Characterization of Synthetic Iron Oxides and their Performance as Support for Au Catalysts.

Centomo, Paolo; Zecca, Marco; Noto, Vito Di; Lavina, Sandra; Bombi, G. Giorgio; Nodari, Luca; Salviulo, Gabriella; Ingoglia, R.; Milone, Candida; Galvagno, S.; Corain, Benedetto

doi:10.1002/cctc.201000049

Cited by 16 publications

(9 citation statements)

References 34 publications

(38 reference statements)

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“…Our research group gained over the years an appreciable experience in the use of cross-linked organic polymers [22][23][24][25] (hereafter referred to as resins) as supports for heterogeneous metal catalysts. Resins are much less popular catalytic supports in comparison with inorganic materials, in view of their lower thermal and mechanical stability.…”

Section: Introductionmentioning

confidence: 99%

Direct Synthesis of Hydrogen Peroxide under Semi-Batch Conditions over Un-Promoted Palladium Catalysts Supported by Ion-Exchange Sulfonated Resins: Effects of the Support Morphology

et al. 2019

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Palladium catalysts supported by a mesoporous form of sulfonated poly-divinylbenzene, Pd/µS-pDVB10 (1%, w/w) and Pd/µS-pDVB35 (3.6% w/w), were applied to the direct synthesis of hydrogen peroxide from dihydrogen and dioxygen. The reaction was carried for 4 h out in a semibatch reactor with continuous feed of the gas mixture (H2/O2 = 1/24, v/v; total flow rate 25 mL·min−1), at 25 °C and 101 kPa. The catalytic performances were compared with those of a commercial egg-shell Pd/C catalyst (1%, w/w) and of a palladium catalyst supported by a macroreticular sulfonated ion-exchange resin, Pd/mS-pSDVB10 (1%, w/w). Pd/µS-pDVB10 and Pd/C showed the highest specific activity (H2 consumption rate of about 75–80 h−1), but the resin supported catalyst was much more selective (ca 50% with no promoters). The nanoparticles (NP) size was somewhat larger in Pd/µS-pDVB10, showing that either the reaction was structure insensitive or diffusion limited to some extent over Pd/C, in which the support is microporous. The open pore structure of Pd/µS-pDVB10, possibly ensuring the fast removal of H2O2 from the catalyst, could also be the cause of the relatively high selectivity of this catalyst. In summary, Pd/µS-pDVB10 was the most productive catalyst, forming ca 375 molH2O2·kgPd−1·h−1, also because it retained a constant selectivity, while the other ones underwent a more or less pronounced loss of selectivity after 80–90 min. Ageing experiments showed that for a palladium catalyst supported on sulfonated mesoporous poly-divinylbenzene storage under oxidative conditions implied some deactivation, but a lower drop in the selectivity; regeneration upon a reductive treatment or storage under strictly anaerobic conditions (dry-box) lead to an increase of the activity but to both a lower initial selectivity and a higher drop of selectivity with time.

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Section: Introductionmentioning

confidence: 99%

Direct Synthesis of Hydrogen Peroxide under Semi-Batch Conditions over Un-Promoted Palladium Catalysts Supported by Ion-Exchange Sulfonated Resins: Effects of the Support Morphology

et al. 2019

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“…In recent decades, magnetic nanoparticles have been under attention due to their important properties such as super‐paramagnetism, coercivity, high surface area and low Curie temperature . These properties make them suitable for use in the fields of drug delivery and MRI, biosensors and other fields especially catalysis ,…”

Section: Introductionmentioning

confidence: 99%

Introduction of a New Magnetic Nanocatalyst as an Organic‐inorganic Hybrid Framework for the Synthesis of Pyrano[2,3‐d]pyrimidinone(thione)s and Pyrido[2,3‐d]pyrimidines

et al. 2019

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In this work, the preparation of bis-[(3-aminopropyl)triethoxysilane]dichloride immobilized on magnetic nano γ-Fe 2 O 3 @SiO 2 is reported. This reagent can be obtained via the reaction of two molecules of 3-aminopropyl)triethoxysilane with 1,4dichlorobutane followed by immobilization of the resulted dicationic compound on silica coated nano γ-Fe 2 O 3 . After characterization using FT-IR, XRD, FE-SEM and TGA techniques, the prepared reagent was used as a highly efficient catalyst for the promotion of the synthesis of pyrano[2,3-d]pyrimidinones (thiones) and pyrido[2,3-d]pyrimidine derivatives. The rates and especially the yields of the reactions were excellent in comparison to the reported catalyst for these reactions. Also, the recovery and reusability of the catalyst were excellent for both of the reactions using an external magnet.the named important heterocyclic compounds are accompanied with drawbacks such as high toxicity, low reusability, high amounts of the used catalyst or organic solvents, high costs, high reaction times and low yields.

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“…During the last few years, increasing attention has been focused on the heterogeneous approach, which leads to several advantages in terms of the process design and plant costs [22][23][24][25]. Some of us have investigated using resins as catalysts or scaffolds in material chemistry [26][27][28][29][30]. These resins could be more advantageous materials than the most commonly employed materials used for the acid hydrolysis of lignocellulosic biomass (e.g., zeolites, carbon and hybrid materials), especially due to their structural and functional versatility and stability in reaction media.…”

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confidence: 99%

Gel-Type and Macroporous Cross-Linked Copolymers Functionalized with Acid Groups for the Hydrolysis of Wheat Straw Pretreated with an Ionic Liquid

et al. 2019

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Several sulfonated cross-linked copolymers functionalized with hydroxyl and carboxylic groups have been synthesized. The amount of the cross-linking monomer was tailored (from 4% up to 40%) to tune the resulting micro-and nano-morphologies, and two types of catalysts, namely, gel-type and macroreticular catalysts, were obtained. These copolymers were employed in the catalytic hydrolysis of wheat straw pretreated in 1-ethyl-3-methylimidazolium acetate to obtain sugars. Remarkably, the presence of additional oxygenated groups enhances the catalytic performances of the polymers by favoring the adsorption of β-(1,4)-glucans and makes these materials significantly more active than an acidic resin bearing only sulfonic groups (i.e., Amberlyst 70). In addition, the structure of the catalyst (gel-type or macroreticular) appears to be a determining factor in the catalytic process. The gel-type structure provides higher glucose concentrations because the morphology in the swollen state is more favorable in terms of the accessibility of the catalytic centers. The observed catalytic behavior suggests that the substrate diffuses within the swollen polymer matrix and indirectly confirms that the pretreatment based on dissolution/precipitation in ionic liquids yields a substantial enhancement of the conversion of lignocellulosic biomass to glucose in the presence of heterogeneous catalysts.Catalysts 2019, 9, 675 2 of 18 substrate [5]. In this way, the particle size can be reduced, the porosity can be improved, and the crystallinity of the cellulose can be altered. After fractioning its main components, e.g., cellulose, hemicellulose and lignin, biomass can be converted into a wide variety of industrial products, such as biofuels, biomaterials, cellulose pulps, cellulose nanofibers, oligosaccharides and a large number of by-products, in addition to lignin derivatives.Numerous studies have shown ionic liquids (ILs) to be effective at solubilizing lignocellulosic biomass, allowing for subsequent regeneration by precipitation with anti-solvents. Depending on the anti-solvent used, it is possible to achieve selective precipitation and separate the lignocellulosic biomass into its main components [6][7][8][9][10][11][12][13][14]. Among the most commonly employed ILs, 1-ethyl-3-methylimidazolium acetate ([EMIM]OAc) holds a privileged position due to its physico-chemical properties.The acid hydrolysis of the polysaccharide fractions of lignocellulosic biomass, which leads to monosaccharides that can be converted into fine chemicals or platform molecules used for industrial applications, can be performed in the presence of enzymes, homogeneous catalysts or heterogeneous catalysts [15][16][17][18][19][20][21]. During the last few years, increasing attention has been focused on the heterogeneous approach, which leads to several advantages in terms of the process design and plant costs [22][23][24][25]. Some of us have investigated using resins as catalysts or scaffolds in material chemistry [26][27][28][29][30]. These resins could be more...

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Characterization of Synthetic Iron Oxides and their Performance as Support for Au Catalysts.

Cited by 16 publications

References 34 publications

Direct Synthesis of Hydrogen Peroxide under Semi-Batch Conditions over Un-Promoted Palladium Catalysts Supported by Ion-Exchange Sulfonated Resins: Effects of the Support Morphology

Direct Synthesis of Hydrogen Peroxide under Semi-Batch Conditions over Un-Promoted Palladium Catalysts Supported by Ion-Exchange Sulfonated Resins: Effects of the Support Morphology

Introduction of a New Magnetic Nanocatalyst as an Organic‐inorganic Hybrid Framework for the Synthesis of Pyrano[2,3‐d]pyrimidinone(thione)s and Pyrido[2,3‐d]pyrimidines

Gel-Type and Macroporous Cross-Linked Copolymers Functionalized with Acid Groups for the Hydrolysis of Wheat Straw Pretreated with an Ionic Liquid

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