Effects of mechanochemical treatment to the vanadium phosphate catalysts derived from VOPO4·2H2O

Taufiq‐Yap, Yun Hin; Goh, Chee Keong; Hutchings, Graham J.; Dummer, Nicholas F.; Bartley, Jonathan K.

doi:10.1016/j.molcata.2006.06.047

Cited by 42 publications

(15 citation statements)

References 27 publications

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“…Figure 4 exhibits the H 2 -TPR profiles of different catalysts. The peaks appearing in the 400–650 °C range are ascribable to the V 5+ reduction, whereas the peaks of 700–850 °C are owing to the V 4+ reduction 47,48 . Notably, there is only one broad peak in the 400–800 °C range on both 33%-VPO/MCF and 5%-VPO/MCF.…”

Section: Resultsmentioning

confidence: 98%

Vanadium Phosphorus Oxide/Siliceous Mesostructured Cellular Foams: efficient and selective for sustainable acrylic acid production via condensation route

Wang

et al. 2019

Sci Rep

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A new type of supported vanadium phosphorus oxide (VPO) with self-phase regulation was simply fabricated (organic solvent free) for the first time by depositing the specific VPO precursor NH4(VO2)HPO4 onto the Siliceous Mesostructured Cellular Foams (MCF) with controlled activation. The resulting materials were found to be highly efficient and selective for sustainable acrylic acid (AA) plus methyl acrylate (MA) production via a condensation route between acetic acid (HAc) and formaldehyde (HCHO). A (AA + MA) yield of 83.7% (HCHO input-based) or a (AA + MA) selectivity of 81.7% (converted HAc-based) are achievable at 360 °C. The systematic characterizations and evaluations demonstrate a unique surface regulation occurring between the MCF and the NH4(VO2)HPO4 precursor. NH3 release upon activation of NH4(VO2)HPO4 precursor together with adsorption of NH3 by MCF automatically induces partial reduction of V5+ whose content is fine-tunable by the VPO loading. Such a functionalization simultaneously modifies phase constitution and surface acidity/basicity of catalyst, hence readily controls catalytic performance.

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Section: Resultsmentioning

confidence: 98%

Vanadium Phosphorus Oxide/Siliceous Mesostructured Cellular Foams: efficient and selective for sustainable acrylic acid production via condensation route

Wang

et al. 2019

Sci Rep

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“…These results are in a good agreement with Hutchings findings [37] which suggested that the best performing catalyst had the higher surface area. Moreover, the availability and behavior the oxygen species play an important role in determining the catalytic activity and supports this idea that the mobility of active oxygen species (O − ) in the catalyst is the main determining step for n-butane activation [41][42][43][44]. As reported earlier, selective oxidation of n-butane over vanadium phosphate catalyst is carried out via a redox mechanism proposed by Mars and van Krevelen [45].…”

Section: Catalystsmentioning

confidence: 57%

“…For partial oxidation of n-butane, the redox cycle of vanadium only involves the reduction of V 4+ and V 5+ and the further reduction of V 3+ is not the main concern of this study. Therefore, the adopted temperature range (from RT to ∼1050 K) for H 2 -TPR is usually sufficient for the reduction of V 4+ and V 5+ according to previous studies [41,42]. Fig.…”

Section: Influence Of Reducing Agent (Catalyst Microstructure) On Amomentioning

confidence: 90%

Solvothermal synthesis of vanadium phosphate catalysts for n-butane oxidation

Rownaghi

Taufiq‐Yap

Rezaei

2009

Chemical Engineering Journal

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a b s t r a c tIn this paper, we have developed a simple, low-cost, template-free and surfactant-free solvothermal process for synthesis of vanadyl hydrogen phosphate hemihydrate (VOHPO 4 ·0.5H 2 O) with well defined crystal size. The synthesis was performed by reaction of VPO 4 ·2H 2 O with an aliphatic alcohol (isobutyl alcohol, 1-pentanol, 1-hexanol, 1-heptanol or 1-decanol). This afforded well crystallized VOHPO 4 ·0.5H 2 O by solvothermal methods at 120 • C temperature. This new method significantly reduced the preparation time and lowered production temperature (50%) of catalyst precursor (VOHPO 4 ·0.5H 2 O) when compared to conventional hydrothermal synthesis methods. By varying the reducing agent, the solvothermal evolution process from layered tetragonal phase VOPO 4 ·2H 2 O to orthorhombic phase VOHPO 4 ·0.5H 2 O was observed. It was found that the length of carbon chain in an alcohol in the solvothermal condition had a great impact on chemical and physical properties of resulting catalysts. Interestingly, there was no trace of VO(H 2 PO 4 ) 2 an impurity noted to be readily formed under solvothermal preparation condition. Therefore, this study introduces a more facile synthetic pathway to V(III) compounds. In addition, the microwave-synthesized catalysts exhibited some properties superior to those of conventionally synthesized catalyst such as better stability, crystallinity, and catalytic activity in the production of maleic anhydride. The characterization of both precursors and calcined catalysts was carried out using X-ray diffraction (XRD), inductively coupled plasma-atomic emission spectrometer (ICP-AES), N 2 physisorption, temperature programmed reduction (H 2 -TPR) and scanning electron microscopy (SEM). The XRD pattern of the active catalyst prepared by this solvothermal method confirmed the presence of smaller crystal size (between 6 and 13 nm along 0 2 0 planes) of vanadium phosphate catalyst with higher specific surface area. Finally, the yield of maleic anhydride was significantly increased from 29% for conventional catalyst to 44% for the new solvothermal catalyst.Crown

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“…phase. A good direct correlation was reported [37] between the amount of oxygen species removed from both phases (V 4? and V 5? )…”

Section: Catalystsmentioning

confidence: 68%

Influence of the Ethylene Glycol, Water Treatment and Microwave Irradiation on the Characteristics and Performance of VPO Catalysts for n-Butane Oxidation to Maleic Anhydride

2009

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In this paper, the preparation of vanadium phosphate catalysts was shown to be improved by (1) using V 2 O 5 and ethylene glycol as starting and reducing agent material, respectively for VOPO 4 Á 2H 2 O, (2) subsequent water treatment and (3) microwave irradiation. In particular, the preparation route, based on the reduction of VOPO 4 Á 2H 2 O with various alcohols, is described in detail and contrasted with other three established methods performed by using ethylene glycol and isobutyl alcohol as reductant and solvent for V 2 O 5 or distilled water as a solvent material. The preparation of catalyst precursor is carried out by two different methods, namely conventional heating and microwave irradiation. With this new technique, catalysts derived from the reduction of VOPO 4 Á 2H 2 O by ethylene glycol exhibit substantially higher surface area (typically [40 m 2 g -1 ) and activity. In fact, the surface area of the catalyst is significantly enhanced when the precursor is refluxed by distilled water and dried by microwave heating. The characterization of catalysts was carried out using X-ray diffraction (XRD), Brunauer-Emmer-Teller (BET) surface area measurement, temperature programmed reduction (H 2 -TPR), temperature-programmed reaction (TPRn) and scanning electron microscopy (SEM). This study shows that employing ethylene glycol as reducing agent, followed by adding the water treatment step to catalyst synthesis procedure, and using microwave irradiation would give rise to enhanced surface area, activity and selectivity of the catalyst. Moreover, it introduces a more energy efficient procedure for preparation of vanadium phosphate catalyst used in selective oxidation of n-butane process.

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Effects of mechanochemical treatment to the vanadium phosphate catalysts derived from VOPO4·2H2O

Cited by 42 publications

References 27 publications

Vanadium Phosphorus Oxide/Siliceous Mesostructured Cellular Foams: efficient and selective for sustainable acrylic acid production via condensation route

Vanadium Phosphorus Oxide/Siliceous Mesostructured Cellular Foams: efficient and selective for sustainable acrylic acid production via condensation route

Solvothermal synthesis of vanadium phosphate catalysts for n-butane oxidation

Influence of the Ethylene Glycol, Water Treatment and Microwave Irradiation on the Characteristics and Performance of VPO Catalysts for n-Butane Oxidation to Maleic Anhydride

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