Nanoscale
·
2014
·Vol. 7
·期 6
·2568-2577
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IF 6.739
Mingying Qiu,Sihui Zhan,Hongbing Yu,Dandan Zhu,Shengqiang Wang
Ordered mesoporous MnCo2O4 nanomaterials were successfully prepared through the nanocasting route using SBA-15 and KIT-6 as hard templates. These mesoporous nanomaterials were characterized using XRD, BET, TEM, NH3-TPD, H2-TPR, NO-TPD, XPS and DRIFT. The low temperature selective catalytic reduction (SCR) activity of NO with NH3 was investigated, which revealed that 3D-MnCo2O4 using KIT-6 as a template can totally clean all NO over a wide temperature range of 100–250 °C with a gas hourly space velocity (GHSV) of 32 000 h−1, while 2D-MnCo2O4 with SBA-15 as a template had 95% conversion rate at the same condition. 3D-MnCo2O4 showed the best performance to clean NO due to its typical three-dimensional porous structure, large specific surface area, abundant active surface oxygen species and Lewis acid sites. All the results indicate that a novel, cheap catalyst for catalytic removal of NO can be designed by controlling the morphology at the nanoscale.
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JOURNAL OF ENVIRONMENTAL MANAGEMENT
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2025
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IF 8.4
Xinyuan Ma,Haobo Bai,Guoxue Li,Lingling Li,Haofeng Meng,Yan Liu,Jing Yuan
In order to reduce N 2 O emissions during composting, the effects of different nitrification inhibitors (NI), dicyandiamide (DCD) and 3,4-dimethylpyrazole phosphate (DMPP), on compost maturity, N 2 O, and NH 3 emissions were studied under continuous incremental addition. This study used pig manure and corn straw as composting materials, based on the total nitrogen (TN) content of the initial mixture, two treatments were set: DCD (2.5% in the early phase and 5.0% in the maturation phase) and DMPP (0.25% in the early phase and 0.75% in the maturation phase) in a composting experiment. The results showed that adding DCD and DMPP did not affect the compost maturity, with the seed germination index (GI) of final compost reaching 80.76%–97.06%. Before the maturity period of compost, ammonia (NH 3 ) emissions accounted for 98.5%–99.4% of total emissions. Compared with the control group (CK), the addition of DCD and DMPP in the early stage reduced NH 3 emissions by 8.85% and 12.83%, respectively, by decreasing the ammonification rate. During the mature stage of composting, N 2 O emissions account for 95.6%–98.9% of the total emissions. The addition of DCD and DMPP delayed N 2 O emissions by 4 and 6 days, respectively, through nitrification inhibition. The DMPP amendment also reduced cumulative N 2 O emissions by 54.50% and increased the nitrogen content of the final compost. Correlation analysis showed that N 2 O was mainly originated from the denitrification of nitrification substrate (NO 2 − -N and NO 3 − -N). This study provides technical support for low-carbon management of agricultural waste.
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CHEMICAL ENGINEERING JOURNAL
·
2022
·
IF 16.744
Rui Li,Xiangqiong Jiang,Jiecheng Lin,Zhiping Zhang,Qintong Huang,Guangying Fu,Yujun Zhu,Jiuxing Jiang
SSZ-16 zeolite with AFX topology was synthesized by hydrothermal method using 1,4-diazabicyclo[2.2.2]-octane-C4-diquat dibromide as organic structure directing agent. Cu x -SSZ-16 catalysts were prepared by exchanging SSZ-16 zeolite with Cu and applied for selective catalytic reduction (SCR) of NO x with ammonia. Among these catalysts, Cu 2.2 -SSZ-16 performs the best SCR denitration (deNO x ) performance that above 90% NO x conversion can be achieved at 175–600 °C. Especially, the influences of the hydrothermal aging at various temperatures (650, 750 and 850 °C) on active species and AFX framework of the Cu 2.2 -SSZ-16 catalyst are investigated in detail by various characterization methods including XRD, SEM , H 2 -TPR, NMR, UV–vis-DRS, EPR, NH 3 -TPD and in situ DRIFTS . Cu 2.2 -SSZ-16 still shows good NH 3 -SCR activity after hydrothermal aging at 650 and 750 °C due to more Cu 2+ -2Z species in the sample. Still, obvious deactivation can be observed after hydrothermal aging at 850 °C because of the collapse of AFX skeleton and the weak interaction between active Cu species and the skeleton. Nevertheless, Cu 2.2 -SSZ-16 is a competitive candidate for NH 3 -SCR deNO x reaction in practical applications.
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APPLIED SURFACE SCIENCE
·
2024
·
IF 6.3
Chen Yang,Hongyan Zhang,Haiyang Zhang
A high-performance ammonia (NH 3 ) gas sensor based on Au nanoparticles (AuNPs) modified CdS (Au/CdS) was synthesized by hydrothermal method, and the sensing mechanism of Au/CdS was studied by first-principles based on density functional theory (DFT). Experimental results show that the addition of AuNPs can effectively enhance CdS-based NH 3 gas sensor performance. Au/CdS sensor exhibits high response (16580), short response/recovery time (2.25 s/1.25 s), and low limit detection (500 ppb), good repeatability and stability. Because AuNPs can effectively increase the generation of sulfur vacancies on the surface of CdS, increasing the amount of chemisorbed oxygen and providing more active sites for NH 3 . Furthermore, the good conductivity of AuNPs promotes the separation and transport of carriers on CdS surface, thereby improving the gas sensing performance. DFT calculations indicate that the ionization energy of Au is less than that of Cd, which causes some Cd atoms to lose their coordination with S atoms and increase sulfur vacancies on the surface of CdS. In Au/CdS sensors, sulfur vacancies accelerate the cleavage of NH 3 , and resulting electrons participate in charge transport, thereby enhancing the adsorption energy. This study introduces a new method for fabricating high performance NH 3 sensor based on CdS rich in sulfur vacancies.
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SEPARATION AND PURIFICATION TECHNOLOGY
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2024
·
IF 8.1
Kai Zong,Dongshun Deng
In this study, we proposed a robust and efficient accelerator-silicic acid (SA) to support metal chlorides (MCl x ) as adsorbents for NH 3 adsorption and separation. Their structures and NH 3 adsorption performance were systematically investigated. Results revealed that SA with abundant hydroxyl group could dissociate and immobilize MCl x to realize synergistic M x + –NH 3 coordination and Cl - –NH 3 hydrogen bonding. Meanwhile, the interactions between the MCl x and SA significantly reduced the desorption energy of the adsorbent. The outstanding LiCl-3@SA composite demonstrated remarkable NH 3 adsorption capacity of 17.20 mmol NH 3 /g-adsorbents at 30 °C and 1.0 bar and adsorption enthalpy of −50.23 kJ/mol. Present work provided valuable information on deep understanding of MCl x −porous support interactions and strategy to design efficient composites for NH 3 capture.
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Journal of Environmental Chemical Engineering
·
2025
·
IF 7.2
Xiteng Yan,Xiaohan Chen,Runping Ye,Jingwen Tao,Gang Feng,Feiyang Hu,Honglin Hu,Claudia Li,Kang Hui Lim,Tao Wen,Yuan Wang,Xinhao Li,Rongbin Zhang,Sibudjing Kawi
Ammonia (NH 3 ) decomposition is a practical approach to overcome the challenges associated with hydrogen storage and transportation. The choice of catalyst and understanding the catalytic mechanism are key factors in optimizing H 2 production by NH 3 decomposition performance. In this work, a series of alkali metal-doped Fe-based catalysts were synthesized via a solvothermal method, and the formation of Fe x N active phases was systematically investigated. The Fe-based catalysts were pretreated under different atmospheres (H 2 , NH 3 , and N 2 ), followed by comprehensive characterization using BET, XRD, SEM, NH 3 -TPD, XPS, and other techniques. The optimized catalytic activity for NH 3 decomposition was attributed to the formation of Fe x N active phases, and the formation pathway of Fe x N active phases and their catalytic promotion mechanism were further elucidated through XRD, NH 3 -TPD-MS, and XPS analyses. Significantly, catalysts treated with pure NH 3 exhibited an increase in the electron density of Fe species and a decrease in the apparent activation energy. The incorporation of alkali metal doping further amplified this effect, ultimately leading to enhanced hydrogen production performance from NH 3 decomposition. This work underscores the critical function of the Fe x N active phase in facilitating efficient NH 3 decomposition for hydrogen generation, offering invaluable insights into the development of sophisticated alkali metal-doped Fe-based catalysts.
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npj Flexible Electronics
·
2025
·Vol. 9
·期 1
·1-11
·
IF 15.5
Liu Kai,Xu Yifan,Tian Xiaozhu,Liang Junxuan,Zhao Zhihui,Wang Jun,Zhang Ziqi,Zhang Kewei,Yang Song
Aiming at the poor selectivity of electrically conductive metal-organic framework (EC-MOF) chemoresistive materials, this study develops a breakthrough room temperature ammonia (NH 3 ) sensor by stacking ionically conductive MOF (IC-MOF) on an environmentally friendly biofabric. The synergism between ionic conductivity, tailored metal-nitrogen interaction, and fabric porosity enables the sensor with high response ( R 0 / R g = 14.7 towards 1 ppm NH 3 ), low detection limit (36 ppb), and remarkable selectivity (coefficient >5.12 against common organic interferents). Notably, the optimized sensor yields a sixfold enhancement in response as compared with traditional EC-MOF powders. A linear regression model validated by fivefold cross-validation achieves 98.4% accuracy in NH 3 concentration prediction, while the kNN classifier shows 96% accuracy in gas identification (tested on 192 samples). Preliminary clinical tests show that the sensor can clearly differentiate the exhaled NH 3 signals of four patients with HE from those of healthy individuals, demonstrating the potential for non-invasive diagnostics.
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CHEMICAL ENGINEERING SCIENCE
·
2025
·
IF 4.3
Zhenwen Yang,Ben Niu,Xiaoxiao Duan,Zheng Wei,Ziyi Shui,Guoxia Jiang,Fenglian Zhang,Zhengping Hao
Supported metal catalysts play a pivotal role in heterogeneous catalysis. However, supported metal species tend to aggregate and grow into large particles during thermal treatment owing to weak metal-support interaction, leading to unsatisfactory catalytic performance for many important catalytic reactions (e.g·NH 3 decomposition). Here we report that tailoring the surface chemistry of SiO 2 by amino-functionalization can effectively enhance the interaction with Ni species, yielding well dispersion of Ni nanoparticles since the strong interfacial bonding restricts the migration and aggregation of metal atoms. Upon support functionalization, the chemical environment of Ni species is also modified, which induces remarkable electronic metal-support interaction. As a result, more Ni 0 sites are exposed, favoring the adsorption of NH 3 and the desorption of N 2 . In addition, the amino ligands can help with the storage and transfer of H atoms from the metallic surface of Ni, resulting in favorable H 2 desorption. All of these effects contribute to superior activity. By contrast, the pristine SiO 2 surface is not suitable for anchoring Ni species due to the weak Ni-SiO 2 interaction. The sintered Ni catalyst after thermal treatment suffers from drastic loss of active surface area and displays poor activity. This work proposes a simple strategy for designing well-dispersed metal catalysts and provides insights into the effects of metal-support interaction on the structure and function of metal catalysts.
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Journal of Environmental Chemical Engineering
·
2025
·
IF 7.2
Tengfei Xu,Qingcai Chen,Huan Liu,Tong Sha,Wenhao Liu,Jingwen Cheng,Yukun Hu
Polyaniline (PANI) is one of the most potential materials as ammonia (NH 3 ) gas sensors owing to its reversible protonation and deprotonation nature. However, the detection limit and reversibility of pristine PANI nanomaterials need to be further improved to meet the requirements for high performance sensors under the premise of lower energy consumption and safety conditions in various fields. A trace sensor for NH 3 based on coral-like pristine PANI nanorods was successfully tailored via modified chemical oxidation polymerization. The distinctive coral-like structure of PANI nanorods facilitates the generation of more reactive active sites and interconnected carrier transport channels, which contribute to the performance of the sensor. The PANI sensor exhibits a sub-ppm detection limit (36 ppb) for NH 3 at 24 ℃, in addition to a favorable selectivity and excellent long-term stability properties. Furthermore, it was observed that the application of high relative humidity treatment facilitated the removal of the ammonium salts that had accumulated on the surface of the reacted PANI sensors, thereby restoring the fixed resistance to its initial value. The feasibility of the application of this sensor was demonstrated through monitoring the spoilage of fresh shrimp by means of an integrated circuit system. The findings demonstrated that the synthesized pristine PANI sensor exhibited notable advantages, rendering it a viable option for practical applications in the detection of NH 3 .
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ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2024
·
IF 0
You Mengyun,Wu Shufeng,Feng Xiaotong,Zhao Yong,Wang Yubin,Zhang Zhang
The enhancement effect of Ce modification on V 2 O 5 -WO 3 /TiO 2 catalysts at low temperatures was investigated for the selective catalytic reduction (SCR) of NO x with NH 3 (NH 3 -SCR). By adding 9% CeO 2 to 0.5%V 2 O 5 -3%WO 3 /TiO 2 catalyst, the low-temperature denitrification performance of Ce 9 V 0.5 W 3 Ti catalyst after Ce modification was significantly improved, achieving a NO conversion above 90% within a broad temperature range of 200–350℃, with catalytic activity comparable to that of 3% V 2 O 5 -3% WO 3 /TiO 2 . The catalysts were characterized by XPS, H 2 -TPR, NH 3 , and NO-TPD. The results indicated that the Ce additive could enhance the adsorption of NO x on Ce 9 V 0.5 W 3 Ti catalyst due to the synergetic interaction among the Ce and V, W species. The interaction between V and Ce also promoted the formation of V 5+ and Ce 3+ on the surface of the catalyst, which was conducive to enhancing the adsorption and oxidation capacity of the catalyst for NO. Additionally, the introduction of Ce led to a substantial deposition of nitrate species on the surface of the catalyst, especially the increase of nitrite species, which was beneficial to the NH 3 -SCR reaction process, resulting in a significant enhancement of the catalyst’s low-temperature catalytic activity.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2025
·
IF 3.9
Jinfeng Chen,Qingze Zhang,Yuanhong Zhong,Zhaoying Wang,Yakun Guo,Ming Sun,Lin Yu
To address the limitations of molecular sieves and metal oxides in the NH3-SCR of NOx, we synthesized a novel hybrid catalyst by integrating FeNbCe metal oxides with Cu-SSZ-13. The FeNbCe comodification significantly enhanced the low-temperature performance and sulfur resistance of Cu-SSZ-13 while maintaining 100% N2 selectivity across a broad activity window. The incorporation of Fe, Nb, and Ce reduced weak-acid and Lewis-acid sites while increasing strong Brønsted-acid sites, crucial for catalytic activity. The FeNbCe/Cu-SSZ-13 catalyst exhibited an enhanced surface oxygen content and redox capacity, promoting the “fast SCR” pathway and improving N2 selectivity at low temperatures. The FeNbCe oxides synergistically reacted with SO2, protecting Cu2+ active sites from sulfur poisoning and maintaining 100% NOx conversion for 4 h after SO2 introduction, maintaining 85% within 24 h. In situ DRIFTS characterization confirmed the dominance of the Langmuir-Hinshelwood (L-H) mechanism. The FeNbCe modification represents a significant advancement in the field of NH3–SCR catalysis, offering a practical and effective solution to enhance the performance of Cu-SSZ-13 while addressing key challenges such as sulfur resistance and low-temperature activity.
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APPLIED CATALYSIS A-GENERAL
·
2025
·
IF 4.8
Zhenhua Ji,Shijing Xie,Hao Chen,Peng Zhang,Ding Luo,Yixuan Chai,Zhuo Wang
Aiming at the key issues of current vehicle Ammonia Slip Catalyst (ASC) catalysts, such as poor low-temperature activity, high noble metal content, and narrow operating window, this study aims to construct multi-scale pore structures in Al 2 O 3 supports of supported catalysts to regulate selective catalytic oxidation of NH 3 (NH 3 -SCO) across broad temperature ranges and space velocities by improving convective diffusion, conduction, migration, and adsorption processes within catalyst voids. Characterization results show that a series of catalyst supports with different pore structures was successfully prepared using different templates. Pt was loaded using an optimized supported catalyst preparation method. Meanwhile, the coating amount of the prepared catalyst on cordierite monolith substrates was significantly reduced, and NH 3 -SCO performance tests were conducted. The results indicate that single mesoporous structures have limited regulation on the intrinsic activity of catalysts, while macroporous structures enhance the influence of desorption and void diffusion of gas-phase reactants and products on catalytic reactions. In the presence of macroporous structures, the promotional effect of mesopores on NH 3 -SCO reactions is enhanced. Among all catalysts, hierarchical porous catalysts with larger pore diameters and better interconnected pore structures exhibit NH₃ conversion rates exceeding 99 % across the full temperature range of 200℃ - 500℃, with NH 3 concentrations below the regulatory limit of 10 ppm throughout the operating window. Macroporous structures and their pore diameters play a dominant role in regulating NH 3 -SCO reactions, particularly with stronger regulation at low temperatures. Increasing space velocity enhances the diffusion rate of NH 3 gas molecules while amplifying the influence of pore structure regulation on catalysts. Notably, compared with traditional Pt/Al 2 O 3 , pore structure regulation does not significantly increase the generation of N 2 O while effectively enhancing the catalytic activity of the ASC catalyst.
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