催化学报

催化学报

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二氧化硅限域Cu2O纳米颗粒用于分子氧丙烯环氧化

程家威a,1, 王凯a,1, 孟俣翰a, 王嘉辰b, 刘作政c, 王静娟a, 刘家旭b, 成康a,*, 张庆红a,*, 王野a,*   

  1. a厦门大学化学化工学院, 福建省能源材料科学与技术创新实验室, 表界面化学全国重点实验室, 福建厦门 361005;
    b大连理工大学化工学院, 大连理工大学智能材料化工前沿科学中心, 精细化工全国重点实验室, 辽宁大连 116024;
    c武汉大学化学与分子科学学院, 湖北武汉 430072
  • 收稿日期:2025-11-17 接受日期:2026-01-20
  • 通讯作者: *电子信箱: kangcheng@xmu.edu.cn (成康), zhangqh@xmu.edu.cn (张庆红) , wangye@xmu.edu.cn (王野).
  • 作者简介:1共同第一作者.
  • 基金资助:
    科技部国家重点研发计划(2022YFA1504500); 国家自然科学基金(22121001, 22222206, U22A20392); 厦门大学校长基金(20720250081).

Silica-confined Cu2O nanoparticles for propylene epoxidation with molecular oxygen

Jiawei Chenga,1, Kai Wanga,1, Yuhan Menga, Jiachen Wangb, Zuozheng Liuc, Jingjuan Wanga, Jiaxu Liub, Kang Chenga,*, Qinghong Zhanga,*, Ye Wanga,*   

  1. aState Key Laboratory of Physical Chemistry of Solid Surfaces, Innovation Laboratory for Science and Technologies of Energy Material of Fujian Province (IKKEM), College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian, China;
    bState Key Laboratory of Fine Chemicals, Frontier Science Center for Smart Materials, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, Liaoning, China;
    cCollege of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, Hubei, China
  • Received:2025-11-17 Accepted:2026-01-20
  • Contact: *E-mail: kangcheng@xmu.edu.cn (K. Cheng), zhangqh@xmu.edu.cn (Q. Zhang), wangye@xmu.edu.cn (Y. Wang).
  • About author:1Contributed to this work equally.
  • Supported by:
    National Key Research and Development Program of Ministry of Science and Technology of China (2022YFA1504500), the National Natural Science Foundation of China (22121001, 22222206, U22A20392), and the Fundamental Research Funds for the Central Universities (20720250081).

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摘要： 环氧丙烷(PO)是生产聚醚、丙二醇和聚氨酯塑料等大宗商品的核心化工中间体. 目前的PO生产技术, 如氯醇法和共氧化法等路线存在氧化剂成本高、副产物多及环境污染严重等缺陷. 分子氧直接催化丙烯环氧化因其高原子经济性和环境友好性, 被视为一条极具潜力的工业化路线. 然而, 该反应不仅机理复杂, 且为了活化氧气通常需要高温条件, 这往往导致丙烯深度氧化以及活性中心的重构, 从而严重影响环氧丙烷的选择性. 因此, 在分子氧丙烯环氧化反应中, 如何设计高效稳定的催化剂, 以实现对低价铜物种(Cu0/Cu+)的有效稳定, 并提升晶格氧的结构稳定性, 最终提高催化反应的活性和稳定性是多相催化领域的研究重点之一.
针对上述难题, 本文利用一种“再分散-限域”策略, 将小尺寸、低价态的Cu纳米粒子限域在SiO2壳层中并稳定在一系列惰性载体上. 首先利用氨水将大尺寸CuO颗粒刻蚀并再分散为纳米颗粒, 通过正硅酸乙酯(TEOS)水解形成SiO2壳层, 随后引入碱金属铯(Cs)进行修饰. 通过扫描透射电镜和相关表征证实, 该方法成功将CuO纳米粒子(2.1 nm左右)均匀分布在SBA-15的介孔内, 且在Cu纳米粒子和SiO2之间形成的Cu-O-Si配位结构促进了Cu+在催化剂中的比例. SiO2壳层的物理限域作用不仅防止了Cu物种的烧结, 还通过Cu-SiO2界面调控了独特的电子性质. 实验结果表明, 最优的Cs-Cu@Si/SBA-15催化剂实现了3.9%的丙烯转化率和68%的PO选择性, 显著优于未包覆SiO2壳层的Cs-Cu/SBA-15催化剂(转化率0.6%, 选择性42%). 与未包覆的催化剂相比, SiO2涂层显著抑制了深度氧化, 降低了CO2选择性. CuOx物种与SiO2壳层之间存在显著的空间和化学态限域效应, Cu-O-Si界面的形成使分子氧适度活化为亲电氧物种的同时也抑制了晶格氧的反应活性从而促进丙烯的选择性氧化生成环氧丙烷. 这种表面限域的Cu-O-Si界面既平衡了O2活化能, 又维持了动态的Cu+ ↔ Cu2+氧化还原循环, 从而降低了决速步的能垒.
综上, 本文使用一种SiO2限域策略, 通过构建Cu-O-Si界面成功实现了对Cu基催化剂活性位几何结构以及电子结构调控. 该催化剂在丙烯环氧化反应中表现出较高的活性、选择性和稳定性, 为设计高效的非均相选择性氧化催化剂提供了新的思路.

关键词: 铜催化剂, 限域, 表面工程, 丙烯环氧化, 氧化还原反应

Abstract: The direct propylene epoxidation with molecular oxygen offers an atom-economical route to propylene oxide (PO). However, the oxidative reaction conditions required at high temperatures often induce complete propylene oxidation and the reconstruction of the active centers, compromising PO selectivity. Herein, we propose a redispersion-confinement strategy to encapsulate small, low-valence Cu nanoparticles (NPs) within a silica shell, thereby achieving stable dispersion across various supports. We confirm that the formation of Cu-O-Si coordination between Cu and silica, together with cesium promotion, could stabilize the small Cu NPs and enhance the PO formation. The optimum Cs-Cu@Si/SBA-15 catalyst delivers a 3.9% propylene conversion and a 68% PO selectivity, markedly surpassing the 0.6% conversion and 42% selectivity obtained over Cs-Cu/SBA-15 without the silica shell. A significant space and chemical state confinement effect is evidenced between CuO and the silica shell, which retards the reactivity of lattice oxygen and allows the moderate activation of molecular oxygen to electrophilic oxygen species; thus, promoting the selective epoxidation of propylene. This strategy offers a general approach for molecular-level control of active-site structure and electronic states in heterogeneous catalysts.

Key words: Copper catalyst, Confinement, Surface engineering, Propylene epoxidation, Oxidation-reduction reactions