Study On Furfural Preparation Via Catalytic Hydrolysis Of Corn Cob By Lewis Acids

With the era of progress and economic development, human society is becoming more and more independent on fossil energy. Fossil energy that is treated as a non-renewable energy sources, will dry up eventually, in the long run. Biomass as a new renewable energy, with the potential to replace fossil fuels, the majority of its researchers are paying attention to the use of biomass more and more. Furfural obtained by macromolecular polysaccharide hydrolysis of hemicellulose in biomass, is widely used in food, pesticides, pharmaceuticals, rubber and petroleum refining and other fields, at the same time furfural either is used directly as a liquid fuel, or is used as intermediates production of other products, which has the potential of forming biomass-based platform chemical industrial chain.In the paper, sulfuric acid is a common effective catalyst in the furfural industrial production, but it is toxic and difficult to recover leading to pollution and other issues. It is important to choose a variety of mild Lewis acid as catalyst. Corncob materials are treated as object of study, discussesing the kind of catalyst, the catalyst concentration, liquid-solid ratio, reaction temperature and reaction time on the hydrolysis of corn cob preparition of furfural.The single factor experiments showed that furfural yield increases as catalyst concentration increases, whereas it first increases and then decreases as the ratio of liquid to solid increase. Furfural yield response to the temperature increasing depends on the catalyst applied, it may rise or fall as temperature increases. As the reaction time increases, the furfural yield first increases and then decreases. As can be seen from furfural yield, when AIN4(SO4)2is applied as catalyst, selectivity of furfural formation from corncob hydrolysis is highest. The optimum condition is as follows. mass fraction of catalyst is10%, liquid to solid ratio (V/M) is10:1, reaction temperature is180℃, reaction time is90min. the furfural yield up to45.74%at this condition.When AlNH4(SO4)2was treated as catalyst, using response surface analysis researched catalyst concentration (0-10%), liquid to solid ratio (5:1to15:1), reaction temperature (150-190℃), reaction time (30-150min) as well as other factors affecting the interaction between various factors on the yield of furfural.By a mathematical model analysis, compared forthe sequence between the factors affecting the reaction temperature> the response time> the concentration of the catalyst> the liquid-solid ratio, the factors of interaction between obvious, but the reaction time and reaction temperature interaction, reaction time and catalyst concentration have some influence on the yield of furfural time interaction. Optimization hydrolyzed corn cobs furfural response surface conditions can obtain AlNH4(SO4)2as the catalyst, the hydrolysis of corn cobs ideal conditions for furfural catalyst concentration9.29%, liquid to solid ratio (V/M)7.14:1, the reaction temperature is175.6℃, reaction time80.19min, furfural yield peaked49.265%. Hydrolysis of com cob residue after the scanning electron microscopy analysis of the morphological changes in the structure, the hydrolysis of com cob after irregular sheet structure, with a dense structure hydrolyzed com cob before rule changes in the larger, presumably already hemicellulose hydrolysis.In the paper, via corncob furfural hydrolysis process kinetic analysis by Arrhenius equation and the experimental data fit to strike when AlNH4(SO4)2was treated as catalyst for the hydrolysis of furfural corncob, corncob hemicellulose hydrolysis to obtain kinetic constants of xylose and xylose dehydration cyclization to form furfural. When the reaction temperature at180℃, the corncob furfural hydrolysis reaction rate constant k is0.01174, and the apparent activation energy for40.25kJ·mol-1, the pre-exponential factor A is623.67, corncob hemicellulose obtained by hydrolysis of wood sugar reaction rate constant k1is0.42264, and the apparent activation energy for40.73kJ·mol-1, the pre-exponential factor A1is25560.67, xylose dehydration cyclization reaction rate constant k2is0.02348furfural, and the apparent activation energy for46.58kJ·mol-1, A2for the6446pre-exponential factor.