid solution structure in the Ti<sub>0.8</sub>Mn<sub>0.2</sub>O<sub>2</sub> support. This modification resulted in a higher specific surface area, improved reducibility, and increased oxygen vacancy compared with pure a-TiO<sub>2</sub>. Consequently, Ru dispersion and electronic metal–support interactions were enhanced in Ru/Ti<sub>0.8</sub>Mn<sub>0.2</sub>O<sub>2</sub> compared to those in Ru/a-TiO<sub>2</sub>. In-situ diffuse reflectance infrared Fourier transform spectroscopy combined with temperature-programmed surface reaction experiments revealed that CO<sub>2</sub> methanation predominantly proceeded via the CO* route on the Ru/a-TiO<sub>2</sub>. The CO<sub>2</sub> adsorption in the presence of decomposed H<sub>2</sub> led to dissociation to linear CO*, followed by CO methanation where CO<sub>2</sub> dissociation to CO* was identified as the rate-determining step (RDS). Mn cation doping induced the formation of oxygen vacancies, significantly enhancing CO<sub>2</sub> dissociation on Ru/Ti<sub>0.8</sub>Mn<sub>0.2</sub>O<sub>2</sub>, thereby shifting the RDS to CO methanation. This mechanism explains the superior activity of Ru/Ti<sub>0.8</sub>Mn<sub>0.2</sub>O<sub>2</sub> at low temperatures for CO<sub>2</sub> methanation compared to the Ru/a-TiO<sub>2</sub>.</p>","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"14 21","pages":"16508–16521 16508–16521"},"PeriodicalIF":11.3000,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"ACS Catalysis ","FirstCategoryId":"92","ListUrlMain":"https://pubs.acs.org/doi/10.1021/acscatal.4c03801","RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
引用次数: 0
Abstract
A series of Ru/Ti1–xMnxO2 catalysts with varying Mn/(Ti + Mn) molar ratios (x = 0.10–0.25) were synthesized to investigate the CO2 methanation mechanism on anatase TiO2-supported Ru catalysts (Ru/a-TiO2) and develop high-performance catalysts at low temperatures. Among these catalysts, the Ru/Ti0.8Mn0.2O2 exhibited the highest activity, achieving approximately 65% CO2 conversion at 230 °C, which is markedly superior to the unmodified Ru/a-TiO2 catalyst yielding only about 15% CO2 conversion. The majority of Mn cations were incorporated into the lattice of a-TiO2 as Mn3+ cations, forming a solid solution structure in the Ti0.8Mn0.2O2 support. This modification resulted in a higher specific surface area, improved reducibility, and increased oxygen vacancy compared with pure a-TiO2. Consequently, Ru dispersion and electronic metal–support interactions were enhanced in Ru/Ti0.8Mn0.2O2 compared to those in Ru/a-TiO2. In-situ diffuse reflectance infrared Fourier transform spectroscopy combined with temperature-programmed surface reaction experiments revealed that CO2 methanation predominantly proceeded via the CO* route on the Ru/a-TiO2. The CO2 adsorption in the presence of decomposed H2 led to dissociation to linear CO*, followed by CO methanation where CO2 dissociation to CO* was identified as the rate-determining step (RDS). Mn cation doping induced the formation of oxygen vacancies, significantly enhancing CO2 dissociation on Ru/Ti0.8Mn0.2O2, thereby shifting the RDS to CO methanation. This mechanism explains the superior activity of Ru/Ti0.8Mn0.2O2 at low temperatures for CO2 methanation compared to the Ru/a-TiO2.
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.
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