质子交换膜反应器中乙醇缓解产物抑制的机制  

Mechanism of ethanol on eliminating product inhibition in proton exchange membrane reactor

作　　者：张少锋[1] 刘释水 金锐 王云晴 吴雪梅[1] 贺高红[1] ZHANG Shaofeng;LIU Shishui;JIN Rui;WANG Yunqing;WU Xuemei;HE Gaohong(State Key Laboratory of Fine Chemicals,Research and Development Center of Membrane Science and Technology,School of Chemical Engineering,Dalian University of Technology,Dalian 116024,China)

机构地区：[1]大连理工大学化工学院膜科学与技术研究中心精细化工国家重点实验室

出　　处：《膜科学与技术》2019年第5期1-8,共8页Membrane Science and Technology

基　　金：国家自然科学基金项目(21776034和U1663223)

摘　　要：质子交换膜反应器反应条件温和、氢气传质阻力小,但产物抑制会导致产物积累和加氢性能下降,是一个具有挑战性的课题.本文采用分子动力学模拟从微观角度探究了模型反应马来酸加氢产生产物抑制的原因,提出乙醇缓解产物抑制的作用机制.通过分析非均相体系中相互作用能、吸附能和吸附形态学,发现产物琥珀酸弱的极性和电离能力及稍强的竞争吸附能力使得其倾向远离溶剂水而吸附在碳载体表面,是产物抑制的主要原因.而乙醇可以通过溶剂化作用和竞争吸附作用降低琥珀酸与碳载体亲和力并增强其与水的亲和力,添加1 mol/L乙醇时,琥珀酸在碳载体上吸附能降低了约1.0 kcal/mol,而与混合溶剂乙醇/水相互作用能增加了2.8 kcal/mol,这可以将琥珀酸从碳载体表面释放并进入溶液中,有效缓解产物抑制.乙醇缓解产物抑制的机制可以为竞争吸附剂的优选提供理论指导,进一步提高质子交换膜反应器的非均相加氢性能.Proton exchange membrane reactor is a promising hydrogenation reactor(EHPR)because of its mild reaction condition and low hydrogen transfer resistance.However,product inhibition in EHPR leads to product accumulation and hydrogenation performance decline,which is a challenging issue.In this work,reasons of product inhibition of maleic acid hydrogenation are explored from microscope through molecular dynamics simulation and propose the mechanism of ethanol on eliminating product inhibition.By analyzing the interaction energy,adsorption energy and morphology in the heterogeneous reaction system,it indicates that weaker polarity and ionization and slightly stronger competitive adsorption capacity of product succinic acid is the main factor for its weaker affinity with solvent H 2O,which is the key reason of product inhibition.Ethanol has both solvation and competitive adsorption effects to reduce SA affinity with carbon carrier and increase its affinity with solvent,e.g.the adsorption energy of SA on carbon carrier reduce by 1.0 kcal/mol but the interaction energy between SA and mixed solvent EtOH/H 2O increase by 2.8 kcal/mol with the addition of 1.0 mol/L EtOH,which expels the product SA away from the carbon carrier and stretch it into the bulk aqueous solution and thus eliminate product inhibition.This mechanism provides a guide to optimize competitive adsorbent and a promising way to improve aqueous system hydrogenation performance in proton exchange membrane reactor.

关 键 词：质子交换膜反应器 产物抑制 溶剂化作用 竞争吸附 分子动力学模拟 

分 类 号：TQ021.4[化学工程]