化学链重整反应中含氧空位α-Fe2O3(001)表面CO反应行为的密度泛函理论研究

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中文摘要：化学链甲烷重整是利用甲烷制备合成气(CO和H2)具有广阔前景的方法之一,其中CO在氧载体表面上的进一步反应对CO选择性起主要决定作用.本文采用密度泛函理论系统地研究了α-Fe2O3(001)氧空位对CO脱附、CO氧化和CO解离的影响.计算结果表明,增加氧空位浓度会导致Fe原子中的电子局域化增强,从而削弱Fe位点上CO的脱附能力.此外,氧空位浓度从1/12ML增加到1/6ML会导致CO氧化能垒从0.64eV增加到1.10eV.增加氧空位浓度虽有利于CO解离,但由于解离反应的高能垒(大于3.00 eV),CO的解离仍然很难发生.综合考虑三条反应途径,CO脱附可以在高于900K的反应温度下自发进行.增加氧空位浓度可以提高合成气选择性,因为在高氧空位浓度(1/6 ML)下,相比于CO脱附,CO氧化的竞争性减弱.这项研究揭示了在Fe2O3的还原程度增加时,化学链甲烷重整中CO选择性增强的微观机制.

外文标题：DFT Studies of CO Reaction Behavior on α-Fe2O3(001)Oxygen-Vacancy Surface in Chemical Looping Reforming

外文摘要：Chemical looping reforming of methane to syngas(CO and H2)is one of the most promising routes for methane utilization,where the further reaction of CO on oxy-gen carrier surfaces is a primary determi-nant of CO selectivity.In this work,the effects of oxygen vacancy(VO)on CO desorption,CO oxidation,and CO disso-ciation are systematically studied by us-ing density functional theory calcula-tions.Our calculated results reveal that increasing VO concentration can weaken CO desorption at Fe sites due to the enhanced localization of electrons in the Fe atoms.Also,the increase in VO concentration from 1/12 ML to 1/6 ML leads to a dramatic increase of ac-tivation energy in the CO oxidation from 0.64 eV to 1.10 eV.Moreover,the increase in Vo concentration is conducive to CO dissociation,but the dissociation is still almost impossible due to the high reaction energies(large than 3.00 eV).Considering these three reaction paths,CO desorption can proceed spontaneously at reaction temperatures above 900 K.Increasing VO concentration can improve the selectivity of syngas production due to the less favorable CO oxidation compared with CO desorption at high Vo concentrations(1/6 ML).This work reveals the microscopic mechanism that CO selectivity rises in the CLRM as the degree of Fe2O3 reduction increases.

外文关键词：

Chemical looping reformingMethaneFe2O3Oxygen vacancyDensity func-tional theory

作者：

张慧欣、黄正清、班涛、苏雪、杨伯伦、常春然

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作者单位：

西安交通大学化学工程与技术学院,陕西省能源化工过程强化重点实验室,西安 710049

榆林学院化学与化工学院,陕西省低变质煤洁净利用重点实验室,榆林 719000

关键词：

化学链重整甲烷 Fe2O3 氧空位密度泛函理论

基金：

国家自然科学基金国家自然科学基金国家自然科学基金国家自然科学基金中国博士后科学基金Joint Fund of the Yulin University and the Dalian National Laboratory for Clean EnergyYoung Talent Support Plan of Shaanxi Province

项目编号：

220380112207825722108213521761422021M6925482022001

出版年：

2024

DOI：

10.1063/1674-0068/cjcp2304028

化学物理学报(英文版)

中国物理学会

化学物理学报(英文版)

CSTPCDEI

影响因子：0.162

ISSN：1674-0068

年,卷(期)：2024.37(1)