固载磷钨酸的大孔道功能化MOFs合成及催化性能  

Synthesis and Characteristics of Functional Mesoporous Metal-Organic Frameworks with Immobilized Phosphotungstic Acid

作　　者：郝金蕾 张桂华[2] 王艳 万金泉 马邕文 黄礼艳 HAO Jinlei;ZHANG Guihua;WANG Yan;WAN Jinquan;MA Yongwen;HUANG Liyan(School of Environment and Energy,South China University of Technology,Guangzhou 510006;Huizhou Institute of Environmental Science,Huizhou 516001;State Key Laboratory of Pulp and Paper Engineering,Guangzhou 510640)

机构地区：[1]华南理工大学环境与能源学院,广州510006 [2]惠州市环境科学研究所,惠州516001 [3]制浆造纸工程国家重点实验室,广州510640

出　　处：《材料导报》2018年第14期2475-2480,2507,共7页Materials Reports

基　　金：国家自然科学基金(31570568;31670585);制浆造纸重点实验室开放基金(201535);广州市科技计划项目(201607010079;201607020007)

摘　　要：获得可固载PTA的大孔道载体,对于大分子物质的催化转化具有重要意义。本研究采用扩孔剂CTAB对MOFs载体进行扩孔并同步实现PTA的化学固载,同时在MOFs的骨架中接枝-Cl和-NH2实现其功能化。研究发现加入CTAB后虽然获得的样品均为MIL-101结构,且随CTAB加入量的增加,样品的晶面生长逐渐变差,但仍具有良好的热稳定性。MOFs的比表面积和孔径随CTAB加入量的增加而逐渐增大,经CTAB扩孔后,MOFs由微孔结构转化为微孔与介孔共存结构,在CTAB加入量为5.4mmol时,样品的介孔结构占比最大,达到87%,孔径以3.9nm和46.1nm为主。CTAB的加入不会影响-NH2与PTA的静电作用,但PTA的固载量随CTAB加入量的增加先增大后减小,当CTAB加入量为3.6mmol时PTA的固载量最大,所获得的催化剂样品催化水解微晶纤维素的葡萄糖产率也达到最大,获得葡萄糖产率可达到等量未固载PTA催化效能的76.35%。样品连续三次催化水解微晶纤维素后,葡萄糖产率仅下降了5%左右,说明接枝-NH2发挥了其通过静电作用固载PTA的功能,从而降低了PTA在反应过程中的流失。Obtaining large pore carriers to immobilize phosphotungstic acid（PTA）is of great significance for the catalytic conversion of big molecular substances.In this study,the surfactant cetyltrimethylammonium bromide（CTAB）was applied as a structure-directing agent for metal-organic frameworks（MOFs）.MIL-101（Cr）was synthesized with-NH2 and-Cl to realize its functionalization,and well-dispersed PTA on MIL-101（Cr）was obtained.It was found that with the addition of CTAB,although the obtained samples maintained the MIL-101 structure,their crystal growth became poor gradually with adding amount of CTAB and possessed great thermal stability.MOFs＇ surface areas and pore sizes increased with the increase of CTAB.Samples switched from microporous structure to micro-mesoporous structure when MOFs coexisted with the adding of CTAB.Moreover,the mesoporous structures increased along with the increase of CTAB.When the adding amount of CTAB was 5.4 mmol,the optimum mesoporous ratio reached the peak with about 87%,mainly with pore sizes of 3.9 nm and 46.1 nm.The addition of CTAB would not interfere with the electrostatic interaction between-NH2 and PTA,but the amount of immobilized PTA increased first and then decreased with the increase of CTAB.The immobilized PTA reached the maximum at CTAB equals to 3.6 mmol.As the amount of loading PTA,the glucose yield of cellulose hydrolysis catalyzed has same trend.The yield of glucose can reach 76.35% of the catalytic effect compared with same amount of non-immobilized PTA.After three consecutive catalytic hydrolysis of microcrystalline cellulose samples,the glucose yield decreased by only about 5%,indicating that grafted-NH2 exerts its function of immobilization PTA by electrostatic interaction and reduces the loss of PTA.

关 键 词：金属有机骨架 MIL-101 磷钨酸 介孔 

分 类 号：TQ426.91[化学工程]