How to Determine the Core-Shell Nature in Bimetallic  Catalyst Particles?

Westsson, Emma; Koper, Ger J. M.

doi:10.3390/catal4040375

Cited by 30 publications

(18 citation statements)

References 68 publications

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“…Besides, the t-plot micropore areas values are negligible, and the FCS samples are mostly mesoporous, with FCS CP having an opposite behavior. Accordingly, the pore size distributions are typical of mesoporous materials with cylindrical/spherical pore geometry with peaks around 6-15 nm, as found elsewhere [5]. Furthermore, all samples prepared via FCS CP exhibit a BET surface area below 3 m 2 g −1 , a pore volume of 0.01 cm 3 g −1 , and a pore diameter of ca.…”

Section: Physicochemical Properties Of the Synthesized Solidsmentioning

confidence: 65%

Styrene Oxidation to Valuable Compounds over Nanosized FeCo-Based Catalysts: Effect of the Third Metal Addition

et al. 2017

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Nanosized FeCo-based solids were prepared via distinct preparation procedures. The catalytic performances of the solids for styrene oxidation in the presence of hydrogen peroxide were evaluated. The addition of promoters in FeCo such as Sn, Mo, or Cu was also investigated. The catalysts were characterized with XRD, Raman spectroscopy, TEM, chemical analyses, EPR and SEM-EDS. Of these solids obtained via four different methods, the catalyst prepared via the NC and CM procedures enabled a partial incorporation of the Sn into the FeCo matrix forming a very active phase, namely the Heusler alloy. This was ascribed to the high initial dispersion of Sn as a promoter into the FeCo matrix, which led to available FeCoSn (FCS) particles well dispersed and stable on the catalyst surface. In the case of incorporating Mo or Cu to the nanosized FeCo catalyst, a poor stability towards leaching was observed when operating under the same reaction conditions. Cu was much less active than both Sn and Mo, mainly leading to acetophenone, ethylbenzene, 2-phenyl ethanol, 2-phenyl acetic acid, and 2-phenyl acetaldehyde products. The best catalytic results under the optimized reaction conditions, especially at 50 • C and styrene/H 2 O 2 molar ratio of 1 were achieved with nanosized FCS. This solid had a conversion of ca. 70% and selectivity for aldehydes of ca. 27%, and the selectivity for the condensation products was 29%.

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Section: Physicochemical Properties Of the Synthesized Solidsmentioning

confidence: 65%

Styrene Oxidation to Valuable Compounds over Nanosized FeCo-Based Catalysts: Effect of the Third Metal Addition

et al. 2017

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“…In contrast to Ni/Al 2 O 3 , where intensive retardation of benzene hydrogenation occurs at ratios H 2 / benzene <10, in case of Ni-CrA/Al 2 O 3 , this ratio may be as low as 4.0 [38]. The effect may be explained by decrease of strong benzene-Ni interaction due to core-shell structure [39] of Ni-Cr catalysts derived from Cr(CO) 6 or CrA (see Figure 2A). As a result, self-poisoning with ArH is excluded and hydrogenation of aromatics may be performed at lower ratios of H 2 /ArH.…”

Section: Resultsmentioning

confidence: 95%

Hydroconversion of Aromatic Hydrocarbons over Bimetallic Catalysts

et al. 2019

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Bimetallic catalysts (BMC) for hydroconversion of aromatic hydrocarbons (ArH) have been designed by modification of Ni/Al2O3 with chromium(0) compounds and phosphoromolybdic heteropolyacid (HPA). Catalysts were tested in hydrogenation of benzene and toluene, in hydrodemethylation of pure toluene and they were shown to possess a high activity, selectivity and sulfur tolerance under conditions of the processes above. The activity of BMC in these processes was much higher as compared with that of two-component (Ni-Cr, Ni-HPA) or conventional Ni/Al2O3 catalysts. Using BMC, hydrogenation of benzene and toluene proceeds with activity increased (up to 34–38 mol/kg·h) and toluene hydrodemethylation may be performed with improved selectivity (90.3%) and benzene yield (81%). The high sulfur tolerance of BMC was demonstrated by performing hydrodemethylation of toluene containing up to 500 ppm S.

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“…By using the microemulsion method, not only bimetallic nanoparticles can be prepared but also core-shell bimetallic nanoparticles, as reported in the article by Westsson et al [28]. Nanoparticles with a Ni core and a shell of Au were prepared and characterized by several techniques such as TEM, XRD, XPS, etc.…”

Section: The Present Issuementioning

confidence: 99%

Synthesis of Nanostructured Catalytic Materials from Microemulsions

Sánchez-Domínguez

Boutonnet

2015

Catalysts

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BackgroundSince the 1980s [1,2], colloidal systems such as microemulsions (ME) have been widely investigated, especially for the synthesis of nanomaterials for various applications. In the field of catalysis, nanoparticles of noble metal or metal oxides, responsible for the catalytic activity and selectivity, are usually involved in the composition of the catalytic material [3]. A catalyst normally consists of metal nanoparticles deposited onto a carrier such as silica or alumina. Ideally, the nanoparticles will present a highly active surface area due to high metal dispersion. In addition, the surface structure of the nanoparticles, which depends on their size and shape, are related to the selectivity of the catalysts, for instance this is important in the case of alkane isomerization, which is a structure sensitive reaction [4].Depending of the size, the nanoparticles will contain various defects, which will correspond to catalytic sites with different selectivities and activities. These active sites correspond to groups of metal atoms placed on the edges, corners, and terraces structures at the surfaces of the metal nanoparticles. These metal atoms will have different coordination states and present different electronic effects, which will consequently result in different catalytic activity and selectivity. This is the reason why the preparation of nanoparticles with well-defined particle size is still of great interest in the field of catalysis. If one is able to obtain well-defined metal nanoparticles, it will be possible to relate the selectivity and activity of the reaction to some specific size and consequently to have a better understanding of the catalytic reaction mechanism. Consequently, by using a well-designed nanomaterial as catalyst, it will be possible to predict its properties regarding its catalytic activity and selectivity.During these last years, it has been shown that nanomaterials obtained from ME present specific properties, especially regarding the catalytic selectivity compared to catalysts prepared from traditional methods. Several catalytic processes have been investigated using these types of catalysts, i.e., high temperature catalytic combustion of methane, electro-catalyst for hydrogen production from methanol, production of polyalcohols from synthesis gas, Diesel production from synthesis gas via Fisher-Tropsch and hydrocracking of waxes, etc. [3][4][5][6][7][8][9][10][11]. These very different processes are associated to a great range of catalytic materials. The microemulsion method, based on water-in-oil, oil-in-water and bicontinuous ME, has shown to be suitable for the preparation of all these different types of materials [12][13][14][15][16][17][18][19][20][21][22].Even though a few valuable efforts were previously done to understand the formation of nanomaterials in ME systems [23][24][25], comprehensive research in this area is still needed to clarify this process, in order to reach a better control of nanoparticle characteristics and to understand why the formed nanopartic...

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How to Determine the Core-Shell Nature in Bimetallic Catalyst Particles?

Cited by 30 publications

References 68 publications

Styrene Oxidation to Valuable Compounds over Nanosized FeCo-Based Catalysts: Effect of the Third Metal Addition

Styrene Oxidation to Valuable Compounds over Nanosized FeCo-Based Catalysts: Effect of the Third Metal Addition

Hydroconversion of Aromatic Hydrocarbons over Bimetallic Catalysts

Synthesis of Nanostructured Catalytic Materials from Microemulsions

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