Future development for furfural production: Comparison of one-step and two-step strategies and life cycle assessment

Furfural (FF) is an important platform chemical that can be produced from lignocellulosic biomass rich in xylan. However, the traditional one-step FF production process produces a large amount of residue rich in sulfuric acid, approximately 15 tons per ton of FF. In this study, a carbon-based solid acid catalyst ZnCS-2 was developed for the two-step catalytic conversion of lignocellulosic biomass to FF. Furfural yields of up to 72.4 % were obtained at 180 °C for 60 min with 10 wt% catalyst ZnCS-2 catalyst. Using this catalytic system, a conceptual process for a two-step FF production system (TSF) was established. With the aim of performing a quantitative comparison with traditional production, a one-step FF production process (OSF) simulation alongside a lifecycle analysis was performed. Comparing the two-step method with the traditional one-step method, the advantages and disadvantages of the two methods and the direction of improvement can be systematically analyzed. The results demonstrated that the TSF process, which employs the ZnCS-2 catalyst and a biphasic solvent system of MIBK/NaCl, achieved a higher furfural yield. Specifically, the final yield of the TSF process exceeded that of the OSF process by 49.9 %. For every ton of furfural produced, the TSF process resulted in reductions of 0.07 kg SO₂ eq, 186.15 kg CO₂ eq, 1 × 10⁻⁵ kg CFC-11 eq, and 66.13 kg 1,4-DB-eq in emissions compared with OSF. Owing to the higher yield and sulfur-free corncob residue, the profitability of TSF process was found to be 6.75 times greater than that of the OSF process.