Attapulgite-supported magnetic dual acid-base catalyst for the catalytic conversion of lignin to phenolic monomers

摘要

BACKGROUND Research on the catalytic conversion of lignin into value-added chemicals has grown rapidly on account of the importance of lignin in the biorefinery. There is thus a need to investigate novel technologies to depolymerize lignin in the absence of hydrogen gas and noble metal catalysts. This study developed a cheap and recyclable catalyst via a facile process involving impregnation and calcination for the conversion of lignin to value-added phenolic monomers. RESULTS Acid sites, basic sites and magnetic components were successfully incorporated into attapulgite. The resulting catalyst displayed high catalytic activity for lignin conversion to phenolic monomers, which resulted in 10.9% total monomers yield at 250 degrees C for 3 h with a catalyst loading of 50% and a solvent-solid ratio of 20:1 in 50% C2H5OH. The total monomers yield decreased observably after eight successive reaction runs. After being calcined at 600 degrees C for 3 h, the recovered catalyst provided a total monomers yield of 6.74% in the ninth reaction run. CONCLUSION A novel catalyst was successfully prepared by incorporation of acid sites, basic sites and magnetic properties using natural attapulgite clay as a precursor via a simple and inexpensive process. The resulting catalyst could depolymerize lignin efficaciously. The reusability of the catalyst was barely satisfactory, however, the activity could be partly recovered by simple calcination. (c) 2018 Society of Chemical Industry