Article
Engineering, Environmental
Yali Shen, Tiantian Li, Jing Yang, Aiyong Wang, Li Wang, Wangcheng Zhan, Yanglong Guo, Yun Guo
Summary: Ce-modified Cu/SSZ-13 catalyst exhibits excellent NH3-SCR activity and hydrothermal stability. The introduction of Ce can inhibit dealumination, prevent Cu ion aggregation, enhance catalyst reducibility, and improve NH3 and NOx adsorption capacity, resulting in higher NH3-SCR activity.
CHEMICAL ENGINEERING JOURNAL
(2023)
Article
Chemistry, Multidisciplinary
Houda Jouini, Imene Mejri, Baker Rhimi, Mourad Mhamdi, Teresa Blasco, Gerard Delahay
Summary: The addition of Ce affects the textural and structural properties of the Fe-Cu-MFI system, with Ce-promoted samples showing better NO conversion activity up to 450 degrees Celsius. The presence of Ce in aged catalysts also reduces the loss of activity.
RESEARCH ON CHEMICAL INTERMEDIATES
(2021)
Article
Chemistry, Physical
Michele De Rosa, Simone Morpurgo
Summary: By using DFT calculations, a new coordination for a pair of Cu+ ions at the M6 ring of ZSM-5 was discovered, which is more stable than previously reported structures. After NO adsorption, the Cu+ ions separate and lose the typical reactivity of a Cu-pair. The destabilization of intermediates and transition states at high temperature leads to a decrease in reaction rate. These findings rule out many possibilities in the search for the actual active site for NO decomposition in ZSM-5.
MOLECULAR CATALYSIS
(2022)
Article
Chemistry, Physical
Yue Ma, Songqi Cheng, Xiaodong Wu, Tongxi Ma, Liping Liu, Baofang Jin, Minghan Liu, Jianbo Liu, Rui Ran, Zhichun Si, Duan Weng
Summary: By coating a thin Al2O3 modification layer on the external surface of Cu-SSZ-13 catalyst using a chemical liquid deposition method, the hydrothermal durability of the catalyst is improved. The Al-modified Cu-SSZ-13 catalyst maintains high-temperature SCR activity and inhibits the over-oxidation of NH3.
JOURNAL OF CATALYSIS
(2022)
Article
Chemistry, Applied
Jiangfeng Guo, Aiyong Wang, He Lin
Summary: The study reveals that CuLTA exhibits excellent hydrothermal stability, while CuCHA is prone to structural damage at high temperatures. Phosphorus poisoning has a significant impact on CuCHA, but has little effect on CuLTA.
MICROPOROUS AND MESOPOROUS MATERIALS
(2022)
Article
Chemistry, Physical
Xiaofeng Wang, Yang Xu, Mengyue Qin, Zhe Zhao, Xinfei Fan, Qingbo Li
Summary: In this study, different Cu precursors were used to adjust the isolated Cu2+ ions and CuO species in the Cu-SSZ-13 catalysts. It was found that the high-temperature activity of the catalysts unexpectedly increased after hydrothermal treatment. The characterization results showed that hydrothermal treatment promoted the production of CuO species and changed the SCR reaction mechanism in the catalysts.
JOURNAL OF COLLOID AND INTERFACE SCIENCE
(2022)
Article
Chemistry, Physical
Rohil Daya, Dylan Trandal, Unmesh Menon, Dhruba J. Deka, William P. Partridge, Saurabh Y. Joshi
Summary: In this study, a kinetic model is developed for the reduction and oxidation reactions of Cu sites in Cu-SSZ-13. The rate parameters of these reactions are investigated using Fourier transform infrared spectroscopy and spatially resolved mass spectrometry. The model is validated with experimental measurements and successfully predicts the formation and consumption of nitrogen oxides. NH3 release is observed during the oxidation reaction at low temperatures, and the presence of NH3 negatively affects the catalyst's activity. This study provides important insights into the reduction and oxidation mechanisms of Cu-SSZ-13 catalysts.
Article
Chemistry, Physical
Congru Gao, Jianwei Li, Jie Zhang, Xiuliang Sun
Summary: A designed binuclear Cu-ZSM-5 catalyst can effectively decompose nitrogen oxides in industrial flue gas and purify the air environment. The catalytic decomposition mechanisms of N2O, NOX-NH3-SCR, and NOX-assisted N2O decomposition over the Cu-ZSM-5 model were simulated using density functional theory method.
Article
Chemistry, Physical
Rohil Daya, Dhruba J. Deka, Anshuman Goswami, Unmesh Menon, Dylan Trandal, William P. Partridge, Saurabh Y. Joshi
Summary: A kinetic model is developed to predict the influence of temperature and hydrothermal aging on the redox of active Cu sites on a Cu-SSZ-13 catalyst. The model calculates the rate parameters associated with NO and NH3 reduction reactions based on the production of NO2 and N2 during titration experiments. It also predicts the transient and integral N2 formation during exposure of CuI sites to a mixture of NO and O2.
APPLIED CATALYSIS B-ENVIRONMENTAL
(2023)
Article
Engineering, Environmental
Ye Li, Xinping Wang, Chuan Shi
Summary: A series of Ba-Ce-Cu catalysts were prepared by the citric acid method and used for N2O decomposition. The doping effects of Ba and Ce on CuO were studied. It was found that the activity and tolerance of the catalyst to impurity gases can be effectively modified by the doping components. Ba0.2Cu displayed high activity due to the stabilizing effect of Ba on the active Cu+ species, while Ba0.2Ce0.5Cu exhibited higher catalytic activity and strong tolerance to NO, thanks to the synergistic effect of Ba and Ce and the ability of CeO2 to remove NOx species.
JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING
(2023)
Article
Chemistry, Applied
Ne Ni, Xiuzhi Gao, Enhui Xing, Yuan Zhu, Jianqiang Liu, Mudi Xin, Ying Ouyang, Yibin Luo, Xingtian Shu
Summary: The promotional effects of phosphorus modification on ZSM-5 zeolites by different molecular sizes of phosphorus oxyacids (H4P2O7, H3PO4, H3PO3, and H3PO2) were studied using catalytic cracking of n-tetradecane as the probe reaction. The diffusion of P precursor molecules into ZSM-5 channels was found to be important for preventing aggregation of P species and improving stabilization on tetra-coordinated framework aluminum. The presence of P-Al interaction was proposed based on the results of 27Al, 31P, and 29Si MAS NMR. H3PO2 as the P precursor showed easy diffusion into ZSM-5 channels, resulting in less formation of polyphosphates, homogeneous distribution of P species, better reserved crystallinity, microporous area, and acidic sites, leading to improved cracking performance of n-tetradecane.
MICROPOROUS AND MESOPOROUS MATERIALS
(2023)
Article
Chemistry, Inorganic & Nuclear
Houda Jouini, Alessandra de Marcos-Galan, Imene Mejri, Rahma Bensouilah, Mourad Mhamdi, Teresa Blasco, Gerard Delahay
Summary: The addition of tungsten can slightly improve the high temperature catalytic activity of Fe-Cu-ZSM-5, and the W-based catalyst shows lower deactivation and better catalytic activity for NO reduction after hydrothermal aging compared to the bimetallic catalyst. Severe aging without tungsten leads to the formation of copper oxide agglomerates responsible for the deterioration of SCR activity of aged Fe-Cu-ZSM-5.
Article
Chemistry, Physical
Jian Cao, Mengjiao Xing, Yuanlong Han, Kun Hao, Ling Zhang, Fei Wang, Wentao Zheng, Zhichao Tao, Xiaodong Wen, Yong Yang, Yongwang Li
Summary: In this study, alkali treatment and phosphorus modification were used to improve the catalytic stability and hydrothermal stability of ZSM-5 catalysts. The introduction of mesopores enhanced the dispersion of phosphorus species and improved the stability of the aromatization reaction. The sample treated with an appropriate concentration of alkali had the highest aromatic selectivity.
Article
Engineering, Environmental
Wenjie Liu, Yifei Long, Jingbo Zhang, Shinian Liu, Yongyan Zhou, Xin Tong, Yajie Yin, Xiaoyi Li, Kang Hu, Jiangjun Hu
Summary: Silver and copper modified ZSM-5 zeolite catalysts showed high conversion efficiency for ammonia and nitrogen oxides in coal-fired plants, with good tolerance to water and sulfur dioxide. The addition of silver and copper oxides did not destroy the structure of the zeolite, but instead enhanced its acidity and ammonia adsorption ability.
JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING
(2022)
Article
Chemistry, Physical
Dhruba J. Deka, Rohil Daya, Saurabh Y. Joshi, William P. Partridge
Summary: In this study, the SCR reaction on Cu-SSZ-13 was investigated through experiments and kinetic modeling. It was found that RHC requires the simultaneous presence of NO and NH3, while OHC requires both NO and O2. Additionally, a previously unreported H2O-mediated OHC pathway was discovered.
APPLIED CATALYSIS A-GENERAL
(2022)