1
|
Zhang S, Meng Y, Pang L, Ding Q, Chen Z, Guo Y, Cai W, Li T. Understanding the direct relationship between various structure-directing agents and low-temperature hydrothermal durability over Cu-SAPO-34 during the NH3-SCR reaction. Catal Sci Technol 2022. [DOI: 10.1039/d1cy02046c] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Hydrolysis of Si–O(H)–Al bonds and the loss of active Cu(OH)+ species jointly contribute towards the deactivation of Cu-SAPO-34 under a moist environment at low temperature (<100 °C).
Collapse
Affiliation(s)
- Shoute Zhang
- Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074, P. R. China
| | - Ying Meng
- Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074, P. R. China
| | - Lei Pang
- DongFeng Trucks R&D Center, Zhushanhu Road No. 653, Wuhan 430056, P. R. China
| | - Qianzhao Ding
- Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074, P. R. China
| | - Zhen Chen
- Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074, P. R. China
| | - Yanbing Guo
- Key Laboratory of Pesticide and Chemical Biology of Ministry of Education, Institute of Environmental and Applied Chemistry, College of Chemistry, Central China Normal University, Wuhan, 430079, PR China
| | - Weiquan Cai
- School of Chemistry and Chemical Engineering, Guangzhou Higher Education Mega Center, Guangzhou University, 230 Wai Huan Xi Road, Guangzhou, 510006, China
| | - Tao Li
- Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074, P. R. China
| |
Collapse
|
2
|
Cai M, Bian X, Xie F, Wu W, Cen P. Formation and Performance of Monolithic Catalysts for Selective Catalytic Reduction of Nitrogen Oxides: A Critical Review. ChemistrySelect 2021. [DOI: 10.1002/slct.202101358] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Ming Cai
- School of Metallurgy Northeastern University NO.3-11 Wenhua Road Shenyang 110819 China
| | - Xue Bian
- School of Metallurgy Northeastern University NO.3-11 Wenhua Road Shenyang 110819 China
| | - Feng Xie
- School of Metallurgy Northeastern University NO.3-11 Wenhua Road Shenyang 110819 China
| | - Wen‐yuan Wu
- School of Metallurgy Northeastern University NO.3-11 Wenhua Road Shenyang 110819 China
| | - Peng Cen
- School of Metallurgy Northeastern University NO.3-11 Wenhua Road Shenyang 110819 China
| |
Collapse
|
3
|
Lin Q, Liu S, Xu S, Xu S, Pei M, Yao P, Xu H, Dan Y, Chen Y. Comprehensive effect of tuning Cu/SAPO-34 crystals using PEG on the enhanced hydrothermal stability for NH 3-SCR. Catal Sci Technol 2021. [DOI: 10.1039/d1cy01194d] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PEG fabricates advantageous hierarchical zeolite crystals, enhancing the high-temperature and low-temperature hydrothermal stability of Cu/SAPO-34.
Collapse
Affiliation(s)
- Qingjin Lin
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute, Sichuan University, Chengdu 610064, China
| | - Shuang Liu
- Institute of New Energy and Low-Carbon Technology, Sichuan University, Chengdu 610064, China
| | - Shuhao Xu
- Key Laboratory of Green Chemistry and Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, Sichuan, China
| | - Shi Xu
- Weichai Power Co., Ltd, Weifang 261061, Shangdong, China
| | - Mingming Pei
- Key Laboratory of Green Chemistry and Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, Sichuan, China
| | - Pan Yao
- Institute of New Energy and Low-Carbon Technology, Sichuan University, Chengdu 610064, China
| | - Haidi Xu
- Institute of New Energy and Low-Carbon Technology, Sichuan University, Chengdu 610064, China
- Center of Engineering of Vehicular Exhaust Gases Abatement, Chengdu 610064, Sichuan, China
- Center of Engineering of Environmental Catalytic Material, Chengdu 610064, Sichuan, China
| | - Yi Dan
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute, Sichuan University, Chengdu 610064, China
| | - Yaoqiang Chen
- Key Laboratory of Green Chemistry and Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, Sichuan, China
- Center of Engineering of Vehicular Exhaust Gases Abatement, Chengdu 610064, Sichuan, China
- Center of Engineering of Environmental Catalytic Material, Chengdu 610064, Sichuan, China
| |
Collapse
|
4
|
Paolucci C, Di Iorio JR, Schneider WF, Gounder R. Solvation and Mobilization of Copper Active Sites in Zeolites by Ammonia: Consequences for the Catalytic Reduction of Nitrogen Oxides. Acc Chem Res 2020; 53:1881-1892. [PMID: 32786332 DOI: 10.1021/acs.accounts.0c00328] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
ConspectusCopper-exchanged chabazite (Cu-CHA) zeolites are catalysts used in diesel emissions control for the abatement of nitrogen oxides (NOx) via selective catalytic reduction (SCR) reactions with ammonia as the reductant. The discovery of these materials in the early 2010s enabled a step-change improvement in diesel emissions aftertreatment technology. Key advantages of Cu-CHA zeolites over prior materials include their effectiveness at the lower temperatures characteristic of diesel exhaust, their durability under high-temperature hydrothermal conditions, and their resistance to poisoning from residual hydrocarbons present in exhaust. Fundamental catalysis research has since uncovered mechanistic and kinetic features that underpin the ability of Cu-CHA to selectively reduce NOx under strongly oxidizing conditions and to achieve improved NOx conversion relative to other zeolite frameworks, particularly at low exhaust temperatures and with ammonia instead of other reductants.One critical mechanistic feature is the NH3 solvation of exchanged Cu ions at low temperatures (<523 K) to create cationic Cu-amine coordination complexes that are ionically tethered to anionic Al framework sites. This ionic tethering confers regulated mobility that facilitates interconversion between mononuclear and binuclear Cu complexes, which is necessary to propagate SCR through a Cu2+/Cu+ redox cycle during catalytic turnover. This dynamic catalytic mechanism, wherein single and dual metal sites interconvert to mediate different half-reactions of the redox cycle, combines features canonically associated with homogeneous and heterogeneous reaction mechanisms.In this Account, we describe how a unified experimental and theoretical interrogation of Cu-CHA catalysts in operando provided quantitative evidence of regulated Cu ion mobility and its role in the SCR mechanism. This approach relied on new synthetic methods to prepare model Cu-CHA zeolites with varied active-site structures and spatial densities in order to verify that the kinetic and mechanistic models describe the catalytic behavior of a family of materials of diverse composition, and on new computational approaches to capture the active-site structure and dynamics under conditions representative of catalysis. Ex situ interrogation revealed that the Cu structure depends on the conditions for the zeolite synthesis, which influence the framework Al substitution patterns, and that statistical and electronic structure models can enumerate Cu site populations for a known Al distribution. This recognition unifies seemingly disparate spectroscopic observations and inferences regarding Cu ion structure and responses to different external conditions. SCR rates depend strongly on the Cu spatial density and zeolite composition in kinetic regimes where Cu+ oxidation with O2 becomes rate-limiting, as occurs at lower temperatures and under fuel-rich conditions. Transient experiments, ab initio molecular dynamics simulations, and statistical models relate these sensitivities to the mobility constraints imposed by the CHA framework on NH3-solvated Cu ions, which regulate the pore volume accessible to these ions and their ability to pair and complete the catalytic cycle. This highlights the key characteristics of the CHA framework that enable superior performance under low-temperature SCR reaction conditions.This work illustrates the power of precise control over a catalytic material, simultaneous kinetic and spectroscopic interrogation over a wide range of reaction conditions, and computational strategies tailored to capture those reaction conditions to reveal in microscopic detail the mechanistic features of a complex and widely practiced catalysis. In doing so, it highlights the key role of ion mobility in catalysis and thus potentially a more general phenomenon of reactant solvation and active site mobilization in reactions catalyzed by exchanged metal ions in zeolites.
Collapse
Affiliation(s)
- Christopher Paolucci
- Department of Chemical Engineering, University of Virginia, Charlottesville, Virginia 22903, United States
| | - John R. Di Iorio
- Charles D. Davidson School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - William F. Schneider
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Rajamani Gounder
- Charles D. Davidson School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| |
Collapse
|