Direct Conversion of CO₂ to Light Olefins via Oxide−Zeolite -Modified Fe - Ni Catalysts: A Hybrid Approach between Fischer−Tropsch Synthesis and OXZEO Concept

In recent years, the excessive consumption of fossil fuels such as oil, coal, and natural gas has significantly contributed to economic development and human society. However, this growth has also led to a sharp increase in CO₂ emissions, resulting in various environmental challenges, including the greenhouse effect, ocean acidification, and climate anomalies. In this context, the direct conversion of CO₂ to light olefins (C₂ –C₄) via the modified Fischer–Tropsch synthesis (CO₂-FTS) using iron-based catalysts has emerged as a cost-effective and sustainable approach. In this study, a novel approach inspired by the OXZEO concept (oxide–zeolite composite catalysts) is proposed to modify conventional Fe-Ni catalysts used in Fischer–Tropsch synthesis. These bifunctional catalysts integrate a metallic component (for redox activity) with a zeolitic component (for acidity and shape selectivity), effectively steering the reaction pathway toward selective light olefin production. The catalyst was prepared via a co-precipitation method followed by physical mixing with HZSM-۵ zeolite and subsequent reduction treatment. Catalytic performance tests were carried out in a fixed-bed reactor under controlled temperature and pressure conditions. The results demonstrate that the inclusion of zeolite in the OXZEO structure leads to a significant improvement in light olefin selectivity especially ethylene and propylene compared to conventional Fe-Ni catalysts. Structural analyses confirmed good thermal stability and uniform dispersion of active phases. Overall, combining FTS catalyst design with the OXZEO concept offers a promising strategy for selective CO₂ conversion to light olefins.

کلیدواژه ها:

CO₂ hydrogenation ، Light olefins ، Modified Fischer–Tropsch synthesis (CO₂-FTS) ، OXZEO (oxide–zeolite composite catalyst)