Article
Chemistry, Physical
Guangyan Xu, Honghong Wang, Yunbo Yu, Hong He
Summary: The study revealed the presence of various silver species on Ag/Al2O3 catalysts, with metallic silver clusters identified as the active sites for nitrate formation and the reduction of silver nitrates being the rate-determining step in the H-2-NH3-SCR reaction.
JOURNAL OF CATALYSIS
(2021)
Article
Chemistry, Applied
Carmine D'Agostino, Sarayute Chansai, Lynn F. Gladden, Christopher Hardacre
Summary: NMR relaxation time ratio T-1/T-2 is used to characterize the strength of surface interaction of reducing agent species in Ag/Al2O3 catalysts for SCR of NOx. The interaction strength plays a crucial role in determining catalyst performance and initial activation, with different reducing agents showing varying affinities with the catalyst.
Article
Engineering, Environmental
Zhi Liu, Yingsheng An, Guangyan Xu, Yunbo Yu, Hong He
Summary: The enhancement mechanism of the C3H6-SCR activity of Ag/Al(2)O(3) by Pd doping and the corresponding structure-property relationship were investigated. Pd doping changed the reaction pathway and improved the water resistance of the catalyst, leading to the formation of a different active intermediate, an enolic species. The study provides valuable insights for the design of efficient HC-SCR catalysts.
ENVIRONMENTAL SCIENCE & TECHNOLOGY
(2023)
Article
Engineering, Chemical
Shivaraj Kumar Kummari, Neha Yedala, Parasuraman Selvam, Niket S. Kaisare, Preeti Aghalayam
Summary: This article investigates Ag/?-Al2O3 catalyst for the selective reduction of NOx and finds that it is effective when using propylene as a reducing agent. Different synthesis methods were analyzed, and the one-pot sol-gel synthesis method showed superior performance. The influence of synthesis conditions on the catalyst properties and activity were examined through experiments and simulations. The optimized catalyst exhibited excellent performance with a wide temperature window.
CANADIAN JOURNAL OF CHEMICAL ENGINEERING
(2023)
Article
Engineering, Environmental
Zhi Liu, Yingsheng An, Guangyan Xu, Yunbo Yu, Hong He
Summary: The mechanistic cause of the enhancement of the C3H6-SCR activity of Ag/Al2O3 by trace Pd doping and the corresponding structure-property relationship were investigated. Pd doping enhanced the water resistance of Ag/Al2O3 for C3H6-SCR by changing the reaction pathway. Under wet conditions, a series of in situ DRIFT studies indicated that the production of an active acetate intermediate on Ag/Al2O3 was suppressed during the partial oxidation of C3H6, while trace Pd doping promoted the formation of another active intermediate, an enolic species. Furthermore, a pathway for the formation of enolic species by the reaction of acrylate with hydroxyl species was proposed. DFT calculations revealed that the surface of Ag clusters was easily covered by hydroxyl in the presence of water vapor, which could inhibit the formation of acetates. Doping with Pd facilitated the activation of acrylate which might further react with hydroxyl species to form enolic species. These findings can be helpful for the future design of efficient HC-SCR catalysts.
ENVIRONMENTAL SCIENCE & TECHNOLOGY
(2023)
Article
Chemistry, Multidisciplinary
Kyungseok Lee, Byungchul Choi, Cheolho Kim, Chunbeom Lee, Kwangchul Oh
Summary: The combination of Ag/Al2O3 and CuSn/ZSM-5 showed superior catalytic performance in reducing NOx and oxidizing C3H6 at lower temperatures. Sequential arrangement of 1Ag/Al2O3 + 2Cu1Sn/ZSM-5 was found to be the best catalytic configuration for simultaneous reduction of NOx, C3H6, and H-2 over a wide temperature range. The reduced NOx was mostly converted to N-2 with minimal generation of N2O, NH3, and HCNO.
JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY
(2021)
Article
Chemistry, Physical
Prateek Khatri, Divesh Bhatia
Summary: The newly developed Ag/MgO γ-Al2O3 catalyst exhibits strong NOx adsorption and reduction capabilities, significantly influenced by the presence of H-2, but not related to its SCR activity or NO oxidation activity.
APPLIED CATALYSIS A-GENERAL
(2021)
Review
Chemistry, Multidisciplinary
Ioannis Yentekakis, Amvrosios G. Georgiadis, Catherine Drosou, Nikolaos D. Charisiou, Maria A. Goula
Summary: This paper reviews the SCR process of NOx on perovskite-based catalysts, focusing on the impact of different reducing agents and perovskite compositions. The correlation between physicochemical properties of the catalysts and their deNO(x) activity is also discussed. Proposed kinetic models provide insights into deNO(x) mechanisms and potential improvements in deNO(x) efficiency.
Article
Engineering, Chemical
Zhongnan Gao, Dongyue Zhao, Yuexi Yang, Xiaotong Jiang, Ye Tian, Tong Ding, Xingang Li
Summary: The study reveals that isolated Cu cations are the active sites for C3H6-SCR, while the presence of CuO species enhances the C3H6 activation ability of the catalysts. Tuning the proportion of various copper species can tailor the active temperature window for hydrocarbons-selective catalytic reduction (HC-SCR) reactions, providing new insights into designing highly efficient Cu-based zeolite catalysts.
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
(2021)
Article
Energy & Fuels
Jun Duan, Ling Zhao, Shengjun Gao, Xinyong Li
Summary: The study prepared spherical xAg-CeZr catalysts using a continuous solvothermal-impregnation method and applied them to H2-assisted C3H6-SCR, finding that the addition of H2 significantly promoted NO conversion and N2 selectivity. Various characterization results indicated that active Ag+, Ce3+, and O alpha species were crucial factors for the catalyst's excellent activity.
Article
Chemistry, Multidisciplinary
Ning Li, Tiantian Zhang, Zuliang Wu, Jing Li, Wei Wang, Jiali Zhu, Shuiliang Yao, Erhao Gao
Summary: The synergistic effects of Sn and Ag in the 1Sn5Ag/gamma-Al2O3 catalyst greatly enhance its C3H6-SCR performance. The presence of AgCl crystallites helps maintain an appropriate redox ability and suppresses over-oxidation of C3H6. The coexistence of Ag and Sn increases the reactivity of surface adsorbed oxygen and hydroxyl groups, and the electron transfer effects increase the ratio of Ag-0/Ag+.
Article
Chemistry, Physical
Tao Yan, Kaiwen Zhao, Zhaojun Gao, Qin He, Qunfei Wang, Wenqi Liu, Zhongfu Li, Jingyan Zhang, Chengyuan Yuan, Conghua Liu
Summary: The effects of Zn and Mg on the selective catalytic reduction (SCR) of NO with C3H6 were investigated. The bimetallic Zn and Mg modification increased the proportion of ZnAl2O4 and MgAl2O4 spinels in the catalysts, regulated the dispersion of Ag on the support, and promoted the conversion of Ag0 to active Ag+ and Ag delta n+. This enhanced the NO adsorption capacity and optimized denitrification performance. In addition, it was found that the presence of H2 facilitated the formation of N2 and improved N2 selectivity.
APPLIED SURFACE SCIENCE
(2023)
Article
Chemistry, Physical
Yingfeng Duan, Lina Wang, Yagang Zhang, Wei Du, Yating Zhang
Summary: The catalytic performance of Cu-SAPO-34 catalysts during the NH3-SCR process was found to be influenced by the presence of propylene, with a decrease in de-NOx activity at low temperatures (<350 degrees C) and an improvement at high temperatures (>350 degrees C). Various experiments were conducted to explore the propylene effect on the structure and performance of the catalysts, revealing that propylene inhibited NOx adsorption and oxidation at low temperatures but contributed to NOx conversion at high temperatures.
Article
Energy & Fuels
Huawang Zhao, Xiaomin Wu, Zhiwei Huang, Huazhen Shen, Jing Dong, Xinyu Li, Guohua Jing
Summary: The deactivation of Cu-SSZ-13 catalyst by hydrocarbons (HCs) was investigated, and the effect of hydrothermal aging treatment (HTA) on the catalyst was studied. The results showed that the activities of the catalyst were significantly decreased after HTA, due to the carbonous deposit formed by HCs. The acidity and pore size of the catalyst affected the types and amounts of carbonous deposit.
Article
Chemistry, Physical
Xinwei Yang, Aiyong Wang, Jiangfeng Guo, Yanglong Guo, Yun Guo, Li Wang, Wangcheng Zhan
Summary: The γ-Al2O3 support was used to support Ag nanoparticles, and the Ag/Al2O3-flake exhibited superior catalytic activity in C3H8-SCR compared to Ag/Al2O3-sphere. The Al2O3-flake with more Al octacoordinated ions promoted the dispersion of Agn δ+ species on Ag/Al2O3-flake. The Agn δ+ species strengthened the low-temperature catalytic activity for HC-SCR, while Ag metal particles were unbeneficial.
CATALYSIS COMMUNICATIONS
(2023)
Article
Chemistry, Applied
Jingjing Liu, Yanlong Huo, Xiaoyan Shi, Zhongqi Liu, Yulong Shan, Yunbo Yu, Wenpo Shan, Hong He
Summary: A series of Ce-Sn catalysts modified with W were prepared and studied for the SCR of NOx by NH3. The Ce-W-Sn catalysts showed higher deNOx efficiency than the Ce-Sn catalysts, and the Ce1W0.24Sn2Ox catalyst prepared by coprecipitation displayed the highest NOx conversion. The mechanism by which W modification improved the structure and function of the Ce1Sn2Oy catalyst was investigated, revealing the promotion of t-Sn(Ce)O2 active phase formation and the inhibition of c-Ce(Sn)O2 phase generation by W species. Additionally, the highly dispersed W species on the Ce1W0.24Sn2Ox catalyst surface formed new Ce-O-W active sites, contributing to enhanced NH3-SCR performance and the suppression of excess NH3 oxidation.
Article
Chemistry, Physical
Jingjing Liu, Xiaoyan Shi, Yunbo Yu, Mengyuan Zhang, Diru Liu, Hong He
Summary: The HC resistance of CeWSnOx, V2O5-WO3/TiO2, and Cu-SSZ-13 catalysts was studied using propene, toluene, and n-pentane as model HCs. The CeWSnOx catalyst showed much better HC tolerance due to its strong HC oxidation capacity, which inhibited side reactions. In contrast, Cu-SSZ-13 and V2O5-WO3/TiO2 showed undesired HC ammoxidation reactions, especially in the presence of propene.
APPLIED CATALYSIS B-ENVIRONMENTAL
(2023)
Article
Chemistry, Physical
Qiaoqi Guo, Ying Luo, Jun Xu, Lidan Deng, Zheng Wang, Hong He
Summary: Photocatalytic conversion of low-concentration CO2 with H2O oxidation is an effective method to achieve sustainable carbon cycling and address the global warming issue. Improving charge separation, surface adsorption, and catalytic process of photocatalysts is crucial to overcome the mass transfer limitation during the conversion of low-concentration CO2. In this study, a highly-crystalline AgxNa1_xTaO3-AgCl heterostructure composite was fabricated, which facilitated the separation and transfer of photogenerated charges. The introduction of Ag cations and AgCl components enhanced the adsorption and activation of CO2 on the surface of the photocatalyst. When combined with metallic Ag cocatalysts, the AgxNa1_xTaO3-AgCl heterostructure photocatalyst exhibited improved activity for CO2 reduction and H2O oxidation at low CO2 concentration conditions. The development of photocatalysts active at low CO2 concentration provides an alternative approach for practical CO2 conversion systems in the future.
APPLIED CATALYSIS B-ENVIRONMENTAL
(2023)
Article
Engineering, Environmental
Junlin Chen, Yulong Shan, Yu Sun, Wenqing Ding, Sen Xue, Xuewang Han, Jinpeng Du, Zidi Yan, Yunbo Yu, Hong He
Summary: This study investigated the effects of phosphorus on Cu-SSZ-39 catalysts before and after hydrothermal aging treatment. Phosphorus poisoning significantly decreased the low-temperature NH3-SCR catalytic activity, but this activity loss was alleviated by further hydrothermal aging treatment. Characterization techniques revealed that Cu-P species produced by phosphorus poisoning decreased the redox ability of active copper species, resulting in the observed low-temperature deactivation. However, after hydrothermal aging treatment, Cu-P species partly decomposed, leading to the recovery of low-temperature NH3-SCR catalytic activity.
ENVIRONMENTAL SCIENCE & TECHNOLOGY
(2023)
Article
Engineering, Environmental
Maofan Li, Meng Gao, Guangzhi He, Yunbo Yu, Hong He
Summary: Mn doping can significantly enhance the low-temperature NH3-SCR activity of Ce-based oxide catalysts, providing important insights for the development of low-temperature Ce-based catalysts.
ENVIRONMENTAL SCIENCE & TECHNOLOGY
(2023)
Article
Engineering, Environmental
Qing Cao, Biwu Chu, Peng Zhang, Qingxin Ma, Jinzhu Ma, Yuan Liu, Jun Liu, Yaqi Zhao, Hong Zhang, Yonghong Wang, Hong He
Summary: The reducibility of SO2 and its acidic products inhibit the production of reactive nitrogen in the photolysis of nitrate, affecting the renoxification process. SO2 has an inhibitory effect on the production of NOx, HONO, and NH3 in the photolysis of ammonium nitrate on different substrates. The interaction between the heterogeneous oxidation of SO2 and nitrate photolysis provides a new perspective on how SO2 affects the photolysis of nitrate absorbed on photoactive oxides.
ENVIRONMENTAL SCIENCE & TECHNOLOGY
(2023)
Article
Soil Science
Na Li, Haibo Du, Mai-He Li, Risu Na, Renkai Dong, Hong S. He, Shengwei Zong, Lirong Huang, Zhengfang Wu
Summary: Global environmental changes have led to the migration of plants into alpine or arctic tundra ecosystems. In the Changbai Mountain, the migration of the low-elevation herb species Deyeuxia angustifolia into the alpine shrubby tundra has resulted in changes in soil properties and soil microbial communities. The upward migration, combined with nitrogen deposition, has altered the soil microbial community composition and led to a shortage of soil phosphorus at higher elevations. These changes may benefit the migration of D. angustifolia and suppress the existing shrubby species.
SOIL BIOLOGY & BIOCHEMISTRY
(2023)
Article
Chemistry, Physical
Qi An, Guangyan Xu, Jianhua Liu, Yingjie Wang, Yunbo Yu, Hong He
Summary: In this study, a bifunctional Pt/Cu-SSZ-13 catalyst with catalytic selectivity and selective catalytic reduction function was successfully prepared. The catalyst exhibited excellent catalytic performance during NH3 oxidation under practical conditions containing water vapor, achieving >85% N2 selectivity over the whole temperature range.
Article
Chemistry, Physical
Shuangye Li, Liyun Song, Jian Li, Hong He
Summary: A series of NdV/Ti-x% catalysts were prepared by a microwave-assisted deposition-precipitation method and their catalytic performance for the selective catalytic reduction (SCR) of NO by NH3 was investigated. The amount of vanadate added significantly influenced the SCR activity of the catalyst. The NdV/Ti-x% catalysts demonstrated good low-temperature catalyst activities and excellent SO2 resistance performances.
Article
Engineering, Environmental
Zhuocan Li, Meng Gao, Zhihui Lv, Rucheng Duan, Yulong Shan, Hongwei Li, Guangzhi He, Hong He
Summary: This study reveals the active sites and working principle of commercial vanadium oxide catalysts in the fast SCR reaction through experimental and computational methods. It demonstrates that polymeric vanadyl species act as the main active sites and provides a fundamental basis for developing high-efficiency and low V2O5-loading SCR catalysts.
ENVIRONMENTAL SCIENCE & TECHNOLOGY
(2023)
Review
Multidisciplinary Sciences
Yuan Liu, Guangzhi He, Biwu Chu, Qingxin Ma, Hong He
Summary: Soot particles, consisting of elemental carbon and organic compounds, have significant impacts on climate, the environment, and human health. They are chemically and physically active in atmospheric aging processes, leading to changes in composition, morphology, hygroscopicity, and optical properties. The interactions between soot and atmospheric substances, as well as the heterogeneous reactions on soot, have been extensively studied to better understand the environmental behaviors of soot.
FUNDAMENTAL RESEARCH
(2023)
Article
Chemistry, Multidisciplinary
Jianhua Liu, Guangyan Xu, Qi An, Yingjie Wang, Yunbo Yu, Hong He
Summary: In this study, Pt/Al2O3 catalysts were synthesized and their state was adjusted by heat treatment. The characterization results showed that high-temperature treatment induced the aggregation of platinum species to form metallic Pt nanoparticles. Pt/Al2O3 catalysts treated at high temperatures exhibited superior activity and water tolerance in the NH3-SCO reaction. Diffuse reflectance infrared Fourier-transform spectroscopy combined with mass spectrometry experiments revealed that Lewis acid sites were more reactive than Bronsted acid sites. It was also found that metallic Pt nanoparticles were beneficial for oxygen activation and less affected by water vapor.
Article
Engineering, Environmental
Yanwei Sun, Guangyan Xu, Yingjie Wang, Wei Shi, Yunbo Yu, Hong He
Summary: In this study, a series of encapsulated structured catalysts with palladium nanoparticles confined in hydrophobic silicalite-2 were prepared, which showed high catalytic activity and long-term stability for methane oxidation under harsh conditions.
ENVIRONMENTAL SCIENCE & TECHNOLOGY
(2023)
Article
Meteorology & Atmospheric Sciences
Yuanyuan Fu, Chang Liu, Hong He, Shaoqiang Wang, Lunche Wang, Zhijie Xie
Summary: Exploring spring phenology dynamics in the Greater Khingan Mountains, Northeast China, we found that preseason temperature strongly influenced the start of the growing season (SOS), while the effects of preseason precipitation and radiation varied by region. The SOS dates showed regional characteristics, with a gradual delay from north to south.
INTERNATIONAL JOURNAL OF CLIMATOLOGY
(2023)
Article
Engineering, Environmental
Zhi Liu, Yingsheng An, Guangyan Xu, Yunbo Yu, Hong He
Summary: The mechanistic cause of the enhancement of the C3H6-SCR activity of Ag/Al2O3 by trace Pd doping and the corresponding structure-property relationship were investigated. Pd doping enhanced the water resistance of Ag/Al2O3 for C3H6-SCR by changing the reaction pathway. Under wet conditions, a series of in situ DRIFT studies indicated that the production of an active acetate intermediate on Ag/Al2O3 was suppressed during the partial oxidation of C3H6, while trace Pd doping promoted the formation of another active intermediate, an enolic species. Furthermore, a pathway for the formation of enolic species by the reaction of acrylate with hydroxyl species was proposed. DFT calculations revealed that the surface of Ag clusters was easily covered by hydroxyl in the presence of water vapor, which could inhibit the formation of acetates. Doping with Pd facilitated the activation of acrylate which might further react with hydroxyl species to form enolic species. These findings can be helpful for the future design of efficient HC-SCR catalysts.
ENVIRONMENTAL SCIENCE & TECHNOLOGY
(2023)
