文献类型：期刊文献

中文题名：Cu/α-MnO_(2)的载体形貌对CO优先氧化反应性能影响

英文题名：Influence of Support Morphology on CO Preferential Oxidation Properties over Cu/α-MnO_(2)

作者：毛晓宇[1];宋丽川[2];张力[1];沈佳[2];葛春亮[1];冯彤彤[2];郭耘[2];王丽[2]

机构：[1]浙江浙能科技环保集团股份有限公司,浙江杭州310000;[2]华东理工大学化学与分子工程学院工业催化研究所绿色化工与工业催化国家重点实验室,上海200237

年份：2025

卷号：49

期号：9

起止页码：1331

中文期刊名：稀有金属

外文期刊名：Chinese Journal of Rare Metals

收录：;EI(收录号：20262721033047);北大核心:【北大核心2023】；

基金：国家自然科学基金(22376063)资助。

语种：中文

中文关键词：CO-PROX;Cu/MnO_(2);载体形貌;反应机制

外文关键词：CO-PROX;Cu/MnO_(2);support morphology;reaction mechanism

摘要：CO优先氧化(CO-PROX)是消除富氢气体中微量CO的有效方法之一。通过水热法制备纳米线(-w)、管(-t)和棒(-r)状的α-MnO_(2),分别暴露(110),(200)和(300)晶面,考察载体的形貌对于Cu/α-MnO_(2)催化CO-PROX性能的影响,并通过X射线衍射(XRD),透射电子显微镜(TEM),氢气程序升温还原(H2-TPR),氧气程序升温脱附(O_(2)-TPD),X射线光电子能谱(XPS)表征催化剂的结构、氧化还原能力,明确元素的存在状态,最终利用原位红外漫反射(in situ DRIFTS)探究反应中间物种。结果表明:载体的形貌与暴露晶面对于反应活性影响显著,Cu/α-MnO_(2)-w可在100℃实现CO的全转化,而该温度下Cu/α-MnO_(2)-r对于CO的转化率仅为21%。活性的差异与载体暴露晶面影响了Cu存在的状态、催化剂的氧化还原能力和反应中间物种的种类及稳定性相关。在Cu/α-MnO_(2)-w中Cu^(+)的存在不仅为CO吸附提供了活性位点,且Cu^(2+)/Cu^(+)与Mn^(3+)/Mn^(4+)的循环也提高了催化剂的供氧能力,此外Cu/α-MnO_(2)-w吸附CO的能力更强,反应气氛下主要生成的是不稳定的碳酸氢盐和碳酸盐物种,而在Cu/α-MnO_(2)-r上则以稳定的碳酸盐为主,不利于CO氧化过程的进行。
Given the escalating global energy crisis,there is now a pressing need for a transition towards cleaner and more sustainable energy sources.In this regard,hydrogen energy has emerged as a frontrunner due to its environmentally friendly characteristics,high calorific value,and versatile applications.Proton exchange membrane fuel cells(PEMFCs)have garnered significant attention for their potential to drive this transition,particularly in both mobile and stationary hydrogen energy sectors.Their operational advantages,such as low temperature specifications,high power densities,and zero carbon dioxide emissions,position them as a key player in the future of clean energy technology.However,one of the challenges faced by PEMFCs is that the process of producing the fuel H,usually involves a water-gas shift reaction,resulting in some residual CO,which can be harmful to the platinum electrodes and cause irreversible damage.In response to this issue,the development of techniques such as preferential oxidation of CO(CO-PROX)has become increasingly crucial in effectively eliminating trace CO from hydrogen-rich gases,thus enhancing the performance and durability of PEMFCs in the long term.Pt-based catalysts are the most commonly used for CO-PROX,but considering the scarcity and high cost of the noble metals,the development of non-precious metal catalysts has become a research hotspot.Cu-based catalysts have been widely investigated because of their excellent catalytic performance in CO oxidation,while MnO,with its high oxygen mobility and oxygen storage capacity,has been widely used in oxidation reactions.Hence,Cu-Mn system catalysts will be the alternative choice for noble catalysts.In loaded catalysts,the role of the support is critical.The morphological diversity of the supports results in different exposed crystalline surfaces,which not only affects the redox properties of the supports themselves,but can also cause changes in the degree of interaction between the supports and the active components.Such changes in interaction will further alter the electronic structure and coordination environment of the active component,change its chemical state and distribution,and thus have a significant impact on the catalyst's reaction performance and reaction mechanism.In this study,α-MnO_(2)nanowires(w),nanotubes(t)and nanorods(r)were successfully synthesized by a hydrothermal method and loaded with 1.5 wt% Cu by excess impregnation,the effect of support morphology and exposed crystal planes on the CO-PROX reaction properties on Cu/MnO_(2)was also investigated.Powder X-ray diffraction(XRD),nitrogen adsorptiondesorption,inductively coupled plasma atomic emission spectrometer(ICP-AES)and transmission electron microscope(TEM)were used to characterize the basic information of the catalyst structure.H,-temperature programmed reduction(H_(2)-TPR)and O_(2)-temperature programming desorption(O_(2)-TPD)were used to compare the redox capacities of the catalysts.X-ray photoelectron(XPS)was used to analyze the chemical states of the elements,and in situ diffuse reflectance infrared Fourier transform spectroscopy(in situ DRIFTS)was used to investigate the reaction mechanism of Cu/α-MnO,with different morphologies.It was found that the reaction properties were strongly influenced by the morphology of the support and the exposed crystal planes.Cu/α-MnO_(2)-w was able to achieve complete CO conversion within a wide operating window of 100-250℃,while Cu/α-MnO_(2)-t only reached the highest conversion of 98%at 200°C.Cu/α-MnO_(2)-w further investigated the effects of H_(2)O and CO_(2)on the performance of CO-PROX,and the results presented that the inhibition of CO oxidation by H_(2)O was more significant than CO_(2),and the temperature for complete CO conversion was shifted to higher temperature of even up to 150℃.Characterization results showed that different morphologies ofα-MnO_(2)exposed different crystalline planes:nanowire(w),tube(t)and rod(r)shapedα-MnO_(2),exposing(110),(200)and(300)crystalline planes,respectively.Differences in support morphology and exposed crystalline planes affected the state of Cu presence.No peaks associated with Cu species were observed in XRD,while TEM showed that Cu existed in different states on different morphologies ofα-MnO_(2):CuO particles were observed only on Cu/α-MnO_(2)-w,whereas lattice fringes of Cu species were not observed on Cu/α-MnO-t and Cu/α-MnO_(2)-r.Cu exerted a consistent effect on theα-MnO_(2)with different morphologies:Cu provided additional CO adsorption sites(Cu^(+))and promoted the creation of Mn^(3+)and oxygen vacancies,favoring the activation of gas-phase oxygen.In addition,valence cycling between Cu^(2+)/Cu^(+)and Mn^(3+)/Mn^(4+)further aggravated the cycling of reactive oxygen species.However,the enhanced redox capacity of different forms of Cu/MnO,varied:Cu/α-MnO_(2)-w had the most enhanced oxygen supply capacity and the lowest reduction peak temperature(224°C)in H-TPR profiles;XPS showed that Cu/α-MnO_(2)-w had the highest Mn^(3+)/Mn^(4+)content and the most oxygen adsorbed on the surface,and the smallest temperature difference between the surface lattice oxygen and the main body lattice oxygen was only 179°C in the O_(2)-TPD.The reaction mechanism was explored by in situ DRIFTS,and the strongest CO adsorption was observed on Cu/α-MnO_(2)-w,which showed a significant red-shift of the CO adsorption peak(2108 cm^(-1))on Cu/α-MnO_(2)-w compared with that on Cu/α-MnO_(2)-t(2132 cm^(-1)).On Cu/α-MnO_(2)-w,the presence of H_(2) promoted the generation of unstable bicarbonates and carbonate,whereas in Cu/α-MnO_(2)-t,H_(2)only promoted the generation of carbonate intermediates that were not easily decomposed.