化学链过程中Cu低浓度掺杂改性Fe-基载氧体反应性能:实验与理论模拟  

Reactivity of low-concentration Cu-doped modified Fe-based oxygen carrier in chemical looping:experiments and theoretical simulations

作　　者：袁妮妮[1] 白红存[1] 安梅[1] 胡修德 郭庆杰 YUAN Nini;BAI Hongcun;AN Mei;HU Xiude;GUO Qingjie(State Key Laboratory of High-Efficiency Utilization of Coal and Green Chemical Engineering,College of Chemistry and Chemical Engineering,Ningxia University,Yinchuan 750021,Ningxia,China)

机构地区：[1]宁夏大学省部共建煤炭高效利用与绿色化工国家重点实验室,化学化工学院,宁夏银川750021

出　　处：《化工学报》2020年第11期5294-5302,共9页CIESC Journal

基　　金：国家重点研发计划项目(2018YFB0605401);国家自然科学基金项目(21868025);宁夏回族自治区重点研发计划(重大科技项目)(2018BCE01002);宁夏高等学校一流学科建设项目(NXYLXK2017A04)。

摘　　要：基于热重实验(TGA)和密度泛函理论(DFT)计算,对Cu低浓度掺杂Fe2O3载氧体(Cu-Fe2O3)与H2在化学链燃烧过程中反应活性和微观分子反应机理进行研究。TGA结果显示,Cu低浓度掺杂降低Fe2O3载氧体与H2反应表观活化能Ea(从83.9kJ/mol降低至72.3kJ/mol),因此,低浓度Cu掺杂由于原子尺度Cu掺杂缺陷的引入的确提高了Fe2O3载氧体转化率和晶格氧释放速率。DFT计算从分子水平证实Cu低浓度掺杂改变了Fe2O3载氧体与H2反应路径,路径分析表明,Cu掺杂使Fe2O3载氧体与H2反应能垒从2.30eV分别降低至1.81eV(Fe原子top位反应)和1.68eV(Cu原子top位反应),Cu掺杂的Fe-基载氧体的氢还原反应优先发生在掺杂的Cu原子位,其次为Fe原子位。此外,计算结果表明,因Cu-O和Cu-Fe键的引入,低浓度Cu掺杂改变了Fe2O3载氧体微观结构,这对于载氧体的晶格氧快速释放是有利的。Based on thermogravimetric experiment(TGA)and density functional theory(DFT)calculations,the reaction activity and microscopic molecular reaction mechanism of Cu low-concentration doped Fe2O3 oxygen carrier(Cu-Fe2O3)and H2 in the process of chemical looping combustion were studied.TGA results showed that the low concentration of Cu-doped reduced the apparent activation energy of Fe2O3 reaction with H2(from 83.9 kJ/mol to 72.3 kJ/mol).And improved the conversion rate and lattice oxygen release rate of Fe2O3 oxygen carrier,which was attributed to the introduction of Cu element.From the atom/molecular level,DFT calculations verified that the low concentration of Cu-doped altered reaction pathway of Fe2O3 oxygen carrier reaction with H2.The calculation results showed that the energy barrier of Fe2O3 oxygen carrier reaction with H2 decreased from 2.30 eV to 1.81 eV(Fe atom top site)and 1.68 eV(Cu atom top site),respectively.The reaction preferentially occurred at the Cu atom site,followed at Fe atom site.Furthermore,the micro-structure characteristic change of Fe2O3 oxygen carrier(Cu—O and Cu—Fe bonds introduced)is more favorable for the rapid lattice oxygen release in chemical looping process.

关 键 词：化学链 CU掺杂 Fe-基载氧体 氢 微观结构 计算化学 

分 类 号：TQ530.11[化学工程—煤化学工程]