Influence Of Halide Salts On Preparing Furfural From Corncob Hydrolysis

In recent years, energy utilization of mankind has caused many environmental pollution problem. Sustainable and effective utilization of energy has become the attention focus of mankind. Seeking renewable substitute is prompt. Biomass is a renewable and abundant source which can be used to produce biofuels and value added fine chemicals, among which furfural is a very important biomass based chemical which can be used as a versatile platform compound for deriving many other value added fine chemicals.Study of catalyst in hydrolysis of corncob to producing furfural has been paid great attention to. At present metal salts have been found to have the catalytic effect for hydrolysis of hemicellulose forming furfural. It has become a hot topic to produce furfural via combination of several metal salts.In this paper, the effect of reaction temperature, reaction time, the type and dosage of the additives on furfural yield in preparation of furfural via hydrolysis of concob using ferric sulfate as the catalyst through single factor experiments. Then the optimal experimental condition for preparation of furfural from hydrolysis of corncob was obtained by a series of experiments.It was found by experiments that ammonium halide is better than the alkali halides. Ammonium iodide, ammonium bromide, ammonium chloride can increase the yield of furfural to59%,66%,77%respectively(reaction conditions:corncob3g,10%ferric sulfate solution30ml, reaction temperature170℃, reaction time150min) compared34%of furfural yield when no additives were added. As a contrast, when alkali metal halide is added under the same conditions, potassium iodide, potassium bromide, potassium chloride can only reach a furfural yield of48.59%,23.81%and17.10%, respectively.The further study showed that with the same halogen ion, the effect of ammonium halide is better than the alkali metal halide. If cation is identical, alkali metal iodide is better than alkali metal bromide and alkali metal chloride. Through inspecting several factors:type of additives, the dosage of additive, reaction time and reaction temperature, we came to a conclusion that in the dehydration reaction ammonium bromide is the best additive. We obtained the optimal conditions of corncob dehydration reaction adding NH4Br is as follows. The dosage is0.3M, reaction temperature is170℃, reaction time is150min, furfural yield is84.79%under these optimum condition.Finally, we use surface response method to optimize the condition of preparation of furfural using ammonium bromide as additive. Optimization results showed that when adding0.4M of NH4Br into the catalytic system of Fe2(SO4)3for corn cob hydrolysis, the yield of furfural can be as high as81.63%under conditions of170min and170℃.