重结晶法制备多级孔Sn-Beta分子筛用于催化葡萄糖异构化为果糖

Catalytic Isomerization of Glucose to Fructose Using a Hierarchical Sn-Beta Molecular Sieve Prepared by Recrystallization

以脱铝Beta分子筛作为硅源,SnCl_4·5H_2O为锡源,在介孔模板剂十六烷基三甲基溴化铵(CTAB)的作用下经过两步水热重结晶法制备了同时具有微孔和介孔的多级孔Sn-Beta分子筛催化剂,并将其用于葡萄糖异构化反应。采用FT-IR、XRD、SEM、TEM、ICP和N2吸附脱附等温线等对多级孔Sn-Beta分子筛进行了表征。考察了分子筛中硅锡摩尔比、反应温度、反应时间和催化剂用量对葡萄糖转化率和果糖得率的影响,并对其重复使用性和再生利用进行了研究。结果表明:该分子筛除了具有典型的BEA微孔分子筛的骨架结构外还具有介孔的结构。在催化葡萄糖异构反应中,当分子筛硅锡摩尔比为100,反应温度120℃,反应时间2 h,40 mL质量分数为10%的葡萄糖,催化剂用量为4 g时,果糖的得率高达47.20%,且具有较好的可再生和多次重复使用性。

With an aluminum-free beta molecular sieve as the silicon source and fin （IV） chloride pentahydmte as the fin source, a microporous and mesoporous hierarchical Sn-Beta zeolite catalyst was prepared by two-step hydrothermal recrystallization under the action of a mesoporous template agent, cetyltrimethylammonium bromide （CTAB）. The hierarchical Sn-Beta molecular sieve was then used in the isomerization of glucose to fructose. The properties of the sieve were characterized by Fourier transform infrared spectroscopy （FT-/R）, X-ray diffraction （XRD）, manning electron microscopy （SEM）, transmission electron microscopy （TEM）, inductively coupled plasma atomic emission spectroscopy （ICP-AES）, and nitrogen adsorption-desorption isotherm. The effects of reaction temperature, reaction time, amount of catalyst, and molar ratio of silicon/fin on glucose conversion and fructose yield were investigated, and the reusability and regeneration of the novel catalyst were also studied. The results showed that the hierarchical Sn-Beta molecular sieve had not only the typical fi＇amework structure of BEA-type micropore molecular sieves, but also the mesopore structure. In the catalytic isomerization of glucose, the yield of fructose could reach 47.20% when the reaction temperature was 120 ℃, the reaction time was two hours, the molar ratio of silicon oxide/fin oxide was 100, and 4 g of catalyst and 40 mL glucose （10 wt%） were used. Additionally, the catalyst exhibited a good regenerative property and reusability.