Upgradation of sugarcane bagasse lignin: Fractionation to cyclic alcohols production

Reductive catalytic fractionation (RCF) is a new class of process that produces mono phenolics close-to-theoretical maximum yield by preserving the biomass polysaccharides as solid residues under hydrogen atmo-sphere or hydrogen transfer conditions. Herein, hydrous ruthenium oxide deposited on carbon (HRO@C) and HY-zeolite (HRO@HYZ) catalysts are prepared and characterized by different analytical techniques (TGA, TPD, TPR, XRD, TEM, XPS, physisorption and chemisorption). Both catalysts have been used for the RCF of sugarcane bagasse (SCB). Effects of catalyst acidity, reaction time, pressure, temperature, and solvent on the RCF of SCB have been investigated. Solid residues after RCF are characterized by FT-IR, TGA, XRD, and fibertec to identify the effects of reaction conditions on lignin-first delignification efficiency (LFDE). High acidity of HRO@HYZ favors a high degree of LFDE (81.2 %) than HRO@C (55.8 %). However, alkyl-substituted phenolic monomers (ASPMs) selectivity is 69 % for HRO@C and 55.7 % for HRO@HYZ, respectively, under the same reaction conditions. NMR and GC-FID/GC-MS analysis indicate the presence of ASPMs in the resulted lignin bio-oil. Moreover, fractionated lignin bio-oil is used for upgradation and the upgraded product analysis confirms > 95 % conversion of lignin bio-oil, in which over 90 % selectivity is towards alkylated cyclic alcohols.