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Malyshev SA, Shlyakhtin OA, Loktev AS, Mazo GN, Timofeev GM, Mukhin IE, Svetogorov RD, Roslyakov IV, Dedov AG. Ni/(R 2O 3,CaO) Nanocomposites Produced by the Exsolution of R 1.5Ca 0.5NiO 4 Nickelates (R = Nd, Sm, Eu): Rare Earth Effect on the Catalytic Performance in the Dry Reforming and Partial Oxidation of Methane. Materials (Basel) 2022; 15:7265. [PMID: 36295329 PMCID: PMC9610205 DOI: 10.3390/ma15207265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 10/13/2022] [Accepted: 10/15/2022] [Indexed: 06/16/2023]
Abstract
In order to clarify the role of R2O3 in the metal-oxide catalysts derived from complex oxide precursors, a series of R1.5Ca0.5NiO4 (R = Nd, Sm, Eu) complex oxides was obtained. A significant systematic increase in the orthorhombic distortion of the R1.5Ca0.5NiO4 structure (K2NiF4 type, Cmce) from Nd to Eu correlates with a corresponding decrease in their ionic radii. A reduction of R1.5Ca0.5NiO4 in the Ar/H2 gas mixture at 800 °C causes a formation of dense agglomerates of CaO and R2O3 coated with spherical 25-30 nm particles of Ni metal. The size of metal particles and oxide agglomerates is similar in all Ni/(R2O3,CaO) composites in the study. Their morphology is rather similar to the products of redox exsolution obtained by the partial reduction of complex oxides. All obtained composites demonstrated a significant catalytic activity in the dry reforming (DRM) and partial oxidation (POM) of methane at 700-800 °C. A systematic decrease in the DRM catalytic activity of composites from Nd to Eu could be attributed to the basicity reduction of R2O3 components of the composite catalysts. The maximum CH4 conversion in POM reaction was observed for Ni/(Sm2O3,CaO), while the maximum selectivity was demonstrated by Nd2O3-based composite. The possible reasons for the observed difference are discussed.
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Affiliation(s)
- Sergey A. Malyshev
- Department of Chemistry, M.V. Lomonosov Moscow State University, 119991 Moscow, Russia
- Department of Materials Sciences, Shenzhen MSU-BIT University, Shenzhen 518172, China
| | - Oleg A. Shlyakhtin
- Department of Chemistry, M.V. Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Alexey S. Loktev
- A.V. Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, 119991 Moscow, Russia
- Department of General and Inorganic Chemistry, Gubkin Russian State University of Oil and Gas, 119991 Moscow, Russia
- N.S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, 119991 Moscow, Russia
| | - Galina N. Mazo
- Department of Chemistry, M.V. Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Grigoriy M. Timofeev
- Department of Chemistry, M.V. Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Igor E. Mukhin
- Department of General and Inorganic Chemistry, Gubkin Russian State University of Oil and Gas, 119991 Moscow, Russia
| | | | - Ilya V. Roslyakov
- N.S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, 119991 Moscow, Russia
- Department of Materials Sciences, M.V. Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Alexey G. Dedov
- A.V. Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, 119991 Moscow, Russia
- Department of General and Inorganic Chemistry, Gubkin Russian State University of Oil and Gas, 119991 Moscow, Russia
- N.S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, 119991 Moscow, Russia
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Nasriddinov A, Rumyantseva M, Marikutsa A, Gaskov A, Lee JH, Kim JH, Kim JY, Kim SS, Kim HW. Sub-ppm Formaldehyde Detection by n- n TiO 2@SnO 2 Nanocomposites. Sensors (Basel) 2019; 19:E3182. [PMID: 31331010 PMCID: PMC6679342 DOI: 10.3390/s19143182] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 07/10/2019] [Accepted: 07/17/2019] [Indexed: 01/27/2023]
Abstract
Formaldehyde (HCHO) is an important indicator of indoor air quality and one of the markers for detecting lung cancer. Both medical and air quality applications require the detection of formaldehyde in the sub-ppm range. Nanocomposites SnO2/TiO2 are promising candidates for HCHO detection, both in dark conditions and under UV illumination. Nanocomposites TiO2@SnO2 were synthesized by ALD method using nanocrystalline SnO2 powder as a substrate for TiO2 layer growth. The microstructure and composition of the samples were characterized by ICP-MS, TEM, XRD and Raman spectroscopy methods. The active surface sites were investigated using FTIR and TPR-H2 methods. The mechanism of formaldehyde oxidation on the surface of semiconductor oxides was studied by in situ DRIFTS method. The sensor properties of nanocrystalline SnO2 and TiO2@SnO2 nanocomposites toward formaldehyde (0.06-0.6 ppm) were studied by in situ electrical conductivity measurements in dark conditions and under periodic UV illumination at 50-300 °C. Nanocomposites TiO2@SnO2 exhibit a higher sensor signal than SnO2 and a decrease in the optimal measurement temperature by 50 °C. This result is explained based on the model considering the formation of n-n heterocontact at the SnO2/TiO2 interface. UV illumination leads to a decrease in sensor response compared with that obtained in dark conditions because of the photodesorption of oxygen involved in the oxidation of formaldehyde.
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Affiliation(s)
- Abulkosim Nasriddinov
- Chemistry Department, Moscow State University, Moscow 119991 Russia
- Faculty of Materials Science, Moscow State University, Moscow 119991 Russia
| | | | - Artem Marikutsa
- Chemistry Department, Moscow State University, Moscow 119991 Russia
| | - Alexander Gaskov
- Chemistry Department, Moscow State University, Moscow 119991 Russia
| | - Jae-Hyoung Lee
- Department of Materials Science and Engineering, Inha University, Incheon 22212, Korea
| | - Jae-Hun Kim
- Department of Materials Science and Engineering, Inha University, Incheon 22212, Korea
| | - Jin-Young Kim
- Department of Materials Science and Engineering, Inha University, Incheon 22212, Korea
| | - Sang Sub Kim
- Department of Materials Science and Engineering, Inha University, Incheon 22212, Korea
| | - Hyoun Woo Kim
- School of Materials Science and Engineering, Hanyang University, Seoul 04763, Korea
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