分子筛催化剂在生物质催化热解高温条件下的择形催化机制研究

项目名称： 分子筛催化剂在生物质催化热解高温条件下的择形催化机制研究

项目编号： No.21306101

项目类型： 青年科学基金项目

立项/批准年度： 2014

项目学科： 化学工业

项目作者： 于艳卿

作者单位： 清华大学

项目金额： 25万元

中文摘要： 分子筛催化剂的择形催化机制在生物质催化热解反应中对反应途径、产物分布等起着重要作用。最近的研究发现，传统的择形催化研究方法(即比较分子筛静态孔道直径与反应物、产物分子的动力学直径的方法)不能很好地解释生物质催化热解的择形催化实验结果。经过分析，我们认为这主要是以下两个原因引起的：(1)静态孔道直径不能反映分子筛在催化热解高温时的孔道变形；(2)动力学直径假设分子为球形，不能真实反映分子的三维尺寸。因此，本课题拟采用量子化学计算与分析裂解试验相结合的方法，研究分子筛在生物质催化热解高温条件下的择形催化机制。通过量子化学计算确定热解产物分子的三维尺寸；通过研究热解产物的分子尺寸及其在催化热解中的转化情况确定分子筛在高温时的有效孔道直径。

中文关键词： 木质素；催化快速热解；择形催化；量子化学计算；热处理

英文摘要： Shape selectivity of zeolite catalysts plays a determining role in the reaction pathway and product distribution in catalytic fast pyrolysis (CFP) of biomass. Recent studies have suggested that the conventional method of evaluating shape selectivity of zeolites, i.e., comparing the crystallographically static pore size of zeolites to the kinetic diameter of molecules, cannot satisfactorily describe the experimental results of shape selectivity in CFP of biomass. We attributed this discrepancy to two main reasons: (1) static pore size of zeolites cannot reflect the pore structure alteration at high temperatures of CFP, and (2) the kinetic diameter, which assumes a molecule to be effectively spherical, cannot represent the real three dimensions of a molecule. Based on this analysis, we aim to investigate the shape selectivity of zeolites at high temperatures of CFP by combining quantum chemical computation and analytical pyrolysis techniques. Quantum chemical computation can provide necessary information on the size and conformation of molecules of pyrolysis products. The effective pore size of zeolites at high temperatures can then be determined by analyzing the molecular size and conversion behavior of the pyrolysis products in analytical CFP tests. This would offer a more realistic measure of the shape selecti

英文关键词： lignin；fast catalysis pyrolysis；shape selectivity；quantum chemistry calculation；thermal treatment