Bismuth phosphate nanoparticle catalyst for direct oxidation of methane into formaldehyde

Matsuda, Ayaka; Obara, Kazuhiko; Ishikawa, Atsushi; Tsai, Meng‐Hsuan; Wang, Chia‐Hsin; Lin, Yu‐Chuan; Hara, Michikazu; Kamata, Keigo

doi:10.1039/d3cy00590a

Cited by 8 publications

(18 citation statements)

References 80 publications

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“…We have recently reported that the basicity of catalysts strongly affects their interaction with C 1 -oxygenated species and that the weak basicity of metal phosphates likely contributes to the suppression of complete oxidation of C 1oxygenates into CO 2 . 22,23 Thus, the basicity was confirmed by Fourier transform infrared (FTIR) spectroscopy for the samples with adsorbed CHCl 3 (Table 1 and Figure S8) 22 and BiPO 4 23 nanoparticles (Figure 4c). Figure 4d shows the HCHO selectivity against the CH 4 conversion for the oxidation of CH 4 over Cu 2 P 2 O 7 − NO 3 , Cu 2 P 2 O 7 −OAc, FePO 4 , and BiPO 4 catalysts.…”

Section: Catalyst Effect Of Metal Phosphate On Ch 4 Oxidation Into Hchomentioning

confidence: 82%

“…The details are described in the Supporting Information. 22,23,38,41,42 4. over various metal phosphate catalysts and Cu-based catalysts was conducted in a fixed-bed continuous-flow reactor operated at atmospheric pressure. All of the catalysts were pressed into pellets, crushed, and sieved to 32−42 mesh before the reaction.…”

Section: Methodsmentioning

confidence: 99%

“…Such dependences have also been reported for FePO 4 and BiPO 4 nanoparticle catalysts. 22,23 Kinetic studies of CH 4 oxidation over Cu 2 P 2 O 7 −NO 3 at 500 °C were conducted. Figure 8b−d shows the dependence of the reaction rate on the partial pressures of CH 4 (P CHd 4 ) and O 2 (P Od 2 ) and the catalyst loading of Cu 2 P 2 O 7 −NO 3 .…”

Section: Mechanistic Studies On the Direct Oxidation Of Ch 4 Over Cu ...mentioning

confidence: 99%

“…Oxide-based materials, − metal-exchanged zeolites, − metal phosphates, − and supported catalysts − have been extensively investigated as effective solid catalysts for the direct synthesis of HCHO from CH 4 . Among them, V-, Mo-, Fe-, and Cu-based supported catalysts and B-based catalysts selectively give HCHO with relatively high yields (0.5–3.9%, Table S1), where the activation mechanism of CH 4 and/or O 2 is dependent on the type of catalyst.…”

Section: Introductionmentioning

confidence: 99%

“…22,23,44 Detailed mechanistic studies revealed that the redox-active Lewis acidic metal sites and the weakly basic phosphate units likely contribute to the activation of CH 4 and/or O 2 and to the suppression of sequential oxidation to CO 2 , respectively. 22 Monoclinic CePO 4 44 and BiPO 4 23 are effective for the electric-fieldassisted oxidative coupling of CH 4 and thermocatalytic oxidation of CH 4 to HCHO, respectively, possibly through the O 2 activation mechanism; by contrast, CH 4 is oxidized on the trigonal FePO 4 22 surface to produce HCHO and partially reduced FePO 4−δ , followed by rapid reoxidation.…”

Section: Introductionmentioning

confidence: 99%

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Copper Phosphate Nanostructures as Catalysts for the Direct Methane Oxidation

Matsuda,

Aihara,

Kiyohara

et al. 2024

ACS Appl. Nano Mater.

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The development of heterogeneous catalysts for the selective direct transformation of methane (CH 4 ) remains a challenge because of the difficulty in activating the strong C−H bond and controlling selectivity to target products. The effect of various metal phosphate catalysts (37 examples) on the direct oxidation of CH 4 to formaldehyde (HCHO) with molecular oxygen (O 2 ) as the sole oxidant was studied using a fixed-bed flow reactor, and the effectiveness of the copper phosphate catalysts was confirmed. Four crystalline copper phosphates (Cu 2 P 2 O 7 , Cu 3 (PO 4 ) 2 , Cu 2 (P 4 O 12 ), and Cu 4 O(PO 4 ) 2 ) with different Cu coordination geometries and Cu/P ratios were synthesized from Cu(OAc) 2 •H 2 O and (NH 4 ) 2 HPO 4 , and the dependence of CH 4 oxidation on their structures, as well as that on the structure of CuO, was investigated. The Cu/P molar ratio strongly affected the oxidation catalysis; CH 4 conversion increased with increasing Cu/P molar ratio, although the selectivity to HCHO decreased. Among the investigated Cu-based catalysts and metal phosphate nanoparticles (FePO 4 and BiPO 4 ), monoclinic Cu 2 P 2 O 7 , which has a Cu/P ratio of 1/1, exhibited the highest HCHO yield. The catalytic activity of Cu 2 P 2 O 7 was improved by changing the copper source to Cu(NO 3 ) 2 •3H 2 O due to the surface nanostructure control. On the basis of mechanistic studies that include catalyst effect, kinetics, isotope-labeling, and pulse reaction experiments, as well as infrared spectroscopic analyses of adsorbed probe molecules, (i) surface lattice oxygen species of Cu 2 P 2 O 7 possibly react with CH 4 to give HCHO as the primary product and (ii) the surface redox-active Lewis acidic Cu 2+ sites and weakly basic phosphate units on Cu 2 P 2 O 7 play important roles in the C−H activation and the suppression of overoxidation to CO 2 , respectively. Density functional theory calculations revealed that the vacancy formation energies at oxygen sites in β-Cu 2 P 2 O 7 , which was formed by the phase transition of α-Cu 2 P 2 O 7 under the catalytic conditions, were lower than those in α-Cu 2 P 2 O 7 . Such a superior oxygen-transfer ability likely contributes to the high catalytic performance and durability of Cu 2 P 2 O 7 for the oxidation of CH 4 to HCHO.

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Section: Catalyst Effect Of Metal Phosphate On Ch 4 Oxidation Into Hchomentioning

confidence: 82%

Section: Methodsmentioning

confidence: 99%

Section: Mechanistic Studies On the Direct Oxidation Of Ch 4 Over Cu ...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Copper Phosphate Nanostructures as Catalysts for the Direct Methane Oxidation

Matsuda,

Aihara,

Kiyohara

et al. 2024

ACS Appl. Nano Mater.

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Improved Catalytic Partial Oxidation of Methane via Lattice Oxygen Modification on Supported Copper Oxide Catalyst System

Ohyama,

Iwai,

Takahashi

et al. 2024

ChemCatChem

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Thirteen kinds of supported copper oxide catalysts (Cu/MOx, MOx: La2O3, Al2O3, SiO2, TiO2, CeO2, ZrO2, SnO2, SrCO3, BaCO3, Ta2O5, Nb2O5, WO3, and MoO3), which form Cu‐O‐M sites at the interface between CuOx and MOx or within the complex oxides (CuMOx), were tested for CH4 partial oxidation to find out catalytically active Cu‐O‐M combinations for production of CH3OH and HCHO. Among the thirteen Cu/MOx tested, Cu/WO3 exhibited the highest total yield of CH3OH and HCHO in a CH4‐O2‐H2O flow reaction at 400 °C. The structural and property analysis of Cu/WO3 revealed the formation of CuWO4, of which the lattice oxygen is active for the partial oxidation of CH4.

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Selective oxidation of methane to formaldehyde and carbon monoxide over V/MSN catalysts with isolated VO4 sites

Song,

Cui,

Gao

et al. 2024

Applied Catalysis A: General

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Bismuth phosphate nanoparticle catalyst for direct oxidation of methane into formaldehyde

Abstract: The direct oxidation of methane (CH4) to formaldehyde (HCHO) with molecular oxygen (O2) as the sole oxidant was studied over various bismuth-based catalysts (BiPO4, α-Bi2O3, β-Bi2O3) using a fixed-bed flow...

Cited by 8 publications

References 80 publications

Copper Phosphate Nanostructures as Catalysts for the Direct Methane Oxidation

Copper Phosphate Nanostructures as Catalysts for the Direct Methane Oxidation

Improved Catalytic Partial Oxidation of Methane via Lattice Oxygen Modification on Supported Copper Oxide Catalyst System

Selective oxidation of methane to formaldehyde and carbon monoxide over V/MSN catalysts with isolated VO4 sites

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