论文总字数：21259字

摘 要

MCM-22分子筛兼具十元环和十二元环的孔道特性、优良的酸性以及热/水热稳定性，已在多种反应中显示出优异的催化性能。长期以来，沸石分子筛都由传统的水热法合成，上世纪九十年代初，人们开发出气相法合成分子筛的新途径。与水热法相比，气相法有着显著的优势：大大减少有机模板剂的使用量、省去产品与母液分离的繁杂步骤、避免产生大量废液、对环境友好等。本文旨在采用气相转移法（VPT）合成Cr-MCM-22分子筛，系统地研究各种产物的物理化学性质。主要结果如下。

采用气相法成功地合成了高结晶度的Cr-MCM-22分子筛，运用XRD、IR、SEM、UV和TG等表征手段对Cr-MCM-22分子筛的结构以及Cr在分子筛中的状态进行分析。XRD和IR结果显示Cr进入分子筛的骨架结构中，UV证明Cr物种以骨架Cr物种和骨架外Cr₂O₃等形式存在。凝胶中Cr/SiO₂比显著影响铬在分子筛骨架中的状态，随着凝胶铬含量的增加，产物中氧化铬量也随之增加。

关键词：气相法合成 Cr-MCM-22 沸石分子筛

ABSTRACT

MCM-22, a novel aluminosilicate zeolite, possesses two independent 10-membered ring and 12-membered ring channels. Due to its unique microstructure, high thermal/hydrothermal stability and mild acid property, MCM-22 has been studied as catalysts for various reactions. Up to date, hydrothermal synthesis is the most important approach for the synthesis of zeolites. In 1990, a novel synthesis method, vapor-phase transport method, was developed. Compared to the conventional hydrothermal route, the VPT method is advantageous in that the amount of organic template is greatly reduced and there is not a separation step for removing the product from the mother liquid. The method involves nearly complete conversion of the gel to zeolite, producing less waste and requiring a smaller reactor volume. In the article, Cr-MCM-22 zeolite was synthesized by vapor-phase transport method (VPT). The main results are follows.

Highly crystalline Cr-MCM-22 zeolites were synthesized by VPT method and were characterized by XRD, IR, SEM, TG and UV. Compared with pure MCM-22 zeolite, the skeleton vibration peaks in IR spectra of Cr-MCM-22 shifted to relative low wavenumbers, which indicates that Cr atoms had incorporated into the MCM-22 frameworks. Based on the UV characterization results, it can be speculated that there were three kinds of Cr species such as framework, extra-framework and chromium cluster species, existing in the Cr-MCM-22 samples. As the Cr/SiO₂ ratios increased, the amount of chromium oxides increased.

KEYWORDS: Vapor-phase transport method; Cr-MCM-22; zeolite

目录

摘要................................................................................................................................I

ABSTRACT.................................................................................................................II

目录................................................................................................................................i

第一章 文献综述........................................................................................................1

1.1 MCM-22分子筛的研究背景.......................................................................1

1.2 MCM-22分子筛概况...................................................................................1

1.3 MCM-22分子筛的结构...............................................................................1

1.4 MCM-22分子筛的合成...............................................................................2

1.4.1 水热晶化合成法..................................................................................2

1.4.2 气相合成法..........................................................................................3

1.4.3 杂原子MCM-22分子筛的合成方法..................................................4

1.5 MCM-22的应用...........................................................................................4

1.5.1 MCM-22分子筛在催化反应中的应用..............................................4

1.5.2 环境保护方面的应用..........................................................................5

1.5.3 烷基芳香族化合物的生产..................................................................5

第二章 试验部分........................................................................................................7

2.1 实验所用试剂及药品...................................................................................7

2.2 沸石分子筛的制备.......................................................................................7

2.2.1 气相法合成杂原子Cr-MCM-22沸石分子筛....................................7

2.3 沸石分子筛的表征.......................................................................................8

2.3.1 X射线衍射仪（XRD）........................................................................8

2.3.2 扫描电镜（SEM）................................................................................8

2.3.3 红外光谱分析（IR）............................................................................9

2.3.4 紫外可见漫反射分析（UV-Vis）......................................................9

2.3.5 电感耦合等离子发射光谱仪（ICP）................................................9

2.3.6 比表面积和孔分布测试（BET）........................................................9

2.3.7 热重分析（TG-DSC）.........................................................................9

第三章 气相法合成Cr-MCM-22分子筛...............................................................10

3.1 影响Cr-MCM-22分子筛合成的因素........................................................10

3.2 Cr-MCM-22分子筛的物化性质................................................................11

3.2.1 SEM分析...........................................................................................11

3.2.2 IR分...................................................................................................12

3.2.3 固体紫外漫反射光谱分析................................................................13

3.2.4 TG分析..............................................................................................14

3.3 本章小结.....................................................................................................15

第四章 结论与展望..................................................................................................17

4.1 结论.............................................................................................................17

4.2 展望.............................................................................................................17

参考文献......................................................................................................................18

致谢..............................................................................................................................20

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