CHEMICAL ENGINEERING JOURNAL
·
2022
·
IF 16.744
Yanke Yu,Desheng Wei,Zhaojian Tong,Jinxiu Wang,Jinsheng Chen,Chi He
Ammonia (NH 3 ) is a critical component causing environmental problems like haze and water pollution. Selective catalytic oxidation of ammonia (NH 3 -SCO) to N 2 and H 2 O is a promising method to abate NH 3 emission. However, inferior SO 2 tolerance is still a tremendous challenge to be conquered for present NH 3 -SCO catalysts regarding practical applications. Application of materials which was difficult to be sulfated by SO 2 should be an effective way to solve this problem. Here, a ReO x -CuSO 4 /TiO 2 catalyst which coupled the advantages of ReO x (Rhenium oxides, supplying highly active adsorbed surface oxygen enhancing NH 3 -SCO reaction) and CuSO 4 (providing Brønsted acid sites inhibiting the formation of N 2 O) was rationally fabricated. Results indicated that ReO x -CuSO 4 /TiO 2 catalyst exhibited excellent catalytic performance in NH 3 -SCO with almost 100% of NH 3 oxidized at 300 °C (N 2 selectivity as high as 96%). Crucially, the composite catalyst exhibited incredible activity and stability under harsh reaction conditions toward SO 2 (600 ppm) and H 2 O (4.0 vol%) owing to the superior inhibition capability for SO 2 adsorption. In situ DRIFTS, in situ Raman and in situ XPS demonstrated that the NH 3 -SCO reaction over ReO x -CuSO 4 /TiO 2 catalyst mainly obeyed a N 2 H 4 reaction mechanism and oxidation–reduction circle between Re 7+ and Re 6+ played a vital role. Moreover, SO 2 would not affect this reaction mechanism on ReO x -CuSO 4 /TiO 2 catalyst. The knowledge and understanding reported could provide critical insights for the design and optimization of efficient materials for industrial NH 3 oxidative elimination.
研究领域:
催化化学
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环境科学
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材料科学
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DOI
高影响因子
ACS Catalysis
·
2023
·
IF 12.9
Yanfei Liu,Zhang Liu,Chengxiong Wang,Jie Xu,Jianping Ai,Xiao Liu,Aimin Zhang,Yunkun Zhao,Chun Du,Bin Shan
Supported Pt catalysts suffer from low reaction selectivity (<65% at 100% conversion) in the selective catalytic oxidation of ammonia (NH3-SCO) because of their intrinsic over-oxidation tendencies. Herein, a strategy based on facilitating byproduct NOx reduction to N2 is demonstrated at CuOx/PtCu catalysts, aiming to tackle the low selectivity challenge. This PtCu alloy sample with a CuOx-rich surface displays an N2 selectivity of 95%, while its turnover frequencies are the highest among reported supported Pt-based catalysts. The enhanced reaction activities and N2 selectivities are primarily attributed to the Pt-Cuδ+ dual-site synergies at the CuOx/PtCu interface, in which dual sites exhibit distinct NH3 adsorption, activation, and dehydrogenation behaviors. The Olat assisted internal selective catalytic reduction mechanism at CuOx/PtCu with N2O22– as the central intermediates is proposed. Density functional theory calculation and temperature-programmed surface reaction measurements show that the N–O bond in N2O22– tends to break simultaneously with the assistance of Ov in CuOx followed by the easy transition from N2O22– to N2, which serve as the origin of the high selectivity.
研究领域:
催化化学
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环境科学
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材料科学
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DOI
高影响因子
NEW JOURNAL OF CHEMISTRY
·
2022
·Vol. 46
·期 43
·20777-20785
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IF 3.925
Yanke Yu,Mengqiao Geng,Desheng Wei,Chi He
Selective catalytic oxidation of NH3 (NH3-SCO) is a promising method to reduce NH3 pollution. The Pt-based catalysts exhibited excellent activity in the NH3-SCO reaction under low temperatures. However, it was easy for the NH3 to be oxidized to N2O and NOx (NO and NO2) over the Pt-based catalyst, causing a low N2 selectivity. The CuSO4, which could supply both Brønsted and Lewis acid sites on the catalyst, was used to promote N2 selectivity. The N2 adsorption–desorption, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), inductively coupled plasma mass spectrometry (ICP-MS), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), NH3-temperature programmed desorption (NH3-TPD), H2-temperature programmed reduction (H2-TPR) and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) were used to characterize the catalyst. The addition of CuSO4 could suppress the formation of N2O and NOx, thus the highest N2 selectivity on the catalyst increased from 21.2% to 78.1%. An imide mechanism was the main reaction mechanism on the Pt/TiO2 catalyst. After adding CuSO4, the NH3-SCO reaction over the CuSO4-Pt/TiO2 catalyst mainly followed an i-SCR mechanism where NH3 was oxidized to N2O and NOx, and then the newly formed N2O and NOx were reacted with NH3/NH4+ adsorbed on the Lewis and Brønsted acid sites via an NH3-SCR reaction over the catalyst, and finally N2 was formed. The acid sites performed an important role in the formation of N2 and this work should provide an effective method to promote N2 selectivity in a NH3-SCO reaction.
研究领域:
催化化学
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环境科学
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DOI
高影响因子
Catalysts
·
2026
·Vol. 16
·期 8
·689
·
IF 4.5
Zhongqiang Bao,Yiwei Zhang,Zhenhua Ji,Zhenguo Li,Peng Zhang,Ding Luo,Zhanming Chen,Han Gao,Lei Zhu,Hao Chen
Supported Pt catalysts are highly active for the selective catalytic oxidation of ammonia (NH3-SCO), but their practical use is limited by poor N2selectivity and insufficient hydrothermal durability under high-temperature exhaust conditions. Herein, we report a composition-regulated high-entropy oxide interface strategy to stabilize Pt–Cu dual sites and steer NH3oxidation toward selective N2formation. A series of fluorite-type Ce-based high-entropy oxides, including CeZrLaPrYOx, CeSmLaPrYOx, and CeSnLaPrYOx, were constructed as thermally robust supports for Pt and Cu loading. Among them, PtCu/HEO-Zr calcined at 1000 °C exhibits the best NH3-SCO performance, achieving 90% NH3conversion at 260 °C while maintaining N2selectivity above 80% over a broad temperature window of 100–300 °C under a high weight hourly space velocity of 100,000 mL·g−1·h−1. More importantly, after harsh hydrothermal aging at 800 °C with 10 vol% H2O for 12 h, the catalyst shows negligible activity loss and nearly unchanged N2selectivity, demonstrating exceptional structural and catalytic robustness. Structural and surface analyses reveal that Zr incorporation optimizes the fluorite high-entropy lattice, increases oxygen vacancy concentration, promotes lattice oxygen mobility, strengthens surface acidity, and enriches active Cu2+species, thereby enhancing the interfacial cooperation between NH3activation and oxygen-assisted intermediate conversion. In situ DRIFTS further reveals that PtCu/HEO-Zr favors an Olat-assisted internal selective catalytic reduction pathway, in which adsorbed NH3is activated to -NH2species and subsequently reacts with lattice oxygen-derived intermediates to form N2O22−-like species that decompose into N2and H2O. Meanwhile, the formation of nonselective NOxand N2O products is suppressed. This work highlights high-entropy oxide-supported Pt–Cu interfaces as a promising platform for designing hydrothermally durable and N2-selective NH3-SCO catalysts.
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高影响因子
CHEMICAL ENGINEERING JOURNAL
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2022
·
IF 16.744
Yixi Wang,Wenqing Xu,Chaoqun Li,Yang Yang,Zanbu Geng,Tingyu Zhu
Gaseous ammonia (NH 3 ), especially that emitted from selective catalytic reduction with NH 3 (NH 3 –SCR) units in the atmosphere is potentially harmful to both human health and the environment. The noble metal catalytic oxidation technology placed behind the SCR unit has been considered to be a promising method for decreasing NH 3 slip. In this study, we prepared Ir/Al 2 O 3 catalysts using two different crystal structures of Al 2 O 3 (α–Al 2 O 3 or γ–Al 2 O 3 ) as supported by an impregnation method and evaluated the performance of the selective catalytic oxidation of NH 3 (NH 3 –SCO). We found that the Ir/γ–Al 2 O 3 catalyst performed better than the Ir/α–Al 2 O 3 catalysts, with 99% of NH 3 converted at 260 °C. The X–ray absorption fine structure revealed that the active species on the Ir/Al 2 O 3 catalysts are mainly oxidized IrO 2 . High–angle annular dark–field images of aberration–corrected scanning transmission electron microscopy revealed that IrO 2 species over 1 nm in diameter are beneficial for activity. In situ diffuse reflectance for infrared Fourier transform spectroscopy studies suggested that the differences in NH 3 –SCO activity were caused by the activity of reactive oxygen species, and the formation of –NH 2 may be the decisive step of the NH 3 oxidation reaction.
研究领域:
催化
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环境科学
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化学工程
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DOI
高影响因子
ACS Catalysis
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2025
·
IF 13.1
Yanfei Liu,Zhang Liu,Yi Yu,Chun Du,Jie Xu,YaoHui Dun,Chengxiong Wang,Yunkun Zhao,Aimin Zhang,Fudong Liu,Wei Li,Rong Chen,Bin Shan
Isolated atom catalysts face challenges in structure-sensitive reactions due to their oxidic electronic states and the lack of ensemble sites. A strategy employing the coupling between the coordination environment and adsorbate species is developed to overcome these limitations by constructing PtCu heteroatom ensembles, which unleashes the latent power of isolated Pt atoms for NH3–SCO reactions. Through the integrated exploration of theoretical calculations and experimental studies, we elucidate the pivotal role of structural sensitivity and isolated Pt coordination environments in shaping the electronic structure of Pt and its interaction with adsorbates. Our work reveals the Cu–Pt1–Cu atomic site as a breakthrough configuration, displaying unprecedented catalytic activity and selectivity in NH3–SCO reactions, far surpassing traditional Pt-based catalysts. Remarkably, the dispersed Cu–Pt1–Cu heteroatom ensemble achieves a turnover frequency of 0.29 s–1 at 150 °C, being the highest among Pt-based catalysts, and outperforming representative Pt1 SACs by an impressive 6 orders of magnitude, while its N2 selectivity remains above 89.7%. This heightened performance is attributed to its distinctive electronic properties, characterized by free-atom-like metallic Pt electronic orbitals embedded within a bulk like Pt1–Cun ensemble structure.
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高影响因子
FUEL
·
2026
·
IF 7.5
Zhenhua Ji,Zhongqiang Bao,Zihao Wu,Peng Zhang,Rui Yang,Ding Luo,Hao Chen
As the most effective after-treatment technology for NH 3 emission control in road vehicles, Ammonia Slip Catalyst still faces challenges such as insufficient catalytic activity and low selectivity to the reaction product N 2 . Especially, the performance bottleneck in anti-aging greatly limits the commercial application of the catalyst, and there are still research gaps. Based on this, this study aims to reconstruct the structure − activity relationship of the catalyst by directionally constructing TiO 2 with a multi − scale channel core − shell structure as the support based on introducing different contents of Pt and Cu dual active components, and to explore the regulation and improvement mechanism of the catalytic performance including anti − aging property under the multi − dimensional synergistic effect. The results indicate that by enhancing the mass transfer capability of the catalyst with three-dimensional mass transfer channels and the influence of the dual active components, Pt 5 -Cu 1 /TiO 2 with a Pt − Cu content ratio of 5:1 achieves the best catalytic activity and N 2 selectivity. The Density Functional Theory calculation results show that due to the relatively low free energy of the key intermediate HNO, the Pt content plays a dominant role in the formation of N 2 O. Based on the relatively low free energy of the key intermediate NH 2 and the sequential dehydrogenation order, the thermodynamic conditions for the N 2 formation pathway under the catalytic action of Cu are extremely favorable, with relatively small kinetic barriers. Compared with Pt, the NO X formation pathway under the catalytic action of Cu has a smooth energy decrease and is more likely to occur, but it is also affected by the complex competition in the synergistic effect of the dual active components. The 17.69 % content of Pt 4+ in the active components of the catalyst after aging is the main reason for the decline in activity. The thicker shell layer reduces the collapse of the core–shell structure at high temperatures, laying a stable structure–activity relationship foundation for maintaining high activity. The prepared Pt 5 -Cu 1 /TiO 2 still meets the emission regulation limits after aging, showing good anti-aging performance.
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高影响因子
Catalysts
·
2026
·Vol. 16
·期 7
·628
·
IF 4.5
Shiqi Ma,Haoyang Li,Yuchen Huang,Kai Sun,Yuejia Huang,Yarong Fang,Yan Du
Selective catalytic oxidation of ammonia (NH3-SCO) is a promising technology for ammonia abatement. Cu/CeO2catalysts have attracted extensive attention because of their strong metal–support interaction and favorable redox properties. However, their practical application is still limited by insufficient low-temperature catalytic activity and unsatisfactory control of by-product formation. Herein, phosphate-functionalized Cu/CeO2catalysts were fabricated to regulate surface acidity and oxygen species behavior, thereby promoting low-temperature NH3-SCO activity. The optimal Acid-Cu/CeO2catalyst achieved 90% NH3conversion at 260 °C, corresponding to a 192 °C decrease in T90compared with pristine Cu/CeO2(452 °C). Kinetic analysis showed that the apparent activation energy decreased from 125.78 to 84.70 kJ mol−1after phosphoric acid modification. In addition, Acid-Cu/CeO2maintained relatively high N2selectivity and lower NOxselectivity over the tested temperature range, indicating that phosphate modification suppresses the deep oxidation of NH3to NOxby-products. Structural and surface characterization results demonstrated that Cu species remained highly dispersed on CeO2after modification, while surface phosphate species modified the local electronic environment and redistributed oxygen species. O 1s XPS and O2-TPD results revealed that phosphate modification decreased the static surface adsorbed/defect-related oxygen fraction but improved the accessibility and mobility of labile surface/subsurface or weakly bound lattice oxygen species. Py-IR and DRIFTS results further showed that phosphate modification increased Brønsted/Lewis acidity, enhanced NH3adsorption and N-H activation, and facilitated the formation and subsequent consumption of NHx/-NHO-related intermediates under reaction conditions. This work provides insights into phosphate-mediated regulation of surface acidity and oxygen mobility and offers a strategy for designing efficient low-temperature Cu/CeO2-based NH3-SCO catalysts.
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DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
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2024
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IF 20.2
Chunxue Wang,Zhao Li,Xin Sun,Yuan Li,Lei Shi,Shunzheng Zhao,Kai Li,Ping Ning,Fei Wang
Ag-based catalysts show high activity in NH 3 -selective catalytic oxidation (NH 3 -SCO). The anchoring states of Ag species determines its valence and dispersion, thereby influencing the performance of Ag-based catalysts. Herein, we elucidated that the content and anchoring strength of the hydroxyl (OH) groups on support together affect the anchoring states of Ag. TiO 2 has few OH groups but high anchoring strength, the anchored Ag is in a highly dispersed oxidized state, while the unanchored Ag is aggregated in a metallic state (Ag 0 ), so it presents an unevenly sized dispersion and mainly in oxidized state. SiO 2 has abundant OH groups but weak anchoring, and can excessively agglomerate into large Ag 0 nanoparticles (Ag 0 NPs). Therefore, the introduction of SiO 2 can regulate the anchoring states of Ag on the TiO 2 support, making Ag presents highly dispersed Ag 0 NPs, thus following a reaction mechanism with lower energy barriers and significantly improving the NH 3 -SCO performance.
研究领域:
催化化学
·
环境科学
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产品关联
DOI
高影响因子
JOURNAL OF CATALYSIS
·
2025
·
IF 6.5
Yanfei Liu,Yanbo Pu,Chun Du,Jie Xu,Yaohui Dun,Chengxiong Wang,Yunkun Zhao,Jun Huang,Bin Shan,Rong Chen
Selective catalytic oxidation of ammonia (NH 3 -SCO) to N 2 is crucial for abating residual NH 3 emissions, but existing catalysts struggle to combine low-temperature activity with high N 2 selectivity due to competitive Pt-NO interactions. Here we design a tandem confinement catalyst by depositing sub-nanometer Pt clusters (∼0.72 nm) inside the supercages of a Cu-exchanged USY zeolite via atomic layer deposition (ALD), creating intimately paired Pt–Cu active sites. This confined Pt/Cu-USY ALD catalyst achieves >90 % NH 3 conversion and >90 % N 2 selectivity across an exceptionally broad 170-300°C window under simulated exhaust conditions, surpassing all previously reported Pt-based NH 3 -SCO catalysts. The simultaneously enhanced low-temperature activity and high-temperature N 2 selectivity of the Pt/Cu-USY ALD catalyst can be attributed to the spatial confinement of Pt clusters within the Cu-USY framework, which leads to an expanded NO desorption window (150–350 °C). Detailed in situ studies further reveal that N 2 O 4 species preferentially serve as NO storage intermediates on the Pt/Cu-USY ALD catalyst surface at low temperatures, exhibiting significantly lower formation barriers compared to free nitrates, which dominate as intermediates in conventional Pt–Cu systems. This effectively mitigates free nitrate–induced site poisoning and overcomes the typical activity–selectivity trade-offs observed in conventional Pt–Cu dual-site catalysts.
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高影响因子
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