Role of Brّnsted acid in selective production of furfural in biomass pyrolysis

In this work, the role of Brّnsted acid for furfural production in biomass pyrolysis on supported sulfates catalysts was investigated. The introduction of Brّnsted acid was shown to improve the degradation of polysaccharides to intermediates for furfural, which did not work well when only Lewis acids were used in the process. Experimental results showed that CuSO4/HZSM-5 catalyst exhibited the best performance for furfural (28% yield), which was much higher than individual HZSM-5 (5%) and CuSO4 (6%). The optimum reaction conditions called for the mass ratio of CuSO4/HZSM-5 to be 0.4 and the catalyst/biomass mass ratio to be 0.5. The recycled catalyst exhibited low productivity (9%). Analysis of the catalysts by Py-IR revealed that the CuSO4/HZSM-5 owned a stronger Brّnsted acid intensity than HZSM-5 or the recycled CuSO4/HZSM-5. Therefore, the existence of Brّnsted acid is necessary to achieve a more productive degradation of biomass for furfural.