Metallic Pt as active sites for the water–gas shift reaction on alkali-promoted supported catalysts

Pazmiño, Jorge H.; Shekhar, Mayank; Williams, W. J.; Akatay, M. Cem; Miller, Jeffrey T.; Delgass, W. Nicholas; Ribeiro, Fabio H.

doi:10.1016/j.jcat.2011.11.017

Cited by 102 publications

(98 citation statements)

References 29 publications

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“…This indicates the suitability of the synthesis method and the anchorage of the active phase on the surface of biochar was in good agreement with previous works [9,28]. It is well known that the interaction of the active metal with the carbon support can be modified by pre-treatment of the surface carbon, altering their point of zero charge (PZC).…”

Section: Physico-chemical Characterisationsupporting

confidence: 89%

“…Because of this, the reaction is normally carried out in two stages: a high-temperature shift (350-400 • C) with iron-based catalysts, and a low-temperature shift (200-250 • C) with copper-based catalysts [7]. Due to the low thermal stability and pyrophoric character of Cu-based catalysts, noble metal-based catalysts have attracted considerable interest for the low-temperature water-gas shift reaction as a potential alternative to industrial copper-based catalysts [8][9][10][11]. Noble-metal-based catalysts offer greater stability during start-up/shut-down cycles than conventional catalysts and their catalytic performance can be enhanced by modifying the support and/or by the addition of promoters.…”

Section: Introductionmentioning

confidence: 99%

“…Noble-metal-based catalysts offer greater stability during start-up/shut-down cycles than conventional catalysts and their catalytic performance can be enhanced by modifying the support and/or by the addition of promoters. Recent reports have shown an increase in the WGS intrinsic activity by adding an alkali metal (Na, K, Li) as a promoter to platinum-based catalysts [8,9,[12][13][14]. It is believed that the role of the alkali in the WGS reaction pathway can be attributed to the modification of the local electronic properties of Pt for increasing the number of water activation sites [15].…”

Section: Introductionmentioning

confidence: 99%

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Operando DRIFTS-MS Study of WGS and rWGS Reaction on Biochar-Based Pt Catalysts: The Promotional Effect of Na

Santos

Bobadilla

Odriozola

2018

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Abstract:Biochar-based Pt catalysts, unpromoted and Na-promoted, were prepared by an incipient wetness impregnation method and characterised by Inductively coupled plasma mass spoectrometry (ICP-MS) analysis, X-ray diffraction, N 2 adsorption and transmission, and scanning electron microscopy. It was demonstrated that a sodium promoter modifies the acid-base properties of the support, altering the Pt-support interaction. An operando Diffuse reflectance infrared fourier transform spectroscopy-mass spectrometry (DRIFTS-MS) study was performed to gain insights into the reaction pathways and the mechanism of the Water-Gass-Shift (WGS) and the Reverse Water-Gass-Shift (rWGS) reactions. It was demonstrated that the addition of Na enhances the catalytic performance due to the changes induced by the alkali in the electronic structure of the Pt active sites. This effect favours the activation of H 2 O molecules during the WGS reaction and the dissociation of CO 2 during the rWGS reaction, although it may also favour the consecutive CO methanation pathway.

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Section: Physico-chemical Characterisationsupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Operando DRIFTS-MS Study of WGS and rWGS Reaction on Biochar-Based Pt Catalysts: The Promotional Effect of Na

Santos

Bobadilla

Odriozola

2018

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“…In the case of Ea of H2 formation differences were much bigger -from 34.8 using Na + as a catalyst to 54.0 using ions of calcium. This sequence could result from the fact that the sodium ions (to a lesser extent potassium ions) may catalyze the water gas shift reaction [24,25]. The results confirmed the catalytic activity of alkali and alkaline-earth metals in the…”

Section: Resultssupporting

confidence: 63%

The influence of catalytic additives on kinetics of coal gasification process

2017

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Abstract. Catalytic coal gasification is a process that has the potential to become one of the efficient industrial technology of energy production. For this reason, the subject of this study was to analyze the kinetics of catalytic gasification of 'Janina' coal with steam. Isothermal measurements were performed at 800 °C, 900 °C, 950 °C and 1000 °C at a pressure of 1 MPa using cations of sodium, potassium and calcium as catalysts. During examination the thermovolumetric method was used. This method allows to determine the formation rates of a gaseous product such as carbon monoxide, hydrogen, methane and carbon dioxide as well as their contribution to the resulting gas. Moreover, the influence of catalysts on the kinetics of CO and H2 formation at various temperatures was determined and the kinetics parameters were calculated with the use of isoconversional model, Random Pore Model and Grain Model. The obtained results confirmed the positive effect of catalysts on the coal gasification process. The catalytic measurements were characterized by higher reaction rate and shorter duration of the process, and the calculated values of the kinetic parameters were lower than for the gasification process without the addition of catalysts.

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“…We have also recently demonstrated some preliminary results that showed that doping of the Pd/C and Pt/C catalysts with K carbonate had a significant promotional effect on the rate of formic acid decomposition [16]; this work was stimulated by reports that alkali metals have a strong promotional effect on the water-gas shift (WGS) reaction [25][26][27][28], the mechanism of which is probably closely related to that of formic acid decomposition [17,18,22]. Our results showed that the temperature required for formic acid decomposition was decreased to <353 K, the rate of hydrogen production being increased considerably (by 1-2 orders of magnitude) by 5 doping with K carbonate.…”

Section: Introductionmentioning

confidence: 95%

Hydrogen production from formic acid vapour over a Pd/C catalyst promoted by potassium salts: Evidence for participation of buffer-like solution in the pores of the catalyst

Liu

Bulushev

Beloshapkin

et al. 2014

Applied Catalysis B: Environmental

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(D.A. Bulushev) 2 A B S T R A C T Doping a 1 wt.% Pd/C catalyst with alkali metal carbonates has a very significant promotional effect on its activity in hydrogen production from the decomposition of formic acid vapour (2 vol.%, 1 bar), potassium and caesium carbonates giving the largest effects. The K carbonate species present on the fresh catalysts react with formic acid to form formate ions, these being dissolved in a formic acid/water solution condensed in the pores of the support. The steadystate activities of the samples containing formate ions were 1-2 orders of magnitude greater than those of the unpromoted Pd/C and CO content was lower than 30 ppm. The activation energies for the reaction increased with doping from 66 to 88-99 kJ mol -1 , relatively independent of the cation of the dopant. Similar but lesser effects were found with unsupported Pd nanocrystals doped with K carbonate. The rate-determining step for the promoted samples appears to be the decomposition of formate ions on the Pd surface.

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Metallic Pt as active sites for the water–gas shift reaction on alkali-promoted supported catalysts

Cited by 102 publications

References 29 publications

Operando DRIFTS-MS Study of WGS and rWGS Reaction on Biochar-Based Pt Catalysts: The Promotional Effect of Na

Operando DRIFTS-MS Study of WGS and rWGS Reaction on Biochar-Based Pt Catalysts: The Promotional Effect of Na

The influence of catalytic additives on kinetics of coal gasification process

Hydrogen production from formic acid vapour over a Pd/C catalyst promoted by potassium salts: Evidence for participation of buffer-like solution in the pores of the catalyst

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