Article
Chemistry, Physical
Joachim D. Bjerregaard, Martin Votsmeier, Henrik Groenbeck
Summary: Density Functional Theory (DFT) calculations were used to investigate the low temperature deactivation of Cu-CHA by SO2 in ammonia assisted selective catalytic reduction of NO (NH3-SCR). The adsorption of SO2 on [CuII2(NH3)4O2]2+ forms a copper sulfate complex. NO and NH3 react on the sulfate complex to form N2, H2O, and H2SO4. H2SO4 undergoes an acid-base reaction with NH3, resulting in the formation of SO4(NH4)2 and HSO4(NH4), with HSO4(NH4) being thermodynamically preferred. The key mechanism for low temperature SO2 deactivation is attributed to physical effects, and the catalyst can be regenerated by exposure to high temperatures.
JOURNAL OF CATALYSIS
(2023)
Article
Chemistry, Applied
Yuta Nakasaka, Keigo Kushima, Shunsaku Yasumura, Ken-ichi Shimizu, Keigo Totani, Gen Shibata, Takao Masuda
Summary: The equilibrium adsorption and intracrystalline diffusion of NO and NH3 in Cu-CHA were studied experimentally using constant volumetric method. The adsorbed amount of NO on Cu-CHA at 373 K increases linearly with Cu loading, indicating that Cu sites are the adsorption site of NO. The calculated result shows that the intracrystalline diffusion of NO in Cu-CHA limits the NH3-SCR reaction.
Article
Chemistry, Physical
Yingxin Feng, Xueting Wang, Ton V. W. Janssens, Peter N. R. Vennestrom, Jonas Jansson, Magnus Skoglundh, Henrik Gronbeck
Summary: The study shows that NH3-SCR on Cu-CHA is facilitated by NH3-solvated Cu sites, promoting the selective reduction of NO; NH3 adsorption inhibits the reaction at low temperatures; the successful formulation of a first-principles microkinetic model links kinetic behavior with materials properties.
Article
Chemistry, Multidisciplinary
Yunzheng Wang, Jinfeng Han, Mengyang Chen, Wenting Lv, Pengtong Meng, Wei Gao, Xiangju Meng, Weibin Fan, Jun Xu, Wenfu Yan, Jihong Yu
Summary: Inspired by the transcription process from duplex DNA to RNA, we synthesized Al pairs enriched low-silica CHA zeolites as promising catalysts for NH3-SCR. After hydrothermal aging, Cu-exchanged CHA-SPAEI showed high NO conversion above 90% within a wide temperature range, indicating the importance of spatial close proximity of Al pairs in the zeolite.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Physical
Jiangfeng Guo, Aiyong Wang, He Lin
Summary: Cu/CHA and sodium-promoted Cu/CHA catalysts were prepared and their catalytic performance in NH3-SCR reaction was investigated. The sodium-promoted Cu/CHA catalyst showed better catalytic performance compared to Cu/CHA catalyst, which was attributed to the optimized distribution of copper active sites. Furthermore, it was demonstrated that sodium ions as sacrificial sites could effectively protect copper active ions and improve the phosphorus poisoning resistance of the sodium-promoted Cu/CHA catalyst.
CATALYSIS COMMUNICATIONS
(2023)
Article
Chemistry, Applied
Jin Hee Park, Kyung Soo Sin, Shuai Chang, Soon Hee Park, Sung June Cho
Summary: Cu-loaded zeolite (Cu/Zeolite or Cu/CHA) was prepared using hydrothermal conversion with trimethyladamantylammonium ion (TMAda) as an organic structure directing agent. Control over the concentration of mineralizing agent resulted in changes to the Si/Al ratio in the resulting zeolite, and affected the formation process. High silica CHA showed superior hydrothermal stability in selective catalytic reduction of NOx.
Article
Chemistry, Physical
Xinwei Ye, Ramon Oord, Matteo Monai, Joel E. Schmidt, Tiehong Chen, Florian Meirer, Bert M. Weckhuysen
Summary: This study investigates the surface changes of Cu-ZSM-5 zeolite catalyst in the NH3-SCR reaction using in situ spectroscopy. It is found that Cu2+ forms complexes with NH3 at low temperatures and facilitates the reaction by forming high coverage nitrate intermediates. After steam treatment, [Cu-x(OH)(2x-1)](+) oligomers/clusters accumulate on the Cu-ZSM-5 surface, strongly adsorbing NH3 and nitrates/nitric acid at low temperatures, limiting the reaction. Additionally, NH3 and nitrates/nitric acid compete for shared adsorption sites, and selective tuning is achieved by prompt removal of nitrates/nitric acid with NO.
CATALYSIS SCIENCE & TECHNOLOGY
(2022)
Article
Chemistry, Physical
Jiebing He, Jiang Deng, Jin Zhang, Lupeng Han, Yongjie Shen, Xin Chen, Xiaonan Hu, Junan Wang, Dengsong Zhang
Summary: The hydrothermal aging method converts sulfur-philic ZCuOH sites into sulfur-phobic Z(2)Cu sites in Cu-SAPO-34 catalyst, improving its resistance to SO2. This reduces the adsorption capacity and deposition of ammonium hydrogen sulfate (ABS) and suppresses the overoxidation and polymerization of Cu species, maintaining the redox balance of the NH3-SCR reaction.
CATALYSIS SCIENCE & TECHNOLOGY
(2023)
Article
Chemistry, Physical
Vitaly Mesilov, Sandra Dahlin, Susanna L. Bergman, Shibo Xi, Joonsoo Han, Louise Olsson, Lars J. Pettersson, Steven L. Bernasek
Summary: Regeneration of sulfur-poisoned Cu-SSZ-13 catalyst via temperature ramp in an inert atmosphere followed by holding under oxidizing conditions at 500 degrees C restores significant activity for NOx conversion under different SCR conditions. Analysis of copper speciation shows different behavior of sulfur-free Cu species in fresh and regenerated catalysts, contributing to the development of regeneration strategies for Cu-SSZ-13 catalysts.
APPLIED CATALYSIS B-ENVIRONMENTAL
(2021)
Article
Chemistry, Applied
M. Bendrich, A. Scheuer, M. Votsmeier
Summary: The study compared a mechanistic model and a global model in predicting NOx conversion rates, with the mechanistic model showing better performance in colder cycles due to its consideration of nitrates. Both models performed similarly in hotter cycles as no ammonium nitrate accumulates at high temperatures. Despite the additional complexity in the mechanistic model, simulation times remained comparable. Additionally, a simple NH3 dosing strategy was found to increase NOx conversion rates, demonstrating the model's utility in optimizing catalyst potential during driving cycles.
Article
Chemistry, Physical
Federica Gramigni, Nicole Daniela Nasello, Nicola Usberti, Umberto Iacobone, Tommaso Selleri, Wenshuo Hu, Shaojun Liu, Xiang Gao, Isabella Nova, Enrico Tronconi
Summary: NO and NH3 can readily reduce CuII at low temperatures according to a 1:1:1:1 stoichiometry over Cu-CHA catalysts. The reduction rates of Cu-II show a quadratic dependence on Cu-II, suggesting a dinuclear-Cu-II mediated RHC pathway. Water significantly inhibits the Cu-II reduction rate in the reaction cascade.
Article
Chemistry, Physical
Wenshuo Hu, Umberto Iacobone, Federica Gramigni, Yu Zhang, Xiaoxiang Wang, Shaojun Liu, Chenghang Zheng, Isabella Nova, Xiang Gao, Enrico Tronconi
Summary: The study finds that NH3-assisted hydrolysis plays a critical role in low-temperature SCR, especially when discussing Z(2)Cu(2+).
Article
Chemistry, Applied
Gen Shibata, Naoki Shibayama, Keita Araki, Yoshimitsu Kobashi, Hideyuki Ogawa, Yuta Nakasaka, Ken-ichi Shimizu
Summary: This study investigates the kinetic modeling of NH3-SCR with a Cu-ion-exchanged chabazite catalyst through flow reactor experiments and computational modeling. A scheme for SCR and side reactions involving 17 reactions is proposed based on previous proposals, and some reactions are validated by experimental results. The Arrhenius parameters for various reactions are obtained through kinetic experiments. A quantitative simulation model is developed and validated using experimental data. The model can predict steady-state SCR data and the adsorption/desorption of NH3 and NO2 under unsteady-state conditions.
Article
Engineering, Environmental
Zijun Yin, Yuxiu Zhong, Jingwen Lu, Tao Liu, Yawei Song, Mengxia Qing, Lele Wang, Yi Wang, Song Hu, Sheng Su, Jun Xiang
Summary: This study investigates the effect of phosphorus addition on the activity of NOx conversion and SO2 oxidation over VW/Ti catalyst. The results show that the P-modified VW/Ti catalyst not only enhances the catalytic activity at low temperature, but also reduces the oxidation rate of SO2. The 1.5PVW/Ti catalyst exhibits the lowest SO2 oxidation rate at 360 degrees C and achieves about 30% reduction in SO2 oxidation rate compared to the 0PVW/Ti catalyst, while the conversion of NOx is still above 95%.
CHEMICAL ENGINEERING JOURNAL
(2023)
Article
Chemistry, Physical
Wenshuo Hu, Federica Gramigni, Nicole Daniela Nasello, Nicola Usberti, Umberto Iacobone, Shaojun Liu, Isabella Nova, Xiang Gao, Enrico Tronconi
Summary: Cu-exchanged chabazite zeolite (Cu-CHA) is an efficient catalyst for the selective catalytic reduction (SCR) of NOx, and the dynamic cycling of Cu cations plays an important role in the SCR process. Cu cations are activated by forming Cu-NH3 complexes through reaction with NH3 under low-temperature conditions, and they exhibit homogeneous features in the heterogeneous catalytic process of low-temperature SCR. These features are influenced by electrostatic interactions between Cu cations and conjugate Al centers.
Article
Chemistry, Physical
Saurabh Y. Joshi, Ashok Kumar, Jinyong Luo, Krishna Kamasamudram, Neal W. Currier, Aleksey Yezerets
APPLIED CATALYSIS B-ENVIRONMENTAL
(2015)
Article
Chemistry, Physical
Supriyanto, Kurnia Wijayanti, Ashok Kumar, Saurabh Joshi, Krishna Kamasamudram, Neal W. Currier, Aleksey Yezerets, Louise Olsson
APPLIED CATALYSIS B-ENVIRONMENTAL
(2015)
Article
Chemistry, Physical
Xavier Auvray, William Partridge, Jae-Soon Choi, Josh Pihl, Filipa Coehlo, Aleksey Yezerets, Krishna Kamasamudram, Neal Currier, Louise Olsson
APPLIED CATALYSIS B-ENVIRONMENTAL
(2015)
Article
Chemistry, Physical
Louise Olsson, Kurnia Wijayanti, Kirsten Leistner, Ashok Kumar, Saurabh Y. Joshi, Krishna Kamasamudram, Neal W. Currier, Aleksey Yezerets
APPLIED CATALYSIS B-ENVIRONMENTAL
(2015)
Article
Chemistry, Physical
Kurnia Wijayanti, Stanislava Andonova, Ashok Kumar, Junhui Li, Krishna Kamasamudram, Neal W. Currier, Aleksey Yezerets, Louise Olsson
APPLIED CATALYSIS B-ENVIRONMENTAL
(2015)
Article
Chemistry, Applied
Junhui Li, Ashok Kumar, Krishna Kamasamudram, Neal Currier, Aleksey Yezerets
Article
Chemistry, Applied
Kirsten Leistner, Oana Mihai, Kurnia Wijayanti, Ashok Kumar, Krishna Kamasamudram, Neal W. Currier, Aleksey Yezerets, Louise Olsson
Article
Chemistry, Physical
Louise Olsson, Kurnia Wijayanti, Kirsten Leistner, Ashok Kumar, Saurabh Y. Joshi, Krishna Kamasamudram, Neal W. Currier, Aleksey Yezerets
APPLIED CATALYSIS B-ENVIRONMENTAL
(2016)
Article
Chemistry, Physical
Chethan K. Gaddam, Randy L. Vander Wal, Xu Chen, Aleksey Yezerets, Krishna Kamasamudram
Article
Chemistry, Applied
Ashok Kumar, Michael A. Smith, Krishna Kamasamudram, Neal W. Currier, Aleksey Yezerets
Article
Chemistry, Applied
Jinyong Luo, Di Wang, Ashok Kumar, Junhui Li, Krishna Kamasamudram, Neal Currier, Aleksey Yezerets
Article
Chemistry, Physical
Kurnia Wijayanti, Kirsten Leistner, Shilpa Chand, Ashok Kumar, Krishna Kamasamudram, Neal W. Currier, Aleksey Yezerets, Louise Olsson
CATALYSIS SCIENCE & TECHNOLOGY
(2016)
Article
Chemistry, Physical
Jinyong Luo, Feng Gao, Krishna Kamasamudram, Neal Currier, Charles H. F. Peden, Aleksey Yezerets
JOURNAL OF CATALYSIS
(2017)
Article
Chemistry, Physical
Jian Gong, Di Wang, Junhui Li, Neal Currier, Aleksey Yezerets
APPLIED CATALYSIS B-ENVIRONMENTAL
(2017)
Article
Transportation Science & Technology
Junhui Li, Neal Currier, Aleksey Yezerets, Hai-Ying Chen, Howard Hess, Shadab Mulla
SAE INTERNATIONAL JOURNAL OF ENGINES
(2016)
Article
Chemistry, Applied
Qingyuan Zheng, Jack H. Williams, Scott Elgersma, Mick D. Mantle, Andrew J. Sederman, G. Leendert Bezemer, Constant M. Guedon, Lynn F. Gladden
Summary: In this study, a pilot-scale fixed-bed reactor compatible with NMR/MRI was developed for Fischer-Tropsch synthesis. Multiple magnetic resonance techniques were applied to quantitatively characterize different product species within catalyst pellets, providing valuable information for catalyst and reactor optimization.
Article
Chemistry, Applied
Lisa Ramisch, Sebastian Pfaff, Sabrina M. Gericke, Edvin Lundgren, Johan Zetterberg
Summary: We present a combination of optical operando techniques that allow simultaneous measurement of adsorbed species on catalyst surfaces, monitoring of surface oxide formation, and imaging of the gas phase above the catalyst surface. The experimental setup was validated by studying CO oxidation on Pd(100) at different pressures, revealing the effects of pressure on the heterogeneous catalytic reaction.
Article
Chemistry, Applied
Marta Paniagua, Gabriel Morales, Juan A. Melero, Daniel Garcia-Salgado
Summary: The influence of common impurities in levulinic acid on the catalytic performance of different acid catalysts for bio-jet fuel production was studied. It was found that furfural had the greatest detrimental effect on catalyst performance, while propyl-sulfonic acid-modified SBA-15 and sulfonic acid resin Amberlyst-70 showed good regeneration ability.
Article
Chemistry, Applied
Jesus Tapiador, Pedro Leo, Guillermo Calleja, Gisela Orcajo
Summary: This study presents a new MOF material, Zn-URJC-13, with acid and basic sites, permanent porosity, and high affinity to CO2 molecules. The Zn-URJC-13 catalyst exhibits efficient performance in CO2 cycloaddition reactions and can be reused multiple times.
Article
Chemistry, Applied
Dan Zhao, Vita A. Kondratenko, Dmitry E. Doronkin, Shanlei Han, Jan-Dierk Grunwaldt, Uwe Rodemerck, David Linke, Evgenii V. Kondratenko
Summary: This study demonstrates the potential of cheap and commercially available Zr or Ti-based supports and ZnO to serve as active and selective catalysts for propane dehydrogenation (PDH). The catalytically active species formed in situ under PDH conditions consist of isolated ZnOx. ZnOx on the surface of LaZrOx shows the highest rate of propene formation.
Article
Chemistry, Applied
Hanbyeol Kim, Jung Rae Kim, Young-Kwon Park, Jeong-Myeong Ha, Jungho Jae
Summary: In this study, metal phosphates were used as catalysts for biomass conversion to produce sustainable aromatics through DielsAlder cycloaddition reactions. The effects of synthesis method, activation method, and P/Ti molar ratio on the structure and acid properties of titanium phosphate catalysts were systematically studied. The mesoporous titanium phosphate catalyst synthesized by hydrothermal method at 180℃ for 12 h followed by ethanol refluxing at 60℃ for 24 h at a molar P/Ti ratio of 1 showed the highest surface area and acid site density.
Article
Chemistry, Applied
Yasin Khani, Sumin Pyo, Kwang-Eun Jeong, Chul-Ung Kim, Moonis Ali Khan, Byong-Hun Jeon, Kun-Yi Andrew Lin, Siyoung Q. Choi, Young-Kwon Park
Summary: A protonated form of Zeolite Socony Mobil-5 (H-ZSM-5) catalyst was synthesized through a hydrothermal method using different sources of silica. The effect of loading the catalyst with yttrium, samarium, and gadolinium on the acidic properties was investigated. Among the metal-loaded catalysts, the Sm/LHZ catalyst showed the best performance in the methanol to propylene conversion due to its high amount of weak and intermediate acid sites, while the Gd-LHZ catalyst increased the selectivity towards ethane and propane.
Article
Chemistry, Applied
Michael Franc, Ivana Cisarova, Jan Vesely
Summary: The present study investigates an enantioselective cyclization of enals with imidazolone derivatives catalyzed by a combination of achiral Pd(0) complex and chiral secondary amine. Corresponding spirocyclic imidazolones were produced in high yields with moderate diastereoselectivity and excellent enantioselectivity. The developed co-operative catalytic methodology provides a highly substituted spirocyclic scaffold with four stereogenic centers under mild conditions.
Article
Chemistry, Applied
Mauro Alvarez, Jennifer Cueto, David P. Serrano, Pablo Marin, Salvador Ordonez
Summary: This study focuses on improving the formulation and preparation methods of catalysts for the production of dimethyl carbonate. By using suitable catalyst preparation methods and copper salt precursors, the researchers successfully produced catalysts with optimal performance for dimethyl carbonate formation.
Article
Chemistry, Applied
Claudia J. Keijzer, Luc C. J. Smulders, Dennie Wezendonk, Jan Willem de Rijk, Petra E. de Jongh
Summary: This study investigates the catalytic behavior of alpha-alumina supported silver catalysts in the presence of chloride. It is found that the particle size of silver can affect the selectivity of the catalyst, but different strategies lead to different results. In this size range, the selectivity of ethylene oxide is correlated to the Ag : Al2O3 surface ratio.
Article
Chemistry, Applied
Takeshi Aihara, Wataru Aoki, Michikazu Hara, Keigo Kamata
Summary: The development of acid-base bifunctional catalysts is important for promoting specific chemical transformations. In this study, Ti-based perovskite oxides were synthesized and used as catalysts for two C-C bond-forming reactions (cyanosilylation and Knoevenagel condensation). The highly pure SrTiO3 nanoparticles with a high specific surface area exhibited the highest catalytic performance, and could be easily recovered and reused.
Article
Chemistry, Applied
Olga Gorlova, Petra Pribylova, Eliska Vyskocilova, Katerina Peroutkova, Jan Kohout, Iva Paterova
Summary: This study investigates the Baeyer-Villiger oxidation of beta-cyclocitral using tin-modified mixed oxides as catalysts. The optimal reaction conditions and the effects of various factors on the reaction course and selectivity were determined. The results show that tin-modified mixed oxides exhibit high activity and selectivity in the oxidation reaction.
Article
Chemistry, Applied
M. I. Avila, M. M. Alonso-Doncel, L. Briones, G. Gomez-Pozuelo, J. M. Escola, D. P. Serrano, A. Peral, J. A. Botas
Summary: The catalytic fast pyrolysis of lignin using ion-exchanged zeolite catalysts showed significant improvements in bio-oil quality and the production of aromatic hydrocarbons and oxygenated compounds.
Article
Chemistry, Applied
Enrico Catizzone, Giorgia Ferrarelli, Paolo Bruno, Girolamo Giordano, Massimo Migliori
Summary: The acid-catalysed alcohol conversion reaction is a promising route for de-fossilization strategies. Research on pure alcohol conversion and simultaneous dehydration of mixed alcohols have shown different product compositions, with the type and distribution of acid sites affecting the reaction mechanism.
Article
Chemistry, Applied
Alireza Ranjbari, Juho Kim, Jihee Yu, Jiyun Kim, Mireu Park, Nayoung Kim, Kristof Demeestere, Philippe M. Heynderickx
Summary: This study investigated a novel kinetic model for the adsorption and photocatalytic degradation of methyl orange using commercial ZnO and reduced ZnO photocatalysts. The results provided new insights into the interaction of catalysts with molecules of different charges and compared with a previous study on methylene blue. The presence of oxygen vacancies in ZnO and their effects on adsorption and photocatalytic degradation were analyzed, and the photocatalytic degradation rate of reduced ZnO was found to increase significantly.