A review on high catalytic efficiency of solid acid catalysts for lignin valorization. (February 2020) - Guan, Weixiang
Graphical abstract: Catalytic valorization of lignin over solid acid catalysts including zeolites, heteropolyacids, metal oxides and phosphates, Lewis acid and metal organic frameworks were reviewed in this work, which not only summarizes the application of solid acid catalysts, but also provides prospects for design of more efficient solid acid catalysts in conversions of lignin in the future. Highlights: Conversion of lignin over several solid acid catalysts were reviewed. Solid acid catalysts are environmentally friendly and easy to be separated. Solid acid catalysts are efficient to convert lignin into valuable products. The challenges and future prospects are concluded. Abstract: It is imminent to develop renewable resources to replace fossil-derived energies as fossil resources are on the brink of exhaustion. Lignin is one of the major components of lignocellulosic biomass, which is a natural amorphous three-dimensional polymer with abundant C–O bonds and aromatic structure. Hence, valorization of lignin into high value-added liquid fuels and chemicals is regarded as a promising strategy to mitigate fossil resource shortages. Solid acid catalysts are extensively studied due to environmentally friendly in terms of the ease of separation, recovery and reduced amount of wastes. Hence, this review focuses on summarizing the recent progress of catalytic valorization of lignin over different kinds of solid acid catalysts including zeolites, heteropolyacids, metal oxides, amorphous SiO2 -Al2 O3, metal phosphates, and Lewis acid. Based on reviewing of current progress of lignin conversion, the challenges and future prospects are emphasized.