Role of metal oxides in OXZEO catalysis: Fundamental roles in syngas conversion via oxzeo beyond Fischer-Tropsch

Syngas, a mixture of carbon monoxide (CO) and hydrogen (H₂), serves as a pivotal platform for producing liquid fuels and chemicals from non-petroleum carbon resources, such as natural gas, coal, and biomass. In 2016, the research team led by Prof. Bao Xinhe, Prof. Pan Xiulian, and Prof. Jiao Feng from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) proposed the metal oxide-zeolite (OXZEO) catalyst concept. This innovation overcame the 58% selectivity limitation imposed by the Anderson–Schulz–Flory (ASF) distribution model inherent in Fischer-Tropsch synthesis (FTS), achieving >80% selectivity for C₂–C₄ olefins via direct syngas conversion.

Recent advances from in-situ and quasi-in situ characterization techniques have enabled deeper insights into the structure of active sites on oxide surfaces and their reaction mechanisms. To advance mechanistic understanding of the mechanism of this innovative OXZEO reaction and improve the efficiency of the catalytic process, Prof. Jiao Feng, Prof. Pan Xiulian and their group intend to provide a systematic overview of the catalytic active sites of metal oxides and reaction mechanisms of CO/H₂ activation, which could help the rational design of high-performance oxide catalysts and bring OXZEO technology one step further to industrial applications.

Recent advances in (quasi-) in situ characterization techniques have enabled systematic investigations into oxygen vacancies and metal defect sites formed on metal oxides under syngas-derived reductive atmospheres.

This review first consolidates key findings on the dynamic evolution of these active sites and their role in catalytic activation. Subsequently, the authors outline the adsorption, dissociation, and activation pathways of CO and H₂ on oxide surfaces, highlighting mechanistic insights derived from time-resolved spectroscopy (e.g., operando IR, XAS) and surface-sensitive probes (e.g., AP-XPS). The group further summarizes experimental evidence—obtained through multimodal characterization (ssNMR, STEM-EELS, and synchrotron-based techniques)—for the identification of critical C1 intermediates (e.g., ketene species) on oxide surfaces during syngas conversion. These intermediates serve as key linkers between CO activation and C–C coupling in zeolites. Finally, the authors discuss emerging strategies that integrate first-principles calculations and machine learning to establish activity descriptors (e.g., CO* and O* adsorption energies) for the rational design of next-generation oxides. This computational-experimental synergy has already yielded breakthroughs.

This review will help scientists to further design high-performance oxides and will provide guidance for taking a new step towards the industrial application of OXZEO technology.