Studies On The Preparation Of Hickory Hull Char Sulfonic Acid Catalyst And Its Applications

As the forestry residue, the Hickory hull is almost discarded directly. It may wasteresources and pollute the environment. With the deepening of thinking and awareness ofenvironmental protection for sustainable development, the research on green solid acidcatalyst green has become a trend. In this paper, a green solid char sulfonic acid catalyst,which was prepared using Hickory hull as the raw materials, is used in the synthesis processof important platform compound5-hydroxymethyl furfural (5-HMF or HMF) fromcarbohydrate compoundFirstly, solid char sulfonic acid catalyst was obtained from Hickory hull usinghydrothermal as the carbonization method and sulfuric acid as the sulfonation agent. Thecatalyst was characterized by ion exchange, scanning electronic microscopy (SEM), X-raydiffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR) andthermal gravimetric analysis (TGA). The results showed that the optimum preparationconditions of solid char sulfonic acid catalyst is under the carbonization temperature265℃,carbonization time17.5h, sulfonation temperature70℃and sulfonated time4h. in thissituation, the acid value of the catalyst can reach up to1.05mmol/g. The solid char sulfonicacid was the reaction products of aromatic char substrate which was prepared from thehydrothermal carbonization Hickory hull, with the sulfuric acid.Secondly, HMF was prepared from the hydrolysis of fructose using Hickory hull charsulfonic acid as the catalyst. In this section, we investigated the five influence factors offructose hydrolysis reaction temperature, reaction time, catalyst dosage and fructose contenton the HMF yield. The experimental results show that the HMF yield reaches85.90%whenthe fructose hydrolysis temperature of160℃, the hydrolysis time of3h, the dosage of catalystof0.75%, fructose concentration of5%and volume ratio of water and organic phase of1:3.The properties of the catalyst have changed few after used for three times. The further studyon the kinetics experiment of preparation HMF from fructose finds that the apparentactivation energy of the fructose hydrolysis reaction system was only47.74kJ/mol withHickory hull char sulfonic acid as the catalyst, however, the apparent activation energy is ashigh as152.60kJ/mol without catalyst. It shows that with Hickory hull char sulfonic acidcatalyst can greatly reduce the apparent activation energy of fructose hydrolysis reaction.Lastly, HMF was also prepared from the hydrolysis of cellulose using Hickory hull charsulfonic acid as the catalyst. In this section, the influence factors,such as hydrolysis temperature, hydrolysis time, the amount or the preparation conditions of catalyst on the yieldof HMF were also discussed.The results showed that the HMF yield reaches33.26%when thecellulose hydrolysis temperature of160℃, the hydrolysis time of60min, the dosage ofcatalyst of13.33mg/mL, but the yield of HMF is only14.55%without using of catalyst.Thediscussion of catalyst preparation conditions on the yield of HMF showed that the HMF yieldis30.22%when the hydrothermal carbonization temperature of265℃, hydrothermalcarbonization time of17.5h, the sulfonated temperature of70℃and sulfonated time of4h.Finally, we compare the properties of Hickory hull char sulfonic acid with other catalysts, theresults indicated that the catalyst we prepared is the best catalyst for cellulose hydrolysis. Ithas some advantage such as easy and good separation from product, good catalytic activity,simple preparation and cheap cost.in a word, the Hickory hull char sulfonic acid is apromising catalyst.