文档介绍：本科毕业设计(论文)
题目
SBA-15介孔分子筛的改性及
其催化性能研究
学生姓名

学号

院(系)
专业

化学工程与工艺
指导教师
时间

2013年 6月 8日
摘要
介孔分子筛SBA-15具有较高比表面积、规则孔道结构及孔径易于控制、热稳定性和水热稳定性较好、表面易官能化等特点,在催化化学和吸附分离等领域有广阔的应用前景。当前,介孔分子筛的发展重点是催化方面的应用。运用恰当的修饰剂与适宜的修饰方法,对其进行功能化修饰是提高其催化性能的有效方法。
纯SBA-15介孔分子筛酸性弱,无催化活性;但在其骨架中引入杂原子之后,可获得一定强度的酸性中心,从而使其具备酸催化的性能。本研究旨在采用浸渍法对SBA-15介孔分子筛进行功能化修饰,以便引入酸性中心。
采用直接水热法合成SBA-15介孔分子筛。并对其掺杂Al和稀土元素RE(La、Ce)负载改性,且考察了改性后的SBA-15在乙酸与乙醇的酯化反应和叔丁醇苯酚烷基化反应中的催化活性。合成的RE-Al/SBA-15介孔分子筛催化剂通过XRD、N2吸附-脱附、TEM、27Al NMR、NH3-TPD、Py-IR等对样品进行了表征。结果表明:负载改性后的SBA-15仍保持规整的孔道排列和六方相介孔结构并具有一定强度的酸性。
将RE-Al/SBA-15应用于催化酯化反应,考察了La、Ce负载添加量、反应温度、反应时间、催化剂类型等因素对酯化反应的影响;对比酯化反应,考察了RE-Al/SBA-15在烷基化中的催化性能。研究结果表明,由于RE-Al/SBA-15只具备中等强度酸中心,因此其在酯化反应中的催化性能较差。而La-Al/SBA-15在烷基化反应中具有优良的催化活性,当叔丁醇/苯酚的物质的量比为4:1、、反应温度190℃、反应时间2h时,%,三种目标主产物(4-TBP、2,4-DTBP、2-TBP)%。
关键词: RE-Al/SBA-15;稀土改性;酯化;烷基化
Abstract
The mesoporous molecular sieve SBA-15 has attracted considerable attention in the fields of catalytic chemistry and adsorption-separation, due to high surface area, uniform pore size and tunable pore structure, high thermal and hydrothermal stability easily functionalized surface. The point of research on mesoporous materials currently focuses on the exploitation of their application in catalysis. Via using appropriate precursors and preparation methods, the functional modification of mesoporous materials has played considerable roles in improving the performance of catalytic properties.
Because of the weak acidicity, SBA-15 can’t be used as acidic catalyst unless a heteroatom was introduced into its skeleton because some acid centers were obtained. The purpose in this study is to functional modification of SBA-15 mesoporous molecular sieves by the impregnation method for the incorporation of acid sites.
The mesoporous molecular sieves SBA-15 were synthesized by hydrothermal synthesis method and modified by incorporating Al atoms and RE (La, Ce). Moreover, the modified RE-Al/SBA-15 catalytic