Theoretical Study of the Direct Synthesis of H<sub>2</sub>O<sub>2</sub> on Pd and Pd/Au Surfaces

Staykov, Aleksandar; Kamachi, Takashi; Ishihara, Tatsumi; Yoshizawa, Kazunari

doi:10.1021/jp803021n

Cited by 123 publications

(120 citation statements)

References 27 publications

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“…For free formic acid in gas phase, the calculated bond lengths are 1.106 (1.097) Å for C-H, 1.357 (1.343) Å for C-O1, 1.218 (1.202) Å for C-O2 and 0.986 (0.972) Å for O1-H, our results are in agreement with previous experimental values [21] displayed in the parentheses. Formic acid has two adsorption modes, ''on top'' and ''bridge'' (shown in Fig.…”

Section: Formic Acidsupporting

confidence: 92%

Comparative Theoretical Study of Adsorption and Dehydrogenation of Formic Acid, Hydrazine and Isopropanol on Pd(111) Surface

2011

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Adsorption and dehydrogenation of formic acid, hydrazine and isopropanol have been investigated using periodic density functional theory (DFT). All the intermediates and transition states have been optimized and the preferred reaction pathways have been found. The adsorption energies for the most stable mode of formic acid, hydrazine and isopropanol are 38.6 kJ/mol, 63.9 kJ/mol and 46.1 kJ/mol, respectively. The dehydrogenation mechanisms of formic acid, hydrazine and isopropanol on Pd(111) surface are proposed and calculated. According to the calculation results, dehydrogenation of formate is more favorable than those of other molecules/groups, and that can be an explanation for the high reactivity of formats in Pd catalyzed transfer hydrogenation.

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Section: Formic Acidsupporting

confidence: 92%

Comparative Theoretical Study of Adsorption and Dehydrogenation of Formic Acid, Hydrazine and Isopropanol on Pd(111) Surface

2011

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“…Ham et al [30] suggested by theoretical studies that Pd monomers surrounded by less active Au atoms suppress O-O bond scission and allow enhancing the selectivity to H 2 O 2 . Staykov et al [34] also by theoretical approach indicated that the presence of surface gold atoms blocks this dissociation of chemisorbed oxygen and increases the selectivity toward H 2 O 2 .…”

Section: Introductionmentioning

confidence: 97%

Performances of Pd Nanoparticles on Different Supports in the Direct Synthesis of H2O2 in CO2-Expanded Methanol

2011

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Catalysts based on Pd supported on SiO 2 , SBA-15, c-Al 2 O 3 and N-CNT were investigated for the direct H 2 O 2 synthesis and decomposition/hydrogenolysis in CO 2 -expanded methanol in batch and semi-batch reactors working at room temperature and a pressure of 6.5 bar. The order of reactivity for the synthesis of H 2 O 2 per g of Pd or for the rate of H 2 O 2 decomposition, or the selectivity to H 2 O 2 does not correlate with the acidity of the support. A relation was observed with the Pd particle sizes, i.e. smaller particles lead to a higher specific activity, but the sample supported on carbon nanotube shows an order of magnitude higher specific activity per g of Pd, indicating the presence of an additional factor attributed to the interaction with the carbon support which determines an intrinsic higher reactivity. However, this higher reactivity corresponds also to a higher activity in the consecutive conversion of H 2 O 2 , probably by hydrogenolysis reaction. A rough relation between activity in H 2 O 2 synthesis and in H 2 O 2 conversion was observed in the samples with the different supports, indicating the similar nature of the active sites responsible for the two reactions. Finally, the analysis of the recyclability of the catalysts and transmission electron microscopy (TEM) characterization data after the catalytic tests indicate that the use of CO 2 -expanded methanol allows improving the catalytic performances in H 2 O 2 direct synthesis due to the enhanced solubility of H 2 and O 2 , but induces a fast catalyst deactivation due to an enhanced mobility and sintering of the supported Pd particles. The effect is present in all the four type of support used.

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“…The exposed facet is one of major factors to determine catalytic properties of Au or AuPd particles. There are several theoretical studies [20,[25][26][27][28][29][30][31][32] of H 2 O 2 synthesis on low index Pd, Au, Pt surfaces or small Au clusters. However, a systematically comparative study of the key elementary reactions for H 2 O 2 and H 2 O formation on these low index Au surfaces, especially Au(111), Au(100) and Au(110) and stepped Au surfaces, is very necessary.…”

Section: Introductionmentioning

confidence: 99%

Brønsted–Evans–Polanyi Relations for H2O2 Synthesis on Gold Surfaces

Wang

2012

Catal Lett

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By means of density functional theory calculations, the reaction mechanisms of H 2 O 2 synthesis on three low index and two stepped Au surfaces have been investigated in detail. This study shows the activation energies of five elementary reaction steps of H 2 O 2 synthesis, which include two hydrogenation and three decomposition steps of key species, are a function of reaction energies, which observe the Brønsted-EvansPolanyi rules on both the flat Au surfaces and the step edge sites of stepped Au surfaces. This study not only provides a simple method to estimate the reaction barriers of elementary steps of H 2 O 2 synthesis by the reaction energies but also predicts the catalytic performances of Au nanoparticles applied in real catalysis.

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Theoretical Study of the Direct Synthesis of H₂O₂ on Pd and Pd/Au Surfaces

Cited by 123 publications

References 27 publications

Comparative Theoretical Study of Adsorption and Dehydrogenation of Formic Acid, Hydrazine and Isopropanol on Pd(111) Surface

Comparative Theoretical Study of Adsorption and Dehydrogenation of Formic Acid, Hydrazine and Isopropanol on Pd(111) Surface

Performances of Pd Nanoparticles on Different Supports in the Direct Synthesis of H2O2 in CO2-Expanded Methanol

Brønsted–Evans–Polanyi Relations for H2O2 Synthesis on Gold Surfaces

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Theoretical Study of the Direct Synthesis of H2O2 on Pd and Pd/Au Surfaces

Cited by 123 publications

References 27 publications

Comparative Theoretical Study of Adsorption and Dehydrogenation of Formic Acid, Hydrazine and Isopropanol on Pd(111) Surface

Comparative Theoretical Study of Adsorption and Dehydrogenation of Formic Acid, Hydrazine and Isopropanol on Pd(111) Surface

Performances of Pd Nanoparticles on Different Supports in the Direct Synthesis of H2O2 in CO2-Expanded Methanol

Brønsted–Evans–Polanyi Relations for H2O2 Synthesis on Gold Surfaces

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Theoretical Study of the Direct Synthesis of H₂O₂ on Pd and Pd/Au Surfaces