催化学报 ›› 2026, Vol. 91: 147-162.DOI: 10.1016/S1872-2067(26)65205-9

• 论文 • 上一篇    下一篇

TiO2催化剂表面结构演变与单原子掺杂对CO2辅助乙烷脱氢性能调控

马可馨a, 薛米风a, 王与涵b,*(), 范貌宏c,d, 凌丽霞a, 章日光a,*()   

  1. a 太原理工大学化学与化工学院, 省部共建煤基能源清洁高效利用国家重点实验室, 山西太原 030024, 中国
    b 山西大学资源与环境工程研究所, 山西太原 030031, 中国
    c 怀俄明大学工程与物理科学学院及能源资源学院, 怀俄明州拉勒米, 美国
    d 佐治亚理工学院工程学院, 佐治亚州亚特兰大, 美国
  • 收稿日期:2026-01-08 接受日期:2026-04-14 出版日期:2026-12-18 发布日期:2026-10-13
  • 通讯作者: *电子信箱: wangyuhan@sxu.edu.cn (王与涵),
    zhangriguang@tyut.edu.cn (章日光).
  • 基金资助:
    国家科技重大专项(2024ZD0606500);国家自然科学基金(U23A20132);国家自然科学基金(22408119);山西省留学回国人员科技活动择优资助项目(20250008)

Unraveling the surface structural evolution and single-atom doping effect in CO2-assisted ethane dehydrogenation over TiO2-based catalysts

Kexin Maa, Mifeng Xuea, Yuhan Wangb,*(), Maohong Fanc,d, Lixia Linga, Riguang Zhanga,*()   

  1. a State Key Laboratory of Clean and Efficient Coal Utilization, College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, Shanxi, China
    b Institute of Resources and Environmental Engineering, Shanxi University, Taiyuan 030031, Shanxi, China
    c College of Engineering and Physical Sciences, and School of Energy Resources, University of Wyoming, Laramie 82071, Wyoming, USA
    d College of Engineering, Georgia Institute of Technology, Atlanta 30332, Georgia, USA
  • Received:2026-01-08 Accepted:2026-04-14 Online:2026-12-18 Published:2026-10-13
  • Supported by:
    Advanced Materials-National Science and Technology Major Project(2024ZD0606500);National Natural Science Foundation of China(U23A20132);National Natural Science Foundation of China(22408119);Fund Program for the Scientific Activities of Selected Returned Overseas Profes-sionals in Shanxi Province(20250008)

摘要:

乙烯是生产塑料、纤维、橡胶等大宗化学品的基础化工原料. 乙烷氧化脱氢(ODHE)是生产乙烯的关键技术路线之一. 目前, 以O2为氧化剂的ODHE虽能突破热力学平衡限制, 降低反应温度, 但O2强氧化性易导致乙烯深度氧化生成COx副产物, 降低目标产物选择性. 相比之下, CO2作为温和氧化剂, 能够有效避免乙烯的过氧化, 在提升烯烃选择性方面展现出独特优势, 但CO2在温和条件下难以高效活化. 二氧化钛(TiO2)基催化剂凭借其出色的表面氧化还原能力在ODHE反应中表现出良好的催化性能, 同时其表面氧空位能够吸附并活化CO2, 有利于CO2辅助ODHE (CO2-ODHE)反应的进行. 然而, 反应中催化剂表面的动态演变规律及其对反应机理的影响尚不明确. 因此, 系统研究TiO2基催化剂在CO2-ODHE中的表面结构演化与单原子掺杂的调控作用, 对于理性设计高效稳定的催化剂具有重要的理论指导意义.
本研究采用密度泛函理论计算与动力学蒙特卡洛模拟相结合的方法, 研究了C2H6与CO2共进料条件下TiO2催化剂表面结构演变过程, 并构建15种单原子金属掺杂M-TiO2(M=V, Cr, Mn, Fe, Co, Ni, Cu, Y, Nb, Ru, Rh, Pd, Ta, Ir和Pt)催化剂, 探究金属掺杂对反应机理与催化性能的调控规律. 在C2H6与CO2共进料条件下, TiO2催化剂表面遵循“TiO2-Ov → CO2-TiO2 → TiO2 → TiO2-Ov”的动态演变循环, 反应遵循MvK机理, CO2快速填补表面晶格氧, 维持氧化还原循环稳定运行, 但催化活性有限. 单原子金属掺杂抑制了CO2在氧空位处的解离, 将反应路径从MvK机理转变为乙烷脱氢与逆水煤气变换反应相耦合机理. CO2的作用从填补表面晶格氧转变为通过形成COOH*中间体高效消耗表面H*物种, 加快反应进程. 在873.15 K, C2H6/CO2进料比2:1的最佳反应条件下, Pd-TiO2-Ov催化剂的乙烯生成活性(TOF)高达4.62×104 s-1, 较未掺杂TiO2-Ov催化剂提升约七个数量级, 同时保持高乙烯选择性. 进一步, 建立了催化活性与表面H*物种共吸附能的线性关联, 为评估M-TiO2催化性能提供了关键描述符. 最后, 阐明了O2与CO2作为氧化剂在乙烷氧化脱氢反应中的作用差异: O2易于解离生成活性氧物种, 虽可驱动乙烷脱氢但易引发乙烯过氧化; CO2作为软氧化剂, 在Pd-TiO2上通过抑制自身解离、促进上述耦合路径, 实现了高选择性的乙烯生成.
综上, 本研究揭示了TiO2催化剂表面结构演变与金属掺杂调控CO2-ODHE反应性能的核心作用, 为高性能烷烃脱氢金属氧化物催化剂的理性设计提供了重要的结构与电子层面的见解; 所建立的描述符及反应机理为实验研究奠定了理论基础, 并为开发高性能催化剂提供了方向.

关键词: TiO2催化剂, CO2辅助乙烷脱氢, 反应机理, 密度泛函理论计算, 动力学蒙特卡洛模拟

Abstract:

CO2-assisted ethane dehydrogenation (CO2-ODHE) provides a promising route for ethylene production; however, the dynamic evolution of catalyst surface and its influence on the reaction mechanism are still not fully elucidated. In this study, we combined density functional theory calculations and kinetic Monte Carlo simulations to explore the surface evolution and catalytic behavior of CO2-ODHE over TiO2-based catalysts. The results show that the pristine TiO2 follows the Mars-van Krevelen (MvK) mechanism, where CO2 replenishes oxygen vacancies, but exhibits limited activity. Doping with single-atom metal (M-TiO2-Ov) suppresses CO2 dissociation at oxygen vacancy sites, shifting the reaction mechanism from MvK to a coupling mechanism that combines ethane dehydrogenation with the reverse water-gas shift reaction. In this coupled mechanism, CO2 primarily participates in hydrogenation via the formation of a COOH* intermediate, thereby efficiently removing surface hydrogen species. Among 15 types of M-doped TiO2 catalysts, Pd-TiO2 catalyst demonstrates the highest C2H4(g) formation activity (TOF=4.62 × 104 s-1) with 99.9% selectivity under optimal conditions (873 K, C2H6/CO2=2: 1), which is seven orders of magnitude higher than that of undoped TiO2. Furthermore, the catalytic activity exhibits a linear correlation with the adsorption energy of H*, identifying the surface hydrogen adsorption strength as an effective descriptor for predicting C2H4(g) formation activity. This work provides a theoretical foundation and structural insights for designing high-performance CO2-ODHE catalysts via second-metal doping to regulate the reaction mechanism and catalytic performance of metal oxide.

Key words: TiO2 catalyst, CO2-assisted ethane dehydrogenation, Reaction mechanism, Density functional theory, Kinetic Monte Carlo simulations