Preparation Of Biochar Catalyst With Saccharide And Lignocellulose Residues Of Corncob Degradation For Corncob Hydrolysis Into Furfural

In this work, a new furfural production process through corncob hydrolysis wasinvestigated over biochar catalysts which made from the degradation solution and solidresidues. From FT-IR spectra of corncob before and after degradation, lignin together withthe partly un-reacted cellulose was confirmed to account for the main composition of solidresidues. The total reducing sugar in the degradation solution of corncob hydrolysis wasmeasured by DNS method, and there were seven sugar components identified usingHPLC-ELSD. Characterization of biochar catalyst was conducted using methods of SEM,FT-IR, XRD,13C MAS NMR, TG-DTG, Raman spectrum, BET, elemental analysis andacid density, which make it clear that biochar catalyst in this work is composed of aromaticcarbon sheets with-SO3H groups oriented in a random fashion.Having examined the process of catalysts preparation, the suitable conditions for thepreparation of biochar catalyst was the mixture composition with1.5:90(w/v) oflignocellulose residue to concentrated saccharide solution, then carbonized at a temperatureof180°C for48h, and finally impregnated in0.5mol/L sulphuric acid at room temperaturefor24h assisted with the ultrasonic vibration. The obtained biochar catalyst with an aciddensity of4.27mmol/g has a good catalytic activity.Effect of reaction temperature, reaction time, mass-volume ratio of corncob to waterand catalyst dosage on the hydrolysis of corncob catalyzed by biochar catalysts were alsoinvestigated. The suitable conditions for the production of furfural were as follows,0.06:1(w/w) of catalyst to corncob,1:12(w/v) of corncob to water, at a reaction temperatureof180°C for170min, and the furfural yield of19.66%and total reducing sugars of63.01%were achieved. In the recycling system of preparation and application of biochar catalyst,8.8%lignocellulose residues and100%concentrated saccharide solution from corncobhydrolysis degradation have been recycled, and the catalyst recovery is not needed.The mechanism for corncob hydrolysis degradation over biochar catalyst to producefurfural is proposed in this paper. The morphology of flexible carbon microspheres makesthe catalyst to be easily adsorbed to the corncob surface by hydrogen bonds among-OHgroups, then the-SO3H groups can cleavage β-1,4glycosidic linkages effectively andhydrolyze the cellulose and hemicellulose to water soluble sugars, as well as to facilitatedehydration of soluble oligosaccharides and monosaccharides to give the products offurfural and a little HMF.