Novel pathways for urea synthesis decarbonization: An analytical review from Bosch–Meiser to electroreduction processes

This paper presents an in-depth analytical review of potential innovation pathways for decarbonizing urea synthesis. The analysis focuses on the key sustainability bottlenecks associated with the Bosch–Meiser process: high energy consumption, reliance on fossil feedstocks, kinetic and thermodynamic limitations, and carbamate-related corrosion. A systematic review of over 50 scientific articles and 50 patents supports a comparative assessment of technological developments across short- and long-term horizons. This review also outlines a comprehensive technical panorama of the Bosch–Meiser process, detailing its operational principles and structural constraints. Industrial strategies — such as energy integration, process intensification, and co-production with methylamine and melamine — are discussed regarding their current implementation and potential for near-term impact. In parallel, emerging approaches, including gasification, water electrolysis, and especially electroreduction - which accounts for 51.6 % of the academic publications covered in this work — are analyzed as promising long-term alternatives to the conventional route. Incorporating alternative feedstocks such as glycerol, biogas, and wastewater is also examined for its potential to diversify input streams and stimulate further innovation. By connecting insights from industrial and academic domains, the review highlights synergies across approaches, identifies key industrial barriers, and outlines strategic directions for future research and development. These findings contribute to structuring a coherent and forward-looking agenda for urea synthesis decarbonization, with the potential to inform decision-making and guide transformative action across the sector.