Study On Hydrolysis Technology Of Wheat Bran And Corncob In Supercritical Water

As a kind of green energy,lignocellulose has high utilization value.It takes a long time to process lignocellulose by traditional process.The hydrolysis of lignocellulose by supercritical water has the advantages of short reaction time,high conversion,environmental protection and no catalyst.In this paper,a set of equipment for continuous and rapid hydrolysis of lignocellulose by supercritical water was established.The hydrolysis process of wheat bran and corncob was studied,and the hydrolysis mechanism and kinetics of lignocellulose were analyzed.First of all,our research group built a high temperature,high pressure supercritical water hydrolysis lignocellulose device,one end of supercritical water as continuous phase,the other end uses high pressure constant flow pump to transport slurry,realizing the direct conversion of lignocellulose into high value-added chemicals.The results show that the experimental technology is controllable and has good reproducibility.Secondly,the effects of hydrolysis temperature(380-410 °C),reaction time(0.3-0.6 s)and slurry concentration(0.1-0.4 wt%)on the yield and mass ratio of glycolaldehyde were investigated with supercritical water as solvent and wheat bran and corncob as raw materials In addition,the conversion of the two raw materials under the optimal conditions was further analyzed.Then,the hydrolysis products were characterized and analyzed by high performance liquid chromatography(HPLC).It was confirmed that the main hydrolysate of wheat bran and corncob was glycolaldehyde,and the hydrolysis law of the two raw materials was determined.The optimal process conditions for the preparation of glycolaldehyde were hydrolysis temperature 400 °C,wheat bran slurry concentration 0.3 %,reaction time 0.5 s,reaction pressure 26 MPa.Under these conditions,the mass ratio and yield of glycolaldehyde to the product were 18.6 % and 16.8 %,respectively,and the conversion rate was 87.5 %,while that of corncob was 16.2 % and 14.2 %,respectively,and the conversion rate was 87.5 %.Finally,with the help of the empirical formula of different physical parameters of water,the changes of physical parameters of water near the critical point with temperature and pressure were investigated.Combined with the experimental results,the influence of supercritical water on lignocellulose hydrolysis was analyzed,and the hydrolysis kineticmodel of lignocellulose was established In order to achieve the maximization of the target product,the physical parameters were precisely controlled.