Polyurethane, a highly versatile and widely used polymer, has garnered significant interest as a candidate material for CO2 incorporation to address climate change. Nevertheless, research into alternative production methods for isocyanate, a key monomer in polyurethane production, remains insufficient, despite the heavy reliance of the conventional approach on phosgene, a highly toxic material. This study proposes a sustainable process for synthesizing methylene diphenyl diisocyanate (MDI). The proposed process involves the production of syngas from CO2, followed by syngas separation via a hydrogenation reaction, oxidative carbonylation of amine to form dicarbamate, and subsequent thermal decomposition to yield MDI. The syngas separation via the hydrogenation reaction eliminates the need for an additional separation process by simultaneously separating reaction products and preparing a reactant for the subsequent step. Moreover, the introduction of a Pd/TiO2 catalyst and a new reactant introduction strategy significantly reduces side reactions during oxidative carbonylation, thereby enhancing the overall yield. Process modeling and a life cycle assessment demonstrated substantial environmental advantages over the conventional MDI manufacturing process, highlighting the potential of this approach as a greener alternative.