CATALYSIS LETTERS
·
2023
·
IF 2.8
Chen Yao,Li Shuyue,Li Yuchao,Zheng Yanxia,Zuo Cuncun,Ge Tingting,Xu Rui,Huang Haofei,An Jiutao
Nano-Au particles are commonly used as an active component in oxidation esterification reactions. To inhibit the agglomeration of nano-Au particles, a series of highly stable Au@CeO 2 /MnO x core–shell structured catalysts were synthesized using inverse microemulsion technology for the oxidative esterification to prepare methyl methacrylate (MMA). The core–shell structured catalysts were prepared by using two different surfactants (CTAB and CO-520) and adjusting the molar ratio of water to oil (ω). XRD, Raman, N 2 adsorption, ICP−MS, TEM, UV–vis, FT-IR, XPS, and H 2 -TPR were applied to characterize the samples. The nano-Au particles were encapsulated by CeO 2 , forming a core–shell structure confirmed with TEM. The Au@CeO 2 /MnO x -C-ω = 10 catalyst prepared with CTAB as the surfactant has the best activity. The Au@CeO 2 /MnO x -C-ω = 10 catalyst has the highest hydrogen consumption and Ce 3+ content, indicating that the catalyst has the strongest interaction among Ce, Au, and Mn and more active oxygen. Active oxygen is beneficial to methanol activation and hemiacetal dehydrogenation, accelerating the formation of esters. The active oxygen content, Ce 3+ content, and H 2 consumption were correlated with the catalytic performance positively. After the catalyst was reused 10 times, the activity remained unchanged and the Au nanoparticles did not agglomerate due to the core–shell structure. Graphical Abstract
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Journal of Environmental Chemical Engineering
·
2023
·
IF 7.7
Ruifeng Zhang,Chuanyun Yang,Qiuyan Niu,Jing Yang
Finding a low-cost and high effective catalyst is an important problem in advanced oxidation processes (AOPs) based on PMS for organic matter removal. In this study, manganese oxide (MnO x ) was extracted from the backwashing sludge of a filter for manganese removal and used to activate peroxymonosulfate (PMS) to remove humic acid from water. It was found that thermal treatment had significant effects on the structure and catalytic activity of MnO x . When MnO x was treated at 500 °C, it showed excellent catalytic activity and the removal rate of HA was up to 81.0%. Characterization indicated that the MnO x was converted from buserite and birnessite to α-MnO x after treated at 500 °C, and the specific surface area and the percentage of Mn (III) and O latt on the surface increased significantly. The repeated utilization experiments indicated that the extracted MnO x still had high activity after reusing for 5 cycles. Quenching experiments showed that 1 O 2 was the dominant reactive oxygen species to oxidize HA in water. Finally, combining the results of FTIR and XPS spectra of MnO x before and after the catalytic reaction , the reaction mechanism was proposed: PMS was activated to be 1 O 2 by Mn (III) and O latt in MnO x with a valence transformation between Mn (II), Mn (III) and Mn (IV) and HA was mainly oxidized by the non-radical pathway through 1 O 2 . The experiments will provide a new strategy for recycling MnO x from backwashing sludge of the filter for Mn 2+ removal to remove natural organic matter from water.
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WATER ENVIRONMENT RESEARCH
·
2021
·Vol. 93
·期 8
·1361-1369
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IF 1.946
Shengkai Xu,Jiaxin Yang,Rafaat Hussein,Guangqing Liu,Bensheng Su
In this study, the performance of ofloxacin (OFX) degradation in synthetic wastewater using synthesized MnO x -CeO x /γ-Al 2 O 3 as a heterogeneous ozonation catalyst was evaluated. The removal rates of OFX and chemical oxygen demand (COD) during 15-day continuous-flow experiments were 98.2% and 76.7% on average, respectively. An ozone index (mgCOD/mgO 3 ) of 1.09 with a high ozone utilization efficiency of 91.39% was achieved. The pseudo-first-order rate constant of ofloxacin degradation reached 15.216 × 10 −2 min −1 , which was five times that (3.085 × 10 −2 min −1 ) without catalysts. The results of gas chromatography-mass spectrometry (GC-MS) demonstrated that a variety of small-molecule organics occurred in the final oxidation products, such as 4-hydroxyl-4-methyl-2-pentanone and 2-oxoadipic acid in addition to homologs of OFX. The results of this study suggested that hydroxyl radicals played critical roles in the degradation and mineralization of OFX via four main pathways: (a) electrophilic addition of nitrogen; (b) breakdown of carbon-carbon double bonds; (c) hydrolysis of ether rings; and (d) halodecarboxylation of carboxyl groups. The biodegradability (BOD 5 /COD) of OFX after catalytic ozonation reached 0.54. Practitioner points Ofloxacin wastewater was treated using catalytic ozonation in a 15-day continuous experiment with MnO x -CeO x /γ-Al 2 O 3 as a catalyst. The ozone index reached 1.09 mgCOD/mgO 3 during ozonation of ofloxacin. The presence of the catalyst increased the reaction rate constant by a factor of five. 4-hydroxy-4-methyl-2-pentanone was the primary ofloxacin oxidation product.
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JOURNAL OF HAZARDOUS MATERIALS
·
2020
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IF 9.038
Pu-Can Guo,Hai-Bin Qiu,Chuan-Wang Yang,Xin Zhang,Xin-Yue Shao,Yang-Li Lai,Guo-Ping Sheng
Persulfate-based advanced oxidation technology exhibits great potential for hazardous organic pollutant removal from wastewater. Acceleration of pollutant degradation needs to be elucidated, particularly for heterogeneous catalytic systems. In this study, manganese oxide ordered mesoporous carbon composites (MnO x @OMC) were prepared by nano-casting method and used for persulfate activation to degrade phenol. Kinetics analysis indicate that the rate of phenol degradation using MnO x @OMC composites was improved by 34.9 folds relative to that using a mixture of MnO x and OMC. The phenol toxicity towards Caenorhabditis elegans could be totally reduced within 8 min. The different roles of MnO x and OMC in persulfate activation were confirmed to validate their synergistic effect. MnO x provided major active sites for persulfate activation in accordance with the surface Mn 3+ /Mn 4+ cycle to induce SO 4 •− radicals. The OMC matrix provided the adsorption sites to enrich phenol molecules on the catalytic surface and promote the interfacial electron transfer process for persulfate activation. Moreover, a novel kinetic model with two distinct kinetic stages was established to verify the effects of phenol and persulfate on phenol removal.
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TALANTA
·
2026
·
IF 6.7
Wenteng Qiao,Caihong Yin,Boyuan Chen,Yue Zhai,Xiuling Song
Total antioxidant capacity represents a critical parameter for assessing food quality and freshness, while conventional detection methodologies are often constrained by operational intricacy or insufficient efficiency. Herein, we developed a rapid and user-friendly colorimetric sensing platform based on manganese oxide (MnOx) nanozymes for the quantification of antioxidants in fruit juice samples. MnOx nanozymes can efficiently catalyze the oxidation of the colorless substrate 3,3′,5,5′-tetramethylbenzidine, yielding a blue reaction product; however, the presence of antioxidants significantly suppresses this catalytic activity, inducing concentration-dependent color shifts in the reaction system. After systematic optimization of key reaction parameters (e.g., nanozyme concentration, TMB dosage, reaction temperature, and incubation time), the proposed platform achieved a detection limit of 1.79 μM, with a naked - eye visual detection limit of 5 μM and a total detection time of <10 min. Practical validation in real fruit juice samples verified the accuracy of the developed method for antioxidant quantification, as evidenced by recovery rates of 88.76%–109.10% and RSDs of all below 3.44%.This work introduces a novel, efficient, and stable approach for the rapid monitoring of TAC in food products, exhibiting considerable potential for food quality control and safety assessment.
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Journal of Environmental Chemical Engineering
·
2024
·
IF 7.4
Xiang Hu,Liping Zhang,Yiyun An,Weiwei Wang,Huitong Li,Zeyu Lian
Manganese and ammonia nitrogen pollution are widespread in the water of northern Chinese mines, exacerbating regional water scarcity and potential ecological issues. This study aimed to remova dissolved manganese(II) and ammonia nitrogen from mine water using a natural zeolite (NZ) modified with sodium hexametaphosphate impregnation (SHMP-NZ) and loaded with 3D manganese(III)/(IV) oxide nanosheets (SHMP-NZ/MnO x ). The influence of factors such as pH value, dissolved oxygen, and coexisting ions on adsorption was investigated. The capacity of NZ to removing ammonium was determined by SHMP impregnation, while the capability to remove manganese was determined by 3D manganese(III)/(IV) oxide nanosheets . Compared to NZ, SHMP-NZ/MnO x exhibited an increased efficiency of 39.93% and 41.54% in the simultaneously removing low-concentration manganese(II) and ammonia nitrogen, respectively. Adsorption processes of manganese and ammonia nitrogen onto NZ and SHMP-NZ/MnO x followed the Elovich and pseudo second order kinetic models, respectively. Both materials exhibited stages of external diffusion, internal diffusion, and reaction equilibrium during adsorption. The maximum adsorption capacities of SHMP-NZ/MnO x for manganese(II) and ammonia nitrogen were 10.12 mg/g and 26.24 mg/g, representing improvements of 72.7% and 113.2%, respectively, compared to NZ. The primary mechanism for ammonia nitrogen removal by SHMP-NZ/MnO x was based on ion exchange, while manganese(II) removal was mediated by Mn 3+ /Mn 4+ species. A regeneration study over five cycles indicated that SHMP-NZ/MnO x possessed promising reusability potential.
研究领域:
环境科学
·
水处理工程
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NEW JOURNAL OF CHEMISTRY
·
2025
·Vol. 49
·期 29
·12875-12883
·
IF 2.5
Ruoxuan Bai,Rongkun Jiang,Zixiao Yu,Junqi Wang,Yiqing Zeng,Shule Zhang
A number of efforts have been made to improve the NH3-SCR activity of MnOx based catalysts at low temperature, but few studies have focused on their long-term stability. In this study, MnOx/TiO2 (MnTi) catalysts prepared via wet impregnation were subjected to 30-h long-term stability tests under laboratory conditions to investigate their stability for the selective catalytic reduction (NH3-SCR) of NOx at low temperatures (80–200 °C), and combined with XRD, BET, XPS, H2-TPR, and in situ DRIFTS analysis to elucidate deactivation mechanisms. The results show that the reaction temperature has a great influence on the formation, decomposition, and transformation of nitrate species. Nitrate species, especially stable nitrate species, continuously accumulate on the catalyst surface at relatively low temperatures (≤160 °C in this work), which might block the active sites and hinder the conversion of Mn3+ to Mn4+, thereby leading to deactivation of the MnTi catalyst. In contrast, nitrate species on the catalyst surface can react or decompose rapidly at a high enough temperature (≥200 °C in this work), which facilitates the exposure of active sites and dynamic equilibrium of the Mn4+/Mn3+ redox cycle, resulting in the high long-term stability. We expect that this work will arouse researchers’ attention toward the long-term stability of NH3-SCR catalysts in the study of improving their catalytic activity at low temperature.
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CATALYSIS LETTERS
·
2023
·
IF 2.8
Wang Yanghui,Jin Luyao,Xu Xintao,Li Jiaying,Fan Kaihao,Hu Bo,Shen Yi,Liu Xuesong
In this paper, MnO x /TiO 2 catalysts with different manganese contents were prepared by using vacuum over-impregnation method to support manganese on TiO 2 support. However, the activity temperature window was narrow and the denitrification efficiency was only 265–365 °C in the temperature zone above 80%. Therefore, doping W was used to improve the high temperature activity and broaden the activity temperature window. The experimental results show that the active temperature window of the catalyst is expanded to 260–550 °C when doping 20%WO 3 . The effects of tungsten doping on the structure and surface properties of the catalysts were investigated by XRD, TEM, Raman, XPS, H 2 -TPR and NH 3 -TPD. It is found that the increase of manganese content would increase the ratio of Mn 4+ and O α , and then improve the NH 3 -SCR activity at low temperature. Tungsten doping can provide more strong acid sites and improve the high temperature activity of the catalyst by inhibiting the oxidation of ammonia. Graphical Abstract
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2022
·
IF 9.965
Kangning Wang,Mengran Qin,Chuantao Wang,Ting Yan,Yanzhong Zhen,Xiaolei Sun,Jianwei Wang,Feng Fu
The construction of composite materials is an effective strategy to solve the problems of poor conductivity, manganese dissolution, and volume expansion of manganese-based materials. Herein, a CeO 2 /MnO x @C hollow composite cathode derived from the self-assembly of Ce-Mn-metal-organic frameworks (Ce-Mn-MOFs) was synthesized. The abundant oxygen vacancies and good electronic/ionic conductivity of CeO 2 improve the electrical conductivity of composite, enhancing the rate performance. The unique hollow structure could inhibit manganese dissolution and alleviate volume expansion. The results indicate that the 1 % CeO 2 /MnO x @C composite cathode possesses a high reversible capacity and excellent cycling stability. Specifically, the 1 % CeO 2 /MnO x @C composite cathode shows a remarkable reversible specific capacity of 130 mAh/g at a current density of 500 mA g −1 , 6.5 times more than the pure MnO x (20 mAh/g). The capacity retention is up to 99.5 % relative to the initial capacity after 800 cycles. This study provides a new strategy for designing rare-earth composite electrodes to improve electrochemical performance.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2021
·
IF 8.128
Yifan Li,Yaqin Hou,Yongzhao Zhang,Yatao Yang,Zhanggen Huang
Surface interface regulation is an important research content in the field of heterogeneous catalysis. To improve the interface interaction between the active component and matrix, tremendous efforts have been dedicated to tailoring the morphology, size, and structure of composite catalysts. In this work, we report a confinement strategy to synthesize a series of core-shell catalysts loaded with metal oxides on titania nanotubes (TNTs), which were applied to the selective catalytic reduction of NO x with ammonia. Interestingly, the core-shell catalyst with confinement of TNTs exhibited the remarkable activity at low temperature region, N 2 selectivity and sulfur tolerance. Benefiting from the superior interfacial confinement characteristic of TNTs and Fe 2 O 3 , strong component interactions, the surface acid sites and strong oxidizability of MnO x were properly regulated, thus obtained the outstanding activity, N 2 selectivity and provide chemical protection to effectively prevent SO 2 poisoning. As far as the reaction mechanism, we found that the adsorption and reactivity of Lewis acid sites were the dominant factors affecting the activity in the NH 3 -SCR process by in situ DRIFT spectra. In general, our work provides an innovative strategy for constructing an TNTs-enwrapped nanocomposite with nano-confinement and core-shell structure to improve the low temperature SCR process.
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APPLIED SURFACE SCIENCE
·
2024
·
IF 6.3
Xiaocong Liu,Yi Wang,Fuping Zhang,Bo Xing,Guo Yang,Kaibin Zhang,Xingyong Liu,Yan Huang,Min Li,Mingliang Wu
Widespread and ineffective dye treatment in aquatic environment leads to serious pollution problems, threatening ecology and human health. Herein, manganese cerium bimetallic oxide cathode material (MnCeO x @GF) was prepared by hydrothermal method combined with calcination, and the electrochemical Fenton degradation performance of a typical dye Rhodamine B (Rh B) was investigated. The results show that the degradation of Rh B by MnCeO x @GF can reach 96.5 % within 2 h in acidic environment and continue to perform effectively after 4 repeated experiments. Combined with SEM and electrochemical test results, it can be seen that the bimetallic composite oxides formed by manganese and cerium on the surface of the support can effectively enhance the catalytic activity of the material, the addition of cerium changes the morphology of manganese oxides and promotes the generation of multiple valence composite oxides of transition metals, and improves the degradation of Rh B. Based on the free radical masking experiments, hydroxyl radical (·OH) is the main active substance in the electro-Fenton degradation process. This work not only provides a way to design and manufacture cathode materials for in situ electrosynthesis of H 2 O 2 , but also provides an important reference for improving the reusability of cathodes for sustainable dye wastewater treatment.
研究领域:
环境科学
·
材料科学
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CHEMISTRY-A EUROPEAN JOURNAL
·
2025
·
IF 3.7
Zhixian Wang,Yuntao Hu,Zhigang Zhang,Bin Wang,Gengxiu Zheng,Huaiqing Zhao
The development of synthetic methods for N-heterocyclic compounds have garnered considerable attention due to their significance in diverse chemical processes. Among various synthesis methods, the direct oxidative dehydrogenation of saturated substances to N-heteroaromatics is a simple and efficient method. This study utilized the pyrolysis of Mn/Ce-BTC MOFs precursor to prepare MnO X -CeO 2 composites as a heterogeneous catalyst for the aerobic oxidative dehydrogenation of N-heterocycles. The MnO X -CeO 2 composites were analyzed with various characterization techniques including XRD, SEM, TEM, BET, XPS, ICP-OES and Raman spectroscopy. The detailed findings from experiments indicate that the catalytic activity of the composites has been significantly improved due to the synergistic effect of MnO X -CeO 2 and the abundant oxygen vacancies on the surface of the catalyst. And the related mechanism experiments reveal that reactive oxygen species (ROS) are involved in this catalytic system. Furthermore, MnO X -CeO 2 composites retain excellent catalytic performance even after ten recycles. Graphical The synthesized bimetallic oxides MnO X -CeO 2 by the pyrolysis of Mn/Ce-BTC MOFs have been employed as a heterogenous catalyst for the oxidative dehydrogenation of N-heterocycles to N-heteroaromatics with oxygen as the solo oxidant.
研究领域:
催化化学
·
材料化学
·
有机合成
·
无机化学
·
环境化学
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