Advances in catalysts for direct syngas conversion to light olefins: A review of mechanistic and performance insights

Abstract

Light olefins are critical chemical materials with high global demand. The syngas-to-olefins (STO) process offers a promising pathway for light olefin production due to the versatility of syngas production technologies from various energy sources. However, achieving high carbon monoxide (CO) conversion and selectivity for olefins remains a challenge in catalytic development. This review categorizes STO catalysts into conventional Fischer-Tropsch catalysts, including unsupported and supported metal-based catalysts (with supports such as carbon, graphene, graphene oxide, zeolites, and metal oxides), as well as bifunctional, hybrid, and emerging core@shell structured catalysts. Another type of catalyst is core@shell structure catalyst, which is a developing method widely used for FT reactions. The performance of these catalysts is influenced by their materials, chemical compositions, operating conditions, and synthesis techniques. Unsupported catalysts, especially Fe-based and Co-based, exhibit high CO conversion but face issues like rapid deactivation and complex processing requirements. Supported catalysts enhance surface area, metal dispersion, and stability, with promoters such as Na, Mg, K, Mn, Zn, V, Zr, and Cu oxides improving catalytic activity through better CO adsorption and bond modulation. Zeolites, due to their acidic properties, significantly impact reactant adsorption and activation. Catalyst preparation methods, including impregnation, co-precipitation, sol-gel, and hydrothermal synthesis, alongside post-synthesis treatments like calcination and reduction, critically affect catalyst performance. This review provides a comprehensive overview of the light olefin production from syngas, detailing the roles of various catalysts and the impact of material types, operating conditions, and synthesis techniques on catalyst activity, and selectivity. The insights aim to guide future research and development towards more efficient and sustainable light olefin production processes.