Dextrin Take One Pot Hydrolysis Hydrogenation Catalyst Design And Preparation Of Sorbitol

Catalysis is the decrease in the activation energy due to the participation of asubstance called a catalyst and thereby increases the rate of chemical reaction withoutchange in the quality and quantity of catalyst during the reaction. Study and usecatalysts can greatly reduce the cost of production, improve product quality, protectthe environment and make rational use of resources. This thesis devotes to thepreparation of highly effective catalyst with large surface area, high catalytic activityand selectity by the nanometer material synthesis technology. The amorphous alloycatalyst prepared by chemical reduction method is a kind of nanocatalyst. Amorphousalloy catalyst is a kind of special material with short-range ordering while long-rangedisordering structure. The composition of alloy and unique structure can be easilymolulated by this chemical reduction method, resulting in excellent catalytic activityand selectivity. Moreover, there is low environmental pollution during the preparationprocess. All these advantages of this highly efficient catalyst is consisten with thedevelopment trend in today’s chemical industrial with the scientific concept of savingenergy and environmental protection, attracting the increasing attention of people.The first part of this thesis modulates the reaction conditions of glucoamylasehydrolyzed dextrin. The second part of the study is the application of Ru-basedcatalyst in the hydrogenation of glucose to sorbitol and its reaction conditions. Thelast part of the study is putting the Ru metal and the enzyme together as the catalyst ofthe hydrolysis-hydrogenation of dextrin to sorbitol. The main content of the thesis isas follow:(1) Starch glucoamylase was used as a catalyst for the hydrolysis of dextrin.Temperature, pressure, the amount of added enzyme and pH value were modulated forthis reaction. A high conversion and high selectivity can be achieved under relativelymild conditions. By using the glucoamylase, the conversion of dextrin reached morethan80%with selectivity of100%, and a glucose aqueous solution with highconcentration can be synthesized. (2) A highly dispersed, high active and high selective Ru-based catalyst forhydrogenation was prepared through impregnation method. In the preparation process,we have adopted the microwave quick-drying method, which decreased the outwardmigration of the metal ions within the pores of the catalyst. Using KBH4as a reducingagent, the metal ions is quickly reduced, preventing the produced metal particles fromagglomeration. Then, a highly dispersed Ru-B amorphous alloy catalyst was preparedfor catalytic hydrogenation. In this chapter, we also optimized the reaction conditionsfor the hydrogenation of glucose. Under the relatively mild reaction conditions, theyield of sorbitol reached99%, and the selectivity was100%. The results showed thatwhen the loading of Ru is2.5%, temperature is75°C, hydrogen pressure is6.0MPa,pH=7.0,80μl of the enzyme is added, the yield of sorbitol is the highest.(3) We studied the problems during one-pot hydrolysis-hydrogenation of dextrinto sorbitol, and produced a catalyst with Yolk-Shell structure to achieve high yield ofsorbitol. We investigated the catalyst preparation method, etching conditions, and therecycling use of the catalyst, and obtained a better result with a sorbitol yield of morethan80%.