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Effects of Wo3 and Moo3 Loadings on Vanadia-Based Catalysts for Nh3-Scr: Revealed by in Situ Infrared and Two-Dimensional Correlation Spectroscopy

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SSRN 2023年

作者： Lv, Zhihui He, Guangzhi Ge, Yanli Liu, Yongchun Yu, Yunbo He, Hong State Key Joint Laboratory of Environment Simulation and Pollution Control Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing100085 China University of Chinese Academy of Sciences Beijing100049 China State Key Joint Laboratory of Environmental Simulation and Pollution Control Beijing Innovation Center for Engineering Science and Advanced Technology College of Environmental Science and Engineering Peking University Beijing100871 China Aerosol and Haze Laboratory Advanced Innovation Center for Soft Matter Science and Engineering Beijing University of Chemical Technology Beijing100029 China Ganjiang Innovation Academy Chinese Academy of Sciences Ganzhou341000 China Center for Excellence in Regional Atmospheric Environment Key Laboratory of Urban Pollutant Conversion Institute of Urban Environment Chinese Academy of Sciences Xiamen361021 China

Vanadia-based catalysts have been widely applied in NOx reduction, while the promoting effects of WO3 and MoO3 are still under debate. Herein, we prepared V2O5/TiO2, V2O5-WO3/TiO2, and V2O5-MoO3/TiO2 catalysts and revealed that WO3 and MoO3 enhanced the activity of V2O5/TiO2, especially under wet conditions. In situ DRIFTS, two-dimensional correlation spectroscopy (2D COS), and DFT calculations demonstrated that NH3 adsorbed on Lewis acid sites of V2O5/TiO2, resulting in the formation of NH3ads-L1 (1284 cm-1, Ti sites of O=V-O-Ti) and NH3ads-L2 (1604 cm-1, V=O sites). By using 2D COS, we found that the NH3ads-L1 exhibited higher reactivity towards NO to produce NH2NO* via NH2*, which was promoted by WO3. Moreover, WO3 and MoO3 doping inhibited H2O adsorption, and promoted its desorption by increasing temperature, thus protecting the V=O sites on V2O5/TiO2. Also, 2D COS provided a new perspective for in-depth understanding of the active sites and intermediates in the NH3-SCR reaction. © 2023, The Authors. All rights reserved.

关键词： Catalysts

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Stress-Resistant Plants Cyndon Dactylon in a Riparian Zone of the Three Gorges Reservoir Has Additional Nitrogen-Fixing Functions from Bacterial Endophytes

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SSRN 2022年

作者： Li, Shanze Wang, Yuchun Hu, Lechen Zhao, Jianwei Liao, Xiaolin Xie, Tian Wen, Jie Bao, Yufei Li, Longfei State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin China Institute of Water Resources and Hydropower Research Beijing100038 China Department of Water Ecology and Environment China Institute of Water Resources and Hydropower Research Beijing100038 China Laboratory of Eco-Environmental Engineering Research State Environmental Protection Key Laboratory of Soil Health and Green Remediation Huazhong Agricultural University Wuhan430070 China College of Biology and the Environment Nanjing Forestry University Jiangsu Nanjing210037 China State Key Joint Laboratory of Environmental Simulation and Pollution Control School of Environment Beijing Normal University Beijing100875 China

Water conservancy and hydropower projects have greatly altered the ecological balances in riparian zones, including nitrogen cycling. The riparian zone of the Three Gorges Reservoir is now dominated by a perennial stress tolerant plant, Cyndon dactylon, where long-term wet and dry alternation has caused severe soil nitrogen leaching. This study investigated whether this plant species employs mechanisms for enhanced nitrogen assimilation or other nitrogen compensation strategies to counter soil nitrogen loss in its habitat. Our study found for the first time that the C. dactylon in the Three Gorges Reservoir riparian zone had endophytic nitrogen-fixing bacteria, which were particularly enriched in the plant leaves. The abundance of endophytic nitrogen-fixing bacteria was significantly negatively correlated with soil ammonia, nitrate, and organic matter, and significantly positively correlated with total phosphorous and moisture content. The endophytic nitrogen-fixing bacteria in C. dactylon were highly diverse, with Proteobacteria as the main dominant genera. The mutual cooperation mode among bacterial species made the endophytic nitrogen-fixing bacteria community of C. dactylon more resilient to environmental pressure, thus were capable of more readily adapting to conditions of repeated flooding in the riparian zone of the Three Gorges Reservoir. © 2022, The Authors. All rights reserved.

关键词： Nitrogen

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Modified Lamno3 Perovskite Oxide as Nox Storage and Reduction Catalyst For Emission control of Hydrogen Internal Combustion Engines

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SSRN 2024年

作者： Zou, Yingtong Xu, Guangyan An, Yingsheng Zhang, Mengyuan Sun, Yanwei Liu, Zhi Yu, Yunbo He, Hong State Key Joint Laboratory of Environment Simulation and Pollution Control Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing100085 China University of Chinese Academy of Sciences Beijing100049 China Center for Excellence in Regional Atmospheric Environment Institute of Urban Environment Chinese Academy of Sciences Xiamen361021 China Ganjiang Innovation Academy Chinese Academy of Sciences Ganzhou341000 China

As a flagship of zero-carbon emission in transportation, hydrogen internal combustion engine vehicles alleviate global warming pressure but are still restricted by high nitrogen oxides (NOx) emission. A promising approach to reduce NOx emission is NOx storage and reduction (NSR) technique by using on-board H2 as a reductant. As the new generation of NSR catalyst, La-based perovskite oxides are plagued by small specific surface area and poor reactivity, thus restricting their usability. Here, we proposed to simply fabricate porous LaMnO3 perovskite oxide via Pechini method (PC) with the addition of pore-forming agent, Pluronic 123 (P123). The modified LaMnO3 catalyst (LMO-PC-P) obtained by PC-P method exhibited large special surface area and abundant oxygen vacancies. Such structure feature not only provided more active sites for NOx storage but also facilitated NO oxidation via forming hyponitrite (N2O22-) rapidly on defective surface in fuel-lean condition. As a result, an excellent static NOx storage capability (NSC) was achieved, with a maximum NSC value of 205 μmol/g. Over the LMO-PC-P sample, meanwhile, desorption of NOx in fuel-rich mode was promoted, thus benefiting the regeneration of active sites. In dynamic NSR test, LMO-PC-P could achieve 82% total NOx conversion with high effectiveness at 350 oC. This study presented a convenient and practical approach for preparing porous and defective NSR perovskite oxide catalysts for NOx emission control of hydrogen internal combustion engines. © 2024, The Authors. All rights reserved.

关键词： Nitrogen oxides

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Unveiling the Confinement and Interface Effect on Low Temperature Degradation of Toluene Over Mesoporous Zeolite Encapsulated Pt-Ceo2 Catalyst

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SSRN 2023年

作者： Zhang, Qiuli Yang, Senyou Zhang, Hongxiang He, Tianyao Liu, Wenming Sun, Xiaomin Li, Guobo Yu, Yunbo Peng, Honggen School of Chemistry and Chemical Engineering Nanchang University 999 Xuefu Road Jiangxi Nanchang330031 China School of Resources and Environment Nanchang University 999 Xuefu Road Jiangxi Nanchang330031 China Ganjiang Innovation Academy Chinese Academy of Sciences Ganzhou341000 China Environment Research Institute Shandong University Qingdao266237 China State Key Joint Laboratory of Environmental Simulation and Pollution Control China

The low-temperature efficient degradation of volatile organic compounds (VOCs) is imminent due to the serious hazards it poses to the environment and human health. Precious metal-based catalysts have excellent performance, but they are prone to sintering and aggregation at high temperatures, which limits their applications. Therefore, inhibiting the migration aggregation of precious metals during the reaction process can effectively improve the utilization of precious metals and alleviate the deactivation of catalysts. In this study, a novel encapsulated catalyst (Pt-CeO2@meso-S1) containing Pt-CeO2 interfaces was constructed by using mesoporous-rich zeolite as a shell layer and applied to the catalytic oxidation of toluene. The introduction of CeO2 constructed a Pt-CeO2 active interface to promote the low-temperature degradation of toluene, achieving complete oxidation of toluene at 160 ℃. The crystalline phase transition strategy enhanced the specific surface area, which improved the dispersion of platinum and facilitated the construction of the Pt-CeO2 interface. The zeolite shell and mesoporous pores could effectively confine/stabilize the Pt-CeO2 active components and inhibit the sintering of Pt to obtain outstanding water resistance and high-temperature stability. DFT calculations demonstrated that the presence of the Pt-CeO2 active interfaces reduces the oxygen vacancy formation energy and facilitates the activation of gas-phase oxygen. The Mars-van-Krevelen (MvK) mechanism governs the degradation of toluene over Pt-CeO2@meso-S1 was revealed by the in situ DRIFTS. This work provides a good candidate for industrial high-performance catalytic removal of VOCs at low temperatures. © 2023, The Authors. All rights reserved.

关键词： Volatile organic compounds

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The Study of Pt/Zeolites for Co Oxidation: Effects of Skeleton Structure and Si/Al Ratio

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SSRN 2023年

作者： Tian, Xudong Shan, Yulong Yu, Yunbo Zhang, Jian Yan, Zidi Sun, Yu Ding, Wenqing School of Rare Earths University of Science and Technology of China Hefei230026 China Ganjiang Innovation Academy Chinese Academy of Sciences Ganzhou341000 China State Key Joint Laboratory of Environment Simulation and Pollution Control Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing100085 China Beijing Advanced Innovation Center for Soft Matter Science and Engineering Beijing University of Chemical Technology Beijing100029 China

Effects of framework and Si/Al of Pt/zeolites on CO catalytic oxidation were investigated. CO conversion increased with decreasing pore size and increasing Si/Al. The optimized Pt/CHA with Si/Al of 17 showed the highest activity, achieving complete CO conversion below 140 °C. The large CHA cavity plays important role, which lead to higher CO conversion of Pt/CHA than Pt/BEA and Pt/MFI zeolites. Increasing Si/Al favors the presence of Pt0, which showed excellent CO catalytic oxidation ability. The framework with high Si/Al protected Pt0 from accumulating and dealumination during hydrothermal aging, resulting in high hydrothermal stability. © 2023, The Authors. All rights reserved.

关键词： Zeolites

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Identifying key Drivers of Short-Term Abnormally Low Dissolved Oxygen Concentrations at a Trans-Provincial Reservoir in the Dongjiang Headwater Watershed, China

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SSRN 2024年

作者： Yang, Kun Peng, Minggang Liu, Yuxian Zhang, Shixi Weng, Shichuang Zhong, Chao Liu, Shuaishuai Chen, Huaxiang South China Institute of Environmental Sciences Ministry of Ecology and Environment Guangzhou510655 China State Environmental Protection Key Laboratory of Water Environmental Simulation and Pollution Control Guangzhou510655 China School of Public Administration Guangzhou University Guangzhou510006 China School of Environmental Science and Engineering Guangzhou University Guangzhou510006 China Shenzhen Municipality Ecology and Environment Intelligent Control Center Shenzhen518034 China Bureau of Hydrology and Water Resources Pearl River Water Resources Commission of Ministry of Water Resources Guangzhou510611 China Ecology and Environment Bureau of Xunwu County Ganzhou342200 China

Study region: The Douyan Reservoir, South China, under a trans-provincial ecological compensation assessment *** focus: Occasional occurrences of dissolved oxygen (DO) concentrations exceeding the regulatory threshold present challenges to reservoir and river basin management. We examined factors causing short-term abnormally low DO events in the reservoir using hydrological, water quality, aquatic ecosystem, and sediment *** hydrological insights: Significant positive correlations were found between nutrient concentrations (ammonia nitrogen and total nitrogen) in the reservoir and its inflow rivers in 2021. Before abnormally low DO events in 2021, substantial total phosphorus (TP) influx from inflow rivers coincided with historically low inflow and outflow rates and peak temperatures in the reservoir. Allochthonous nutrient inputs (nitrogen and phosphorus), water temperature, and flow rates may have facilitated blooms and subsequent declines of algae, causing sudden DO declines in the reservoir. Moreover, intensified aquatic ecological monitoring in May 2021 (before pH approached its regulatory limit) indicated significant positive correlations: chlorophyll-a with DO and pH, and with total nitrogen (TN) and TP, and pH with DO. These suggest short-term abnormal events resulted from phytoplankton lifecycle activities, driven by an internal-external coupling mechanism, with continuous allochthonous TN inputs and short-term adequate TP influxes acting as primary drivers, and hydrological conditions as inducing factors. This study recommends incorporating TN into ecological compensation assessments for enhanced China’s reservoir and river basin management. © 2024, The Authors. All rights reserved.

关键词： Dissolved oxygen

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Changes of Nitrogen and Phosphorus Removal Pattern Causing by Alternating Aerobic/Anoxia from the Perspective of Microbial Characteristics

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SSRN 2022年

作者： Yao, Kai Huang, Xiao Dong, Wenyi Wang, Fupeng Liu, Xueyong Yan, Yu Qu, Yanhui Fu, Yicheng Collaborative Innovation Center of Atmospheric Environment and Equipment Technology Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control School of Environmental Science and Engineering Nanjing University of Information Science & Technology Nanjing210044 China Shenzhen518055 China Northeast China Municipal Engineering Design and Research Institute Co Ltd Jilin130021 China Urban and Rural Water Environment Technology R&D Center China Communications Construction Co Ltd Jilin130021 China China Urban and Rural Holdings Group Co Ltd Beijing100029 China State Key Laboratory of Simulation and Regulation of River Basin Water Cycle China Institute of Water Resources and Hydropower Research Beijing100038 China

To investigate the effect of alternating aerobic/anoxic (A/O) on pollutant removal performance and microbial community structure, three sequencing batch reactors (SBR) processes with different alternating A/O times were set up. The results showed that alternating A/O was beneficial for organic matter degradation and promote nitrogen (N) and phosphorus (P) removal performance, and the removal efficiencies of chemical oxygen demand (COD), ammonia nitrogen (NH4+-N), total nitrogen (TN), and total phosphorus (TP) increased 3.41%, 4.76%, 3.51%, and 6.27%, respectively. Besides, alternating A/O affected the dominant microbial community relative abundance (Proteobacteria and Bacteroidetes) and increased microbial richness and diversity. It also increased the relative abundance of aerobic denitrifying, heterotrophic nitrifying, and denitrifying phosphorus removal bacteria to change N and P removal patterns. Furthermore, the abundance of carbohydrate metabolism and amino acid metabolism were improved by alternating A/O to improve organic matter and TN removal. © 2022, The Authors. All rights reserved.

关键词： Chemical oxygen demand

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Method of Calculating Lake Water Storage in Areas without Topographical Data Based on Google Earth Engine

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IOP Conference Series: Earth and Environmental Science 2021年第1期668卷

作者： Jiajun Sun Yingjie Cui Hongbin Cao Beijing Engineering Research Center of Process Pollution Control Institute of Process Engineering Chinese Academy of Sciences Beijing 100190 China University of Chinese Academy of Sciences Beijing 100049 China China Xiongan Group Co. Ltd Xiongan New Area Hebei Province China State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin China Institute of Water Resources and Hydropower Research Beijing 100038 China

Accurate ecological lake water calculation plays an important role in maintaining ecological health of and protecting lakes. However, the lack of topographical data for the bottom of the lake results in some complexity to the calculation of ecological lake water storage. This study uses remote sensing big data to overcome the data limitations of water calculations and accurately calculates the ecological water storage of Baiyangdian Lake. The results show that the water surface area of Baiyangdian Lake can be divided into a dry period (average water area of 7.15 km2), a decline period (155.64 km2), a stable period (67.29 km2), and a recovery period (119.17 km2). The ecological water storage of the lake has evolved from 200 million m3 to the current 300–600 million m3. This study provides an important reference for the ecological lake water calculations when topographical data is not available and for lakes with complex bottom topography.

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Y-doped Cu-SSZ-13 synthesized via one-step method with superior catalytic activity and hydrothermal stability for NH 3 -SCR reaction

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Journal of Rare Earths 2024年

作者： Tao Shen Jinpeng Du Yong Yan Jianqi Liu Yanting Hu Hang Xiao Zidi Yan Yulong Shan Yunbo Yu Hong He School of Rare Earths University of Science and Technology of China Hefei 230026 China Ganjiang Innovation Academy Chinese Academy of Sciences Ganzhou 341119 China State Key Joint Laboratory of Environment Simulation and Pollution Control Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China University of Chinese Academy of Sciences Beijing 100049 China Center for Excellence in Regional Atmospheric Environment Institute of Urban Environment Chinese Academy of Sciences Xiamen 361021 China

Cu-SSZ-13 zeolite is the leading commercial catalyst for NO x purification on diesel vehicles. Although the synthesis via the one-pot method improves the preparation efficiency, the obtained Cu-SSZ-13 zeolites usually suffer from insufficient catalytic activity and limited hydrothermal stability. Our research demonstrates that doping with 0.3 wt% Y can significantly enhance both the selective catalytic reduction with NH 3 (NH 3 -SCR) performances and hydrothermal stability of Cu-SSZ-13 catalysts synthesized via dual-template one-pot method. X-ray diffraction (XRD), Raman, and transmission electron microscopy-energy dispersive spectroscopy (TEM-EDS) analyses reveal that Y enters the zeolite framework during the crystallization process, promoting the generation of active [Cu(OH)] + -Z species. Meanwhile, nuclear magnetic resonance (NMR) and NH 3 -temperature programmed desorption (NH 3 -TPD) confirm that the addition of Y preserves the structures of framework and prevents the de-alumination against hydrothermal aging and thus enhances the stability of the Cu-SSZ-13. These findings offer valuable insights into optimizing SCR catalysts for the control of NO x emission in diesel vehicles and highlight the expanded utility of rare earth metal Y in catalyst development.

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Rare earth metals as bi-functional sites in Cu-SSZ-39 catalysts for promotion of phosphorous and HCs resistance

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Journal of Rare Earths 2024年

作者： Jinpeng Du Junlin Chen Jingyi Wang Yulong Shan Yu Sun Zhongqi Liu Tao Shen Zhi Liu Xusheng Xiang Zhen Chen Wenpo Shan Yunbo Yu Hong He State Key Joint Laboratory of Environment Simulation and Pollution Control Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China Ganjiang Innovation Academy Chinese Academy of Sciences Ganzhou 341119 China University of Chinese Academy of Sciences Beijing 100049 China Center for Excellence in Regional Atmospheric Environment Institute of Urban Environment Chinese Academy of Sciences Xiamen 361021 China Dongfeng Trucks R&D Center Wuhan 430056 China

The abatement of NO x from diesel vehicle exhaust is of great importance for improving the atmospheric environment. Cu-SSZ-39 zeolites possess the potential for application in the diesel vehicle aftertreatment system. Phosphorus (P) and hydrocarbons (HCs) present in the exhaust have negative impacts on the catalysts. To enhance the resistance of Cu-SSZ-39 catalysts to P and HCs, various rare earth metals were doped. Loading of 1 wt% Ce on the Cu-SSZ-39 catalyst improves the resistance to P and HCs simultaneously. The promotion mechanism was investigated through H 2 -temperature programmed reduction (H 2 -TPR), ultraviolet visible diffuse reflectance spectroscopy (UV–vis-DRS), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS) and theoretical calculation. On the one hand, Ce species can act as sacrificial sites, preferentially binding with P. On the other hand, Ce doping induces the formation of CuO species, promoting the oxidation of C 3 H 6 and preventing the consumption of NH 3 from the reaction with C 3 H 6 . Ce acting as bi-functional sites enhances the P and HCs resistance of Cu-SSZ-39 catalysts, further brightening its practical application.

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