Evolution of the PVP–Pd Surface Interaction in Nanoparticles through the Case Study of Formic Acid Decomposition

García-Aguilar, Jaime; Navlani‐García, Miriam; Berenguer-Murcia, Ángel; Mori, Kohsuke; Kuwahara, Yasutaka; Yamashita, Hiromi; Cazorla‐Amorós, Diego

doi:10.1021/acs.langmuir.6b03149

Cited by 65 publications

(50 citation statements)

References 57 publications

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“…Some of the strategies tackled in this matter include the optimization of the active phase features (in terms of size, composition, structure, and so forth) as well as the impact of the support properties in modulating the final behavior of the catalysts by controlling the metal-support interaction or the acid/base properties. There are a number of supports investigated for this application, including silica (García-Aguilar et al, 2016b;Mori et al, 2017a), zeolites (Navlani-García et al, 2015a), metal-organic frameworks (MOFs) (Wen et al, 2017), etc. Among them, carbon materials are certainly the most extensively investigated so far.…”

Section: Introductionmentioning

confidence: 99%

New Approaches Toward the Hydrogen Production From Formic Acid Dehydrogenation Over Pd-Based Heterogeneous Catalysts

et al. 2019

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The urgency for finding clean energy sources is nowadays latent, and the role of hydrogen in the future of energy is well-recognized. However, there are still various barriers that limit the widespread utilization of hydrogen, which are mainly related to its storage and transportation. Chemical hydrogen storage stands out as a suitable alternative to traditional physical storage methods, and formic acid holds tremendous promise within the molecules studied so far. This review summarizes some of the recent approaches considered in our research group for the preparation of efficient catalysts for the production of hydrogen via dehydrogenation of formic acid by using Pd-based heterogeneous catalysts supported on carbon or carbon-containing materials. Several routes were considered to attain efficient catalysts, from the optimization of the size and composition of the nanoparticles to the modulation of important features of the support, such as the porous texture and nitrogen doping level.

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Section: Introductionmentioning

confidence: 99%

New Approaches Toward the Hydrogen Production From Formic Acid Dehydrogenation Over Pd-Based Heterogeneous Catalysts

et al. 2019

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“…Notably, microwave-assisted reduction with ethanol generated nanoparticles of similar sizes for all five metals, which is difficult by other methods because of the varying properties of the metals 13), 14) . We also found that the amount of PVP, which is a crucial determinant of catalytic activity 9) , varied over a narrow range (74.1-84.5 wt%). As described later, particle size greatly affects catalytic performance, so consistent particle sizes are important for comparing the intrinsic catalytic activities of various metals.…”

Section: Particle-size Distributions Of Noble-metal Nanoparticles mentioning

confidence: 71%

Preparation of Noble-metal Nanoparticles by Microwave-assisted Chemical Reduction and Evaluation as Catalysts for Nitrile Hydrogenation under Ambient Conditions

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Wada

Chaudhari

et al. 2019

J. Jpn. Petrol. Inst.

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Herein, we report a protocol for rapid preparation of uniformly sized Ru, Rh, Pd, Ir, and Pt nanoparticles stabilized by poly(N-vinyl-2-pyrrolidone) via microwave-assisted chemical reduction with ethanol. Although the boiling point of ethanol, which has high reduction ability, is much lower than the temperature required for metal cation reduction, this solvent could be used as a reductant because the preparation was carried out in a sealed vessel. All metal nanoparticles showed similar sizes and amounts of poly(N-vinyl-2-pyrrolidone). The crystallite size of the Pd and Pt nanoparticles could be controlled by changing the ethanol concentration. The catalytic performance of the prepared metal nanoparticles was evaluated for the hydrogenation of benzonitrile under ambient conditions (25 °C, 1 bar H2). Rh nanoparticles showed the highest benzonitrile conversion and highest selectivity for secondary imine product. Interestingly, the particle-size dependence of the catalytic activity of the Rh nanoparticles showed volcano-type behavior; that is, the second smallest Rh nanoparticles (3.3 nm) showed the highest activity, which was attributed to high metal surface area and high turnover frequency. Notably, this is the first report of nitrile hydrogenation to afford a secondary imine under ambient conditions.

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“…Charge transfer from PVP to Rh occurs easily in nanoparticles stabilized by a large amount of PVP. 15 In the case of small Rh nanoparticles, the fact that large numbers of Rh atoms are in contact with PVP facilitates charge transfer, and thus, more electron-enriched Rh surface is formed. In addition, this charge transfer may induce a peak shift of the XRD pattern to a lower angle ( Figure 1); i.e., charge transfer from PVP to the antibonding e g orbital of Rh may result in expansion of the Rh lattice.…”

Section: +mentioning

confidence: 99%

“…The amount of PVP, a crucial determinant of catalytic activity, varied over a small range (72.384.1 wt %). 15 We discovered that the Rh particle size was dependent on the reduction ability of the alcohol. We also studied the particle size dependence of the CO oxidation ability of the Rh nanoparticles, because Rh is known to be an excellent catalyst for the oxidation of CO in car exhaust gas.…”

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confidence: 99%

Facile Synthesis of Size-controlled Rh Nanoparticles via Microwave-assisted Alcohol Reduction and Their Catalysis of CO Oxidation

et al. 2017

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Size-controlled Rh nanoparticles stabilized by poly(vinylpyrrolidone) were quickly synthesized via alcohol reduction. Microwave-assisted synthesis in closed vessels allowed alcohols with low-to-high boiling points to be used as reductants under the same preparation conditions. Pure ethanol has not been used previously because its boiling point is lower than the temperature required for Rh 3+ reduction. Alcohols with relatively strong reduction ability were found to lead to smaller Rh nanoparticles. The ability to oxidize CO was enhanced as the Rh particle size decreased. additives, 10 pH, 11 and preparation temperature. 12 In this method, high-boiling-point alcohols such as polyols are often used to reduce metal cations in the presence of polymers that inhibit aggregation of the nanoparticles and stabilize metals in colloids because the boiling points of the polyols are higher than the temperatures required to reduce the metal cations. In contrast, the boiling points of monovalent alcohol including a small number of carbon such as ethanol are lower than the temperatures required to reduce metal cations such as Ru 3+ , Rh 3+, and Pd 2+ . To enable the use of low-boiling-point alcohols, the alcohols are mixed with water to increase the boiling point, and reduction is performed under reflux 13 or solvothermal 6 conditions. On the other hand, heating the alcohols with a conventional electric heater is slow and produces heterogeneous temperatures; thus, it takes a long time to prepare nanoparticles, and nanometals with a wide particle-size distribution are obtained. 14 Furthermore, because of differences in the equipment and physicochemical properties of the alcohol, the influence of the reduction ability of low-and high-boiling-point alcohols on the synthesis of nanoparticles has not been investigated under the same preparation conditions.In this study, we prepared Rh nanoparticles using different kinds of alcohols, including low-and high-boiling-point alcohols, as reductants under the same preparation conditions. The experimental design was enabled by using a microwaveassisted alcohol reduction method in a closed vessel, in which rapid and homogeneous heating and solvothermal conditions were achieved. We were thereby able to easily synthesize sizecontrolled Rh nanoparticles within 20min under the same preparation conditions. The average diameters of the nanoparticles, stabilized in poly(vinylpyrrolidone) (PVP), were 3.3 10.9 nm. The amount of PVP, a crucial determinant of catalytic activity, varied over a small range (72.384.1 wt %). 15 We discovered that the Rh particle size was dependent on the reduction ability of the alcohol. We also studied the particle size dependence of the CO oxidation ability of the Rh nanoparticles, because Rh is known to be an excellent catalyst for the oxidation of CO in car exhaust gas.Rh nanoparticles with different sizes were prepared by microwave-assisted alcohol reduction. Initially, RhCl 3 ¢3H 2 O as the metal precursor and PVP as the stabilizer were dissolved in either ethanol, e...

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Evolution of the PVP–Pd Surface Interaction in Nanoparticles through the Case Study of Formic Acid Decomposition

Cited by 65 publications

References 57 publications

New Approaches Toward the Hydrogen Production From Formic Acid Dehydrogenation Over Pd-Based Heterogeneous Catalysts

New Approaches Toward the Hydrogen Production From Formic Acid Dehydrogenation Over Pd-Based Heterogeneous Catalysts

Preparation of Noble-metal Nanoparticles by Microwave-assisted Chemical Reduction and Evaluation as Catalysts for Nitrile Hydrogenation under Ambient Conditions

Facile Synthesis of Size-controlled Rh Nanoparticles via Microwave-assisted Alcohol Reduction and Their Catalysis of CO Oxidation

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