RSC Advances
·
2017
·Vol. 7
·期 60
·37787-37796
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IF 3.108
Xuesong Liu,Xiaodong Wu,Duan Weng,Zhichun Si,Rui Ran
Cu/SAPO-34 catalysts were prepared by wet impregnation and ion-exchange methods, and both the catalysts were hydrothermally treated at 750 °C in 10 vol% H2O/air for 24 h. Subsequently, the as-received and hydrothermally treated catalysts were exposed to a sulfur poisoning treatment at 350 °C in 100 ppm SO2/10 vol% H2O/air for 24 h and examined for NOx conversion. Sulfur poisoning considerably decreased the NOx conversion efficiency of the catalysts at low temperatures. In contrast, it improved the high-temperature selective catalytic reduction (SCR) activities of the as-received catalysts. The ion-exchange-prepared catalysts displayed higher sulfur tolerance than the impregnation-prepared catalysts at 150–350 °C. The electron paramagnetic resonance, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy and H2-temperature-programmed reduction results showed that sulfur poisoning significantly influenced the migration of the copper species and thereby the amount of active isolated Cu2+. More dispersed CuSO4 was produced on the ion-exchange-prepared catalysts than on the impregnation-prepared catalysts after sulfur poisoning. The dispersed CuSO4 showed considerably higher SCR activity than the crystalline CuSO4. Both the dispersed CuSO4 and remaining isolated Cu2+ determined the low-temperature SCR behavior of the sulfur-poisoned catalysts.
研究领域:
催化化学
·
环境科学
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DOI
高影响因子
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
CHEMICAL ENGINEERING JOURNAL
·
2022
·
IF 16.744
Xiao Wang,Asad Mahmood,Guanhong Lu,Xiaofeng Xie,Jing Sun
The photocatalytic oxidation (PCO) mechanisms of single aromatic hydrocarbons/NO x gases and the synergistic photocatalytic treatment of their mixtures over TiO 2 (anatase) are proposed by analyzing the evolution of adsorbed and gas-phase intermediates through in-situ FTIR and mass-spectroscopy. Photo-activated surface lattice oxygen of TiO 2 (TiO 2 (·O L )) is found to be a strong oxidant for the PCO of both o-xylene and NO x and their consumption led to the deactivation of photocatalysts. As an important coexist air pollutant, NO is firstly discovered as a helper for the persistent ring-opening and degradation of aromatics including o-xylene, toluene, styrene and benzene. NO 2 , a PCO intermediate of NO, acts as a powerful oxidant for replenishing lattice oxygen of TiO 2 , which guarantees the continuous generation of active TiO 2 (·O L ) and prevents the deactivation of photocatalyst. With the introduction of NO, the PCO efficiency of o-xylene increases from ∼65% to 100% and no performance decay of TiO 2 happens in 6 h. The existence of aromatics prevents the escape of toxic NO 2 into air and promotes the harmless transformation of NO into nitrite/nitrate ions and N 2 . This work outlines the essential role of activation and replenishment of lattice oxygen in the PCO process by analyzing the synergistic and stable photocatalytic treatment of aromatic hydrocarbon/NO x mixtures, which explores the practical potentiality of photocatalysis in air purification.
研究领域:
环境科学
·
化学
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产品关联
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
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环境工程
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产品关联
DOI
高影响因子
RSC Advances
·
2017
·Vol. 7
·期 51
·32146-32154
·
IF 3.108
Chengkai Pang,Yuqun Zhuo,Qiyu Weng
A series of Mn-exchanged SAPO-34 catalysts were synthesized and developed as catalysts for the low temperature selective catalytic reduction (SCR) of NO with ammonia in the presence of excess oxygen. 4Mn/SAPO-34 showed the highest SCR activity in the temperature range of 120–210 °C. The microstructure of zeolite supports, acidity, manganese species and reaction mechanism were investigated in detail by BET, NH3-TPD, UV-Vis, H2-TPR, XPS and in situ DRIFTS. Mn3+ and Mn4+ related species were proved to be the active sites for the SCR reaction. The Eley–Rideal mechanism was proved to be effective on 4Mn/SAPO-34 for the low temperature SCR reaction in which coordinated NH4+ species react with gas-phase NO to form an activated transition state and subsequently decomposed to N2 and H2O.
研究领域:
环境科学
·
催化化学
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING RESEARCH & DESIGN
·
2025
·
IF 3.9
Chenhui Hu,Kaimin Du,Zuoxi Zhuo,Chunhong Liu,Hongbing Lv,Wanjue Wang
To address the challenges of efficient and safe denitrification under actual flue gas conditions of internal combustion engine, high-temperature SCR molecular sieve catalyst were prepared and evaluated both in laboratory scale and industrial scale. A comprehensive characterization via TG, XRD, N₂ adsorption-desorption, SEM, and TEM confirmed the robust thermal stability of the molecular sieves catalyst. The molecular sieve catalyst system was commissioned in a 4275 kW distributed natural gas internal combustion engine demonstration facility and successfully passed the 72 h trial running, achieving with over 94 % NO x conversion efficiency and less than 40 mg/m 3 outlet NO x concentration at a temperature range of 440–525 °C. Compared to conventional V-based catalyst, the molecular sieve catalyst not only achieved additional reductions of 2 kg/h NO x and 38 kg/h CO 2 emissions, along with a nearly 2 % improvement in internal combustion engine efficiency, but also effectively mitigated the risk of system shutdown caused by low cylinder temperatures in exhaust gas purification systems, being considered as a promising catalyst for high-temperature applications, including gas-fired, hydrogen/ammonia-fueled, and biogas internal combustion engines.
研究领域:
环境催化
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能源工程
·
污染控制技术
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2021
·
IF 3.764
Wenshuo Hu,Renzhi Zou,Yi Dong,Yu Zhang,Mingchu Ran,Qi Xin,Yang Yang,Hao Song,Weihong Wu,Shaojun Liu,Chenghang Zheng,Xiang Gao
Enhancement of the low-temperature (LT) performance of selective catalytic reduction (SCR) of NOx with NH3 has been a spotlight in environmental catalysis. Here, we use a bifunctional catalytic system mixing V–W/Ti with an oxidative component, i.e., MnOx/CeO2, to achieve both improved LT-SCR activity and N2 selectivity. An integrated approach of steady-state kinetic measurements, chemical trapping techniques, time-resolved in situ FTIR spectroscopy, and density functional theory (DFT) calculations reveals that such a synergistic enhancement is at a short distance and is significant when V–W/Ti and MnOx/CeO2 are in intimate contact. These findings further suggest a bifunctional LT-SCR pathway mediated by a short-lived, mobile nitrite-precursor intermediate, which is facilely generated on the oxidative component and then communicates with the adjacent SCR phase through reacting with the abundant NH3 adsorbates there. Assembling such a mechanism with commercial SCR catalysts, accordingly, acts as a promising way to enhance the LT-SCR performance.
研究领域:
环境催化
·
材料科学
✓ 已验证
DOI
高影响因子
TALANTA
·
2025
·
IF 6.1
Rui Yang,Luji Yang,Jiahui Yang,Zhi-ang Li,Chengbin Zheng
Pollution caused by nitrogen oxides (NO x , mainly NO and NO 2 ) has attracted considerable attention due to its negative implications on the environment and human health. Herein, a novel, portable, and battery-operated system integrating a purge and trap (P&T) system with a miniaturized point discharge optical emission spectrometer ( μ PD-OES) was developed for monitoring atmospheric NO x . Among NO x , NO 2 can be selectively and directly absorbed by sodium hydroxide (NaOH) solution and converted to nitrite (NO 2 − ). In contrast to NO 2 , NO cannot be absorbed by NaOH and must be oxidized to NO 2 by KMnO 4 prior to its absorption. When NO 2 and NO x samplers were exposed simultaneously, NO can be calculated as the difference. The concentration of NO x in the air was determined by analyzing the NO 2 − . The obtained NO 2 − solution was purged with an argon carrier gas at a rate of 400 mL min −1 for 5 min to remove all the volatile organic compounds contained in the solution before reacting with cyclamate to generate volatile cyclohexene, which was efficiently isolated and preconcentrated by P&T. Subsequently, the cyclohexene was desorbed from the P&T unit and swept into the μ PD-OES for its detection under optimized conditions. The system demonstrated a detection limit of 0.02 ppbv (0.04 μg/m 3 ) for NO 2 , surpassing conventional methods. Precision expressed as the relative standard deviation (RSD, n = 11) was better than 3.5 %. The system was validated by analyzing two NO 2 standard gases and fourteen ambient air samples, and the obtained analytical results demonstrated its promising potential for rapid, sensitive, and precise NO x evaluation and monitoring.
研究领域:
环境科学
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分析化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ATMOSPHERIC ENVIRONMENT
·
2026
·
IF 3.8
Shijie Liu,Jie Wang,Zhifei Wang,Feiyong Chen,Yusi Liu,Xiaofeng Wei,Youmin Sun,Zaifeng Wang,Guiqin Zhang
α-Pinene is a key precursor in the formation of secondary organic aerosols (SOA) in the atmosphere. SOA formation via atmospheric photooxidation of α-pinene under varying nitrogen oxides (NO x ) and ammonia (NH 3 ) concentrations was investigated in a laboratory smog chamber, with a focus on SOA mass concentration and chemical composition. The experimental results demonstrated that increasing NO x concentrations from 30 to 80 ppb reduced the α-pinene SOA yield from 15.5% to 9.0%. In contrast, the presence of NH 3 enhanced the SOA yield. The investigation revealed that the suppressive effect of NO x on SOA yield gradually weakened with increasing NH 3 concentration, whereas the promoting effect of lower NH 3 concentrations on SOA yield was more pronounced under lower NO x conditions. The chemical composition of SOA revealed that NH 3 promoted the formation of nitrogen-containing organic compounds (NOCs). Furthermore, NO x increased the abundance of nitrogen-containing functional groups within NOCs. A comparison of the volatile components of SOA indicated that the increase in volatile organic component (VOC) and intermediate-volatility organic component (IVOC) contents with increasing NO x concentration was responsible for the suppression of SOA formation. Furthermore, the enhancement of SOA yield by NH 3 was mainly attributed to the increase in IVOC and semi-volatile organic component (SVOC) contents. Overall, these results demonstrated that NH 3 and NO x exerted distinct effects on α-pinene-derived SOA formation. These findings provide valuable insights into the mechanism of SOA formation under complex pollution conditions involving the coexistence of NO x and NH 3 .
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DOI
高影响因子
Catalysts
·
2025
·Vol. 15
·期 10
·971
·
IF 4
Shaogang Wang,Pengxin Zeng,Ning Li,Yuansheng Yi,Yongsheng Qin,Xin Yu,Lei Liu,Qi Guo,Zijian Zhou
The narrow operating temperature window of commercial V-W/TiO2catalysts severely limits NOxremoval efficiency, especially during low-load boiler operations. To achieve broad-temperature NOxabatement, we developed Ce-M/Ti (M = Co, Fe, Mn, Mo) catalysts via a dual-site strategy. The temperatures required for 80% NO conversion (T80) were 302 °C for Ce-Mo/Ti, 372 °C for Ce-Fe/Ti, 393 °C for Ce-Mn/Ti, and 415 °C for Ce-Co/Ti. Among them, Ce-Mo/Ti exhibited the most favorable low-temperature activity, outperforming a commercial catalyst (324 °C). Its turnover frequency (3.12 × 10−3s−1) was 1.29 times higher. Combined physicochemical characterization and density functional theory (DFT) calculations further reveal the mechanism behind the enhanced dual-site synergy in Ce-Mo/Ti. In the Ce-Co, Ce-Fe, and Ce-Mn sites, weak orbital hybridization leads to limited charge transfer. In contrast, Ce-Mo/Ti exhibits stronger hybridization between the Ce 4f/5dand Mo 4dorbitals, which breaks the inherent limitation of the Ce-based (Ce3+/Ce4+) redox capability and enables reverse electron transfer from Mo to Ce. This distinctive electron transfer direction creates a unique electronic environment, activating an efficient redox cycle between Mo6+/Mo5+and Ce4+/Ce3+. This work offers a promising design strategy for dual-site catalysts with high NOxremoval efficiency over a wide temperature range.
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产品关联
DOI
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2025
·
IF 9.7
Pengxin Zeng,Zijian Zhou,Lei Liu,Xin Yu,Xiaowei Liu,Minghou Xu
Commercial V-W/TiO 2 catalysts are extensively applied for NO x emission control in coal-fired power plants. However, their limited operating temperature range and low active site utilisation significantly restrict NO x removal efficiency, particularly during boiler load fluctuations. This study introduces atomically dispersed Ce-V/TiO 2 catalysts synthesised using a dual-site coordination strategy, enhancing active site dispersion. This method addresses the limitations of low active site turnover frequency (TOF) and high energy barriers in rate-determining steps, resulting in an extended operating temperature range and improved NO x removal efficiency. Under identical conditions, Ce-V/TiO 2 achieved 90 % NO x conversion from 290 to 450 °C, a substantial increase over the commercial catalyst (365–425 °C). Additionally, Ce-V/TiO 2 exhibited a TOF of 3.58 × 10 − 3 s − 1 , 1.52 times higher than the commercial catalyst. Density functional theory (DFT) analysis demonstrated that Ce V synergy accelerates the Eley-Rideal rate-determining step by lowering the activation energy for NH 3 dissociation into -NH 2 , and reduces the energy barrier for -NHNO intermediate formation in the Langmuir-Hinshelwood pathway. This work overcomes poor low-temperature activity by leveraging Ce V synergy, offering a strategy for efficient NO x removal across a broad temperature range with selective catalytic reduction catalysts.
研究领域:
环境催化
·
材料科学
·
化学工程
·
理论化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
·
2025
·
IF 11.3
Junjie Jiang,Yongqi Zhao,Xue Li,Xiaolong Liu,Tingyu Zhu
Nitrogen oxides (NO x ) and volatile organic compounds (VOCs) released from industrial sources react to generate pollutants such as O 3 through photochemical reactions. In order to realize the simultaneous removal of NO x and VOCs, this work provides a reaction site-isolation (RSI) catalyst with isolated reaction zones of toluene oxidation over Cu-Ce sites and NH 3 -SCR over V-W sites, respectively. Reaction site-isolation significantly weakens the impact of competitive adsorption between different reactants and reduces the formation of by-products during the reaction. The NO and toluene conversion both reached to 100 % at 275 ℃ and the catalyst demonstrated great sulfur resistance and stability. Characterization of the catalyst revealed that the interaction between Cu and Ce promoted the formation of oxygen vacancies, while the introduction of Cu increased the adsorption sites of toluene. Notably, DFT calculation and activation energy calculation reveal that the adsorption performance of active sites for reactant and the reaction activation energy required for reactions are different. Therefore, this work achieves adsorption and reaction co-induced bifunctional catalysis by isolating active sites.
研究领域:
环境科学
·
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）