The effect of the metal precursor-reduction with hydrogen on a library of bimetallic Pd-Au and Pd-Pt catalysts for the direct synthesis of H2O2

Sterchele, Stefano; Biasi, Pierdomenico; Centomo, Paolo; Campestrini, Sandro; Shchukarev, Andrey; Rautio, Anne-Riikka; Mikkola, Jyri‐Pekka; Salmi, Tapio; Zecca, Marco

doi:10.1016/j.cattod.2014.02.021

Cited by 35 publications

(36 citation statements)

References 28 publications

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“…A more detailed description of the reactor is given in previous work 9,10,32 . The H 2 conversion and the selectivity to H 2 O 2 , S H2O2 were calculated as:…”

Section: Activity Measurementsmentioning

confidence: 99%

“…So far, in order to solve the selectivity dilemma, different approaches have been tried in order to modify the catalytic properties of the palladium based catalysts: 1) addition of halides and mineral acids in the reaction mixture 3 , 2) addition of a second metal to the palladium catalyst 6,9,10 , 3) pretreatment of the support with nitric acid [11][12][13] , 4) functionalization of different supports 14 , 5) fine-tuning of the reaction conditions [15][16][17][18][19] and 6) reactor design 16,[20][21][22][23][24][25][26] . All these aspects are important but if applied simultaneously, will not lead to a real understanding of the process since each and every of these parameters are correlated and will influence each other (positively or negatively).…”

Section: Introductionmentioning

confidence: 99%

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Revealing the role of bromide in the H₂O₂ direct synthesis with the catalyst wet pretreatment method (CWPM)

et al. 2016

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A tailor-made Pd 0 /K2621 catalyst was subjected to post synthesis modification via a wet treatment procedure. The aim was the understanding of the role of promoters and how -if any -improvements could be qualitatively related to the catalyst performance for the H 2 O 2 direct synthesis. The Catalyst Wet Pretreatment Method (CWPM) was applied in different methanolic solutions containing H 2 O 2 , NaBr and H 3 PO 4 , either as single modifiers or as a mixture. The catalyst was characterized by Transmission Electron Microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS). It was concluded that the modified catalysts give rise to higher selectivities compared to the pristine reference catalyst thus opening a possibility to exclude the addition of the undesirable selectivity enhancers in the reaction medium. This work provides original evidence on the role of promoters, especially bromide, allowing the formulation of a new reaction mechanism for one of the most ISCRE 24 -Foundations and

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“…A more detailed description of the reactor is given in previous work 9,10,32 . The H 2 conversion and the selectivity to H 2 O 2 , S H2O2 were calculated as:…”

Section: Activity Measurementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Revealing the role of bromide in the H₂O₂ direct synthesis with the catalyst wet pretreatment method (CWPM)

et al. 2016

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“…7a and b shows the cyclic voltammograms (CVs) of the different catalysts at a scan rate of 50 mV s À1 in 0.5 M HClO 4 solution. 35,36 The reason that the electrocatalytic activity of Pt 3 Pd 1_5.20 bimetallic NPs is better than monometallic Pt _5.20 NPs can be explained as follows. The semi-reversible peaks appeared at around À0.1 V correspond to the hydrogen adsorption and desorption while irreversible peaks at around +0.6 V are due to the platinum oxidation and reduction.…”

Section: Resultsmentioning

confidence: 99%

“…However, it was reported that these agents oen strongly adsorb and cap the surfaces of NPs, blocking the exposure of the surface active sites. 10,[33][34][35][36] Therefore, a facile green method for the preparation of "naked" metal nanocatalysts with clean surfaces is still of great challenge. [30][31][32] Therefore, partly loss of activity of these synthesized catalysts is unavoidable during the catalytic or electrocatalytic reactions.…”

Section: Introductionmentioning

confidence: 99%

A green synthesis of “naked” Pt and PtPd catalysts for highly efficient methanol electrooxidation

et al. 2016

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Up to now, green synthesis of "naked" nanoobjects with clean surfaces is still a great challenge since structure-directing agents such as surfactants are usually used to induce the anisotropic particle growth for interesting nanostructures in solution. Here, a green synthesis approach for preparing "naked" Pt nanoparticles (NPs) in acetic acid solution was reported. Interestingly, Pt NPs with different morphologies (well-defined polyhedrons, irregular polyhedron-constructed chain networks and nanoflower-constructed chain networks) could be successfully synthesized at different concentrations of acetic acid without adding additional structure-directing agents and reducing agents. The acetic acid itself works both as structure-directing agent and reducing agent for the formation of these interesting Pt NPs. Specifically; the synthesized NPs are "naked" with clean surfaces since the acetic acid is a weakly-capping agent which can be easily removed after the washing process. The versatility of this method is further demonstrated by preparation of "naked" PtPd alloy NPs. In particular, the as-prepared "naked" Pt _5.20 and Pt 3 Pd 1_5.20 NPs are demonstrated to be excellent catalysts with much higher electroactivity and better durability than the commercial Pt black catalyst (Hispec™ 1000) for the methanol oxidation reaction. The method reported in this work may pave the way for simple, low-cost, green and eco-friendly synthesis of "naked" metal catalysts for advanced electrocatalytic applications.

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“…The main issue is still the design of appropriated catalysts [5] (active metal or support [6][7][8][9][10][11][12][13][14][15][16][17]), followed by the focus on the addition of promoters (acids and halides) [6,11,16,17], selection of liquid solvent (water, methanol, ethanol or a mixture of them) and optimization of reaction conditions since appropriate selection of operational parameters are crucial in aiming at high selectivities in the H 2 O 2 direct synthesis [18][19][20][21][22][23][24][25][26][27][28][29]. Finally, the gas phase concentration is limited by flammability limits of hydrogen-oxygen mixtures.…”

Section: Introductionmentioning

confidence: 99%

Continuous H₂O₂ direct synthesis process: an analysis of the process conditions that make the difference

Huerta

Biasi

Juan-Garcia

et al. 2016

Green Processing and Synthesis

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A trickle bed reactor (TBR) was used to study different process parameters upon hydrogen peroxide direct synthesis. The catalysts used were commercial palladium on active carbon. The influence of pressure (1.75-25 barg), temperature (5-60°C), liquid flow rate (2-13.8 ml·min -1 ), gas flow rate (3.4-58.5 ml·min -1 ), catalyst amount (90-540 mg), Pd percentage on the support (5% wt., 10% wt. and 30% wt. Pd/C) as well as promoter concentrations (0.0005-0.001 m) were all varied as process parameters to better understand the behaviour of the system. By contrast, the gas phase molar composition of the feed (4:20:76 = H 2 :O 2 :CO 2 ) was kept constant. The strong influence between liquid flow rate, gas flow rate and catalyst amount were identified as the key parameters to tune the reaction, and related to the activity of the catalyst. In essence, these parameters must be carefully tuned to control the hydrogen consumption. The maximum productivity (289 μmol H 2 O 2 ·min -1 ) and yield (83.8%) were obtained when a diluted bed of 30% Pd/C was applied. The H 2 O 2 hydrogenation was studied in order to understand its role in the H 2 O 2 direct synthesis reaction network. The hydrogenation reaction mechanism and the role of NaBr were identified thanks to the experiment proposed in the present work. Consequently, understanding the whole reaction mechanism from the process conditions studied led to a deeper understanding of all of the phenomena involved in the H 2 O 2 direct synthesis.

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The effect of the metal precursor-reduction with hydrogen on a library of bimetallic Pd-Au and Pd-Pt catalysts for the direct synthesis of H2O2

Cited by 35 publications

References 28 publications

Revealing the role of bromide in the H₂O₂ direct synthesis with the catalyst wet pretreatment method (CWPM)

Revealing the role of bromide in the H₂O₂ direct synthesis with the catalyst wet pretreatment method (CWPM)

A green synthesis of “naked” Pt and PtPd catalysts for highly efficient methanol electrooxidation

Continuous H₂O₂ direct synthesis process: an analysis of the process conditions that make the difference

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The effect of the metal precursor-reduction with hydrogen on a library of bimetallic Pd-Au and Pd-Pt catalysts for the direct synthesis of H2O2

Cited by 35 publications

References 28 publications

Revealing the role of bromide in the H2O2 direct synthesis with the catalyst wet pretreatment method (CWPM)

Revealing the role of bromide in the H2O2 direct synthesis with the catalyst wet pretreatment method (CWPM)

A green synthesis of “naked” Pt and PtPd catalysts for highly efficient methanol electrooxidation

Continuous H2O2 direct synthesis process: an analysis of the process conditions that make the difference

Contact Info

Product

Resources

About

Revealing the role of bromide in the H₂O₂ direct synthesis with the catalyst wet pretreatment method (CWPM)

Revealing the role of bromide in the H₂O₂ direct synthesis with the catalyst wet pretreatment method (CWPM)

Continuous H₂O₂ direct synthesis process: an analysis of the process conditions that make the difference