Catalytic Conversion Of Biomass-based Carbohydrates To 5-ethoxymethylfurfural And Other Chemicals

The exploration and valorization of the renewable biomass resource have drawn trenmendous attention of the society and has been regarded as the promising way to compensate the diminishing fossile resources and solve the environmental issues.However,there exist problems of low product yields,low selectivity,and restrict catalytic conditions in the catalytic conversion of biomass material to value-added chemicals.With the target of efficient conversion of biomass resources,this work concentrated on the catalysts design and catalytic system choice for different target products.The key research findings are shown as follows:1.Several carbon-based solid acids were successfully prepared using various biomass?glucose,microcrystalline cellulose,bamboo,and rice husk?and used to catalyze cellulose hydrolysis.The acid groups?-SO3H and-COOH?were successfully introduced onto the surface of the carbon-based solid acid catalysts.The catalysts showed excellent catalytic performance for hydrolysis of cellulose.A maximum total reducing sugar yield of 81.8%was obtained in ionic liquid[BMIM]Cl at 125? for 90 min when the water addition was 10%of ionic liquid.Water is a necessary solvent in the reaction.The addition of 0-20%water may increase the TRS and glucose yields.The dosage of catalyst positively affected the hydrolyzation ability,but it reduced the yields of TRS and glucose when a certain limit was reached.It is confirmed that the co-effects between surface carboxylic acid and sulfonic acid groups facilitate the efficient conversion of cellulose.2.Catalytic conversion of bamboo hemicelluloses into XOS was developed using novel solid acid catalysts of sulfonated bamboo-based carbon material?BCS?.The Fourier Transform Infrared Spectroscopy characterization of BCS confirmed the successful introduction of acid groups?including-SO3H,-COOH and phenolic-OH?onto its surface.The maximum XOS yield of 54.7%wt%?based on xylan content?was obtained at 150? for 45 min with a solid acid to water ratio of 1:200?0.1 g hemicellulose in 20 mL solvent?.The use of water solvent and microwave-assisted method with BCS provides a green and efficient procedure for hemicellulose conversion.3.MHGC-SO₃H synthesized by hydrothermal carbonization of glucose,magnetization and sulfonation processes could be applied as a heterogeneous solid acid catalyst for the one-pot transformation of carbohydrates into high-energy liquid biofuels.MHGC-SO3H exhibited a good performance for the etherification of 5-HMF and the 5-EMF yield was as high as 95.7%.MHGC-SO3H was also efficient in the one-pot conversion of fructose in the GVL-ethanol solvent system and achieved a maximum 5-EMF yield of 67.4%.The introduction of GVL not only improved the 5-EMF yield,but also suppressed the decomposition of products to by-products and the humins formation.The reaction temperature showed more notable effects on the 5-EMF yield than the reaction time.Finally,MHGC-SO3H has been recycled several times and each time it showed good efficiency in the reaction.4.One-step synthesis of hierarchical meso-/microporous lamellar MFI-Sn/Al zeolite?i.e.,containing both Lewis acidic Sn-site and Br???nsted acidic Al-0?H?-Si site?and its catalytic application for conversion of glucose into 5-?ethoxymethyl?furfural?5-EMF?are reported.Particularly,the MFI-Sn/Al zeolite was prepared with a diquaternary ammonium?[C22H45-N+?CH3?2-C6H12-N+?CH3?2-C6H13]Br-2,C22-6-6?template in a composition of 100SiO2/5C22-6-6/18.5Na2O/xAl2O3/ySnO2/2957H2O?x=0.5,1,and 2,y=1 and 2,respectively?.The co-existence of multiple acidities in one single zeolite catalyst enabled one-pot cascade reactions for carbohydrate upgrading.The dual meso-/microporosity in the MFI-Sn/Al zeolites facilitated mass transport in processing of bulky biomass molecules.The balance of both types of acidity and meso-/microporosity realized 5-EMF yield as high as 44%from the glucose reactant.