Synthesis Of Sn-Beta Molecular Sieves And Their Application In Isomerization Of Glucose

Currently,as a result of the petroleum-based fossil energy are being consumed rapidly,the nonrenewable fossil resources problem and environment problem are becoming more and more serious.The exploration of sustainable clean resources has aroused attention increasingly.There is a growing interest in producing fuels and chemicals from biomass resources.Carbohydrates are the major components of biomass.Glucose is the most abundant simple sugar in nature,which can be obtained by the hydrolysis of cellulose.Sn-Beta can catalyze glucose to fructose efficiently,meanwhile,fructose can be easily converted into siginificant platform compounds than glucose,such as 5-hydroxymethyl furfural,levulinic acid,lactic acid and so on.However,the conventional Sn-Beta still relies on using TEOS as the silica sources and HF as the mineralizer.The method requires long crystallization time(at least ten days)and the HF can bring environment pollution.The dissertation focus on developing three facile,rapid and efficient synthesis Sn-Beta method and is used for glucose isomerization:1.Sn-Beta zeolite was successfully synthesized by hydrothermal crystallization reaction,using fumed silica as the silica source and NH4 F as the mineralizer.The method avoid the TEOS hydrolysis process and simplify the synthesis procedure.Investigate the catalytic activity of the as-synthesized Sn-Beta in the glucose isomerization.The effects of reaction temperature,reaction time,amount of catalyst in the reaction were studied.When 4 g Sn-Beta was added into 40 ml of 10% glucose solution(mass fraction),glucose conversion,fructose yield and mannose yield were 57.8%,31.8% and 9.4%.2.Sn-Beta was prepared rapidly by Dry-gel conversion.The amorphous gel which contains template(TEAOH)was converted into highly crystalline Sn-Beta within 36 h~48 h at reaction temperature of 180 ?.Compared with the conventional hydrothermal Sn-Beta,the Sn-Beta by dry-gel method has similar catalytic activity.The zeolite has high hydrothermal stability.3.A novel strategy,combined through hydrothermal crystallization and dry-gel conversion method,has been designed for the synthesis of hierarchical Sn-Beta.In the first step,dealuminated Al-Beta and SnCl4·5H2O were dissolved in TEAOH and fomed mixture.Then,the mixture formed Sn-Beta primary crystal by hydrothermal synthesis.In the second step,the primary crystal will be further converted to the hierarchical Sn-Beta by CTAB through dry-gel crystallization.Compared with the dry-gel Sn-Beta in the glucose isomerization,the hierarchical Sn-Beta with micro/meso-structure has excellent catalytic performance and high hydrothermal stability against mesostructural collapse.