甲烷和二氧化碳是化学性质非常稳定的小分子，也是自然界最丰富的碳源。因此，在温和条件下，通过原子经济反应将甲烷与二氧化碳定向转化为乙酸等高附加值化学品成为C1化工领域的研究热点。以提高乙酸的时空收率为导向，本项目通过吸附、配位和键合等方式在氮化碳材料中引入金属单原子，实现金属单原子高度分散的二维g-C3N4催化材料的可控制备。通过原位表征方法和工艺条件优化，探究催化剂的微观结构和表面性质等因素对反应转化率和选择性的影响规律。建立CH4和CO2定向催化反应的本征与宏观动力学模型，确定最佳工艺条件，乙酸时空收率≥300µmol/(gcat∙h)。结合密度泛函理论计算，揭示金属单原子/g-C3N4催化材料对CH4和CO2定向催化转化行为的作用本质，明确催化材料的作用机制。本项目的实施，不仅为富二氧化碳天然气的高效催化转化提供新的路径，而且为南海非常规天然气的规模化利用提供新的解决思路。

Methane and carbon dioxide are chemical stable small molecules and the most abundant carbon source in nature. Therefore, how to realize the co-conversion of methane and carbon dioxide into valuable chemicals under mild conditions by atom economic reactions has become the hot topic in C1 chemical engineering. Metal single-atoms were introduced by different methods such as adsorption, coordination and bonding to realize the fabrication of two-dimensional g-C3N4 with highly dispersed metal single-atoms. Through the in-situ characterization method and process conditions optimization, the effects of the microstructure and surface properties of the catalyst on the reactivity and selectivity of CH4 and CO2 for the direct preparation of acetic acid will be investigated. The intrinsic and macroscopic kinetics model of the directional catalytic reaction of CH4 and CO2 will be established, the optimum process conditions will be determined and the space-time yield of acetic acid will be above 300µmol/(gcat∙h). Combined with density functional theory, the reaction mechanism of metal single-atomic/g-C3N4 catalytic materials in the direct catalytic conversion behavior of CH4 and CO2 will be revealed, the role of catalytic materials will also be clarified. The implementation of this project not only provides a new route for the efficient catalytic conversion of carbon dioxide-rich natural gas, but also provides a new solution for the large-scale utilization of unconventional natural gas in the South China Sea.