张伟, 高秀娟, 杨媛, 曹国壮, 王佳豪, 宋法恩, 伞晓广, 韩怡卓, 张清德. Mo-Sn催化剂上CO催化氧化的研究[J]. 燃料化学学报(中英文). DOI: 10.3724/2097-213X.2024.JFCT.0020
引用本文: 张伟, 高秀娟, 杨媛, 曹国壮, 王佳豪, 宋法恩, 伞晓广, 韩怡卓, 张清德. Mo-Sn催化剂上CO催化氧化的研究[J]. 燃料化学学报(中英文). DOI: 10.3724/2097-213X.2024.JFCT.0020
ZHANG Wei, GAO Xiujuan, YANG Yuan, CAO Guozhuang, WANG Jiahao, SONG Faen, SAN Xiaoguang, HAN Yizhuo, ZHANG Qingde. Investigation on catalytic oxidation of CO over Mo-Sn catalysts[J]. Journal of Fuel Chemistry and Technology. DOI: 10.3724/2097-213X.2024.JFCT.0020
Citation: ZHANG Wei, GAO Xiujuan, YANG Yuan, CAO Guozhuang, WANG Jiahao, SONG Faen, SAN Xiaoguang, HAN Yizhuo, ZHANG Qingde. Investigation on catalytic oxidation of CO over Mo-Sn catalysts[J]. Journal of Fuel Chemistry and Technology. DOI: 10.3724/2097-213X.2024.JFCT.0020

Mo-Sn催化剂上CO催化氧化的研究

Investigation on catalytic oxidation of CO over Mo-Sn catalysts

  • 摘要: 采用沉淀浸渍法制备了一系列不同Mo/Sn物质的量比的Mo-Sn催化剂,以CO氧化反应作为探针反应考察不同Mo含量对CO催化氧化反应性能的影响,进一步研究催化剂的活性中心结构及构效关系。结果表明,Mo1Sn20催化剂在300 ℃实现了CO完全转化,相比纯SnO2催化剂的转化温度降低了50 ℃。采用XRD、Raman、XPS、H2-TPR及in-situ FT-IR等表征手段对催化剂的结构、钼物种价态、氧化还原性等进行了研究。相较于纯SnO2催化剂,当引入较少含量的Mo物种后,Mo1Sn20催化剂比表面积增大为反应提供了更多的活性位点,Mo-Sn之间的相互作用增强使得MoO3部分向MoOx转变,产生较多的Mo5+物种,Mo5+物种的存在促进了氧气的吸附活化以及氧原子的迁移,晶格氧与Mo5+物种共同作用增强了CO的催化性能。

     

    Abstract: With the rapid development of industry and the gradual improvement of environmental awareness, air pollution has emerged as a prominent environmental issue. Carbon monoxide (CO), generated from the incomplete combustion of carbon-containing substances such as coal and oil, as well as produced by the exhaust emissions of vehicles, is one of the primary sources of atmospheric pollution. Herein, the elimination of low-concentration CO has been widely used in various applications, including industrial flue gas purification, automobile exhaust treatment, and hydrogen fuel cell purification, etc. Therefore, studying the elimination process of low-concentration CO has important practical significance. At present, low-temperature catalytic oxidation of CO is widely recognized as the most direct, simple, inexpensive, and effective method for CO elimination. Additionally, as a classic and simple reaction process, CO oxidation reaction can be often used as a probe reaction to investigate metal-support interactions, adsorption/dissociation behaviors, the structure of active centers, and the structure-activity relationship of catalysts. SnO2 has been used as a catalyst for CO catalytic oxidation due to its low energy for oxygen vacancy formation and the proven reducibility and reactivity of lattice oxygen. However, due to less active sites on the surface of SnO2 for CO catalytic oxidation, complete conversion of CO can only be achieved at higher reaction temperatures, thereby limiting its application. Specifically, molybdenum oxide is a typical non-precious metal catalytic material that is widely used in low-temperature selective oxidation reactions due to its diverse coordination structures and easily adjustable electronic states. Previous research has found that the directional oxidation of alcohol/ethers to target products can be achieved by regulating the active site structure of Mo-Sn catalysts, which exhibited unique and excellent low-temperature oxidation performance. Its adjustable structure, variable valence state, and highly active oxygen species provide new ideas for expanding the application of Mo-Sn catalysts in low-temperature oxidation of CO. In order to further investigate the mechanism and structure-activity relationship of Mo-Sn catalysts in CO catalytic oxidation reaction, in this work, a series of Mo-Sn catalysts with different Mo/Sn molar ratios were prepared by precipitation impregnation method. CO oxidation reaction was used as a probe reaction to investigate the effect of different Mo contents on the catalytic performance of CO oxidation, and further elucidate the active center structure and structure-activity relationships of the catalysts. The results showed that the Mo1Sn20 catalyst achieved complete conversion of CO at 300 ℃, which was 50 ℃ lower than that of pure SnO2. XRD, Raman, XPS, H2-TPR and in-situ FT-IR were used to analyze the crystal structure, valence state of molybdenum species, and redox properties of the catalysts. Compared with pure SnO2 catalyst, when a lower content of Mo species is introduced, the increase in specific surface area of Mo1Sn20 catalyst provides more active sites for the reaction. The enhanced interaction between Mo and Sn leads to the partial transformation of MoO3 to MoOx, producing more Mo5+ species. The presence of Mo5+ species promotes the adsorption activation of oxygen as well as the migration of oxygen atoms. The synergistic effect of lattice oxygen and Mo5+ species enhances the catalytic performance of the CO. This study not only provides a new strategy for efficient catalytic elimination of low concentration CO, but also deeply reveals the structure-activity relationship and active center structure of Mo-Sn catalysts in CO oxidation reactions. Also, it provides theoretical basis and experimental reference for the application of Mo-Sn catalysts in more important catalytic oxidation reactions.

     

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