催化剂孔道结构设计及孔内反应-扩散耦合模拟  

Simulation of pores-scale reaction-diffusion coupling for the design of catalyst structure

作　　者：魏格林 李成祥 葛蔚[1,2,3] 李金兵 Gelin WEI;Chengxiang LI;Wei GE;Jinbing LI(State Key Laboratory of Multiphase Complex Systems,Institute of Process Engineering,Chinese Academy of Sciences,Beijing 100190,China;School of Chemical Engineering,University of Chinese Academy of Sciences,Beijing 100049,China;Innovation Academy for Green Manufacture,Chinese Academy of Sciences,Beijing 100190,China;Dalian National Laboratory for Clean Energy,Chinese Academy of Sciences,Dalian,Liaoning 116023,China;Sinopec Beijing Research Institute of Chemical Industry Yanshan Branch,Beijing 102500,China)

机构地区：[1]中国科学院过程工程研究所多相复杂系统国家重点实验室,北京100190 [2]中国科学院大学化学工程学院,北京100049 [3]中国科学院绿色过程制造创新研究院,北京100190 [4]中国科学院洁净能源创新研究院,辽宁大连116023 [5]中国石化北京北化院燕山分院,北京102500

出　　处：《过程工程学报》2021年第3期265-276,共12页The Chinese Journal of Process Engineering

基　　金：国家数值风洞工程资助项目(编号:NNW2019ZT2-B03);中国科学院洁净能源创新研究院合作基金(编号:DNL201905)。

摘　　要：采用硬球-拟颗粒(HS-PPM)耦合方法并结合简化的集总反应模型,模拟了碳四(C4)烯烃催化裂解过程中反应物和产物在孔道内的反应-扩散耦合过程,提出了一种多级孔道结构可控设计方法,实现了对孔隙率、孔径和孔体积占比等参数的独立量化调控,建立了包含三种不同孔径分布的催化剂孔道模型并定义了量化参数对反应-扩散耦合进行表征。结果表明,各组分在复杂孔道内的扩散过程显著受限,反应-扩散耦合性能较差,导致催化剂总体性能降低,达不到本征动力学允许的高反应速率。提出的可控设计孔道模型结合HS-PPM耦合模拟方法有助于催化剂材料的孔尺度结构的设计。Most catalysts have complicated pore structures,and the coupling of reaction and diffusion processes in the pores determines the overall performance of catalysts.Understanding the reaction-diffusion coupling in the pores is important for better design of catalysts to improve their performance.In this work,the coupling of reaction and diffusion of reactants and products in catalyst pore structures was simulated by using the hard-sphere/pseudoparticle modeling(HS-PPM)approach which is combined with a simplified lumped reaction model for the C4 olefin cracking process.A controllable approach was proposed to construct more realistic model for the pore structure in catalyst materials,with which the effect of porosity,pore diameter and pore volume ratio could be studied independently and quantitatively.In addition to the effectiveness factorη,a quantitative parameter JC was proposed to characterize the coupling of reaction and diffusion processes.The results showed that JC tended to be zero,which indicated that the overall diffusion process was significantly limited due to the competition between reactant diffusion and product diffusion in the complex pores.The reactant molecules were mainly diffused into the catalyst through the larger pores,and the larger product molecules were also mainly diffuse out of the catalyst through the larger pores.The competition between these two processes made it difficult for the reactants to diffuse into the pore,and the products to diffuse out of the pore,which led to the decrease of the overall performance of the catalyst albeit the potentially high reaction rate allowed by the intrinsic kinetics.The simulation approach used in this study could be helpful for the design of pore-scale structure of catalyst materials.

关 键 词：多级孔结构调控 反应-扩散耦合 硬球-拟颗粒模型 分子模拟 催化剂 

分 类 号：O643.36[理学—物理化学]