Low-temperature catalytic methane deep oxidation over sol-gel derived mesoporous hausmannite (Mn_(3)O_(4)) spherical particles  

作　　者：Patrick Ndouka Ndouka Stephane Kenmoe Jacques Richard Mache Elie Acayanka Dick Hartmann Douma Ralph Gebauer Patrick Mountapmbeme Kouotou 

机构地区：[1]Department of Chemistry,Faculty of Sciences,University of Maroua,P.O.Box 814 Maroua,Cameroon [2]Department of Theoretical Chemistry,University of Duisburg-Essen,D-45141 Essen,Germany [3]Department of Mining Engineering,School of Geology and Mining Engineering,University of Ngaoundéré,P.O.Box 115 Meiganga,Cameroon [4]Department of Inorganic Chemistry,Faculty of Science,University of YaoundéI,P.O.Box 812 Yaoundé,Cameroon [5]Groupe de Simulations Numériques en Magnétisme et Catalyse,Facultédes Sciences et Techniques,UniversitéMarien Ngouabi,B.P.69 Brazzaville,Congo [6]The Abdus Salam International Centre for Theoretical Physics(ICTP),34151 Trieste,Italy [7]National Advanced School of Engineering of Maroua,University of Maroua,P.O.Box 46 Maroua,Cameroon [8]Higher Institute of Agriculture,Wood,Water and Environment,University of Ebolowa,P.O.Box 118 Ebolowa,Cameroon

出　　处：《ChemPhysMater》2024年第3期329-340,共12页化学物理材料（英文）

基　　金：S.K.acknowledges computing time granted by the Center for Computational Sciences and Simulation(CCSS);the Universität DuisburgEssen and provided on the supercomputer magnitude(DFG grants INST 20876/209-1 FUGG,INST 20876/243-1 FUGG);the Zentrum für Informations-und Mediendienste(ZIM).S.K.gratefully acknowledges the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)for funding 388390466-TRR 247.

摘　　要：In this study,Mn_(3)O_(4) spherical particles(SPs)were synthesized by the sol-gel process,after which they were thermally annealed at 400℃,and comprehensively characterized.X-ray Diffraction(XRD)revealed that Mn_(3)O_(4) exhibited a tetragonal spinel structure,and Fourier transformed infrared(FTIR)spectroscopy identified surfaceadsorbed functional groups.Scanning electron microscopy(SEM)and the specific surface area analyses by Brunauer−Emmett−Teller(BET)revealed a porous,homogeneous surface composed of strongly agglomerated spherical grains with an estimated average particle size of∼35 nm,which corresponded to a large specific surface area of∼81.5 m^(2)/g.X-ray photoelectron spectroscopy(XPS)analysis indicated that Mn_(3)O_(4) was composed of metallic cations(Mn^(4+),Mn^(3)+,and Mn^(2+))and oxygen species(O_(2)−,OH−and CO_(3)^(2−)).The optical bandgap energy is∼2.55 eV.Assessment of the catalytic performance of the Mn_(3)O_(4) SPs indicated T90 conversion of CH4 to CO_(2) and H_(2)O at 398℃ for gas hourly space velocity(GHSV)of 72000 mL^(3) g^(−1) h^(−1).This observed performance can be attributed to the cooperative effects of the smallest spherical grain size with a mesoporous structure,which is responsible for the larger specific surface area and available surface-active oxygenated species.The cooperative effect of the good reducibility,higher ratio of active species(OLat/OAds),and results of density functional theory(DFT)calculations suggested that the total oxidation of CH_(4) over the mesoporous Mn_(3)O_(4) SPs might take place via a two-term process in which both the Langmuir−Hinshelwood and Mars−van Krevelen mechanisms are cooperatively involved.

关 键 词：SOL-GEL Manganese oxide Catalytic oxidation METHANE Langmuir−Hinshelwood mechanism Mars−van Krevelen route Two−term process 

分 类 号：O64[理学—物理化学]