择形分子筛催化剂反应-扩散的介尺度耦合机制及其调控方法

This project tries to clarify the coupling mechanism of reaction – diffusion, the interface mesoscale structures, theoretical mathematical model and controlling method over shape-selective zeolite catalysts, in order to develop the catalyst for alkylation of coking benzene with methanol to produce para-xylene. Firstly, the in-situ & dynamic characterization methods will be established accurately to determine the properties of shape-selective catalysts and alkylation reaction respectively. In addition, a variety of shape-selective zeolite catalysts with the typical acidity & structure will be prepared. By using the fixed bed reactor and the internal circulation gradientless reactor, under the different reaction conditions, the effect of the reactive sites on the external surface and in the channel of zeolites and their catalytic reaction, the diffusion in the microporous channel of zeolites and the diffusion in the mesoporous channel among zeolites /adhesives on the reaction conversion and product composition will be investigated, and their relationship among these mesoscale factors will be studied as well. Moreover, the coupling process of reaction – diffusion in the shape-selective zeolite catalyst will be analyzed, and the formation of the interface mesoscale structures and its transformation is clarified. By means of differential calculation in the multi-dimensions and the multi-factors & objectives, the dynamic composition distribution of the reactants & products will be simulated in the zeolite channels and the pores of catalyst particles. The process between the catalytic reaction and microporous and mesoporous diffusion will be simulated. The mesoscale mathematical model for shape-selective catalysts will be established. Based on the above results, the effective controlling method will be proposed, and the new shape-selective catalyst for alkylation will be designed and prepared with the high performance.

本项目以焦化苯与甲醇烷基化反应制对二甲苯择形催化剂为研究对象，以揭示择形分子筛催化剂表界面介尺度结构与反应-扩散耦合机制、建立理论量化模型与调控方法为研究目标。首先建立真实反映择形催化剂性能与反应过程的原位动态测试方法，并设计制备一系列具有不同酸性和孔结构特性的分子筛催化剂；分别采用固定床积分反应器与内循环等梯度微分反应器，研究在不同反应条件下催化剂分子筛外表面、孔道内的区域活性位及其催化反应、分子筛内微孔反应扩散、分子筛粘接间中孔扩散对反应转化率与产物组成的影响及其相互关系，深入分析择形催化中反应-扩散的耦合过程，揭示表界面介尺度结构形成机制与演化规律；通过多目标变分的多尺度计算方式，对反应组分在分子筛晶粒、催化剂颗粒内部的动态分布进行微分衡算，模拟催化反应受孔内外传质扩散影响的过程，建立择形催化材料的介尺度数学量化理论模型；据此提出有效的反向调控方法，指导制备出新型的烷基化择形催化剂。

本项目以我国煤化工与石化工业中甲醇烷基化反应制对二甲苯择形催化剂为研究对象，以揭示择形分子筛催化剂表界面介尺度结构与反应-扩散耦合机制、建立理论量化模型与调控方法为研究目标。首先试验建立了真实反映择形催化剂性能与反应过程的原位动态测试方法，并设计制备了一系列具有不同酸性和孔结构的特征分子筛催化剂；分别研究了在不同反应条件下催化剂分子筛外表面、孔道内的区域活性位及其催化反应、分子筛内微孔反应扩散、分子筛粘接间中孔扩散对甲醇烷基化催化反应转化率、产物组成、择形选择性的影响，进一步深入分析了择形催化中反应与扩散的耦合过程及其相互关系,基本弄清了择形催化过程中产生“逆向效应”矛盾的主要原因，初步揭示了分子筛择形催化剂的表界面介尺度结构形成机制与演化规律,并建立了分子筛择形催化材料表界面介尺度结构的理论模型；据此提出了解决择形催化“逆向效应”矛盾的有效反向调控方法与手段，并指导开展了二个新型的甲醇烷基化制对二甲苯择形催化剂的制备创新, 结果表明甲醇烷基化择形催化剂的反应性能优异，主要技术指标达到国际先进水平，从而为开发绿色的甲醇烷基化反应制对二甲苯新技术奠定了坚实的研究基础。