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Dong N, Chen M, Ye Q, Zhang D, Dai H. Promotional effect of cobalt doping on catalytic performance of cryptomelane-type manganese oxide in toluene oxidation. J Environ Sci (China) 2023; 126:263-274. [PMID: 36503754 DOI: 10.1016/j.jes.2022.03.024] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 02/17/2022] [Accepted: 03/14/2022] [Indexed: 06/17/2023]
Abstract
The cryptomelane-type manganese oxide (OMS-2)-supported Co (xCo/OMS-2; x = 5, 10, and 15 wt.%) catalysts were prepared via a pre-incorporation route. The as-prepared materials were used as catalysts for catalytic oxidation of toluene (2000 ppmV). Physical and chemical properties of the catalysts were measured using the X-ray diffraction (XRD), Fourier transform infrared spectroscopic (FT-IR), scanning electron microscopic (SEM), X-ray photoelectron spectroscopy (XPS), and hydrogen temperature-programmed reduction (H2-TPR) techniques. Among all of the catalysts, 10Co/OMS-2 performed the best, with the T90%, specific reaction rate at 245°C, and turnover frequency at 245°C (TOFCo) being 245°C, 1.23 × 10-3 moltoluene/(gcat·sec), and 11.58 × 10-3 sec-1 for toluene oxidation at a space velocity of 60,000 mL/(g·hr), respectively. The excellent catalytic performance of 10Co/OMS-2 were due to more oxygen vacancies, enhanced redox ability and oxygen mobility, and strong synergistic effect between Co species and OMS-2 support. Moreover, in the presence of poisoning gases CO2, SO2 or NH3, the activity of 10Co/OMS-2 decreased for the carbonate, sulfate and ammonia species covered the active sites and oxygen vacancies, respectively. After the activation treatment, the catalytic activity was partly recovered. The good low-temperature reducibility of 10Co/OMS-2 could also facilitate the redox process accompanied by the consecutive electron transfer between the adsorbed O2 and the cobalt or manganese ions. In the oxidation process of toluene, the benzoic and aldehydic intermediates were first generated, which were further oxidized to the benzoate intermediate that were eventually converted into H2O and CO2.
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Affiliation(s)
- Ning Dong
- Key Laboratory of Beijing on Regional Air Pollution Control, Department of Environmental Science, School of Environmental and Chemical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing 100124, China
| | - Mengyue Chen
- Key Laboratory of Beijing on Regional Air Pollution Control, Department of Environmental Science, School of Environmental and Chemical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing 100124, China; R&D Department of Atmospheric Prevention and Control Technology, Guangdong Suncere Technology Co., Ltd., Guangzhou 510220, China
| | - Qing Ye
- Key Laboratory of Beijing on Regional Air Pollution Control, Department of Environmental Science, School of Environmental and Chemical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing 100124, China.
| | - Dan Zhang
- Key Laboratory of Beijing on Regional Air Pollution Control, Department of Environmental Science, School of Environmental and Chemical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing 100124, China
| | - Hongxing Dai
- Beijing Key Laboratory for Green Catalysis and Separation, Key Laboratory of Beijing on Regional Air Pollution Control, Key Laboratory of Advanced Functional Materials, Education Ministry of China, and Laboratory of Catalysis Chemistry and Nanoscience, Department of Environmental Chemical Engineering, School of Environmental and Chemical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing 100124, China.
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Vishwanathan S, Das S. Glucose-mediated one-pot hydrothermal synthesis of hollow magnesium oxide-zinc oxide (MgO-ZnO) microspheres with enhanced natural sunlight photocatalytic activity. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:8512-8525. [PMID: 35460004 DOI: 10.1007/s11356-022-20283-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 04/11/2022] [Indexed: 06/14/2023]
Abstract
Glucose -mediated one-pot hydrothermal method has been utilized to synthesize hollow spherical MgO-ZnO (xMgO-(1-x)ZnO, x = 0, 0.2, 0.4, 0.6) microstructures which are highly efficient in high-energy ultraviolet (UV) region of natural sunlight. In this process, glucose formed roundish spheres, and simultaneously metal precursors were coated on that spheres during the hydrothermal reaction. X-ray diffraction analysis (XRD) supports the formation of highly crystalline wurtzite structure of MgO-ZnO for Mg loading less than 20%. Higher concentration of Mg produces wurtzite hexagonal ZnO and cubic MgO in the composites. The widening in band gap energy of synthesized MgO-ZnO microspheres compared to ZnO was analyzed by UV-visible diffuse reflectance spectroscopy (UV-DRS) result. Brunauer-Emmett-Teller (BET) surface area analysis showed that with the increase in Mg loading, the specific surface area increases up to 14.27 times as compared to pristine ZnO. The synthesized catalysts were used as an efficient photocatalyst towards the degradation of rhodamine B (RhB), methylene blue (MB), and phenol under natural solar irradiation. Results illustrated that MB and RhB dye solutions were 100% degraded by 0.6 MgO-ZnO in 100 min and 150 min, respectively, whereas pure ZnO samples showed only 65% and 79% degradation. Also, for phenol solution, 0.6 MgO-ZnO showed enhanced degradation efficiency of 72% in 240 min in comparison with 58% degradation shown by ZnO. Additionally, the MgO-ZnO catalysts were stable and showed excellent degradation efficiency up to four consecutive cycles which open a new direction towards potential industrial applications. Hence, the novelty of the current work is to prepare hollow MgO-ZnO microspheres by a single-step hydrothermal process where separate carbon template preparation is not required and to utilize these hollow microspheres as a highly efficient photocatalyst by harnessing the high-energy UV fraction of natural sunlight.
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Affiliation(s)
- Shalini Vishwanathan
- Department of Chemical Engineering, National Institute of Technology Calicut, Calicut, 673601, India
| | - Susmita Das
- Department of Chemical Engineering, National Institute of Technology Calicut, Calicut, 673601, India.
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Cui X, Zhang X, Yang Y, Chen T, Wang Y. The noble metals M (M = Pd, Ag, Au) decorated CeO 2catalysts derived from solution combustion method for efficient low-temperature CO catalytic oxidation: effects of different M loading on catalytic performances. NANOTECHNOLOGY 2022; 33:415705. [PMID: 35793617 DOI: 10.1088/1361-6528/ac7ed3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2022] [Accepted: 07/06/2022] [Indexed: 06/15/2023]
Abstract
The noble metal nanoparticles have attracted attention due to their excellent catalytic performance for CO oxidation at low temperatures. M-CeO2(M = Pd, Ag, Au) catalysts with different atomic ratios of M/Ce were deposited via solution combustion method. Among them, 3 at% Pd-CeO2, 5 at% Ag-CeO2and 1 at% Au-CeO2catalysts have better catalytic performances. Especially, 5 at% Ag-CeO2catalyst shows better low-temperature CO oxidation performance. The catalytic activity for CO oxidation follows the follows the following sequence: 5 at% Ag-CeO2(T50 = 69 °C) > 3 at% Pd-CeO2(T50 = 99 °C) >1 at% Au-CeO2(T50 = 115 °C). Meanwhile, the catalysts are characterized by means of powder x-ray diffraction, scanning electron microscope, transmission electron microscopy, Raman spectroscopy, x-ray photoelectron spectroscopy, Brunauer-Emmett-Teller and H2-TPR. The characterization results show that the 5 at% Ag-CeO2catalyst has excellent catalytic activity due to the good dispersion of Ag nanoparticles, the specific surface area of the material, and the reduction catalyst between different valence ions. Moreover, the surface of the catalyst enhances the mutual synergy, effectively promotes the generation of oxygen vacancies, and increases the active oxygen content of the catalyst surface. Finally, the catalytic mechanism of M-CeO2catalysts is summarized.
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Affiliation(s)
- Xiuxiu Cui
- School of Materials and Energy, Yunnan University, 650091 Kunming, People's Republic of China
| | - Xu Zhang
- School of Materials and Energy, Yunnan University, 650091 Kunming, People's Republic of China
| | - Yaqi Yang
- School of Materials and Energy, Yunnan University, 650091 Kunming, People's Republic of China
| | - Ting Chen
- Institute of Materials Science & Devices, School of Materials Science and Engineering, Suzhou University of Science and Technology, Suzhou, 215009, People's Republic of China
| | - Yude Wang
- Key Lab of Quantum Information of Yunnan Province, Yunnan University, 650091 Kunming, People's Republic of China
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Solvent-free catalytic oxidation of toluene over heterogeneous CeMnOx composite oxides. RESEARCH ON CHEMICAL INTERMEDIATES 2022. [DOI: 10.1007/s11164-022-04727-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Pandey PH, Pawar HS. Mingled Metal Oxides Catalyst for Direct Carbonylation of Glycerol into Glycerol Carbonate. ChemistrySelect 2022. [DOI: 10.1002/slct.202104264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Preeti H. Pandey
- DBT-ICT Centre for Energy Biosciences Institute of Chemical Technology, Matunga Mumbai 400 019 India
| | - Hitesh S. Pawar
- DBT-ICT Centre for Energy Biosciences Institute of Chemical Technology, Matunga Mumbai 400 019 India
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Chen G, You K, Gong X, Zhao F, Chen Z, Luo H. Solvent-free liquid-phase selective catalytic oxidation of toluene to benzyl alcohol and benzaldehyde over CeO2–MnOx composite oxides. REACT CHEM ENG 2022. [DOI: 10.1039/d1re00488c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A novel CeO2–MnOx composite oxide was prepared by the improved sol–gel method. The synergistic catalysis of Mn3+/Mn2+ and Ce4+/Ce3+ was responsible for the good catalytic performance in the liquid phase solvent-free selective oxidation of toluene.
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Affiliation(s)
- Gui Chen
- School of Chemical Engineering, Xiangtan University, Xiangtan 411105, P. R. China
- College of Chemistry and Materials, Huaihua University, Huaihua 418000, P. R. China
| | - Kuiyi You
- School of Chemical Engineering, Xiangtan University, Xiangtan 411105, P. R. China
- National & Local United Engineering Research Center for Chemical Process Simulation and Intensification, Xiangtan University, Xiangtan 411105, P. R. China
| | - Xiangbo Gong
- School of Chemical Engineering, Xiangtan University, Xiangtan 411105, P. R. China
| | - Fangfang Zhao
- School of Chemical Engineering, Xiangtan University, Xiangtan 411105, P. R. China
| | - Zhenpan Chen
- School of Chemical Engineering, Xiangtan University, Xiangtan 411105, P. R. China
| | - He'an Luo
- School of Chemical Engineering, Xiangtan University, Xiangtan 411105, P. R. China
- National & Local United Engineering Research Center for Chemical Process Simulation and Intensification, Xiangtan University, Xiangtan 411105, P. R. China
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Synthesis of Ce/MgO Catalysts for Direct Oxidation of Hibiscus cannabinus Stalks to Vanillin. Catalysts 2021. [DOI: 10.3390/catal11121449] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
One possible method of producing vanillin from biomass is through controlled oxidation of lignin. Direct oxidation of kenaf stalks was chosen without having to separate the cellulose and hemicellulose components from the lignocellulosic biomass. This makes the process greener, as well as saving time. In this paper, Ce/MgO catalysts were developed for oxidation of kenaf stalks and kenaf lignin under microwave irradiation. The catalysts were characterized for their physicochemical properties using XRD and N2 adsorption–desorption isotherms. The synthesized MgO showed the presence of diffraction peaks assigned to cubic MgO while the 30Ce/MgO catalysts showed the presence of cubic fluorite of CeO2. N2 adsorption–desorption isotherms showed that all catalysts possess Type III isotherm according to IUPAC classification, indicating a nonporous structure. All catalysts were tested for direct oxidation of kenaf stalks under 300 W of microwave irradiation using H2O2 as the oxidizing agent at pH 11.5 and temperatures between 160 and 180 °C for 10–30 min with 5–15% catalyst loading. The highest vanillin yields of 3.70% and 2.90% for extracted lignin and direct biomass oxidation were achieved using 30Ce/MgO-48. In comparison, 7.80% and 4.45% were obtained using 2N of NaOH homogeneous catalyst for extracted lignin and direct biomass, respectively, at 170 °C for 20 min. The reusability test shows that 30Ce/MgO can be used up to three cycles without significant loss in catalytic activity. Other compounds detected were 4-vinylguaiacol, syringol and syringaldehyde.
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Degradation Kinetics of Methyl Orange Dye in Water Using Trimetallic Fe/Cu/Ag Nanoparticles. Catalysts 2021. [DOI: 10.3390/catal11040428] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The release of azo dye contaminants from textile industries into the environment is an issue of major concern. Nanoscale zerovalent iron (nZVI) has been extensively studied in the degradation of azo dye pollutants such as methyl orange (MO). In this study, iron was coupled with copper and silver to make trimetallic Fe/Cu/Ag nanoparticles, in order to enhance the degradation of MO and increase reactivity of the catalyst by delaying the rate of oxidation of iron. The synthesis of the trimetallic nanoparticles (Fe/Cu/Ag) was carried out using the sodium borohydride reduction method. The characterization of the particles was performed using XRD, XPS, EDX, and TEM. The analyses confirmed the successful synthesis of the nanoparticles; the TEM images also showed the desired structures and geometry of the nanoscale zerovalent iron particles. The assessment of the nanoparticles in the degradation of methyl orange showed a notable degradation within few minutes into the reaction. The effect of parameters such as nanoparticle dosage, initial MO concentration, and the solution pH on the degradation of MO using the nanoparticles was investigated. Methyl orange degradation efficiency reached 100% within 1 min into the reaction at a low pH, with lower initial MO concentration and higher nanoparticle dosage. The degradation rate of MO using the nanoparticles followed pseudo first-order kinetics and was greatly influenced by the studied parameters. Additionally, LC-MS technique confirmed the degradation of MO within 1 min and that the degradation occurs through the splitting of the azo bond. The Fe/Cu/Ag trimetallic nanoparticles have proven to be an appropriate and efficient alternative for the treatment of dye wastewater.
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Abstract
Gold catalysts have found applications in many reactions of both industrial and environmental importance. Great interest has been paid to the development of new processes that reduce energy consumption and minimize pollution. Among these reactions, the catalytic oxidation of carbon monoxide (CO) is an important one, considering that a high concentration of CO in the atmosphere creates serious health and environmental problems. This paper examines the most important achievements and conclusions arising from the own authorship contributions concerning (2 wt. % Au)/Ce1−xZrxO2 catalyst’s active sites in low-temperature CO oxidation. The main findings of the present review are: (1) The effect of preparing conditions on Au crystallite size, highlighting some of the fundamental underpinnings of gold catalysis: the Au surface composition and the poisoning effect of residual chloride on the catalytic activity of (2 wt. % Au)/Ce1−xZrxO2 catalysts in CO oxidation; (2) The identification of ion clusters related to gold and their effect on catalyst’ surface composition; (3) The importance of physicochemical properties of oxide support (e.g., its particle size, oxygen mobility at low temperature and redox properties) in the creation of catalytic performance of Au catalysts; (4) The importance of oxygen vacancies, on the support surface, as the centers for oxygen molecule activation in CO reaction; (5) The role of moisture (200–1000 ppm) in the generation of enhanced CO conversion; (6) The Au-assisted Mars-van Krevelen (MvK) adsorption–reaction model was pertinent to describe CO oxidation mechanism. The principal role of Au in CO oxidation over (2 wt. % Au)/Ce1−xZrxO2 catalysts was related to the promotion in the transformation process of reversibly adsorbed or inactive surface oxygen into irreversibly adsorbed active species; (7) Combination of metallic gold (Au0) and Au-OH species was proposed as active sites for CO adsorption. These findings can help in the optimization of Au-containing catalysts.
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