Molecular Catalysis
·
2022
·
IF 5.089
Yiqing Zeng,Fengye Lyu,Yanan Wang,Shule Zhang,Qin Zhong,Zhaoxiang Zhong
High N 2 O selectivity of MnO x -TiO 2 catalyst hinders its development in ammonia selective catalytic reduction (NH 3 -SCR) of NO x . Herein, a series of MnO x -TiO 2 catalyst with different Mn/Ti ratio were prepared by wet-impregnation method to study the N 2 O formation during ammonia selective catalytic reduction (NH 3 -SCR) of NO x from the perspective of catalyst. It is found that MnO x and TiO 2 species are the mainly redox and acid sites for the NH 3 -SCR denitration reaction over MnO x -TiO 2 catalyst, respectively. As the Mn/Ti ratio increases, MnO x species layer expanded on TiO 2 support, leading to increase of redox sites but decrease of surface acid sites. These changes contribute to the occurrence of the no-selective oxidation of NH 3 on MnO x species and the over-activation of NH 3 at Mn-Ti interface, resulting in the formation of N 2 O via the route of 2NH 3 + 2O 2 → N 2 O + 3H 2 O and 4NO + 4NH 3 + 3O 2 → 4N 2 O + 6H 2 O, respectively. Through this work, it can be speculated that both improving MnO x dispersion and increasing surface acidity of catalyst are feasible strategy for suppressing the N 2 O formation on MnO x -TiO 2 .
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
APPLIED CATALYSIS A-GENERAL
·
2016
·
IF 4.012
Peng Sun,Rui-tang Guo,Shu-ming Liu,Shu-xian Wang,Wei-guo Pan,Ming-yuan Li
A series of MnEuOx catalysts were prepared by the co-precipitation method and used for selective catalytic reduction of NOx with NH 3 . It was found that the modification of MnOx catalyst by Eu with a Eu/Mn molar ratio of 0.1 could greatly enhance its SCR activity and broaden its operating temperature window, accompanied by good resistance to SO 2 and H 2 O. From the characterization results of N 2 adsorption, XRD, XPS, H 2 -TPR, it could be concluded that the larger surface area resulted from the inhibited crystallization of MnOx, the enrichment of surface Mn 4+ and chemisorbed oxygen, and the higher reducibility all made a contribution to the high SCR activity of MnEuOx-0.1 catalyst. Furthermore, the results of in situ DRIFTS study revealed the NH 3 -SCR reactions over MnOx and MnEuOx-0.1 were mainly controlled by L-H mechanism (<150 °C) and E-R mechanism (>150 °C) respectively, and the contribution of E–R mechanism became more important with increasing reaction temperature. The enhanced NO oxidation and NH 3 adsorption should be mainly contribute to the distinguished SCR performance of MnEuOx catalyst in the lower temperature range (<150 °C) and higher temperature range (>150 °C) respectively.
研究领域:
催化化学
·
环境科学
✓ 已验证
DOI
高影响因子
Journal of Environmental Chemical Engineering
·
2021
·
IF 5.909
Hailu Fu,Jilei Lin,Shuang Cao,Bosheng Chen,Renhua Huang,Hao Chen,Tao Ding,Pengfei Sun,Ligang Luo
A series of cobalt-based catalysts (Co 3 O 4 , Mn/Co 3 O 4 , K-Co 3 O 4, and K-Mn/Co 3 O 4 ) were prepared for toluene catalytic combustion and anti-K poisoning experiments. Co 3 O 4 catalyst has exhibited good performance in toluene oxidation , but it has poor anti-K poisoning performance. The Mn/Co 3 O 4 catalyst has shown excellent low-temperature catalytic activity , good resistance to K poisoning at T 90 of 226 °C, and achieved a complete toluene conversion at about 235 °C; the activity after the addition of K slightly reduced at T 90 of 237 °C. A series of characterizations indicated that adding Mn can effectively promote the Co 2+ ↔Co 3+ cycle, increase the Co 3+ content on the catalyst surface, and enhance the redox performance of the catalyst. On the other hand, MnO x intercepts K species and generates Mn-O-K, blocking most of the poisonous effects of K on cobalt oxide , thereby protecting the active species (Co 3+ and surface-adsorbed oxygen) and acidic sites on the Co 3 O 4 surface. Finally, GC-MS and in-situ infrared characterization were adopted to investigate the reaction mechanism of the catalysts. Two reaction paths of the Co 3 O 4 catalyst may co-occur. Still, the reaction path of the Mn/Co 3 O 4 catalyst is relatively simple; that is, the chemically adsorbed toluene molecules are oxidized through surface-active oxygen, after which various intermediate by-products are formed successively. Finally, they are completely degraded into CO 2 .
研究领域:
环境科学
·
催化化学
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2021
·
IF 4.311
Tingting Qi,Linyu Zhou,Yingjiao Li,Guang-Wen Chu,Yong Luo,Jie Shi,Haikui Zou,Bao-Chang Sun
Oxygen vacancy (OV) plays a significant role in the catalytic performance of oxidation catalysts. Herein, ZSM-5@MnO x catalyst with abundant OVs was firstly prepared by in-situ growth method. The prepared catalyst exhibits good catalytic activity for the selective oxidation of benzyl alcohol (BA) to benzaldehyde (BAD) with ~100% BA conversion and ~100% BAD selectivity within 3 h. We have proved that the OV in ZSM-5@MnO x catalyst is the main active site for the BA oxidation. Besides, the OV formation mechanism is proposed based on the influences of modified ZSM-5 supports on OVs. Results show that sodium ions in ZSM-5 are conducive to enhancing the coating of MnO x on supports, and protons in ZSM-5 are beneficial for the formation of OVs by dehydrating with hydroxyls on MnO x . Based on the mechanism, we further enrich OVs by the deep dehydration to improve its catalytic performance. This work provides a novel route for the design of OVs in the ZSM-5@MnO x catalyst.
研究领域:
催化
·
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
JOURNAL OF THE ENERGY INSTITUTE
·
2023
·
IF 5.7
Yongjin Hu,Zhichang Jiang,Runxian Wang,Shujie Gao,Hui Liu,Haining Wang,Dong Ye
In this article, the effects of K species, including K 2 O, KCl, and K 2 SO 4 , on the Hg 0 removal capability of MnO x /HZSM-5 adsorbent were investigated. Adding K 2 O and K 2 SO 4 interfered with the Hg 0 removal process; as the loading amount of these two K species increased, this adverse impact became more obvious. This was because the added K 2 O or K 2 SO 4 lowered the acidity and oxidizability of the adsorbents via the interactions with MnO x , which exerted an inhibitory effect on the adsorption and oxidation of Hg 0 . By contrast, introducing KCl made almost no adverse impacts on the Hg 0 elimination ability of the adsorbents. With rising the KCl content to 4 wt%, even ∼92.7% Hg 0 removal efficiency was obtained. This could be attributed to the presence of Cl − ; with the guidance of high-valence-state metal cations and O 2 , Cl − could be converted to active chlorine species, which was capable of transforming Hg 0 to HgCl 2 . This finding supplied a theoretical basis for developing new adsorbents that were capable of stably operating in the power plants with high-alkali-content coal utilized.
研究领域:
环境科学
·
能源工程
✓ 已验证
产品关联
DOI
高影响因子
Small
·
2025
·
IF 12.1
Hui Luo,Lingxin Kong,Sihai Lv,Qifan Li,Mi Tang,Xujin Ge,Fu Chen,Yongzhi Cheng,Xiangcheng Li
The rational manipulation of interfacial properties, composition, and morphology of materials has emerged as an effective strategy for enhancing their microwave absorption performance. The crystal phase composition, microstructure, and electromagnetic properties can be regulated by varying the thermal treatment temperature. The synergistic integration of heterogeneous interfaces, magnetic materials, microstructures, and defect engineering helps optimize impedance matching and enhance polarization and magnetic losses. Herein, multi-interface core–shell FeSiAl@MnO x @C composites with various morphologies demonstrated superior microwave absorption performance. A minimum reflection loss of −56.3 dB is achieved at an absorber thickness of 1.41 mm, and effective absorption bandwidth of 5.0 GHz is obtained at a thickness of 1.59 mm. The radar cross-section reduction value reached 19.448 at an incidence angle of 0°. The excellent microwave absorption performance is due to the synergistic effect of the significant magnetic and dielectric losses and improved impedance matching. This study establishes a foundation for designing next-generation high-performance microwave-absorbing materials with high magnetic losses.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2019
·
IF 14.229
Md Manik Mian,Guijian Liu,Biao Fu,Yu Song
Sewage sludge (SS), the inevitable byproduct of wastewater treatment plants, is facing numerous challenges of environmentally safe and cost-effective disposal. Thus, exploration of efficient SS valorization technique is highly desired. In this study, a sludge derived carbon-supported MnO x as a catalyst (ASMn-Nb) was synthesized through NH 4 OH activation and pyrolysis (800 °C) to enhance peroxymonosulfate (PMS) decomposition and subsequent degradation of acid orange 7 and rhodamine B. The sample characterization indicated that MnCl 2 conditioning produces mixed valent Mn oxides on ASMn-Nb, while NH 4 OH activation significantly enhances N-heteroatoms, surface area, and microporosity. The as-synthesized hybrid catalyst exhibited excellent PMS decomposition ability in a wide range of pH, which enhances AO7 removal efficiency 16%–100% in 40 min compared with that treated with raw sludge biochar. Moreover, the catalyst is recyclable, chemically stable, and produce negligible metal leaching during catalysis. Further investigation of catalytic mechanisms revealed that both radicle and non-radicle processes governing PMS decomposition, whereas mediated electron transfer as the primary and 1 O 2 , SO 4 − , and OH radicals induced catalysis as the secondary mechanisms of PMS activation and subsequent AO7 degradation. Finally, a probable mechanism of PMS decomposition over ASMn-Nb and AO7 degradation path is proposed. This study concurrently provides a facile route of improving the catalytic performance of sludge derived-biochar and a probable SS valorization technique.
研究领域:
环境科学
·
材料科学
✓ 已验证
DOI
高影响因子
CATALYSIS TODAY
·
2018
·
IF 4.667
Chuanhui Zhang,He Huang,Genqin Li,Lei Wang,Liang Song,Xuebing Li
Series of 10% MnO x /HZSM-5 catalysts with different zeolitic Si/Al ratios were prepared by an incipient impregnation method and evaluated for the catalytic oxidation of toluene. Characterization results indicated that all catalysts exhibited similar textural and redox properties but variable surface acidity. Catalytic testing results showed that the catalytic activities over these catalysts followed a descending order of 10% MnO x /HZSM-5-25 > 10% MnO x /HZSM-5-50 > 10% MnO x /HZSM-5-75, where 10% MnO x /HZSM-5-25 exhibited the optimum catalytic activity and excellent catalytic durability under dry condition and good water-resistant ability under humid condition. A good linear relationship between the toluene conversion efficiency (TOF Mn ) and the total acidity over MnO x /HZSM-5 catalysts was obtained, which revealed the crucial role and promotional effect of zeolitic acidity acting as a promoter on the catalytic activity for toluene oxidation.
研究领域:
催化化学
·
环境科学
✓ 已验证
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2020
·
IF 16.683
Shangchao Xiong,Jianjun Chen,Nan Huang,Tao Yan,Yue Peng,Junhua Li
The degradation of catalyst properties, rather than the deposition of NH 4 Cl, was the main reason for the deactivation of the MnCe low-temperature SCR (selective catalytic reduction) catalyst under HCl atmosphere. Cl ions prefer to be located at the oxygen vacancies around Mn cations on the MnCe surface. The adsorbed Cl ions could further promote the formation of oxygen vacancies. Therefore, the active Mn sites on the surface of MnCe would be quickly covered by Cl ions when HCl was present and thus promote the formation of Brønsted acid sites. However, the ionic NH 4 + adsorbed on the Brønsted acid sites of MnCe and MnCe − Cl were not fully utilized in the SCR reaction. Meanwhile, the reactivity of the coordinated NH 3 bonded with Lewis acid sites was significantly restrained by HCl due to the significant inhibition of the redox performance. Overall, HCl could obviously restrain the low-temperature SCR activity of MnCe.
研究领域:
催化化学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2020
·
IF 3.573
Jun Tang,Yali Cao,Fei Ruan,Fengfeng Li,Yangxin Jin,Minh Ngoc Ha,Xinya Han,Qingping Ke
Condensation of 2-amino-phenols with carboxylic acid derivatives has been practically used for the production of benzoxazoles, wherein the homogeneous catalytic system including strong acids and dangerous peroxides is generally employed. Herein, we report the novel approach for controlled synthesis of nitrogen-doped MnOx (denoted as N-MnO2, N-Mn5O8, and N-Mn3O4), by adjusting the heteroatom nitrogen amount, and uncover that the N-MnO2 catalyst as a sustainable and cost-effective heterogeneous catalyst exhibits high catalytic performance for condensation of 2-amino-phenols and o-phenylenediamine with alcohols into the corresponding benzoxazoles and benzimidazole, respectively. The N-MnO2 catalyst displays >99.9% yield for benzoxazole synthesis under room temperature and no decay (10 cycles), compared with the neglect activity (∼0%) for MnO2 catalysts. X-ray absorption spectroscopies and experimental studies uncovered that oxygen vacancies generated by heteroatom N doping play a key role for promoting intramolecular oxidative dehydrogenation of alcohol and 2-aminophenol derivatives to directly yield desired products. N-MnO2 catalyst rapidly oxidative dehydrogenated the reactants into corresponding benzoxazoles for 10 examples with >87.6% yields.
研究领域:
材料科学
·
催化化学
·
有机合成
✓ 已验证
DOI
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2022
·
IF 7.139
Rui Yu,Ying-Xia Du,Heng-Fan Zhao,Fei-Fei Cao,Wang-Ting Lu,Geng Zhang
The electrochemical water splitting in alkaline media is troubled by the lack of efficient electrocatalysts for hydrogen evolution reaction (HER). Herein, a crystalline/amorphous CoP/MnO x heterostructure is converted from a single-phase bimetallic Co–Mn oxide by phase separation strategy. The CoP/MnO x heterostructure only requires an overpotential of 135 mV to reach 10 mA cm −2 in 1 M KOH, which is lower than that of CoP (184 mV). The interface effect between CoP and MnO x is beneficial to the improvement of HER activity, which is confirmed by means of selective etching of MnO x and infrared spectroscopy . Moreover, the crystal size of CoP phase in the heterostructure is lower than that of the mono-component CoP. Furthermore, the decrease of precursor crystal size will give rise to a decrease in the CoP crystal size of heterostructure. The decline of crystal size results in higher active surface area and greater number of interfaces.
研究领域:
材料科学
·
电化学
·
催化
✓ 已验证
产品关联
DOI
高影响因子
Catalysts
·
2019
·Vol. 9
·期 6
·519
·
IF 3.444
Jiaming Shao,Fawei Lin,Yan Li,Hairong Tang,Zhihua Wang,Peixi Liu,Guanyi Chen
NO oxidation was conducted over MnOx-CeO2catalysts, which were synthesized by the co-precipitation method. The calcination temperature and third metal doping were the main considerations. MnCe catalysts calcined at 350 °C and 450 °C attained the highest NO conversion efficiency, compared to 550 °C. XRD results suggested that the higher the calcination temperature, the higher the crystallization degree, which led to a negative effect on catalytic activity. Subsequently, Sn, Fe, Co, Cr, and Cu were separately doped into MnCe composites, but no improvement was observed for these trimetallic catalysts in NO conversion. Nevertheless, MnCeSn, MnCeFe, and MnCeCo still exhibited a desirable NO conversion efficiency, so they were tested under SO2addition together with MnCe catalyst. Among them, MnCeFe exhibited the highest NO conversion after whole poisoning testing. XPS results indicated that Fe could protect Mn and Ce metal oxides from being reduced during SO2poisoning process. Furthermore, in in-situ DRIFTS measurement, part of nitrate species maintained undestroyed on the MnCeFe catalyst surface after SO2poisoning. These characteristics reinforced that Fe dropping would achieve better performance under SO2atmosphere.Keywords:MnOx-CeO2;co-precipitation;NO oxidation;SO2resistance;metal addition
研究领域:
环境科学
·
催化化学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）