Anchoring Bimetal Zinc–Aluminum Sites on Nitrogen-Doped Carbon Catalyst for Efficient Conversion of CO2 Into Cyclic Carbonates

The design and synthesis of efficient carbon-based materials incorporating multifunctional sites is prospective technology for converting carbon dioxide (CO₂) into high-value chemicals. Here, nitrogen-doped carbon catalysts (ZnAl-NC) with bimetal zinc–aluminum sites were synthesized using nitrogen-rich polyaniline (PANI) and ZnAl-LDH through hydrothermal and in situ pyrolysis methods. ZnAl-NC-400, in the presence of tetrabutylammonium bromide (TBAB), exhibited excellent catalytic activity without solvent, achieving high yields (97.2% or 98.5%) in the cycloaddition of CO₂ with propylene oxide (PO) under traditional or mild conditions. NH₃-TPD and CO₂-TPD results indicated that the enhanced catalytic activity resulted from the acid–base synergistic effect, involving Lewis acid sites from Zn and Al species and abundant Lewis base sites from the PANI matrix. The impact of calcination temperature on catalyst morphology, structure, and performance was investigated, along with catalyst recycling and adaptability to various epoxides. This work presents an efficient catalyst for CO₂ conversion and suggests new approaches for designing catalytic sites in carbon-based catalysts for CO₂ capture and utilization.