Catalytic oxidation of CO by heteropolyacids (HPA) and dioxygen in the presence of Pd(II) salt-HPA-H2O system

Golodov, V.A.; Jumakaeva, B.S.

doi:10.1016/0304-5102(86)87078-x

Cited by 13 publications

(7 citation statements)

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“…In contrast, Pd was leached from Pd/C into the aqueous solution under the reaction conditions, which led to dissolved species, such as Pd 2+ , that might serve as a homogeneous catalyst. [20] Slow leaching of metal may take place upon exposure of carbon-supported Pt and Ir catalysts to reaction conditions, ICP analyses detected 10-20 ppm of Pt and 5 ppm of Ir species in 0.05 m POM solutions contacted for 24 h with the Pt/C and Ir/C catalysts, respectively.…”

Section: Methodsmentioning

confidence: 99%

Preferential Oxidation of CO in H₂ by Aqueous Polyoxometalates over Metal Catalysts

et al. 2005

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Production of H 2 for fuel cells is usually accomplished by a multistep process, which starts with catalytic reforming of hydrocarbons [1] or oxygenated hydrocarbons over metal catalysts [2,3] to produce a mixture of H 2 , CO, and CO 2 . These reformate gases are subsequently treated by several steps, such as water-gas shift (WGS) (CO + H 2 O!CO 2 + H 2 ) [4,5] and preferential oxidation of CO in the H 2 -rich gas stream (PROX; CO + 1/2 O 2 !CO 2 ), [6,7] for applications involving proton-exchange membrane (PEM) fuel cells, this oxidation of CO is necessary owing to the strong poisoning effects of CO on Pt-based anodes.[8] While these methods for removing CO from H 2 gas stream are well established, they suffer from several limitations. For example, the WGS reaction is slow at the low temperatures (e.g., 500 K) required to achieve favorable thermodynamics for this reaction, [9] and PROX requires the injection of O 2 (or air) into the H 2 gas stream and consumes a fraction of the H 2 as well. Moreover, these processes for CO conversion often involve the use of platinum or platinum-alloy catalysts, which are expensive and compete with fuel-cell electrodes for the limited supply of this precious metal, compared with the abundant holdings of gold in the world.[10]Recently, we reported the discovery of a room-temperature process for production of electrical energy using a fuel cell containing a carbon anode and operating with an aqueous solution of a polyoxometalate (POM) compound that had been reduced with pure CO over gold-nanotube catalysts. [11] This process for the oxidation and utilization of CO involves the reaction of CO and liquid water with a reducible POM, such as [H 3 PMo 12 O 40 ], which serves as an oxidizing agent for reaction of CO with liquid water and as an energy-storage agent for electrons; the process takes advantage of the high catalytic activities of gold for CO oxidation, [12][13][14] especially in the presence of liquid water, as shown experimentally using gold-nanotube membrane catalysts [15] and as predicted by density functional theory calculations. [16,17] A representative

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Section: Methodsmentioning

confidence: 99%

Preferential Oxidation of CO in H₂ by Aqueous Polyoxometalates over Metal Catalysts

et al. 2005

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“…In early work, it was shown that the combination of Pd(II) salts and H 3+x PV x Mo 12-x O 40 in methanol or ethanol with 0.5−1 M H 2 O was effective for the oxidation of CO to CO 2 with the coformation of dimethylcarbonate and diethylcarbonate, respectively. 109,110 It was proposed that the oxidation occurred upon the coordination of CO to reduced palladium species; the presence of VO 2+ inhibited the reaction. 111,112 In further research by the Neumann group the oxidation of CO to CO 2 catalyzed by Pd(0)/H 5 PV 2 Mo 10 O 40 in 9:1 AcOH/ water showed by isotope labeling that under anaerobic conditions the oxidation to CO 2 takes place through oxygen transfer from the polyoxometalate framework to CO. 113 See section 5.2 below for further discussion for such oxygen transfer reactions.…”

Section: Oxidation Of Co To Co 2 and Co/o 2 Oxidation Reactionsmentioning

confidence: 99%

“…In the context of remediation of carbon monoxide there is an interest in its oxidation to CO 2 . In early work, it was shown that the combination of Pd(II) salts and H 3+ x PV x Mo 12‑ x O 40 in methanol or ethanol with 0.5–1 M H 2 O was effective for the oxidation of CO to CO 2 with the coformation of dimethylcarbonate and diethylcarbonate, respectively. , It was proposed that the oxidation occurred upon the coordination of CO to reduced palladium species; the presence of VO 2+ inhibited the reaction. , …”

Section: Palladium(ii) Catalyzed Reactionsmentioning

confidence: 99%

Dioxygen in Polyoxometalate Mediated Reactions

2017

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In this review article, we consider the use of molecular oxygen in reactions mediated by polyoxometalates. Polyoxometalates are anionic metal oxide clusters of a variety of structures that are soluble in liquid phases and therefore amenable to homogeneous catalytic transformations. Often, they are active for electron transfer oxidations of a myriad of substrates and upon reduction can be reoxidized by molecular oxygen. For example, the phosphovanadomolybdate, HPVMoO, can oxidize Pd(0) thereby enabling aerobic reactions catalyzed by Pd and HPVMoO. In a similar vein, polyoxometalates can stabilize metal nanoparticles, leading to additional transformations. Furthermore, electron transfer oxidation of other substrates such as halides and sulfur-containing compounds is possible. More uniquely, HPVMoO and its analogues can mediate electron transfer-oxygen transfer reactions where oxygen atoms are transferred from the polyoxometalate to the substrate. This unique property has enabled correspondingly unique transformations involving carbon-carbon, carbon-hydrogen, and carbon-metal bond activation. The pathway for the reoxidation of vanadomolybdates with O appears to be an inner-sphere reaction, but the oxidation of one-electron reduced polyoxotungstates has been shown through intensive research to be an outer-sphere reaction. Beyond electron transfer and electron transfer-oxygen transfer aerobic transformations, there a few examples of apparent dioxygenase activity where both oxygen atoms are donated to a substrate.

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“…Heteropolyacids (HPAs) are useful molecular metal oxide acids, which have served as catalysts for a number of processes due to their good acidity and high-performance oxidation-reduction [31]. Early research results of Golodov [32] and Zhizhina [33,34] showed that HPAs could oxidize CO with H 2 O in the presence of O 2 and Pd or Pt. The presence of HPAs with a Keggin structure could also significantly improve the CO tolerance of a Pt/C catalyst in PEMFCs [35].…”

Section: Introductionmentioning

confidence: 99%

Promotion Effect of the Keggin Structure on the Sulfur and Water Resistance of Pt/CeTi Catalysts for CO Oxidation

et al. 2021

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Developing a catalyst with high SO2 and H2O resistance to achieve high-performance CO oxidation for specific industrial applications is highly desirable. Here, three catalysts were prepared using cerium titanium composite oxide (CeTi), molybdophosphate with Keggin structure-modified CeTi (Keg-CeTi), and molybdophosphate without Keggin structure-modified CeTi (MoP-CeTi) as supports, and their sulfur and water resistance in CO oxidation were tested. The characterization of XRD, BET, SO2/H2O-DRIFTS, XPS, TEM, SEM, NH3/SO2-TPD, H2-TPR, and ICP techniques revealed that the high SO2 and H2O resistance of Pt/Keg-CeTi in CO oxidation was related to its stronger surface acidity, better reduction of surface cerium and molybdenum species, and lower SO2 adsorption and transformation compared to Pt/CeTi and Pt/MoP-CeTi.

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Catalytic oxidation of CO by heteropolyacids (HPA) and dioxygen in the presence of Pd(II) salt-HPA-H2O system

Cited by 13 publications

References 1 publication

Preferential Oxidation of CO in H₂ by Aqueous Polyoxometalates over Metal Catalysts

Preferential Oxidation of CO in H₂ by Aqueous Polyoxometalates over Metal Catalysts

Dioxygen in Polyoxometalate Mediated Reactions

Promotion Effect of the Keggin Structure on the Sulfur and Water Resistance of Pt/CeTi Catalysts for CO Oxidation

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Catalytic oxidation of CO by heteropolyacids (HPA) and dioxygen in the presence of Pd(II) salt-HPA-H2O system

Cited by 13 publications

References 1 publication

Preferential Oxidation of CO in H2 by Aqueous Polyoxometalates over Metal Catalysts

Preferential Oxidation of CO in H2 by Aqueous Polyoxometalates over Metal Catalysts

Dioxygen in Polyoxometalate Mediated Reactions

Promotion Effect of the Keggin Structure on the Sulfur and Water Resistance of Pt/CeTi Catalysts for CO Oxidation

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Preferential Oxidation of CO in H₂ by Aqueous Polyoxometalates over Metal Catalysts

Preferential Oxidation of CO in H₂ by Aqueous Polyoxometalates over Metal Catalysts