“木质素优先”策略下生物质还原催化分离技术研究进展

Progress of reductive catalytic fractionation of lignocellulosic biomassbased on the lignin-first strategy

木质纤维素生物质是地球上最丰富的可再生碳资源,有潜力替代石油来生产清洁燃料和化工产品。当前木质素组分的高效利用很困难,木质素高值化是实现生物质全组分利用的关键。为实现生物质全组分的高值化利用,本文研究了基于“木质素优先”策略的分离机制,综述了木质纤维素还原催化分离的研究进展,探索了木质素脱除率、单酚产率和选择性及碳水化合物保留率等的影响因素,分析了生物质原料、溶剂、酸碱添加剂、催化剂和反应器对“木质素优先”策略的影响规律,提出了新型催化剂和反应器的设计思路,展望了木质素还原催化分离的研究方向。分析表明:单酚产率按照硬木→草本作物→软木顺序依次递减,醇水两相体系有利于木质素和半纤维素的提取与溶解以及纤维素结构的保留,酸的加入不仅提高木质素脱除率和单体收率还能促进半纤维素的水解,半/全流动反应器有效避免后续催化剂和碳水化合物的分离。

Lignocellulosic biomass is the most abundant renewable carbon resource on the planet,which has the potential to replace oil to produce clean fuels and chemicals.At present,the efficient utilization of lignin components is difficult,which is the key to realizing the utilization of all components of biomass.To achieve the high-value utilization of lignocellulosic components,this review investigates the separation mechanism based on the"lignin-first"strategy,compiles the research progress of reductive catalytic fractionation,and explores the factors of yield and selectivity of phenolic monomers,degree of delignification and retention of carbohydrate pulp,analyzed the influence of biomass feedstock,solvent,acid and base additives,catalyst,and reactors on the"lignin-first"strategy.In addition,this review also proposes new design ideas for catalysts and reactors and the research direction of reductive catalytic fractionation.The analysis shows that the yield of phenolic monomers decreases in the order of hardwood→herbaceous crop→softwood.The alcohol-water two-phase system is favorable for the extraction and dissolution of lignin and hemicellulose as well as the retention of cellulose structure.The addition of acid not only improves the degree of delignification and monomer yield but also promotes the hydrolysis of hemicellulose.The semi/full flow reactor effectively avoids the separation of catalysts and carbohydrate pulp.