Catalytic Conversion Of Biomass Based On The Integration Of Depolymerization And Hydrogenation

The depletion of fossil resource and environmental concern has accelerated the utilization of renewable energy such as lignocellulosic biomass.Integrating depolymerization of the entire biomass and in situ hydrogenation of the depolymerized fragments is an efficient way to the conversion of lignocellulosic biomass.The addition of acid or alkali catalysts can accelerate the depolymerization of carbohydrates with hydrogenation catalysts.Meanwhile,reductive depolymerization of protolignin in biomass and Kraft liginin with hydrogen can provide a high yield bio-oil.This study proposes four pathways for the converson of carbohydrates and/or lignin:(1)The HOTf-Ru/C system was found to be effective to depolymerize carbohydrates,especially cleaving glycosidic bonds,and applicable to a wide range of feedstocks.Typically,the high yield of bio-oil with the conversion of lignin simultaneously from pine wood can be achieved,and the H/Ceff of 1.24 was compatible to be co-processed in the existing refineries;(2)Carbohydrates can produce branched oxygenates in methanol by one-pot conversion,employing Ru/C and alkali cation as catalysts.The main product was isobutyroin and highly concentrated under the low ratio of feedstock/alkali and the present of K+ and methanol.The formation of isobutyroin was explained by a series of reactions with model compound and based on an isotope labeling experiment.The isobutyroin-rich products can be used as high-quality gasoline precursors or high-value-added chemicals;(3)Lignin-first biorefinery was a novel concept that lignin in biomass was preferentially converted to lignin oil leaving the carbohydrates in solid form.It was found that Ru/SiC was an effective and regenerable catalyst in this system,and the catalytic performance was comparable to commercial Ru/C.Furthermore,the Ru/SiC catalyst can be regenerated by calcination with excellent catalytic performance;(4)Kraft lignin can be efficiently depolymerized using NiW/SiC catalyst.The NiW/SiC was a milder catalyst than NiW/C catalyst under the identical conditions and supplied a higher liquid product yield.Besides,the NiW/SiC catalyst can be easily regenerated by calcination and subsequent acid washing.The performance of the regenerated catalyst with only 4%Ni input was almost unchanged compared with that of the fresh catalyst.