Nano-sized crystallites of vanadyl pyrophosphate as a highly selective catalyst for n-butane oxidation

Kamiya, Yuichi; Ryumon, Naonori; Imai, Hiroyuki; Okuhara, Toshio

doi:10.1007/s10562-006-0140-9

Cited by 11 publications

(9 citation statements)

References 20 publications

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“…We previously succeeded in carrying out exfoliation of VOPO 4 ·2H 2 O in various alcohols [13], and demonstrated that subsequent reduction of the exfoliated VOPO 4 sheets with alcohol produced VOHPO 4 ·0.5H 2 O. In particular, as we described in a preliminary report [14], (VO) 2 P 2 O 7 catalyst derived from VOHPO 4 ·0.5H 2 O which had been prepared by exfoliation-reduction of VOPO 4 ·2H 2 O in a mixed alcohol solvent (2-butanol and ethanol) was found to be superior, in terms of activity and selectivity, to the catalyst derived from VOHPO 4 ·0.5H 2 O prepared in 2-butanol alone and by the direct-reduction method for n-butane oxidation [15].…”

Section: Introductionmentioning

confidence: 73%

Selective oxidation of n-butane over nanosized crystallites of (VO)2P2O7 synthesized by an exfoliation–reduction process of VOPO4⋅2H2O in a mixture of 2-butanol and ethanol

Imai

Kamiya

Okuhara

2007

Journal of Catalysis

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Intercalation, exfoliation, and reduction of VOPO 4 ·2H 2 O were conducted in 2-butanol alone and in a mixed alcohol solvent (2-butanol and ethanol). While both processes produced crystallites of pure VOHPO 4 ·0.5H 2 O, much smaller and thinner crystallites (av. 340 nm × 35 nm) were formed in the mixed alcohol compared with 2-butanol alone (av. 950 nm × 200 nm).The small, thin crystallites of precursor VOHPO 4 ·0.5H 2 O could be transformed into sharply angular nano-sized crystallites (60 nm in length and 31 nm in thickness) of highly crystalline (VO) 2 P 2 O 7 , without mesopores. When used as a catalyst, this compound exhibited higher activity and selectivity to maleic anhydride (75% at 80% conversion) for selective oxidation of n-butane than that derived from the precursor prepared in 2-butanol alone. The high activity of the nano-sized crystallites of (VO) 2 P 2 O 7 is attributed to their large surface area (40 m 2 g -1 ), which is due to their smaller dimensions, and their high selectivity may be attributed to the lack of mesopores as well as their highly crystalline state.

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Section: Introductionmentioning

confidence: 73%

Selective oxidation of n-butane over nanosized crystallites of (VO)2P2O7 synthesized by an exfoliation–reduction process of VOPO4⋅2H2O in a mixture of 2-butanol and ethanol

Imai

Kamiya

Okuhara

2007

Journal of Catalysis

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“…Thus, the observed gain in n-butane conversion and maleic anhydride selectivity had been attributed to the good reducibility and oxidizibility of the (VO) 2 P 2 O 7 catalyst [15,16,18]. Apart from the above matters pertaining to the performance of VPO catalysts, a number of factors can influence its performance such as its preparative route, starting material type for preparations, detailed phase composition and reaction medium [19][20][21][22]. The (VO) 2 P 2 O 7 phase is obtained from VOHPO 4 Á0.5H 2 O precursor that is transformed under reaction conditions (n-butane/O 2 flow, 400°C) or calcination in N 2 at 550°C [19].…”

Section: Introductionmentioning

confidence: 99%

Liquid Phase Oxidation of p-cymene by (VO)2P2O7 and VO(PO3)2 Catalysts

et al. 2010

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Vanadium phosphate oxide (VPO) catalysts derived from VOHPO 4 Á0.5H 2 O and VO(H 2 PO 4 ) 2 precursors showed improved rates in the catalysed liquid phase oxidation of p-cymene. Both catalysts showed high performance with conversions of up to 30% achieved within 3 h with a selectivity towards the tertiary cymene hydroperoxide (TCHP) of 75-80% when compared to lower conversions and poorer TCHP selectivity in the non-catalysed industrial oxidation processes that takes about 8-12 h reaction time. The temperature dependent structural changes during activation within the catalysts were studied by in situ XRD and TGA-MS. The in situ XRD showed that the VO(H 2 PO 4 ) 2 form mainly an amorphous phase at temperature up to 600°C while above 650-750°C a stable VO(PO 3 ) 2 phase was obtained. The in situ XRD studies of the (VO) 2 P 2 O 7 phase derived from VOHPO 4 Á0.5H 2 O showed to became more crystalline with increasing temperature from 400 to 750°C. No formation of VOPO 4 phases were observed in the activated (VO) 2 P 2 O 7 catalyst even at high temperature under the in situ XRD conditions.

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“…Another interesting point to note is that, by changing the solvent from 2-butanol to isobutanol in the intercalation and exfoliation stage, the (001), (101), (021), and (121) appeared to be less intense and broader as compared to those catalysts precursor that using 2-butanol as solvent in the mentioned stage above. erefore, this also indicated that using isobutanol instead of 2-butanol as solvent in the intercalation and exfoliation stage somehow promotes the formation of more amorphous VPD precursor compared to the VPD precursor that used 2-butanol as solvent in the intercalation and exfoliation stage which has been well studied by Kamiya and coworkers [11]. Figure 2 exhibited the XRD patterns of intercalationexfoliation-reduction VPD catalysts, aer being activated at 733 K in reaction environment (0.75% n-butane/air mixture) for 18 h. All the catalysts produced are very similar and show the characteristic of (VO) 2 P 2 O 7 phase with (020), (204), and (221) lines at 22.9 ∘ , 28.4 ∘ , and 29.9 ∘ , respectively.…”

Section: X-ray Diffraction (Xrd)mentioning

confidence: 79%

Influence of Intercalation‐Exfoliation‐Reduction Technique towards the Physico‐Chemical of VPO Catalysts

Wong

Taufiq‐Yap

2012

Journal of Chemistry

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Four VPO catalysts were synthesized through intercalation and exfoliation in various alcohols and subsequent reduction of the exfoliated VOPO4sheets with various alcohols to produce VOHPO4⋅0.5H2O. The resulting VOHPO4⋅0.5H2O that undergoes the intercalation-exfoliation-reduction (IER) process will be further activated into VPO catalysts, and addition of 1 mole % Bi(NO3)3⋅5H2O in the first stage of this experiment has also being investigated. The synthesized materials were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and temperature-programmed reduction (TPR) in H2. Catalytic evaluation of the IER-treated and Bi-doped VPO catalysts was also studied on microreactor. The VPO catalyst produced through IER using 2-butanol and ethanol with addition of Bi, IERC(2Bu-Et)RBi1, gave the highest MA selectivity due to reactive O2−species released from the additional crystalline V5+phase formed by doping 1% bismuth as promoter (O2−-V5+pair) at relative lower temperature. Nevertheless, the VPO catalyst produced through IER using isobutanol, IERC(isoBu), gave the highest activity due to high amount of reactive O−species released from V4+phase (O−-V4+pair) whereby the IERC(isoBu) catalyst synthesized consists of high percentage of V4+(93 %).

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Nano-sized crystallites of vanadyl pyrophosphate as a highly selective catalyst for n-butane oxidation

Cited by 11 publications

References 20 publications

Selective oxidation of n-butane over nanosized crystallites of (VO)2P2O7 synthesized by an exfoliation–reduction process of VOPO4⋅2H2O in a mixture of 2-butanol and ethanol

Selective oxidation of n-butane over nanosized crystallites of (VO)2P2O7 synthesized by an exfoliation–reduction process of VOPO4⋅2H2O in a mixture of 2-butanol and ethanol

Liquid Phase Oxidation of p-cymene by (VO)2P2O7 and VO(PO3)2 Catalysts

Influence of Intercalation‐Exfoliation‐Reduction Technique towards the Physico‐Chemical of VPO Catalysts

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