Integrating life cycle assessment and process simulation for sustainable design of dimethyl carbonate production via the direct-urea methanolysis route

Direct-urea methanolysis is gaining interest as a green chemical pathway because it relies on non-toxic materials, affordable solid catalysts, and mild conditions, producing less waste. Since urea can be synthesized from CO₂, this route contributes to reducing greenhouse gas emissions, especially given that DMC sales are expected to reach 1.5 million tons by 2032. Additionally, ammonia’s potential as a hydrogen carrier enhances its attractiveness. The study addresses critical research gaps and provides a sustainable design of the DMC production process by integrating process simulation with a comprehensive environmental assessment. For the first time, kinetic models based on experimental data were used to simulate the methanolysis of both urea and methyl carbamate (MC) as well as the side reaction leading to the formation of N-methyl, methyl carbamate (NMMC). Multiple process designs, incorporating a reactive distillation (RD) column were modelled using ProSimPlus®. Mass and energy balance results were integrated into the Life Cycle Assessment inventory data. Rigorous environmental assessment was conducted within a cradle-to-gate framework, using SimaPro® software and the Ecoinvent database. The results revealed that raw material production and heat consumption are the main environmental impact drivers, emphasizing the importance of applying heat integration strategies. The most sustainable DMC alternative was compared to Eni commercial process across 16 impact categories. Direct-urea methanolysis route exhibited a better environmental performance. The results provide a basis for future techno-economic optimization, highlighting the need for further studies, including cost-benefit analysis, to make the DMC production process based on direct-urea methanolysis commercially competitive.