Waste paper-derived magnetic carbon composite: A novel eco-friendly solid acid for the synthesis of n-butyl levulinate from furfuryl alcohol

Waste paper, a promising renewable source of cellulose, was successfully prepared into a magnetic carbonaceous solid acid (SMWP) via a facile and integrated impregnation-pyrolysis–sulfonation process. The resultant catalyst was confirmed to possess a porous structure with a high surface area, various oxygen-containing functional groups and contain Fe₃O₄ components. The SMWP catalyst also exhibited a high catalytic activity in the alcoholysis of furfuryl alcohol with n-butanol, up to 90.6% yield of n-butyl levulinate and 100% conversion of furfuryl alcohol was achieved by optimizing the reaction conditions. In comparison with other solid acids such as HZSM-5 zeolite and Nafion-212 resin, the better performance of SMWP could be explained by its strong acidity and good affinity to furfuryl alcohol, which results from the synergistic effect of SO₃H, COOH and phenolic OH groups on the carbon surface. Moreover, the catalyst could be easily recycled with an external magnet and reused 7 times without a distinct loss of activity. The findings in this work provided an environmentally friendly manner for waste paper utilization and fuel additive production.