CATALYTIC ACTIVITY OF VANADIUM OXIDE DOPED WITH PALLADIUM NANOPARTICLES ON OXIDATION OF 5-HYDROXYMETHYLFURFURAL

2,5-Furan dicarboxylic acid (FDCA) is a bio-based chemical used as a feedstock for a wide range of industrial applications - particularly the bioplastic industries. It is derived from 5-hydroxymethylfurfural (HMF) through a reaction of oxidation using either homogeneous or heterogeneous catalysts. According to the advantages of heterogeneous catalysts, this research aims to seek a novel catalyst type with high selectivity and high activity. We performed an investigation of the synergic effect of palladium nanoparticles and V2O5 catalysts on catalytic oxidation of HMF and physicochemical properties. A commercial vanadium oxide powder (V2O5) was doped with 1 wt.% palladium nanoparticles (Pd NPs). The Pd NPs were prepared by the colloid-chemical reduction method. Two different synthesis processes were performed base on the consequence of the combination of colloid-chemical reduction and immobilization steps, herein stepwise (ST) and simultaneous (SI) process. For the ST process, Pd NPs were reduced and then immobilized on V2O5 powder. During the SI process, the reduction and immobilization steps took place simultaneously. Physical and chemical properties of a prepared catalyst such as morphology, particle size distribution, and chemical structure and composition were characterized using various techniques, e.g. TEM, BET, X-ray diffraction, UV-vis spectrophotometer. It was distinctly found the synergic effect between Pd NPs and V2O5 catalysts on the surface catalytic activity of HMF oxidation and catalytic selectivity. The Pd NPs incorporated catalysts (ST and SI processes) gave catalytic activity at 63%, which are 2-fold in catalytic activity in comparison with bare V2O5 catalysts as well as they were selective to FDCA up to 19-24%. The step of catalyst preparation slightly influenced on catalytic activity and yield of FDCA; however, it did alter particle size distribution of Pd NPs and surface characteristics

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Study of the microstructure and particles of vanadium (III) oxide, vanadium (V) oxide and lithium aluminate powders

Industrial laboratory Diagnostics of materials ◽

10.26896/1028-6861-2020-86-1-32-37 ◽

2020 ◽

Vol 86 (1) ◽

pp. 32-37

Author(s):

Valeria A. Brodskaya ◽

Oksana A. Molkova ◽

Kira B. Zhogova ◽

Inga V. Astakhova

Keyword(s):

Particle Size ◽

Particle Size Distribution ◽

Vanadium Oxide ◽

Size Distribution ◽

Microstructural Analysis ◽

Coherent Scattering ◽

Powder Materials ◽

Lithium Aluminate ◽

Range Limit ◽

Oxide Particles

Powder materials are widely used in the manufacture of electrochemical elements of thermal chemical sources of current. Electrochemical behavior of the powders depends on the shape and size of their particles. The results of the study of the microstructure and particles of the powders of vanadium (III), (V) oxides and lithium aluminate obtained by transmission electron and atomic force microscopy, X-ray diffraction and gas adsorption analyses are presented. It is found that the sizes of vanadium (III) and vanadium (V) oxide particles range within 70 – 600 and 40 – 350 nm, respectively. The size of the coherent-scattering regions of the vanadium oxide particles lies in the lower range limit which can be attributed to small size of the structural elements (crystallites). An average volumetric-surface diameter calculated on the basis of the surface specific area is close to the upper range limit which can be explained by the partial agglomeration of the powder particles. Unlike the vanadium oxide particles, the range of the particle size distribution of the lithium aluminate powder is narrower — 50 – 110 nm. The values of crystallite sizes are close to the maximum of the particle size distribution. Microstructural analysis showed that the particles in the samples of vanadium oxides have a rounded (V2O3) or elongated (V2O5) shape; whereas the particles of lithium aluminate powder exhibit lamellar structure. At the same time, for different batches of the same material, the particle size distribution is similar, which indicates the reproducibility of the technologies for their manufacture. The data obtained can be used to control the constancy of the particle size distribution of powder materials.

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The Effect of Alcohol on Palladium Nanoparticles in i-Pd(OAc)2(TPPTS)2 for Aerobic Oxidation of Benzyl Alcohol

Metals ◽

10.3390/met11091443 ◽

2021 ◽

Vol 11 (9) ◽

pp. 1443

Author(s):

Oshrat Levy-Ontman ◽

Eliraz Stamker ◽

Adi Wolfson

Keyword(s):

Particle Size ◽

Particle Size Distribution ◽

Benzyl Alcohol ◽

Size Distribution ◽

Palladium Nanoparticles ◽

Aerobic Oxidation ◽

Secondary Alcohol ◽

Oxidation Of Benzyl Alcohol ◽

Conversion Rates ◽

Impregnation Time

In the heterogeneous catalyst i-Pd(OAc)2(TPPTS)2, Pd(II) was reduced to Pd(0) by using different alcohol solvents, and the catalyst’s activity was studied in the aerobic oxidation of benzyl alcohol. We studied the effects of the impregnation time in ethanol as a solvent and the use of various alcoholic solvents on the size of palladium nanoparticles. We found that the reduction of palladium by the various alcohols yielded palladium nanoparticles that were active in the aerobic oxidation of benzyl alcohol. As determined by DLS, TEM, and zeta potential analyses, both the impregnation time in ethanol and the type of alcohol used were observed to affect nanoparticle formation, particle size distribution, and agglomeration, as well as the conversion rate. The palladium nanoparticles’ hydrodynamic diameter sizes obtained during the 24 h of impregnation time were in the range of 10–200 nm. However, following 24 h of impregnation in ethanol the nanoparticles tended to form aggregates. The conversion rates of all the primary alcohols were similar, while for secondary alcohol, in which the hydrogen of the hydroxyl is less acidic and there is steric hindrance, the conversion was the lowest. Performing the oxidation using the solvent 1-propanol yielded smaller nanoparticles with narrower distributions in comparison to the reaction that was observed when using the ethanol solvent. On the other hand, the relatively high particle size distribution in 1-hexanol yielded agglomerates.

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Effect of Dispersant on the Particle Size Distribution of Cu Powders Prepared by Wet-Reduction Process

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.336-338.2118 ◽

2007 ◽

Vol 336-338 ◽

pp. 2118-2121

Author(s):

Yong Yee Kim ◽

Young Min Park ◽

Hoy Yul Park ◽

Hong Chae Park ◽

Seog Young Yoon

Keyword(s):

Particle Size ◽

Particle Size Distribution ◽

Size Distribution ◽

Reaction Temperature ◽

Chemical Reduction ◽

Reduction Process ◽

Particle Size Distributions ◽

Water Solvent ◽

Carboxymethyl Cellulose Sodium ◽

Wet Chemical

Monodispersed Cu powders were prepared in aqueous solution through a wet-reduction process with hydrazine hydrate (N2H4·H2O). In particular, the effect of the dispersant such as sodium pyrophosphate decahydrate (Na4O7P2·10H2O), carboxymethyl cellulose sodium salt (CMC) in water solvent on the particle size for the prepared Cu powders was investigated. The Cu powders essentially were monodispersed and irregular in shape regardless of reaction temperature and dispersant. In the case of adding the Na4O7P2·10H2O, the particle size of Cu powders increased with the increase of reaction temperature, which the particles were agglomerated in irregular shape and became to be large. The particle size distributions was asymmetry and to be broad regardless of reaction temperature. On the other hand, when the CMC was added, the particle size of Cu powders, which were much finer compared with adding the Na4O7P2·10H2O as a dispersant, was not much changed with reaction temperature. The particle size distribution of Cu powder was much narrow regardless of reaction temperature. As a result, it would be suggested that the CMC was more effective dispersant reagent to produce the monodispersed and fine Cu powders with narrow size distribution using the wet chemical reduction process

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