Sustainable repurpose of waste melamine foam into bifunctional catalysts for efficient CO2 capture and conversion

Global climate change has driven the scientific community to improve the utilization of a critical C1 resource carbon dioxide (CO) through carbon capture utilization (CCU) technology. The cycloaddition of CO with epoxides provides perfect atom economy and economic feasibility to produce versatile cyclic carbonates used in various industries. However, the stable nature of CO and epoxides requires highly active catalysts. In this work, the repurpose of nitrogenous waste melamine foams (MFs) as high-performance catalysts for the cycloaddition of CO was explored. The pyrolyzed MF was modified with Cu to prepare a series of acid-base bifunctional porous catalysts (MFC-X-Cu). The results demonstrate that the acid-base synergy of the MFC-X-Cu catalysts increases the efficiency of the cycloaddition of various epoxides, yielding target products at 96–99% under mild conditions. Moreover, the characterization results revealed that the superior performance of MFC-X-Cu stems from its hollow structure and acid-base synergy, which are derived from nitrogen species in the repurposed MF and the post-modified copper component. The catalyst maintained consistent catalytic efficiency over five cycles, highlighting its strong recyclability. This work presents an eco-friendly and sustainable approach towards carbon neutrality by utilizing modified waste materials for CO conversion into high-value chemicals.