APPLIED CATALYSIS B-ENVIRONMENTAL
·
2024
·
IF 20.2
Hongchun Sun,Cui Dong,Chao Feng,Hui Wang,Zhenping Qu
Co 3 O 4 catalysts possess high activity in selective catalytic oxidation of NH 3 (NH 3 -SCO), but the low N 2 selectivity hinders their potential application. To enhance N 2 selectivity, the chemical bonded Nb-O-Co catalyst by the deposition of Nb species onto Co 3 O 4 (Nb/Co 3 O 4 -0.03) is constructed. It shows 100 % NH 3 conversion and 82 % N 2 selectivity at 180°C, and the N 2 selectivity is 2.2-fold higher than that of Co 3 O 4 (38 %). The failure of enhancement in N 2 selectivity for physically mixed Co 3 O 4 and NbO x (NbO x |Co 3 O 4 -0.03) further indicates the crucial role of chemical bonded Nb-O-Co in enhancing N 2 selectivity. In situ diffuse reflectance infrared Fourier transform spectra and NH 3 temperature-programmed desorption results show the formation of new NH 3 adsorption sites. Importantly, intermediates NO - stabled on Nb/Co 3 O 4 -0.03 tends to react with -NH 2 to produce N 2 through internal selective catalytic reduction (iSCR). This work offers insights into enhancing the N 2 selectivity in NH 3 -SCO and advances understanding of iSCR mechanism.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2024
·
IF 8.1
Bo Zhao,Mingze Han,Qiushi Wang,Zikun Huang,Yunhong Liang,Kaniki Tumba,Mo Li,Weiwei Chen,Masroor Kamal,Zhiyong Chang,Jiangtao Qi,Li Guo
Particulate matter (PM), ammonia (NH 3 ) and other polluted gases emitted from animal feeding operations have emerged as significant risks to workers, surrounding residents, and the regional environment. Therefore, the development of air filters capable of simultaneously filtering PM and adsorbing toxic gases is particularly important. In this study, a three-layer gradient structure nanofiber filter was prepared by electrospinning technology, consisting of fluorinated Polylactic acid (PLA)/SiO 2 as the outer layer, PLA nanofibers as the middle layer, and PLA/UiO-66-NH 2 as the inner layer. This gradient structure of composite filter featured gradually decreasing pore sizes, exhibited optimal air filtration performance compared to PLA filter and commercial glass fiber filter. At 5.3 cm/s flow rate, the composite nanofiber filter achieved high filtration efficiency (99.15 % for PM 0.5 ) and low pressure drop (89.65 Pa). Furthermore, the composite nanofiber filter exhibited highest dust holding capacity, indicating longer service life. It also featured excellent self-cleaning capabilities, allowing for reuse after simple water rinsing. Additionally, the results of ammonia (NH 3 ) adsorption tests demonstrated the prepared composite filter’s highest adsorption capacity for NH 3 . Therefore, this work enhanced the application potential of high-performance air filters in the removal of PM pollution and hazardous gases.
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ENERGY & FUELS
·
2024
·
IF 5.2
Tianxu Su,Bin Guan,Chunzheng Zheng,Jiefei Zhou,Zhen Huang
Developing low-temperature, high-efficiency ammonia decomposition catalysts for hydrogen production is essential for the broad application of hydrogen. This study conducted a systematic investigation of Ru/MgO catalysts modified with different alkali metals (Na, K, Cs), unveiling the impact of these modifications on catalyst performance and developing a highly efficient low-temperature ammonia decomposition catalyst. The addition of all alkali metals enhances the catalytic performance of Ru/MgO for ammonia decomposition, especially the addition of K, which results in the optimal enhancement of the catalyst, achieving a 75% ammonia decomposition efficiency at 350 °C (GHSV= 2,000 mL/h·gcat), more than doubling the performance of the unmodified Ru/MgO catalyst. The study revealed that the addition of potassium (K) altered the rate-determining step of the ammonia decomposition reaction from nitrogen recombination to the dissociation of the first hydrogen atom, and reduced the overall energy barrier required for the reaction. This facilitated the desorption of nitrogen from the Ru surface and the conversion of NH3, thereby accelerating the rate of the ammonia decomposition reaction.
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Surfaces and Interfaces
·
2024
·
IF 5.7
Binbin Wu,Chaorui Xue,Chi Zhang,Jinfang Zhang,Qing Chang,Caihong Hao,Lei Liu,Ning Li,Xiangqian Fan,Shengliang Hu
At present, the limited efficiency in ammonia generation poses significant challenge to the widespread practical implementation of photocatalytic nitrogen reduction to ammonia (PNRN). In this study, we synthesized a nanoporous TiO x powder (Alloy-RTO) by rapid breakdown anodization of TA13 alloy and subsequent magnesiothermic reduction. The Alloy-RTO exhibited superior photothermal and photocatalytic properties owing to its multicomponent and interconnective nanoporous structure, and the electronic band structure is suitable for efficient PNRN. Notably, through synergistic integration of PNRN with solar-driven interfacial water evaporation technology (SDIWE), the ammonia production rate was further enhanced, and a multifaceted role of SDIWE in enhancing PNRN was proposed: (1) increasing temperature of Alloy-RTO to promote PNRN; (2) raising temperature to accelerate ammonia water decomposition and facilitate PNRN; and (3) generating plenty of gaseous water to accelerate PNRN. This study presents an effective strategy for preparing nanoporous TiO x and highlights the pivotal role of SDIWE in promoting PNRN.
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MICROCHEMICAL JOURNAL
·
2024
·
IF 4.9
Mingjun Sun,Kuan Ding,Yujie Lu,Xiaopeng She,Yi Chen,Mengqing Wang,Cheng Zou,Xiaoyu Liu,Yong Zhou
Of diverse NH 3 gas-detection strategies applied in the fields of individual healthcare and industrial production, chemiresistive gas sensors gain the most popularity owing to the superior merits of low cost, convenient signal processing and high sensitivity. However, severe challenges still exist such as elevated operation temperature (>200 °C), limited sensitivity and unsatisfactory selectivity especially under low-concentration and high-humidity conditions. To overcome these hindrances, a sensing layer of black phosphorus nanosheets (BP)-modified α-MoO 3 nanoflakes was prepared in this work. After subtle optimization of ingredient composition and operation temperature, the composite sensor S2 could recognize NH 3 gas with the concentration spanning from 0.4 to 25 ppm at 40 °C. In particular, a larger mean response (27 % vs. ∼ 2.3 %) with a response/recovery speed of 275/388 s toward 10 ppm NH 3 and lower detection of limit (LoD, 0.4 ppm vs. 10 ppm) was achieved with respect to pure BP counterpart. In addition, excellent repeatability, selectivity, long-term stability and humidity-tolerant features were demonstrated for Sensor S2 . The improved sensing performance after α-MoO 3 incorporation was primarily ascribed to abundant p-n heterojunctions, excellent conductivity of BP and hydrophilic MoO 3 that mitigated the water corrosion effect on susceptible BP nanosheets. This work offers an alternative strategy for sensitive and low-temperature NH 3 detection, and well cater for the demanding requirements of high sensitivity and low-power consumption in the field of novel gas sensors applicable in the future Internet of Things and exhaled breath-oriented medical diagnosis.
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RESEARCH ON CHEMICAL INTERMEDIATES
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2025
·
IF 3.5
Hu Lan,Zhao Qiuyue,Zhang Xinling,Li Huipeng,Bian Cheng,Zeng Yiqing
Redox sites and acidic sites are the main active sites of bimetallic oxide catalysts used for selective catalytic oxidation of NH 3 (NH 3 -SCO). In this work, three MMoO x (M = Cr, Fe, and Mn) bimetallic oxides catalysts were prepared by simple grinding and calcination to investigate the effect of redox sites (M sites) on the NH 3 -SCO performance. The NH 3 -SCO test results showed that the activity of MMoO x is in the order of CrMoO x > MnMoO x > FeMoO x . The characterization results of H 2 -TPR, O 2 -TPD, NH 3 -TPD, and in situ DRIFTS proposed that the NH 3 -SCO reaction on MMoO x catalysts is proceed via i-SCR mechanism, and the formation of the intermediates of NH 3 -SCR reaction is the decisive reaction step. Owing to the excellent ability in promoting the formation of nitrate/nitrite species, CrMoO x and MnMoO x samples show much higher NH 3 -SCO activity than FeMoO x sample . CrMoO x can facilitate the formation of a large amount of –NH 2 species, which together with nitrate/nitrite species enhance the NH 3 -SCO reaction via i-SCR reaction route. Therefore, CrMoO x shows the highest NH 3 -SCO activity among the MMoO x catalysts. Through this work, the redox sites of bimetallic oxide catalysts are demonstrated as a vital role in inducing the formation of reaction-active intermediates, which highlight the importance of choosing the redox sites in designing NH 3 -SCO catalyst.
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CATALYSIS LETTERS
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2025
·Vol. 155
·期 10
·322
·
IF 2.4
Li Xuewen,Li Yaru,Wang Menglin,Wang Can,Jing Wenxian,Fang Lisheng,Hu Yonghua,Liang Yundong,Wang Xianbiao
Manganese oxides (MnO x ) catalysts are promising for low-temperature ammonia-selective catalytic reduction (NH₃-SCR), however, the limited N₂ selectivity and the narrow operational temperature range remain challenges. To address these issues, we developed a method involving impregnation doping and high-temperature calcination to hybridize Mn₂O₃ with iron lattice and oxide. This hybrid catalyst maintains a NO x conversion rate above 90% within the broad temperature window of 175–300 °C, while achieving N₂ selectivity above 99%. The as prepared Fe-Mn (0.15) exhibits spherical morphology with Fe and Mn uniformly distributed. Through XPS, XAFS, H₂-TPR, NH₃-TPD and catalytic activity tests, we verified that lattice iron doping slightly reduces the reducibility of the catalyst and enhances low-temperature activity (100–200 °C) by increasing Lewis acid sites. Meanwhile, the Fe₂O₃ domains promote high-temperature performance (200–300 °C) by enriching surface oxygen species and Bronsted acid sites. These synergistic effect regulates both the acidic and redox properties of the catalyst, facilitating NH 3 activation while suppressing over-oxidation, leading to superior NH 3 -SCR performance. Furthermore, in situ DRIFTS measurements confirmed that the reaction proceeds predominantly via a Langmuir-Hinshelwood (L-H) mechanism. This work reveals the synergistic effects of Fe lattice doping and Fe₂O₃ composite on MnO x , offering new insights for developing advanced low-temperature catalysts. Graphical
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PROCESS SAFETY AND ENVIRONMENTAL PROTECTION
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2025
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IF 7.8
Wenjing Liu,Mingyue Kou,Shan Yang,Peng Cao
The development of low-temperature selective catalytic reduction (SCR) denitrification catalysts suitable for high-moisture flue gas environments remains a significant challenge, with the research gap regarding monolithic catalysts particularly hindering practical applications of this technology. In this study, the prepared Fe-Mn-Ce/Al 2 O 3 monolithic catalyst maintained a denitrification efficiency of 73.6 % even under 16 vol% water vapor conditions, meeting industrial requirements. This study reveals that the influence of H 2 O on the denitrification reaction exhibits a distinct concentration dependence: at low water content (< 8 vol%), inhibition primarily occurs through competitive adsorption with reactants for active sites. At high water content (> 8 vol%), H 2 O significantly reduces the surface active oxygen concentration, leading to impeded re-oxidation of the metal active sites, which consequently results in a decline in redox cycle efficiency. This is considered the primary reason for the reduction in denitrification performance under high-humidity conditions. This study provides an important theoretical foundation for the development of low-temperature denitrification catalysts suitable for high-moisture industrial flue gas conditions.
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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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Journal of Materials Chemistry A
·
2019
·Vol. 7
·期 36
·20945-20951
·
IF 10.733
Xue Zhao,Chen Yao,Hao Chen,Yunfan Fu,Changjun Xiang,Suhang He,Xiaohai Zhou,Haibo Zhang
Ammonia has been obtained from the Haber–Bosch process for decades, which requires an unendurably high temperature and high pressure. Alternatively, electrochemical conversion of N2 to NH3 turns out to be a promising method with much lower energy consumption and accessible reaction conditions. In this work, a novel nano-gold catalyst supported on a boron organic polymer (Au/M-BOP) was prepared and achieved both excellent ammonia yield and faradaic efficiency at low potential (r(NH3): 45.54 μg h−1 cm−2 or 75.89 μg h−1 mgcat.−1 FE: 10.35%), results that are close to the top of the pyramid compared to published literature results. Moreover, the catalyst is conveniently accessible through a pre-immobilized in situ reduction, and can maintain its electrocatalytic activity for multiple uses, which could have potential implications in the industrialization of the electrocatalytic production of ammonia.
研究领域:
材料科学
·
电化学
·
催化化学
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PHYSICAL CHEMISTRY CHEMICAL PHYSICS
·
2018
·Vol. 20
·期 35
·22744-22752
·
IF 3.906
Yiqing Zeng,Yanan Wang,Shule Zhang,Qin Zhong
In this paper, black TiO2 without adding active components was developed for NH3-SCR-DeNOx. The catalytic activity tests showed that the NO removal efficiency of black TiO2 was always greater than 90% at 330–390 °C, which almost reached that of the commercial NH3-SCR-DeNOx catalyst. XRD, UV-vis, TG, EPR, XPS, H2-TPR, DFT and NH3-TPD analyses were carried out to study the structure–effectiveness relationship. We found that a large number of oxygen vacancies were formed over the black TiO2 surface. It was not only promoted the adsorption of NH3via direct (oxygen vacancies as Lewis acid sites for NH3 adsorption) and indirect (oxygen vacancies promote the formation of surface hydroxyl groups, which are Brønsted acid sites for NH3 adsorption) forms, but also improved the redox properties by promoting the reduction of Ti4+ to Ti3+. These changes lead to the superior catalytic activity of black TiO2 for NH3-SCR-DeNOx. Additionally, an in situ DRIFT study demonstrated that the NH3-SCR-DeNOx reaction over black TiO2 occurred via the Eley–Rideal (E–R) mechanism. Finally, the catalytic stability and resistance to H2O and SO2 of the black TiO2 catalyst were studied, and it showed good performances. This study offered new and important insights into the understanding of the role of oxygen vacancies in determining the physical and chemical properties of catalysts.
研究领域:
环境催化
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材料科学
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物理化学
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大气污染控制
·
表面科学
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CHEMICAL ENGINEERING JOURNAL
·
2017
·
IF 6.216
Hailong Li,Weilin Zhang,Jun Wang,Zequn Yang,Liqing Li,Kaimin Shih
Simultaneous nitrogen monoxide (NO) reduction and elemental mercury (Hg 0 ) oxidation in the presence of ammonia (NH 3 ) was for the first time studied on a copper oxide/titanium dioxide (CuO/TiO 2 ) catalyst at low flue gas temperatures. More than 80% NO reduction and 90% Hg 0 oxidation were concurrently achieved on the CuO/TiO 2 catalyst at 250 °C under a simulated NH 3 selective catalytic reduction (SCR) atmosphere. NO was likely oxidized on the CuO/TiO 2 catalyst to form active nitrogenous species, particularly with the aid of oxygen. The active nitrogenous species then significantly promoted Hg 0 oxidation. NH 3 itself did not affect Hg 0 conversion on the CuO/TiO 2 catalyst. The co-occurrences of NO and NH 3 led to a reduction in oxidized mercury (HgO in this work), which partially offset the Hg 0 oxidation and therefore resulted in a relatively lower Hg 0 conversion efficiency. However, compared to flue gas without NO and NH 3 , the combined presence of NO and NH 3 still enhanced Hg 0 oxidation over the CuO/TiO 2 catalyst, primarily because of the overwhelming benefit from NO. This is superior to many other SCR catalysts, including commercial vanadia-based SCR catalysts, on which an SCR atmosphere generally inhibits Hg 0 conversion.
研究领域:
环境催化
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大气污染控制
·
化学工程
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材料科学
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环境化学
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工业生态学
·
能源与环境技术
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