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Bimetallic Copper-Silver Systems Supported on Natural Clinoptilolite: Long-Term Changes in Nanospecies’ Composition and Stability. INORGANICS 2022. [DOI: 10.3390/inorganics10030034] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Long-term changes in species of copper-silver bimetallic systems on natural clinoptilolite obtained by ion exchange of Cu2+ and Ag+ and then reduced at different temperatures were studied. Even after storage under ambient conditions, XRD and UV-Vis diffuse reflectance spectra indicate the presence of nanospecies and larger particles of reduced copper and silver. Scanning electron microscopy of aged bimetallic samples, reduced at the highest temperature (450 °C) and the pristine sample for their preparation, also aged, showed the presence of silver particles with a size of about 100 nm. They are formed in the initial ion-exchanged sample (without reduction) due to the degradation of Ag+ ions. The particles in the reduced sample are larger; in both samples they are evenly distributed over the surface. The presence of silver affects the stability and the mechanism of decomposition/oxidation of reduced copper species, and this stability is higher in bimetallic systems. The decomposition pattern of recently reduced species includes the formation of smaller nanoparticles and few-atomic clusters. This can occur, preceding the complete oxidation of Cu to ions. Quasicolloidal silver, which is present in fresh bimetallic samples reduced at lower temperatures, transforms after aging into Ag8 clusters, which indicates the stability of these nanospecies on natural clinoptilolite.
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Fadaee Takmil N, Jaleh B, Feizi Mohazzab B, Khazalpour S, Rostami-Vartooni A, Hong Chuong Nguyen T, Cuong Nguyen X, Varma RS. Hydrogen production by Electrochemical reaction using waste zeolite boosted with Titania and Au nanoparticles. INORG CHEM COMMUN 2021. [DOI: 10.1016/j.inoche.2021.108891] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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The Application of Copper-Gold Catalysts in the Selective Oxidation of Glycerol at Acid and Basic Conditions. Catalysts 2021. [DOI: 10.3390/catal11010094] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The crude glycerol is produced during the transesterification of animal fats and vegetable oils, but it is a by-product of this process. Currently, its elimination is a problem in the chemical industry. The main goal of this work was the preparation, characterization and application of mesoporous cerium-zirconium oxide as supports for copper and gold species and the comparison of selected factors on the properties of catalysts in glycerol oxidation in the liquid phase. The samples were characterized using adsorption and desorption of nitrogen, XRD, UV-vis, XPS, TEM, SEM, and STEM-EDXS. The obtained results of glycerol oxidation show that the bimetallic copper-gold catalysts are more active and selective to glyceric acid in this reaction than analogous monometallic gold catalysts. Additionally, bimetallic catalysts are also characterized by the catalytic stability, and their application leads to the increase of selectivity to glyceric acid during their reusing in glycerol oxidation in alkali media. In this work, the influence of selected factors, e.g., oxygen source and its pressure, solution pH, and base content on the catalytic activity of bimetallic catalysts is discussed.
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Effect of the Chemical Composition of Mesoporous Cerium-Zirconium Oxides on the Modification with Sulfur and Gold Species and Their Application in Glycerol Oxidation. CHEMENGINEERING 2017. [DOI: 10.3390/chemengineering1020018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Kotolevich Y, Kolobova E, Khramov E, Cabrera Ortega JE, Farías MH, Zubavichus Y, Zanella R, Mota-Morales JD, Pestryakov A, Bogdanchikova N, Cortés Corberán V. Identification of Subnanometric Ag Species, Their Interaction with Supports and Role in Catalytic CO Oxidation. Molecules 2016; 21:532. [PMID: 27110757 PMCID: PMC6273660 DOI: 10.3390/molecules21040532] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2016] [Revised: 04/07/2016] [Accepted: 04/15/2016] [Indexed: 11/16/2022] Open
Abstract
The nature and size of the real active species of nanoparticulated metal supported catalysts is still an unresolved question. The technique of choice to measure particle sizes at the nanoscale, HRTEM, has a practical limit of 1 nm. This work is aimed to identify the catalytic role of subnanometer species and methods to detect and characterize them. In this frame, we investigated the sensitivity to redox pretreatments of Ag/Fe/TiO₂, Ag/Mg/TiO₂ and Ag/Ce/TiO₂ catalysts in CO oxidation. The joint application of HRTEM, SR-XRD, DRS, XPS, EXAFS and XANES methods indicated that most of the silver in all samples is in the form of Ag species with size <1 nm. The differences in catalytic properties and sensitivity to pretreatments, observed for the studied Ag catalysts, could not be explained taking into account only the Ag particles whose size distribution is measured by HRTEM, but may be explained by the presence of the subnanometer Ag species, undetectable by HRTEM, and their interaction with supports. This result highlights their role as active species and the need to take them into account to understand integrally the catalysis by supported nanometals.
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Affiliation(s)
- Yulia Kotolevich
- Departamento de Fisicoquímica de Nanomateriales, Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México (UNAM), Ensenada 22860, Mexico.
| | - Ekaterina Kolobova
- Department of Physical and Analytical Chemistry, Tomsk Polytechnic University, Tomsk 634050, Russia.
| | - Evgeniy Khramov
- National Research Center "Kurchatov Institute", Moscow 123182, Russia.
| | - Jesús Efren Cabrera Ortega
- Departamento de Fisica Aplicada, Centro de Investigación Científica y de Educación Superior de Ensenada, Ensenada 22860, Mexico.
| | - Mario H Farías
- Departamento de Fisicoquímica de Nanomateriales, Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México (UNAM), Ensenada 22860, Mexico.
| | - Yan Zubavichus
- National Research Center "Kurchatov Institute", Moscow 123182, Russia.
| | - Rodolfo Zanella
- Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México (UNAM), México, DF 04510, Mexico.
| | - Josué D Mota-Morales
- Departamento de Fisicoquímica de Nanomateriales, Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México (UNAM), Ensenada 22860, Mexico.
- CONACYT Research Fellow at Centro de Nanociencias y Nanotecnología, UNAM, Ensenada 22860, Mexico.
| | - Alexey Pestryakov
- Department of Physical and Analytical Chemistry, Tomsk Polytechnic University, Tomsk 634050, Russia.
| | - Nina Bogdanchikova
- Departamento de Fisicoquímica de Nanomateriales, Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México (UNAM), Ensenada 22860, Mexico.
| | - Vicente Cortés Corberán
- Institute of Catalysis and Petroleumchemistry (ICP), Spanish Council for Scientific Research (CSIC), Madrid 28049, Spain.
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Kolobova E, Kotolevich Y, Pakrieva E, Mamontov G, Farías MH, Bogdanchikova N, Cortés Corberán V, Pestryakov A. Causes of Activation and Deactivation of Modified Nanogold Catalysts during Prolonged Storage and Redox Treatments. Molecules 2016; 21:486. [PMID: 27089310 PMCID: PMC6273705 DOI: 10.3390/molecules21040486] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2016] [Revised: 03/29/2016] [Accepted: 04/08/2016] [Indexed: 11/17/2022] Open
Abstract
The catalytic properties of modified Au/TiO2 catalysts for low-temperature CO oxidation are affected by deactivation and reactivation after long-term storage and by redox treatments. The effect of these phenomena on the catalysts was studied by HRTEM, BET, SEM, FTIR CO, XPS and H2 TPR methods. The main cause for the deactivation and reactivation of catalytic properties is the variation in the electronic state of the supported gold, mainly, the proportion of singly charged ions Au+. The most active samples are those with the highest proportion of singly charged gold ions, while catalysts with a high content of trivalent gold ions are inactive at low-temperatures. Active states of gold, resistant to changes caused by the reaction process and storage conditions, can be stabilized by modification of the titanium oxide support with transition metals oxides. The catalyst modified with lanthanum oxide shows the highest stability and activity.
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Affiliation(s)
- Ekaterina Kolobova
- Department of Physical and Analytical Chemistry, Tomsk Polytechnic University, Tomsk 634050, Russia.
| | - Yulia Kotolevich
- Centro de Nanociencias y Nanotecnología, UNAM, Ensenada 22860, Mexico.
| | - Ekaterina Pakrieva
- Department of Physical and Analytical Chemistry, Tomsk Polytechnic University, Tomsk 634050, Russia.
| | - Grigory Mamontov
- Laboratory of Catalytic Research, Tomsk State University, Tomsk 634050, Russia.
| | - Mario H Farías
- Centro de Nanociencias y Nanotecnología, UNAM, Ensenada 22860, Mexico.
| | | | | | - Alexey Pestryakov
- Department of Physical and Analytical Chemistry, Tomsk Polytechnic University, Tomsk 634050, Russia.
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Selective oxidation of 1-octanol over gold supported on mesoporous metal-modified HMS: The effect of the support. Catal Today 2014. [DOI: 10.1016/j.cattod.2013.10.035] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Synthesis and properties of crystalline silver nanoparticles supported in natural zeolite chabazite. J Mol Struct 2012. [DOI: 10.1016/j.molstruc.2012.05.080] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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From woody biomass extractives to health-promoting substances: Selective oxidation of the lignan hydroxymatairesinol to oxomatairesinol over Au, Pd, and Au–Pd heterogeneous catalysts. J Catal 2012. [DOI: 10.1016/j.jcat.2012.04.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Preparation of Au/SBA-15 and Its Catalytic Activity for CO Oxidation. CHINESE JOURNAL OF CATALYSIS 2010. [DOI: 10.3724/sp.j.1088.2010.00111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Simakov A, Tuzovskaya I, Bogdanchikova N, Pestryakov A, Avalos M, Farias M, Smolentseva E. Influence of sodium on activation of gold species in Y–zeolites. CATAL COMMUN 2008. [DOI: 10.1016/j.catcom.2007.11.027] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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