Ex-ante life cycle assessment of methoxymethylfurfural and furfural coproduction from residual woody biomass

Abstract

Synthesising aromatic chemicals from biomass is considered a promising strategy to reduce the reliance on fossil feedstocks of the chemical industry while prioritising the high-value application of biomass resources. To support decision-making on future upscaling and optimisation, a deeper understanding of the environmental sustainability of these emerging synthesis technologies is needed. This study presents a cradle-to-gate ex-ante life cycle assessment of the coproduction of two key intermediate aromatic chemicals - methoxymethylfurfural (MMF) and furfural - from woodchips. The main objective is to identify environmental hotspots of the technology at an early stage and advise on process optimisation. Results show that energy supply for the separation of chemicals is the dominant contributor to environmental impacts, accounting for over 55% on average across most categories. Cleaner energy scenarios modelled for 2030 reveal the potential for substantial impact reductions; however, realising this potential requires more detailed projections of future industrial heat supply. Also, carbon flow mapping indicates that this technology can retain up to 91 wt% of the input carbon in its main and by-products, with only minor direct emissions. However, high carbon content in process wastewater highlights the need for better treatment strategies. Furthermore, an alternative scenario assessing humins treatment shows that the environmental burdens from their production outweigh the environmental benefits of recovering energy from their incineration, emphasising the need to explore high-value applications of humins. Finally, compared to a conventional furfural production route, this technology generates much lower environmental impacts due to less energy-intensive reactions and less resource-intensive biomass harvesting.