Studies On Preparation Of Furfural From Xylose Dehydration

As the scarcity of fossil resource, people start to investigate renewable sources.Biomass is among those sources. Effective utilization of biomass has received moreand more concerns. Hemicellulose, a primary component of biomass, could beutilized to produce xylose and furfural. Preparation of furfural from corncob hasalready industrialized. A wide variety of chemicals in the fields of food, medicine,pesticide, resin synthesis, fiber synthesis and petroleum refining could derive fromfurfural. The furfural industry is a successful prototype to produce chemicals frombiomass as an alternative of fossil resource, and brings new prospect to sustainabledevelopment. However, traditional furfural producing process has a conversion rateas low as30%and generates waste water. Thus, its further development is restricted.According to the above problems, this thesis studies the influence of variousreaction conditions on the yield of furfural. The main aim is to establish a new andclean process of furfural production which could not only improve the furfural yield,but also reduce waste water.A threshold attempt is to change the micro-environment. Using corncob as rawmaterial and toluene as extracting agent, furfural is synthesized and extractedsimultaneously. Under optimal reaction conditions, furfural yield is about45.95%.Though organic solvent is added, the yield of such one-step process merely increases15%.When using triple hydrolysis, the hydrolysis rate of hemicellulose in corncob could be as high as95%, and the xylose concentration could reach no less than13wt%. Furfural is prepared from triple hydrolyzed xylose solution. Compared totraditional process, the yield reaches63.45wt%, and furfural concentration of theoutput solution keeps over35g/L. After separated with furfural, water is recycled tothe hydrolysis process. Therefore, the waste water problem is solved.In order to test feasibility, a new route of xylose dehydrating into furfural,including continuous feeding and discharging, and acid catalyzing, is established.Pure xylose was utilized as raw material. After systematically studying, optimalexperimental conditions with a furfural yield of72.54%was found. By adjustingheating rate, the volume of the xylose solution in is kept equal to that of the furfuralsolution out, so that the concentrations of acid catalyst and co-catalyst could remainconstant, and the volume of the catalyst bed layer stays unchanged. Under stirring,xylose dehydrates on the rolling liquid surface. The continuously feeding anddischarging process become a stable and continuous patent technology of "fixed bedacid catalyzed xylose dehydrates into furfural".