The Preparation Of Solid Superacid Catalyst And It’s Application In Catalytic Synthesis Of Levulinic Acid

In this thesis, proposed a twice impregnated-roasting method for the preparationof solid superacid, which was applied to the development of a variety of solidsuperacid catalyst of high catalytic activity, the study of the catalytic properties ofdifferent solid superacid catalyst hydrolysis and synthesis of levulinic acid, andexplores the relevant catalytic reaction mechanism. The specific results are as follows:The twice impregnated-roasting method for preparing solid superacid is presentedon the basis of the precipitation-impregnation and sol-gel methods. Various solidsuperacid catalysts have been developed by roasting, dipping, baking and otherprocesses, and the characterizations of those solid superacid catalysts are investigatedas well through methods like automatic diffractometer，scanning electron microscopyand specific surface area tester.With brown granulated sugar as the raw material, which along with S2O82-/ZrO₂TiO₂-M₂O₃（M=Al, Fe） as a solid superacid catalyst,5-hydroxymethyl furfural weresynthesised by using catalyzed hydrolysis method. The effects of technologicalconditions, such as catalyst calcination time, brown granulated sugar concentration,reaction temperature, reaction time, catalyst dosage, on the relative yield of5-hydroxymethyl furfural were investigated with univariate mothod. And orthogonalexperiment is adopted to determine the optimal condition. The result shows that thebest relative yield of5-hydroxymethyl furfural is51.31%under the optimal condition:the reaction medium of butanol: water=2:1，the catalyst calcination time of120min,brown granulated sugar concentration of15g/L, reaction temperature of180℃,reaction time of30min, and the catalyst dosage of10%.Levulinic acid were prepared through catalyzed hydrolysis, with microcrystallinecellulose as raw material and SO₄^2-/Polyacrylamide-ZrO₂-TiO₂-Al₂O₃as the solidsuperacid catalyst. The effects of technological conditions, such as catalyst calcinationtemperature, micro-crystalline cellulose dosage, reaction temperature, reaction time,catalyst dosage on the relative yield of levulinic acid were investigated throughunivariate method. The orthogonal experiment was employed to determine theoptimum conditions. The result demonstrates that the best relative yield of levulinicacid is88.36%under the optimal conditions: the reaction medium of butanol: water=2:1，the catalyst calcination temperature of550℃, sucrose concentration of0.3g,reaction temperature of200℃, reaction time of70min, the catalyst dosage being10%of the amount of Microcrystalline Cellulose added to the reaction. With lactose as the raw material and SO42/kaolin as a solid superacid catalyst,the solid superacid catalyst SO42/kaolin was developed through twiceimpregnated-roasting method. Univariate method was employed to investigatethe effects of the synthesis mechanism of conversion of lactose to levulinic acid，such as catalyst calcination temperature，catalyst dosage，lactose concentration，reaction temperature，reaction time on the relative yield of levulinic acid.Orthogonal experiment was used to determine the optimum conditions.The resultindicates that the best relative yield of levulinic acid was83.17%under theoptimal conditions: the reaction medium of butanol: water=2:1，catalystcalcination temperature of550℃，lactose concentration of15g/L，reactiontemperature of190℃，reaction time of80min，catalyst dosage of10%oflactose.In addition, the study of the impact of different reaction mediums on the yieldof levulinic acid and products’ separation and explores the reaction mechanismhow levulinic acid was synthesized by ecatalyzed hydrolysis of biomass.Moreover, the author analyzes qualitatively and quantitatively by HPLC methodthe5-hydroxymethyl furfural, levulinic acid and formic acid in the syntheticproducts, as well as characterizes the structure of levulinic acid by InfraredSpectroscopy and Mass Spectrometry.