Integrated Multiproduct Biorefinery for Furfural Production with Acetic Acid and Lignin Recovery: Design, Scale-Up Evaluation, and Technoeconomic Analysis

Furfural is a versatile platform and multipurpose chemical that can be produced with no carbon efficiency loss from pentose sugars present in prehydrolysate streams. Existing processes for the production of furfural are typically energy-intensive with limitations to recover value-added molecules and byproducts such as lignin and acetic acid. In this work, we demonstrate a novel integrated biorefinery process for furfural production with significant sustainability improvements to current production pathways. Higher conversion efficiency for C-5 sugars into furfural is achieved with a novel reactor for producing and recovering furfural in the vapor phase that has been validated at the laboratory scale. Low molecular weight and sulfur-free lignin is also recovered while minimizing energy consumption by employing membrane filtration. Synergy was observed when lignin recovery is performed prior to furfural production. On the basis of experimental results, the scalability of the process for valorizing 3200 metric tonne/day of prehydrolysate solutions that is typically combusted in kraft dissolving pulp mills was evaluated. For a furfural production capacity of 36 tonne/day, a process configuration that stands out among four proposed alternatives was identified and designed. Significant heat energy savings (99.5%) for driving the process was achieved through a heat exchanger network design for internal heat recovery, which resulted in an energy intensity of 0.47 GJ/tonne, corresponding to 1% of the energy intensity for conventional processes. The technoeconomic assessment confirmed that even the least performing process is profitable, robust, and capital-efficient as indicated by metrics such as the internal rate of return (IRR) ranging from 30% to 46%, resistance to market uncertainty (RTMU) between 0.9 and 4.3 $/$, as well as return on capital employed (ROCE) between 49% and 91%.