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Cu-Promoted Cobalt Oxide Film Catalyst for Efficient Gas Emissions Abatement

Journal of Thermal Science 2019年第2期28卷 225-231页

作者： EL KASMI Achraf WAQAS Muhammad mountapmbeme koutou patrick TIAN Zhenyu Institute of Engineering Thermophysics Chinese Academy of Sciences University of Chinese Academy of Sciences National Advanced School Engineering of Maroua University of Maroua

Thin film catalysts have been recently reported as promising catalysts owing to their good catalytic activity and reduced material amount, leading to low-cost efficient catalysts for gaseous emissions control. Here, we report the slight loading of Cu in cobalt spinel using a one-step pulsed-spray evaporation chemical vapor deposition(PSE-CVD) synthesis technique for efficient short-chain volatile organic compounds(VOCs) emissions treatment. Crystalline structure and morphology analyses revealed nano-crystallite sizes and open-like morphology. The catalytic performance was evaluated through the complete oxidation of C_3H_6, as a short-chain representative model of VOCs, at a high gas hourly space velocity(GHSV). Very good activity was obtained towards the complete abatement of C_3H_6 at low temperature and no carbon monoxide(CO) was formed during the oxidation process. Slightly-promoted Co_3O_4 catalyst with Cu introduction resulted in high catalytic activity comparing to the performance of the catalysts in the literature, due to the high dispersion of Cu and high active surface oxygen amount. Moreover, to evaluate the capability of the used catalysts under near realistic reaction conditions, CO_2 effect on the catalytic activity was performed and the catalyst exhibited very good results. Thus, the adopted slightly-doping strategy to tailor a high active catalyst at low temperature could establish a very promising route to strongly enhance the activity of such other catalysts towards gas emissions abatement at low temperature.

关键词： low Cu-doping PSE-CVD technique thin film catalysts complete catalytic oxidation VOCs

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

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ChemPhysMater 2024年第3期3卷 329-340页

作者： patrick Ndouka Ndouka Stephane Kenmoe Jacques Richard Mache Elie Acayanka Dick Hartmann Douma Ralph Gebauer patrick mountapmbeme Kouotou Department of Chemistry Faculty of SciencesUniversity of MarouaP.O.Box 814 MarouaCameroon Department of Theoretical Chemistry University of Duisburg-EssenD-45141 EssenGermany Department of Mining Engineering School of Geology and Mining EngineeringUniversity of NgaoundéréP.O.Box 115 MeigangaCameroon Department of Inorganic Chemistry Faculty of ScienceUniversity of YaoundéIP.O.Box 812 YaoundéCameroon Groupe de Simulations Numériques en Magnétisme et Catalyse Facultédes Sciences et TechniquesUniversitéMarien NgouabiB.P.69 BrazzavilleCongo The Abdus Salam International Centre for Theoretical Physics(ICTP) 34151 TriesteItaly National Advanced School of Engineering of Maroua University of MarouaP.O.Box 46 MarouaCameroon Higher Institute of Agriculture WoodWater and EnvironmentUniversity of EbolowaP.O.Box 118 EbolowaCameroon

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 *** 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 *** of the catalytic performance of the Mn_(3)O_(4) SPs indicated T90 conversion of CH4 to CO_(2) and H2O 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 *** 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 CH4 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

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Physicochemical and Thermal Properties of Some Key Tropical Sawdust Woods for Energy Production

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Journal of Sustainable Bioenergy Systems 2024年第1期14卷 1-22页

作者： Davy Fiwa Kaoke Yann Le Brech Emmanuel Talla Anthony Dufour patrick mountapmbeme Kouotou Department of Chemical Engineering School of Chemical Engineering and Mineral Industries University of Ngaoundere Ngaoundere Cameroon National Advanced School of Engineering of Maroua University of Maroua Maroua Cameroon Laboratory of Reactions and Process Engineering University of Lorraine-France Nancy France Higher Institute of Agriculture Wood Water and Environment University of Ebolowa Ebolowa Cameroon

In South Saharan countries, 85% of the population uses biomass as a primary energy source. Cameroon presents one of the highest biomass energy and sawmills produce important sawdust resources which are not used and are burnt in piles leading to significant air toxic emissions. Therefore, we have to valorize industrially these available sawdusts. This study focuses on the physicochemical and thermochemical analysis of Ayous, Sapelli and Tali sawdust. The proximate and ultimate analysis, particle size, structural composition, as well as heavy metal content and calorific value were determined. In addition, the thermogravimetric mass losses were also estimated. The results showed that high water contents (24% - 41%) were recorded in the raw sawdust, and the thermal treatment reduced these contents from 78% to values in the range of 4% - 9%. The values for ash and volatile matter content were respectively between 0.25% - 0.74% and 68% - 76%. The LHV is higher in Ayous (17.5 MJ/kg) and Sapelli (16.8 MJ/kg) than that of Tali (15.7 MJ/kg). The concentration of heavy metals is very low in each species. Extractives are more present in Tali (16.06%) than in the other sawdusts. Pyrolysis of sawdust shows the typical decomposition of hemicellulose (270˚C - 325˚C), cellulose (325˚C - 400˚C) and lignin (200˚C - 550˚C) with a maximum loss of 75% at 370˚C and the melting point is 320˚C. The results of the sawdust parameters determined in the paper can be valorized to reduce pollutants emissions by developing the efficiency and effectiveness of biomass energy processes and promoting the use of biomass as a sustainable alternative to traditional fossil fuels.

关键词： Wood Sawmills Sawdust Combustion Energy

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Clay Materials for Ceramics Application from N’Djamena in the Chad Republic: Mineralogical, Physicochemical and Microstructural Characterization

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Journal of Materials Science and Chemical Engineering 2024年第2期12卷 31-48页

作者： Ndjolba Madjihingam Djoda Pagore Jacques Richard Mache Bebbata Warabi Bertin Pagna Kagonbe patrick mountapmbeme Kouotou Department of Civil Engineering National Advanced School of Engineering University of Maroua Maroua Cameroon Department of Mining Engineering School of Geology and Mining Engineering University of Ngaoundere Meiganga Cameroon Local Materials Authority Promotion (MIPROMALO) Yaoundé Cameroon Department of Environmental Sciences Advanced School of Agriculture Forestry Water and Environment University of Ebolowa Ebolowa Cameroon

Herein, we report some characteristics of the clayey materials (CMs) collected from Kaliwa (C1), Kabé (C2) and Malo (C3) district in N’Djamena (Chad). Three samples were characterized applying XRF, XRD, FTIR, SEM. In addition, TGA/DSC were performed to control decomposition/mass loss and show phase transitions respectively of CMs. Geochemical analysis by XRF reveals the following minerals composition: SiO2 (~57% - 66%), Al2O3 (~13% - 15%), Fe2O3 (~6% - 10%), TiO2 (~1% - 2%) were the predominant oxides with a reduced proportion in C1, and (~7%) of fluxing agents (K2O, CaO, Na2O). Negligible and trace of MgO (~1%) and P2O5 was noted. The mineralogical composition by XRD shows that, C1, C2 and C3 display close mineralogy with: Quartz (~50%), feldspar (~20%) as non-clay minerals, whereas clays minerals were mostly kaolinite (~15%), illite (~5%) and smectite (~10%). FTIR analysis exhibits almost seemingly similar absorption bands characteristic of hydroxyls elongation, OH valence vibration of Kaolinite and stretching vibration of some Metal-Oxygen bond. SEM micrographs of the samples exhibit microstructureformed by inter-aggregates particles with porous cavities. TGA/DSCconfirm the existence of quartz (570˚C to 870˚C), carbonates (600˚C - 760˚C), kaolinite (569˚C - 988˚C), illite (566˚C - 966˚C), MgO (410˚C - 720˚C) and smectite (650˚C - 900˚C). The overall characterization indicates that, these clayey soils exhibit good properties for ceramic application.

关键词： Clay Soils Characterization Mineralogy Physicochemical Properties Ceramic Application

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In situ Fourier Transform Infrared Spectroscopy Diagnostic for Characterization and Performance Test of Catalysts

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Chinese Journal of Chemical Physics 2017年第5期30卷 513-520,I0001页

作者： patrick mountapmbeme Kouotou 田振玉中国科学院工程热物理研究所北京100190 中国科学院大学北京100049 马鲁阿大学萨赫拉高等研究院喀麦隆

The present work establishes a systematic approach based on the application of in-situ Fourier transform infrared spectroscopy （FTIR） for the investigation of the crystal structure, thermal stability, redox behavior （temperature-programmed reduction/temperatureprogrammed re-oxidation） as well as the catalytic properties of Co3O4 thin films. The syntheses of Co3O4 were achieved by chemical vapor deposition in the temperature range of 400-500℃. The structure analysis of the as-prepared material revealed the presence of two prominent IR bands peaking at 544 cm-1 （υ1） and 650 cm-1 （υ2） respectively, which originate from the stretching vibrations of the Co-O bond, characteristic of the Co3O4 spinel. The lattice stability limit of Co3O4 was estimated to be above 650℃. The redox properties of the spinel structure were determined by integrating the area under the emission bands υ1 and υ2 as a function of the temperature. Moreover, Co3O4 has been successfully tested as a catalyst towards complete oxidation of dimethyl ether below 340 ℃. The exhaust gas analysis during the catalytic process by in situ absorption FTIR revealed that only CO2 and H2O were detected as the final products in the catalytic reaction. The redox behavior suggests that the oxidation of dimethyl ether over Co3O4 follows a Mars-van Krevelen type mechanism. The comprehensive application of in situ FTIR provides a novel diagnostic tool in characterization and performance test of catalysts.

关键词： In situ Fourier transform infrared spectroscopy Diagnostic Thermal stability Redox property Catalytic mechanism

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Role of copper grid mesh in the catalytic oxidation of CO over one-step synthesized Cu-Fe-Co ternary oxides thin film

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Chinese Chemical Letters 2020年第5期31卷 1201-1206页

作者： Muhammad Waqas patrick mountapmbeme Kouotou Achraf El Kasmi Yu Wang Zhen-Yu Tian Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China National Advanced School of Engineering of Maroua University of MarouaMaroua P.O.Box 46Cameroon Shanghai Research Institute of Petrochemical Technology Shanghai 201208China

The effective valuation of catalyst supports in the catalytic oxidation makes the contribution to understand the support effect of great ***,the role of active substrate in the performance and stability of CuFe-Co ternary oxides was studied towards the complete catalytic oxidation of *** Cu-Fe-Co oxide thin films were deposited on copper grid mesh(CUGM)using one-step pulsed-spray evaporation chemical vapor deposition *** structure and morphology analyses revealed nano-crystallite sizes and do me-top-like *** effects between Cu,Fe and Co,which affect the surface Cu^2+,Fe^3+,Co^3+and chemisorbed oxygen species(O2 and OH)of thin films over the active support and thus result in better *** thin film catalysts supported on CUGM exhibited attractive catalytic activity compared to the te rnary oxides supported on ine rt grid mesh at a high gas hourly space *** r,the stability in time-on-stream of the ternary oxides on CUGM was evaluated in the CO oxidation for 30 *** ad opted deposition strategy ofternary oxides on CUGM presents an excessive amount of adsorbed active oxygen species that play an impo rtant role in the complete CO *** catalysts supported on CUGM showed better catalytic conve rsion than that on inert grid mesh and some literature-reported noble metal oxides as well as transition metal oxides counterparts,revealing the beneficial effect of the CUGM suppo rt in the improvement of the catalytic performance.

关键词： Cu-Fe-Co ternary oxides PSE-CVD technique Support effect Time-on-stream Copper grid mesh

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My Story with CAS:From Africa,Europe,to China

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Bulletin of the Chinese Academy of Sciences 2017年第1期31卷 27-31页

作者： patrick mountapmbeme Kouotou Institute of Engineering Thermophysics(IET)

*** mountapmbeme Kouotou,Cameroonian Researcher working at the Institute of Engineering Thermophysics(IET),CAS shares his experience as a recipient of the CAS Visiting Professorship for Senior International Sciences.

关键词：英语阅读理解科技

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Physicochemical and Thermal Properties of Some Key Tropical Sawdust Woods for Energy Production

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Journal of Sustainable Bioenergy Systems（可持续生物质能源系统） 2024年第1期 1页

作者： Davy Fiwa Kaoke Yann Le Brech Emmanuel Talla Anthony Dufour patrick mountapmbeme Kouotou

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