Catalysts
·
2019
·Vol. 9
·期 9
·726
·
IF 3.444
Jian Wang,Hainan Zhao,Jianfei Song,Tingyu Zhu,Wenqing Xu
Manganese oxide catalysts, including γ-MnO2, Mn2O3and Mn3O4, were synthesized by a precipitation method using different precipitants and calcination temperatures. The catalytic oxidations of benzene and 1,2-dichloroethane (1,2-DCE) were then carried out. The effects of the calcination temperature on the catalyst morphology and activity were investigated. It was found that the specific surface area and reducibility of the catalysts decreased with the increase in the calcination temperature, and both the γ-MnO2and Mn3O4were converted to Mn2O3. These catalysts showed good activity and selectivity for the benzene and 1,2-DCE oxidation. The γ-MnO2exhibited the highest activity, followed by the Mn2O3and Mn3O4. The high activity could be associated with the large specific surface area, abundant surface oxygen species and excellent low-temperature reducibility. Additionally, the catalysts were inevitably chlorinated during the 1,2-DCE oxidation, and a decrease in the catalytic activity was observed. It suggested that a higher reaction temperature could facilitate the removal of the chlorine species. However, the reduction of the catalytic reaction interface was irreversible.Keywords:benzene;1,2-Dichloroethane;catalytic oxidation;manganese oxide catalysts
研究领域:
环境科学
·
催化化学
✓ 已验证
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2025
·
IF 9
Yanping Yang,Shengchen Li,Shunli Shi,Jie Hu,Zexi Xuchen,Shunmin Ding,Dan zhao,Shengjun Deng,Weiming Xiao,Shuhua Wang,Chao Chen
Manganese oxide (MnO x ) catalysts are promising for low-temperature NH 3 -Selective Catalytic Reduction (NH 3 -SCR) with their superior catalytic performance. However, the presence of alkali metals in flue gases, particularly potassium (K), leads to catalyst deactivation and limits their industrial application. This study investigates the synergistic effects of Ce and Nb doping on the K resistance and low-temperature NH 3 -SCR activity of MnO x . The surface acidity and redox properties of MnO x were modulated by Ce and Nb modification. In addition, the phase structure, surface state and active sites of the catalysts were characterized before and after K poisoning. The results indicated that Nb 0.05 Ce 0.05 MnO x exhibited exceptional low-temperature performance, achieving over 90 % NO conversion at 125-250°C, along with significant resistance to K poisoning·NH 3 -TPD and in-situ experiments revealed that the loss of acid sites is the primary cause of K poisoning. The mechanism follows the L-H mechanism with L-acid sites as the main active sites on the catalyst surface and bridging nitrate as the key intermediate state. This research provides valuable insights into enhancing the industrial applicability of MnO x- based catalysts for low-temperature denitrification.
研究领域:
催化化学
·
环境工程
✓ 已验证
产品关联
DOI
高影响因子
Energy Storage Materials
·
2019
·
IF 0
Bingcheng Ge,Yangyang Wang,Yong Sun,Yunping Li,Jianyu Huang,Qiuming Peng
Developing a rechargeable metal-nitrogen battery is desirable for energy conversion and nitrogen fixation as well as an alternative route for a potential and mild ammonia synthesis . Herein, we realized a proof-of-concept for sodium-nitrogen (Na-N 2 ) rechargeable batteries by introducing the alpha-MnO 2 (α-MnO 2 ) nanowire as a catalyst. In addition, we have also demonstrated a reversible reaction of 6Na + N 2. ↔ 2Na 3 N. This system reveals an outstanding reversible capacity of 600 mAh g −1 at 50 mAg −1 , runs ∼80 cycles with a controlled capacity of 400 mAh g −1 at discharge terminal voltage below 1.6 V and achieves a high actual specific energy density based on total active materials (about 4900 Wh/Kg MnO2 ) at the current density of 100 mAg −1 . In addition, a good efficiency of nitrogen fixation (∼26%) has been achieved. These attractive performances are mainly associated with the distinctive channel structure, high conductivity, and outstanding catalytic activity in terms of in-situ environmental transmission electron microscopy investigations. The success of Na-N 2 batteries not only provides an alternative strategy for the next-generation of electrochemical energy-storage devices, but also builds a new trajectory toward green recycling and utilization of N 2 .
研究领域:
能源化学
·
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2018
·Vol. 25
·期 21
·20575-20590
·
IF 2.8
Lu Pei,Yue Huifang,Xing Yi,Wei Jianjun,Zeng Zheng,Li Rui,Wu Wanrong
In this study, series of Ce x Zr y Mn z O 2 /r-Al 2 O 3 catalysts were prepared by impregnation method and explored to co-purification of NO x and Hg 0 at low temperature. The physical and chemical properties of the catalysts were investigated by XRD, BET, FTIR, NH 3 -TPD, H 2 -TPR, and XPS. The experimental results showed that 10% Ce 0.2 Zr 0.3 Mn 0.5 O 2 /r-Al 2 O 3 yielded higher conversion on co-purification of NO x and Hg 0 than the other prepared catalysts at low temperature, especially at 200–300 °C. 91% and 97% convert rate of NO x and Hg 0 were obtained, respectively, when 10% Ce 0.2 Zr 0.3 Mn 0.5 O 2 /r-Al 2 O 3 catalyst was used at 250 °C. Moreover, the presence of H 2 O slightly decreased the removal of NO x and Hg 0 owing to the competitive adsorption of H 2 O and Hg 0 . When SO 2 was added, the removal of Hg 0 first increased slightly and then presented a decrease due to the generation of SO 3 and (NH 4 ) 2 SO 4 . The results of NH 3 -TPD indicated that the strong acid of 10% Ce 0.2 Zr 0.3 Mn 0.5 O 2 /r-Al 2 O 3 improved its high-temperature activity. XPS and H 2 -TPR results showed there were high-valence Mn and Ce species in 10% Ce 0.2 Zr 0.3 Mn 0.5 O 2 /r-Al 2 O 3 , which could effectively promote the removal of NO x and Hg 0 . Therefore, the mechanisms of Hg 0 and NO x removal were proposed as Hg (ad) + [O] → HgO (ad), and 2NH 3 /NH 4 + (ad) + NO 2 (ad) + NO (g) → 2 N 2 + 3H 2 O/2H + , respectively.
ᅟ
研究领域:
环境科学
·
催化化学
✓ 已验证
DOI
PubMed
高影响因子
CHINESE JOURNAL OF CHEMISTRY
·
2017
·Vol. 35
·期 6
·984-990
·
IF 1.852
Xiaofang Li,Xiuquan Jia,Jiping Ma,Yongming Xu,Yizheng Huang,Jie Xu
2,5-Furandicarboxamide was firstly synthesized in yield of 85% via catalytic oxidative amidation of 5-hydroxymethylfurfural with aqueous NH 3 over alkali manganese oxides of α -MnO 2 /Na x MnO 2 . The intermediates of 5-hydroxymethyl-furonitrile, 2,5-dicyanofuran, and 5-cyano-2-furancarboxamide were verified and their reactivities were further examined. The kinetic analysis results showed that the transformation of intermediate product of 5-cyano-2-furancarboxamide to 2,5-furan-dicarboxamide is a slower step, which is closely relative to the reaction temperature and basicity of catalyst.
研究领域:
化学工程
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
CATALYSIS TODAY
·
2022
·
IF 6.562
Zhanyu Zhang,Jun Tang,Junbao Chen,Peixin Cui,Siyu Jiao,Wei Yi,Qingping Ke,Hengquan Yang
The epoxidation of styrene is an important route to synthesize organic intermediate, but how to effectively promote the formation of target superoxide radicals and then regulate the production of styrene oxide in two-phase reaction system remains an urgent challenge. In this study, MnO x nanocatalysts with abundant oxygen vacancies were fabricated using reverse-micelle as template, and then were endowed with an amphiphilic surface through post-modification. With such MnO x catalysts, Pickering emulsion could be formulated, in which numerous compartmentalized droplet microreactors were created for the epoxidation of styrene. The rich oxygen defects on MnO x were found to be useful to improve the chemisorption of t -butylhydroperoxide, and the active complexes formed by coordination of Mn 3+ with N, N-dimethylformamide favored the generation of preferable superoxide radicals for the synthesis of styrene oxide. Moreover, it was also found that compartmentalization effects arising from Pickering emulsion droplets modifies the radicals reaction path, significantly improving the catalytic efficiency and selectivity. As a result, in the Pickering emulsion system, 90.0% selectivity towards styrene oxide and a turnover frequency of 581 h −1 could be obtained, which were higher than ever reported results. The Pickering emulsion-based compartmentalized microreactors can provide versatile platforms to efficiently control the epoxidation of styrene involving free radicals.
研究领域:
化学工程
·
催化科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2024
·
IF 9.4
Lixia Wang,Jia Huang,Xinran Hu,Zhiyang Huang,Mingcheng Gao,Di Yao,Tayirjan Taylor Isimjan,Xiulin Yang
The pursuit of efficient and economically viable catalysts for liquid/solid-state zinc-air batteries (ZABs) is of paramount importance yet presents formidable challenge. Herein, we synthesized a vacancy-rich cobalt/manganese oxide catalyst (Co/MnO@NC) stabilized on a nitrogen-doped mesoporous carbon (NC) nanosphere matrix by leveraging hydrothermal and high-temperature pyrolysis strategy. The optimized Co/MnO@NC demonstrates fast reaction kinetics and large limiting current densities comparable to commercial Pt/C in alkaline electrolyte for oxygen reduction reaction (ORR). Moreover, the Co/MnO@NC serves as an incredible cathode material for both liquid and flexible solid-state ZABs, delivering impressive peak power densities of 217.7 and 63.3 mW cm −2 and robust long-term stability (459 h), outperforming the state-of-the-art Pt/C and majority of the currently reported catalysts. Research indicates that the superior performance of the Co/MnO@NC catalyst primarily stems from the synergy between the heightened electrical conductivity of metallic Co and the regulatory capacity of MnO on adsorbed oxygen intermediates. In addition, the abundance of vacancies regulates the electronic configuration, and superhydrophilicity facilitates efficient electrolyte diffusion, thereby effectively ensuring optimal contact between the active site and reactants. Besides, the coexisting NC layer avoids the shedding of active sites, resulting in high stability. This work provides a viable approach for designing and advancing high-performance liquid/solid-state ZABs, highlighting the great potential of energy storage technology.
研究领域:
材料科学
·
电化学
·
能源存储技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Catalysis Science & Technology
·
2016
·Vol. 6
·期 20
·7429-7436
·
IF 5.287
Xiuquan Jia,Jiping Ma,Min Wang,Xiaofang Li,Jin Gao,Jie Xu
The tandem reaction is a growing field to yield important advances toward green and sustainable chemistry. Herein, we report a bifunctional manganese oxide catalyst with an interface binding redox phase (α-MnO2) and a basic phase (NaxMnO2). The molar ratio of NaOH/Mn plays a great role in the formation of α-MnO2/NaxMnO2. The sodium cation is essential for the formation of a basic NaxMnO2 phase while the potassium cation promotes the formation of a redox-active α-MnO2 phase. The interface structure of α-MnO2/NaxMnO2 geometrically favors the ammoxidation–Pinner tandem reaction to synthesize imidates in a 58–96% yield from aldehydes. Thus a phase collaborative effect is observed. In the ammoxidation process, the redox cycle of MnIV/MnIII is involved and the lattice oxygen in the α-MnO2 phase acts as an active oxygen species. The O–H in methanol is activated and dissociated on the basic sites of NaxMnO2 to the adsorbed methoxyl species to facilitate the Pinner synthesis. This approach bypasses the conventional synthesis of imidates, which suffer from harsh reaction conditions and the requirement for multiple steps.
研究领域:
催化化学
·
材料科学
·
有机合成
✓ 已验证
产品关联
DOI
高影响因子
Catalysis Science & Technology
·
2015
·Vol. 6
·期 6
·1940-1945
·
IF 5.426
Min Wang,Jiping Ma,Miao Yu,Zhe Zhang,Feng Wang
We herein report the transition metal oxide-catalyzed synthesis of azobenzenes through the oxidative coupling of anilines. An octahedral molecular sieve of manganese oxide, OMS-2, exhibited the best activity and selectivity. Nine examples of symmetric azobenzenes and twenty unsymmetric ones were synthesized with 62–99% conversion and 64–99% selectivity. In the aniline cross-coupling reactions, the difference of the Hammett constants of two substituted groups (Δσ) determines the selectivity to unsymmetric azobenzenes, which are the major products at Δσ < 0.32. In-depth studies reveal that the surface defect sites of the mixed-valence manganese oxide play a key role in facilitating electron transfer and activating molecular oxygen. The single-electron transfer (SET) reaction mechanism is proposed based on electron paramagnetic resonance and X-ray powder diffraction characterization.
研究领域:
有机化学
·
催化化学
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2017
·
IF 6.216
Jinjun Li,Xiaofei Lu,Feng Wu,Shaoli Qin,Zhixiong You
Structured catalysts and reactors have wide applications in environmental remediation and production of important energy-related chemicals. In thermal catalytic processes, external heater are often required to raise the temperature and ignite the reactions, which might lead to huge setups. Herein, we introduce a novel Joule-heat-ignition catalytic reactor. Using Fe-Cr-Al alloy as catalyst substrate, electric currents can pass directly through the substrate, generating Joule heat and bringing the catalysts to the target temperatures. Therefore, the setup can be simplified by omitting the additional heater; the heat produced inside the substrates can be transferred directly to the catalyst coat to achieve rapid ignition; and the reaction temperature can be flexibly controlled by adjusting the input power. In this work, we loaded manganese oxide catalyst onto an alloy wire and used it to build a Joule-heat-ignition reactor for the catalytic oxidation of carbon monoxide and toluene. The anodization pretreatment generated channels on the alloy surface, which effectively enhanced the catalyst loading. The use of alumina as a secondary support also favored catalyst loading and promoted catalyst dispersion. By adding proper amounts of zirconium, the mechanical stability of the catalyst layer increased. The Joule-heat-ignition catalytic system might provide some inspiration in related environmental catalysis.
研究领域:
环境科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
ACS ES&T Engineering
·
2024
·
IF 7.4
Lin-Feng Zhai,Shu-Ya Xu,Jun Yu,Zhao-Jian Hu,Min Sun,Yan Wang
Nonradical oxidation is a promising pathway for the selective removal of organic pollutants in complex wastewaters. However, traditional catalytic oxidation processes generally depend on free radicals to achieve favorable pollutant removal. Herein, we developed a nonradical pathway-governed catalytic oxidation process by applying an electric field to selectively activate a surface O2-complex on a MnO catalyst. On the surface of positively polarized MnO, adsorbed O2 was activated into positively charged peroxide species as the main reactive species. A Langmuir–Hinshelwood model based on irreversible bimolecular reaction between adsorbed reaction species was developed to kinetically differentiate the oxidation behaviors of twelve substituted phenolic compounds. The surface reaction rate constant was identified as the key parameter controlling the reaction kinetics. To unveil the substrate-dependent reaction rules of the nonradical pathway, quantitative structure–activity relationship (QSAR) analysis was performed to correlate the surface reaction rate constants of phenolic compounds to their molecular features. A QSAR model was constructed by synergizing IE, EHOMO, and q(C–)n together to predict the reactivity of a phenolic compound in the nonradical pathway. Guided by the QSAR model, the catalytic oxidation process was applied for safe and energy-saving treatment of triclosan-contaminated water. This work is anticipated to provide valuable information for triggering and manipulating nonradical catalytic oxidation processes as well as understanding their selective oxidation nature.
研究领域:
环境科学
·
催化化学
·
计算化学
✓ 已验证
产品关联
DOI
高影响因子
RESEARCH ON CHEMICAL INTERMEDIATES
·
2025
·
IF 3.5
Huhe Dule,Ma Zhengxiang,Zheng Jiali,Wang Yanji
2,5-Furandicarboxamide (FDA) is a promising bio-based platform compound for synthesizing high-value chemicals. Conventional synthesis methods, including strong acid/base-catalyzed reactions and ammonia oxidation, present significant environmental concerns and safety risks. In this paper, we investigated the performance of various oxide catalysts and the kinetics of the hydration reaction of 2,5-dicyanofuran (DCF) to produce FDA. The nanorod manganese oxide (NR-MnO 2 ) catalyst demonstrated remarkable efficacy, achieving an FDA yield of 97.5% at a reaction temperature of 110 °C over 2.5 h. Additionally, integrating cerium oxide (CeO 2 ) with NR-MnO 2 enhanced the selectivity for the single cyano hydration reaction. Specifically, the Mn 1 -Ce 0.25 oxide catalyst yielded 76.1% for 5-cyano- 2-furancarboxamide (DFFA) with an impressive selectivity of 89.2%. A kinetic model for the DCF hydration reaction was successfully developed using NR-MnO 2 as the catalyst. The model revealed that the initial stages involve the hydration of monocyano to form DFFA, followed by further hydration to form the FDA. Based on the Arrhenius model, the apparent activation energies were 48.5 kJ/mol and 35.4 kJ/mol, respectively. The results of this study provide a scientific foundation for the hydration of DCF in the production of DFFA or FDA, offering a more selective and environmentally friendly approach to the synthesis of bio-based amides.
研究领域:
化学工程
·
催化化学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）