Co-precipitation synthesis of mesoporous maghemite for catalysis application

Talgatov, E. T.; Auyezkhanova, A. S.; Seitkalieva, K. S.; Tumabayev, N. Zh.; Akhmetova, S.N.; Жармагамбетова, А. К.

doi:10.1007/s10934-020-00869-1

Cited by 16 publications

(11 citation statements)

References 51 publications

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“…The effect of several synthesis parameters (e.g., type of precipitating agent, stoichiometric ratio, temperature, etc.) on the chemical composition, morphology, size distribution and magnetic properties of MNPs have been investigated [19][20][21][22][23][24], but few, and often contradictory works, on the effect of reaction atmosphere have been carried out. It has been reported that a normal reaction atmosphere (i.e., air), leads to higher saturation magnetization (M s ) and narrower size distribution [25,26].…”

Section: Introductionmentioning

confidence: 99%

Spinel Iron Oxide by the Co-Precipitation Method: Effect of the Reaction Atmosphere

et al. 2021

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Synthesis atmosphere (i.e., air and nitrogen) effects on the physical properties and formation mechanism of spinel iron oxide nanoparticles prepared via the co-precipitation method have been investigated using a multi-technique approach. The obtained magnetic nanoparticles (MNPs) were characterized using the X-ray diffraction, transmission electron microscopy (TEM), SQUID magnetometry, Mössbauer spectroscopy and X-ray absorption near-edge Structure spectroscopy techniques. The synthesis procedure leads to the formation of a spinel structure with an average crystallite size of 9.0(9) nm. The morphology of the particles synthetized under an inert atmosphere was quasi-spherical, while the nanoparticles prepared in air present a faceted shape. The small differences observed in morphological properties are explained by the influence of the reaction atmosphere on the formation mechanism of the MNPs. The magnetic characterization indicates that both samples exhibit superparamagnetic behavior at 300 K. The investigation by means of the Langevin approach at 300 K also leads to equal values for the mean size of the magnetic cores (Dm). Additionally, the analysis of the Mössbauer spectra revealed the lack of spin disorder for both samples, resulting in a high saturation magnetization. The fit of XANES spectrum suggests that about 2/3 of the iron ions reside in a local environment close to that of γ-Fe2O3 and about 1/3 close to that of Fe3O4 for the sample synthetized in inert atmosphere.

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Section: Introductionmentioning

confidence: 99%

Spinel Iron Oxide by the Co-Precipitation Method: Effect of the Reaction Atmosphere

et al. 2021

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“…The magnetization of the catalysts was lower than that of 11–13 nm magnetite nanoparticles (M S = 71–75 emu g −1 ), 28,29 and was not far from the value (M S = 45–47 emu g −1 ) of the γ‐Fe 2 O 3 nanoparticles of 10–14 nm in size 30,31 . The M r and H C values showed that both materials exhibit weak ferromagnetic and soft magnetic behaviors, 32 apparently due to an agglomeration of magnetic nanoparticles 26 …”

Section: Resultsmentioning

confidence: 81%

“…The appearance of six characteristic peaks at 30.2°, 35.5°, 43.3°, 53.8°, 57.2°, and 62.8° corresponding to the (220), (311), (400), (422), (511), and (440) crystal planes of a maghemite (γ‐Fe 2 O 3 , JCPDS Card No. 39‐1346) with a cubic spinel structure was observed on both XRD patterns 26 . The crystalline size of magnetic nanoparticles calculated using Scherrer's formula was 8.4 nm for both catalysts.…”

Section: Resultsmentioning

confidence: 91%

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Behavior of Pd‐supported catalysts in phenylacetylene hydrogenation: Effect of combined use of polyvinylpyrrolidone and NaOH for magnetic support modification

Жармагамбетова¹,

Talgatov²,

Auyezkhanova³

et al. 2021

Polymers for Advanced Techs

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Recently, magnetic nanoparticles have attracted the attention as catalyst supports due to the possibility of magnetic separation, allowing for easy, fast, and clean recovery of the catalysts. A synthesis strategy of such supports plays an important role in improving the properties of the magnetic catalysts. Here, we proposed a simple and effective method to increase the activity and lifetime of the Pd magnetic catalyst. Polyvinylpyrrolidone‐maghemite nanoparticles were synthesized via one‐pot coprecipitation method using an excess of the NaOH. This was followed by adsorption of Pd2+ on the magnetic nanoparticles. The resulting catalyst showed activity (WCC = 4.0 × 10−6 mol s−1, WCC = 12.7 × 10−6 mol s−1) and selectivity (94%) in phenylacetylene hydrogenation. The catalyst was then magnetically recovered and reused 58 times. The activity of the catalyst increased significantly during the first three runs, changing the rate ratio of WCC to WCC from 1:3.2 to 1:1.6, and then decreased in the following runs. To understand the reason for this behavior, the catalyst was characterized, as well as catalytic studies were performed using similar catalysts for comparison. The results show that the NaOH adsorbed on magnetic support affects the size, stability, and catalytic properties of the Pd particles, and the effect of alkali is enhanced in the presence of the polymer.

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“…Além disso, pode-se monitorar o tamanho destas nanoestruturas para que não percam seu poder de magnetização [36]. Por exemplo, a adição lenta de hidróxido de sódio (NaOH) como um precipitante (em quantidades estequiométricas) durante a reação de coprecipitação promove agregação e formação de um material mesoporoso com alta saturação magnética [28,37].…”

Section: Obtenção E Caracterização Das Nanopartículas Magnéticas (Npmag)unclassified

Obtenção de nanopartículas magnéticas utilizando materiais do cotidiano: síntese, caracterização e abordagem didática para o ensino médio

Ribeiro

Costa

Santos

et al. 2021

Rev. Bras. Ensino Fís.

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Neste trabalho é apresentada uma prática experimental com materiais do cotidiano para obtenção de nanopartículas magnéticas e uma proposta didática com o tema Nanociências e Nanotecnologia, baseada na abordagem CTSA. As NPmag foram caracterizadas por espalhamento de luz e microscopia eletrônica de varredura. A proposta aliou a atividade experimental, discussões referentes à caracterização, introdução aos temas e suas aplicações. Os resultados da caracterização sugerem que a metodologia para obtenção das NPmag é eficiente para fins didáticos e a proposta didática proporcionou aprendizagem de conteúdos científicos e suas aplicações.

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Co-precipitation synthesis of mesoporous maghemite for catalysis application

Cited by 16 publications

References 51 publications

Spinel Iron Oxide by the Co-Precipitation Method: Effect of the Reaction Atmosphere

Spinel Iron Oxide by the Co-Precipitation Method: Effect of the Reaction Atmosphere

Behavior of Pd‐supported catalysts in phenylacetylene hydrogenation: Effect of combined use of polyvinylpyrrolidone and NaOH for magnetic support modification

Obtenção de nanopartículas magnéticas utilizando materiais do cotidiano: síntese, caracterização e abordagem didática para o ensino médio

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