Synthesis Of MCM-48Mesoporous Molecular Sieve And L-proline Adsorption On Aldol Reaction And Its Application

M41S sieves mesoporous materials with2～10nm ordered pore structure, MCM-48mesoporous molecular sieves contains two unique cross three-dimensional pore systems willreduce the pore clogging and is conducive to the transmission of the guest molecules incatalytic and separation applications. From the point of view of adsorbent and catalyst, it hasgreat development potential which attracted much attention.In recent years, proline in a variety of catalytic asymmetric reactions showed excellentcatalytic performance, it is simple structure, good stability, low cost and available chiralorganocatalysts, small organic molecules can be used for catalytic asymmetric reactions, andthe reaction conditions are relatively mild, it does not require any metal reagents can achieveefficient asymmetric transformation. But it also has some disadvantages,such as large amountof catalyst, reaction is in the majority of organic solvents on the environment have a certainpollution, as well as the catalyst is difficult to be recycled and reused.Organic small moleculeimmobilized as catalytic asymmetric reagent,greatly simplifies reaction product purificationprocess,can also achieve the reuse of the catalyst.Based on this,the present experiment byvacuum pumping method L-proline adsorption to MCM-48and SBA-15mesoporousmaterials sieves made of Pro/MCM-48and Pro/SBA-15catalyst,and examines in asymmetricAldol reactiona in the catalytic performance.This paper adopts the different template synthesis of MCM-48, on the basis of theresearch on the modification. The synthetic productes were characterized by X-ray powderdiffraction (XRD), nitrogen adsorption, transmission electron microscopy (TEM) and infraredspectroscopy (FT-IR). The main results and conclusions are as follows:1.Using a single template synthesis of high quality MCM-48mesoporous molecularsieve,on the basis of adding inorganic salts(NaF)and solvent(TMB), And effects of the addingamount of inorganic salt and adding time for crystal phase of resulting samples andhydrothermal stability of MCM-48mesoporous molecular sieve were studied.2. MCM-48mesoporous molecular sieve is prepared by using the template method(P123and CTAB), and tetraethylorthosilicate (TEOS) as silicon source, while the ratio ofreactants is investigated on the impact of pore size. Characterization of resulting samples byXRD, SEM, N2physical adsorption and IR indicated that the use of a single templatesynthesis MCM-48was reduced greatly because of adding of P123and resulting MCM-48had high specific surface area, highly ordered pore structure, pore size distribution uniformand high hydrothermal stability. 3.Preliminary study on different mesorous molecular sieves(MCM-48,SBA-15) as thecarrier,immobilized L-proline preparation of Pro/MCM-48and Pro/SBA-15catalyst,and thecatalysts in asymmetric Aldol reactions in the catalytic performance.The results showed thatthe praline and does not affect the MCM-48and SBA-15ordered mesoporous structure,butits pore size,pore volume and specific surface area decreased,catalysts in asymmetric Aldolreactiona have catalytic activity and enantioselectivity.And homogeneous catalysis, catalystvery easy separation, Pro/MCM48and Pro/SBA15catalyst respectively can be used2times and4times, their catalytic properties remain unchanged, but the enantioselectivity isnot very good, hope in the catalyst also need to do more in-depth study.