Selective oxidation of methanol to dimethoxymethane over V2O5/TiO2–Al2O3 catalysts

Wang, Tuo; Meng, Yali; Zeng, Liang; Gong, Jinlong

doi:10.1007/s11434-015-0782-3

Cited by 21 publications

(11 citation statements)

References 30 publications

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“…Only one peak at around 500 °C was observed for all the samples, which is associated to the reduction of VO x species. [34][35] The consumed H atoms per V atom was then calculated ( Additionally, similar phenomena has also been observed in the chromium oxide system. [37][38] XPS measurements have been carried out to acquire the quantitative information of the valence distribution of vanadium on the catalyst surface.…”

Section: Distribution Of Valence Statementioning

confidence: 75%

Nature of the Active Sites of VO_x/Al₂O₃ Catalysts for Propane Dehydrogenation

et al. 2016

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Supported VO x catalysts are promising for propane dehydrogenation (PDH) due to relatively superior activity and stable performance upon regeneration.However, the nature of active sites and reaction mechanism during PDH over VO x based catalysts remains elusive. This paper describes the understanding of active species through attaining various fraction of V 5+ /V 4+ /V 3+ ions by adjusting surface vanadium density on an alumina support. The results presented a close relationship between E a /TOF and the fraction of V 3+ ion, indicating that the V 3+ was more active for PDH. In situ DRIFTS showed the same strong adsorbed species during both propane dehydrogenation and propylene hydrogenation. The results indicated that such intermediate may correspond with V species containing C=C double bond i.e. V-C 3 H 5 , and a reaction mechanism was proposed accordingly.

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Section: Distribution Of Valence Statementioning

confidence: 75%

Nature of the Active Sites of VO_x/Al₂O₃ Catalysts for Propane Dehydrogenation

et al. 2016

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“…Many transition metal oxide-based catalysts can also catalyze this reaction, such as RuO x /ZrO 2 , , ReO x /CeO 2 , and V 2 O 5 /TiO 2 -based catalysts. ,,, With the V 2 O 5 /TiO 2 catalyst, dimethoxymethane (CH 3 OCH 2 OCH 3 , DMM) is formed at relatively low temperature of 70–100 °C with selectivity of 88–95%, whereas MF is produced at relatively high temperature of ∼150 °C with selectivity of ∼85% . Most of the studies on the V 2 O 5 /TiO 2 -based catalysts were focused on the selective synthesis of DMM, − although we recently synthesized a vanadia–titania–sulfate (VTS) catalyst, which can catalyze CH 3 OH oxidation with very high MF selectivity of 98.6% at very high CH 3 OH conversion of ∼98.7% at 145 °C . The very high MF yield of ∼97.3% is crucial for the efficient production of MF from CH 3 OH.…”

Section: Introductionmentioning

confidence: 99%

Catalytic Mechanisms of Methanol Oxidation to Methyl Formate on Vanadia–Titania and Vanadia–Titania–Sulfate Catalysts

Wang

Ren

et al. 2016

J. Phys. Chem. C

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Density functional theory calculations were carried out using both cluster and slab models to investigate the catalytic reaction network and the effect of sulfate promoter on methanol selective oxidation using the V2O5/TiO2 catalyst. The hemiacetal mechanism was reaffirmed to be the most favorable reaction pathway for the formation of methyl formate (MF) by the prediction of another reaction pathway involving formic acid. Molecular oxygen was found to assist the desorption of the reaction products from the reduced catalyst active site, both formaldehyde and methyl formate (MF). The mechanism of catalyst regeneration was elucidated based solely on first-principles calculations, which involve the conversion of another methanol molecule to formaldehyde over a peroxo species. This leads to our formulation of a complete catalytic reaction network for methanol selective oxidation to formaldehyde and MF on the V2O5/TiO2 catalyst. In addition, the detailed mechanism for the formation of formaldehyde and MF was also predicted on the sulfate-promoted V2O5/TiO2 catalyst. Based on the calculated reaction networks, the preferred formation of MF on the V2O5/TiO2-based catalysts was attributed to the lower energy barrier of the oxidative dehydrogenation (ODH) of the CH3OCH2O* intermediate than that of CH3O*. Furthermore, our calculated energy barriers also suggest that the sulfate-promoted V2O5/TiO2 catalyst has not only higher catalytic activity for methanol conversion but also higher selectivity of MF over CH2O, consistent with previous experimental observations. The sulfate promoter was found to increase the positive charge at the V site, leading to a lower energy barrier for the ODH of CH3O* than the unpromoted catalyst.

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“…Since FA needs to be oxidized from methanol, two steps are involved in converting methanol to DMM in the traditional process. 16 The silver or ironmolybdenum catalyst with oxidation-reduction properties is initially used to selectively oxidize methanol to FA and FA and methanol are subsequently condensed on an acid catalyst to form DMM. Although the conditions of this process are relatively mature, energy consumption is high, equipment investment is relatively high and resulting pollution is serious and these can limit the costeffectiveness and widespread use of DMM.…”

Section: Introductionmentioning

confidence: 99%

“…The catalysts used are mainly cationic acid resins and molecular sieves. Since FA needs to be oxidized from methanol, two steps are involved in converting methanol to DMM in the traditional process 16 . The silver or iron‐molybdenum catalyst with oxidation‐reduction properties is initially used to selectively oxidize methanol to FA and FA and methanol are subsequently condensed on an acid catalyst to form DMM.…”

Section: Introductionmentioning

confidence: 99%

Effects of reaction conditions on one‐step synthesis of methylal via methanol oxidation catalyzed by Mo:Fe(2)/ HZSM ‐5 catalyst

et al. 2021

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In the process of one-step synthesis of methylal via methanol oxidation, the design and research of various dual-function catalysts are important and studies on the influence of reaction conditions on this type of process are scarce. We explored the influence of reaction temperature, reaction space velocity, and the feed ratio of methanol to air on the catalytic effect of the process based on the Fe-Mo-based bifunction catalyst and discovered the most appropriate reaction conditions for the process. Results showed that excessively high reaction temperatures were not conducive to the formation of target product Dimethoxymethane (DMM) and this was verified from the perspective of thermodynamic analysis. At the same time, through Brunaure Emmett Teller (BET), X-ray diffraction, scanning electron microscope, NH 3-temperatureprogrammed chemisorption, and Pyridine Fourier Infrared (PY-FTIR) characterization, analysis of the microstructure and surface characteristics of the catalyst showed that an excessively high reaction temperature caused accumulation of metal oxides on the catalyst surface to block pores and reduce the specific surface area. This also destroyed the active acidic sites on the catalyst surface and weakened the acidity of the catalyst, thereby reducing catalytic activity. Investigation showed that excessively high reaction space velocity caused most of the formaldehyde obtained by catalyzing the initial oxidative dehydrogenation to fail to undergo polycondensation with methanol after desorption in time to obtain DMM, leading to a significant decrease in DMM selectivity. Investigation of the methanol-air feed ratio showed that when CH 3 OH:air = 1.5, the methylal selectivity was highest and catalytic activity had improved. Orthogonal experiments showed that optimal reaction conditions of the process were 663 K, 15 000 h −1 and CH 3 OH: air = 0.82. In addition, compared with other bifunctional catalysts of this process, the self-made Mo:Fe(2)/HZSM-5 bifunctional catalyst exhibited high stability and carbon deposition resistance under severe operating conditions. Meng Yuan contributed to the work equally and should be regarded as co-first authors.

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Selective oxidation of methanol to dimethoxymethane over V2O5/TiO2–Al2O3 catalysts

Cited by 21 publications

References 30 publications

Nature of the Active Sites of VO_x/Al₂O₃ Catalysts for Propane Dehydrogenation

Nature of the Active Sites of VO_x/Al₂O₃ Catalysts for Propane Dehydrogenation

Catalytic Mechanisms of Methanol Oxidation to Methyl Formate on Vanadia–Titania and Vanadia–Titania–Sulfate Catalysts

Effects of reaction conditions on one‐step synthesis of methylal via methanol oxidation catalyzed by Mo:Fe(2)/ HZSM ‐5 catalyst

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Selective oxidation of methanol to dimethoxymethane over V2O5/TiO2–Al2O3 catalysts

Cited by 21 publications

References 30 publications

Nature of the Active Sites of VOx/Al2O3 Catalysts for Propane Dehydrogenation

Nature of the Active Sites of VOx/Al2O3 Catalysts for Propane Dehydrogenation

Catalytic Mechanisms of Methanol Oxidation to Methyl Formate on Vanadia–Titania and Vanadia–Titania–Sulfate Catalysts

Effects of reaction conditions on one‐step synthesis of methylal via methanol oxidation catalyzed by Mo:Fe(2)/ HZSM ‐5 catalyst

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Nature of the Active Sites of VO_x/Al₂O₃ Catalysts for Propane Dehydrogenation

Nature of the Active Sites of VO_x/Al₂O₃ Catalysts for Propane Dehydrogenation