Metal-free conversion of CO2 to non-isocyanate polyurethane for solid amine sorbent pellets design for CO2 capture

Abstract

Green synthesis of non-isocyanate polyurethanes (NIPUs) has attracted considerable interest as an eco-friendly alternative to traditional isocyanate-based routes. In this work, a metal-free catalytic system based on cetyltrimethylammonium bromide (CTAB) was used to transform polyfunctional epoxides into cyclic carbonates with more than 90 % conversion, which can act as key monomer precursors for NIPU formation. Furthermore, the performance of this metal-free catalyst was evaluated in a one-pot process that directly couples epoxides, CO₂ and diamine to yield NIPUs, thereby demonstrating a sustainable strategy for NIPU synthesis that leverages benign catalytic conditions and CO₂ fixation. The synthesized NIPU was explored as a binder to produce shaped solid amine sorbents for CO₂ capture using a 15 % CO₂ stream, with the resulting hollow pellets exhibiting a carbon capture capacity of 29.5 mg/g.