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Heard CJ, Grajciar L, Erlebach A. Migration of zeolite-encapsulated subnanometre platinum clusters via reactive neural network potentials. NANOSCALE 2024; 16:8108-8118. [PMID: 38567421 DOI: 10.1039/d4nr00017j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
The migration of atoms and small clusters is an important process in sub-nanometre scale heterogeneous catalysis, affecting activity, accessibility and deactivation through sintering. Control of migration can be partially achieved via encapsulation of sub-nanometre metal particles into porous media such as zeolites. However, a general understanding of the migration mechanisms and their sensitivity to particle size and framework environment is lacking. Here, we extend the time-scale and sampling of atomistic simulations of platinum cluster diffusion in siliceous zeolite frameworks, by introducing a reactive neural network potential of density functional quality. We observe that Pt atoms migrate in a qualitatively different manner from clusters, occupying the dense region of the framework and avoiding the free pore space. We also find that for cage-like zeolite CHA there exists a maximum in self diffusivity for the Pt dimer beyond which, confinement effects hinder intercage migration. By extending the quality of sampling, NNP-based methods allow for the discovery of novel dynamical processes at the atomistic scale, bringing modelling closer to operando experimental characterization of catalytic materials.
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Affiliation(s)
- Christopher J Heard
- Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Praha 2, 12843, Czech Republic.
| | - Lukáš Grajciar
- Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Praha 2, 12843, Czech Republic.
| | - Andreas Erlebach
- Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Praha 2, 12843, Czech Republic.
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Liu C, Zhang J, Zhao X, Xu M, Liu H, Zhou H. Stability, biomechanics and biocompatibility analysis following different preparation strategies of hierarchical zeolite coatings on titanium alloy surfaces. Front Bioeng Biotechnol 2023; 11:1337709. [PMID: 38188487 PMCID: PMC10766723 DOI: 10.3389/fbioe.2023.1337709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Accepted: 12/07/2023] [Indexed: 01/09/2024] Open
Abstract
Traditional titanium alloy implant surfaces are inherently smooth and often lack effective osteoinductive properties. To overcome these limitations, coating technologies are frequently employed to enhance the efficiency of bone integration at the implant-host bone interface. Hierarchical zeolites, characterized by their chemical stability, can be applied to 3D-printed porous titanium alloy (pTi) surfaces as coating. The resulting novel implants with a "microporous-mesoporous-macroporous" spatial gradient structure can influence the behavior of adjacent cells; thereby, promoting the integration of bone at the implant interface. Consequently, a thorough exploration of various preparation methods is warranted for hierarchical zeolite coatings with respect to biocompatibility, coating stability, and osteogenesis. In this study, we employed three methods: in situ crystal growth, secondary growth, and layer-by-layer assembly, to construct hierarchical zeolite coatings on pTi, resulting in the development of a gradient structure. The findings of this investigation unequivocally demonstrated that the LBL-coating method consistently produced coatings characterized by superior uniformity, heightened surface roughness, and increased hydrophilicity, as well as increased biomechanical properties. These advantages considerably amplified cell adhesion, spreading, osteogenic differentiation, and mineralization of MC3T3-E1 cells, presenting superior biological functionality when compared to alternative coating methods. The outcomes of this research provide a solid theoretical basis for the clinical translation of hierarchical zeolite coatings in surface modifications for orthopedic implants.
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Affiliation(s)
- Chang Liu
- School of Materials Science and Engineering, Central South University, Changsha, China
| | - Jiaxin Zhang
- Department of Orthopedics, The Second Hospital of Jilin University, Changchun, China
| | - Xin Zhao
- Department of Orthopedics, The Second Hospital of Jilin University, Changchun, China
| | - Mingwei Xu
- Department of Orthopedics, The Second Hospital of Jilin University, Changchun, China
| | - He Liu
- Department of Orthopedics, The Second Hospital of Jilin University, Changchun, China
| | - Hongming Zhou
- School of Materials Science and Engineering, Central South University, Changsha, China
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Li C, Dong X, Yu H, Yu Y. Al distribution and structural stability of H-BEA zeolites at different Si/Al ratios and temperatures: a first-principles study. Phys Chem Chem Phys 2023; 25:24547-24562. [PMID: 37661842 DOI: 10.1039/d3cp02380j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
Beta zeolites have been widely used in acid-catalyzed reactions because of their excellent properties. An in-depth study of the position, quantity, and distribution of beta zeolites substituted by Al is significant to understand the catalytic performance of the active site of zeolite catalysts. The distribution of Al in H-BEA and the structure of silanol nests in dealuminated BEA at different Si/Al ratios and synthesis temperatures were studied by the DFT method. T1, T2, T7, and T9 sites were chosen to be simulated. The synthesis temperature can change the distribution of Al and the proportion of T sites at different Si/Al ratios. The proportion of T7 and T9 is more than 70% at different Si/Al ratios of H-BEA and decreases with the synthesis temperature. T1 and T2 sites begin to appear when Si/Al < 20 and the proportion of T1 and T2 sites is less than 20%. When Si/Al < 8, the substitution energy of the AlSiAl structure, which has Si(2Al, 2Si) species, is obviously lower than that of the normal structure, which indicates that the Al-O-Si-O-Al species will appear in H-BEA. The Al(T7)Si(T5)Al(T9)Si(T5)Al(T7) and Al(T1)Si(T1)Al(T9) groups can not only stabilize H-BEA but also play an essential role in the formation of Si(2Al, 2Si) species. For dealuminated BEA zeolites, the silanol nest forms four hydrogen bonds through four silanols. The orientation of silanol groups in the silanol nest formed after dealumination at different T sites is different. The T7 and T9 sites in H-BEA are more likely to undergo dealumination. By contrast, the dealumination of the T1 and T2 sites is a challenge.
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Affiliation(s)
- Changdong Li
- Key Laboratory for Green Chemical Technology of Ministry of Education, R&D Center for Petrochemical Technology, Tianjin University, Tianjin 300072, China.
- Zhejiang Institute of Tianjin University, Ningbo, Zhejiang, 315201, China
- State Key Laboratory of Engines, Tianjin University, Tianjin 300072, China
| | - Xiuqin Dong
- Key Laboratory for Green Chemical Technology of Ministry of Education, R&D Center for Petrochemical Technology, Tianjin University, Tianjin 300072, China.
- Zhejiang Institute of Tianjin University, Ningbo, Zhejiang, 315201, China
- State Key Laboratory of Engines, Tianjin University, Tianjin 300072, China
| | - Haipeng Yu
- Key Laboratory for Green Chemical Technology of Ministry of Education, R&D Center for Petrochemical Technology, Tianjin University, Tianjin 300072, China.
- Zhejiang Institute of Tianjin University, Ningbo, Zhejiang, 315201, China
- State Key Laboratory of Engines, Tianjin University, Tianjin 300072, China
| | - Yingzhe Yu
- Key Laboratory for Green Chemical Technology of Ministry of Education, R&D Center for Petrochemical Technology, Tianjin University, Tianjin 300072, China.
- Zhejiang Institute of Tianjin University, Ningbo, Zhejiang, 315201, China
- State Key Laboratory of Engines, Tianjin University, Tianjin 300072, China
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Origin for superior adsorption of metal ions and efficient control of heavy metals by montmorillonite: A molecular dynamics exploration. CHEMICAL ENGINEERING JOURNAL ADVANCES 2023. [DOI: 10.1016/j.ceja.2023.100467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023] Open
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Li Y, Chen D, Xu X, Wang X, Kang R, Fu M, Guo Y, Chen P, Li Y, Ye D. Cold-Start NO x Mitigation by Passive Adsorption Using Pd-Exchanged Zeolites: From Material Design to Mechanism Understanding and System Integration. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:3467-3485. [PMID: 36802541 DOI: 10.1021/acs.est.2c06207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
It remains a major challenge to abate efficiently the harmful nitrogen oxides (NOx) in low-temperature diesel exhausts emitted during the cold-start period of engine operation. Passive NOx adsorbers (PNA), which could temporarily capture NOx at low temperatures (below 200 °C) and release the stored NOx at higher temperatures (normally 250-450 °C) to downstream selective catalytic reduction unit for complete abatement, hold promise to mitigate cold-start NOx emissions. In this review, recent advances in material design, mechanism understanding, and system integration are summarized for PNA based on palladium-exchanged zeolites. First, we discuss the choices of parent zeolite, Pd precursor, and synthetic method for the synthesis of Pd-zeolites with atomic Pd dispersions, and review the effect of hydrothermal aging on the properties and PNA performance of Pd-zeolites. Then, we show how different experimental and theoretical methodologies can be integrated to gain mechanistic insights into the nature of Pd active sites, the NOx storage/release chemistry, as well as the interactions between Pd and typical components/poisons in engine exhausts. This review also gathers several novel designs of PNA integration into modern exhaust after-treatment systems for practical application. At the end, we discuss the major challenges, as well as important implications, for the further development and real application of Pd-zeolite-based PNA in cold-start NOx mitigation.
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Affiliation(s)
- Ying Li
- National Engineering Laboratory for VOCs Pollution Control Technology and Equipment, Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control, School of Environment and Energy, South China University of Technology, 510006 Guangzhou, China
| | - Dongdong Chen
- National Engineering Laboratory for VOCs Pollution Control Technology and Equipment, Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control, School of Environment and Energy, South China University of Technology, 510006 Guangzhou, China
| | - Xin Xu
- National Engineering Laboratory for VOCs Pollution Control Technology and Equipment, Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control, School of Environment and Energy, South China University of Technology, 510006 Guangzhou, China
| | - Xinyu Wang
- National Engineering Laboratory for VOCs Pollution Control Technology and Equipment, Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control, School of Environment and Energy, South China University of Technology, 510006 Guangzhou, China
| | - Running Kang
- Department of Chemical and Metallurgical Engineering, School of Chemical Engineering, Aalto University, 02150 Espoo, Finland
| | - Mingli Fu
- National Engineering Laboratory for VOCs Pollution Control Technology and Equipment, Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control, School of Environment and Energy, South China University of Technology, 510006 Guangzhou, China
| | - Yanbing Guo
- Institute of Environmental and Applied Chemistry, College of Chemistry, Central China Normal University, 430079 Wuhan, China
| | - Peirong Chen
- National Engineering Laboratory for VOCs Pollution Control Technology and Equipment, Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control, School of Environment and Energy, South China University of Technology, 510006 Guangzhou, China
| | - Yongdan Li
- Department of Chemical and Metallurgical Engineering, School of Chemical Engineering, Aalto University, 02150 Espoo, Finland
| | - Daiqi Ye
- National Engineering Laboratory for VOCs Pollution Control Technology and Equipment, Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control, School of Environment and Energy, South China University of Technology, 510006 Guangzhou, China
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Bramley GA, Beynon OT, Stishenko PV, Logsdail AJ. The application of QM/MM simulations in heterogeneous catalysis. Phys Chem Chem Phys 2023; 25:6562-6585. [PMID: 36810655 DOI: 10.1039/d2cp04537k] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
The QM/MM simulation method is provenly efficient for the simulation of biological systems, where an interplay of extensive environment and delicate local interactions drives a process of interest through a funnel on a complex energy landscape. Recent advances in quantum chemistry and force-field methods present opportunities for the adoption of QM/MM to simulate heterogeneous catalytic processes, and their related systems, where similar intricacies exist on the energy landscape. Herein, the fundamental theoretical considerations for performing QM/MM simulations, and the practical considerations for setting up QM/MM simulations of catalytic systems, are introduced; then, areas of heterogeneous catalysis are explored where QM/MM methods have been most fruitfully applied. The discussion includes simulations performed for adsorption processes in solvent at metallic interfaces, reaction mechanisms within zeolitic systems, nanoparticles, and defect chemistry within ionic solids. We conclude with a perspective on the current state of the field and areas where future opportunities for development and application exist.
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Affiliation(s)
- Gabriel Adrian Bramley
- Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Park Place, CF10 3AT, UK.
| | - Owain Tomos Beynon
- Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Park Place, CF10 3AT, UK.
| | | | - Andrew James Logsdail
- Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Park Place, CF10 3AT, UK.
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