Preparation Of 5-Hydroxymethyfurfural From Wheat Stalk By The Catalysis Of Solid Acid And Base

As a renewable resource, biomass has the potential to ease the deficiency of fossil resource. It is extremely significant to achieve its integrative and high efficient application. In this article, wheat stalk powder(WSP) was as the raw material and lignin was removed from WSP with alkaline hydrogen peroxide and alcohol under ultrasonic radiation to afford treated WSP(TWSP). Then, 5-hydroxymethyfurfural(5-HMF) was produced from TWSP over solid acid(S-AC) and solid base(Zr O2), which is a one-step process. According to 5-HMF yield(Y5-HMF) and wheat stalk residue ratio(YRS), influences of reaction and catalyst preparation conditions were optimized and selected by orthogonal experiments and Box-Behnken experiments. Finally, the mechanism of producing 5-HMF was studied.Firstly, the pretreatment of WSP was studied. The optimum conditions of pretreatment are: the alkaline H2O2 solution containing 2% Na OH and 1.5% H2O2, the volume ratio of alkaline H2O2 to ethanol of 1:1, the ratio of solid to liquid of 1: 20, 80 oC, for 3 h. In the optimal conditions, the removal rate of lignin from WSP reaches 91.0%.Secondly, the influence of reaction temperature, reaction time, volume ratio of n-butyl alcohol and water, as well as substrate concentration on Y5-HMF and YRS was investigated and the optimize production conditions were determined, which are: reaction temperature of 220 oC, reaction time 4 h, volume ratio of n-butyl alcohol and water of 2, substrate concentration of 3.8%. Under these conditions, Y5-HMF and YRS are 14.9% and 5.3%, respectively.Thirdly,according to the above optimal conditions, the difference influences of using S-AC and Zr O2 alone or together on Y5-HMF and YRS were investigated. The optimizational preparation temperature and time for S-AC were 140 oC and 6h, respectively. The optimizational calcining temperature for Zr O2 was 400 oC. When S-AC and Zr O2 were used together, the amount of catalyst was 30% and the mass ratio of S-AC and Zr O2 was 4:1.Finally, the significant factors affecting the Y5-HMF and YRS from the above selected 9 single factors by orthogonal experiment are the preparation time of S-AC, reaction time and amount of catalyst. On that basis, the Box-Behnken experiment and Design-Expert 8.0 software were used to develop regression model for the significant factors affecting Y5-HMF and the regression equation is: Y5-HMF = 19.06 + 0.70×A + 2.86×B + 0.64×C + 1.00×A×B + 0.30×A×C- 1.10×B×C- 6.42×A2- 5.56×B2- 8.30×C2。 According the equation, the optimizational conditions for preparation process are: S-AC preparation time of 6.1 h, reaction time of 225.3oC, and amount of catalyst of 20.2%. The response value and experiment value of Y5-HMF are 19.5% and 19.1% is under above conditions. The results show that the equation may replace experimental value to analyze the experimental results.