The Selective Oxidation of Methanol on Iron Molybdate Catalysts

Bowker, Michael; Holroyd, Richard; House, Matthew Peter; Bracey, R.; Bamroongwongdee, Chanut; Shannon, M. D.; Carley, Albert Frederick

doi:10.1007/s11244-008-9058-3

Cited by 40 publications

(71 citation statements)

References 20 publications

(39 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…CO production is observed at higher temperatures, reaching its peak at approximately 230 °C; similar behaviour was observed for previous Mobased systems, though formaldehyde production peaks at higher temperatures for MoO x /Fe 2 O 3 [18,19]. It is suggested that isolated cation sites are responsible for CO generation [18,20,24,25]; surface VO x is present in sufficient quantity to preclude multiple neighbouring Fe sites ( : this can be ascribed to the shell-core process, which is known to enhance surface area [18,19].…”

Section: Resultssupporting

confidence: 82%

VOx/Fe2O3 Shell–Core Catalysts for the Selective Oxidation of Methanol to Formaldehyde

et al. 2017

Self Cite

View full text Add to dashboard Cite

Efficient oxidation catalysts are important in many current industrial processes, including the selective oxidation of methanol to formaldehyde. Vanadium-containing catalysts have been shown to be effective selective oxidation catalysts for certain reactions, and research continues to examine their applicability to other reactions of interest. Several VO x /Fe 2 O 3 shell–core catalysts with varying VO x coverage have been produced to investigate the stability of VO x monolayers and their selectivity for methanol oxidation. Catalyst formation proceeds via a clear progression of distinct surface species produced during catalyst calcination. At 300 °C the selective VO x overlayer has formed; by 500 °C a sandwich layer of FeVO 4 arises between the VO x shell and the Fe 2 O 3 core, inhibiting iron cation participation in the catalysis and enhancing catalyst selectivity. The resulting catalysts, comprising a shell–subshell–core system of VO x /FeVO 4 /Fe 2 O 3 , possess good catalytic activity and selectivity to formaldehyde. Electronic supplementary material The online version of this article (10.1007/s11244-017-0873-2) contains supplementary material, which is available to authorized users.

show abstract

Section: Resultssupporting

confidence: 82%

VOx/Fe2O3 Shell–Core Catalysts for the Selective Oxidation of Methanol to Formaldehyde

et al. 2017

Self Cite

View full text Add to dashboard Cite

show abstract

“…With even further reduction, loss of H occurs with subsequent MoO 2 formation, a known reduced state of MoO 3 . The reactivity of iron molybdate is comparable to that of the pure α-MoO 3 in terms of selectivity [22], however, the activity of this mixed phase oxide supersedes that of MoO 3 , due to the greater number of exposed catalytic active sites present for isotropic Fe 2 (MoO 4 ) 3 than for anisotropic MoO 3 . Only the edge sites for MoO 3 can carry out the catalysis, whereas all the exposed planes in Fe 2 (MoO 4 ) 3 can dissociatively chemisorb CH 3 OH as well as oxidise methanol to formaldehyde.…”

Section: Initial Investigations Into the Mechanism And Reaction Site mentioning

confidence: 92%

“…Characterisation of bulk FeMo catalysts has been possible through a number of techniques, most commonly through Raman, FT-IR, DRIFTS, XRD and XPS [14,22,[26][27][28][29]. The structures of MoO 3 and Fe 2 (MoO 4 ) 3 are reasonably well understood, however there still remains some doubt in how they react with methanol, and which phase is predominantly involved in the reaction.…”

Section: Making Xafs Surface Sensitivementioning

confidence: 99%

“…House et al [22,41] have exploited TPD and pulsed flow studies to investigate this reduction phenomenon in more detail. The reaction and reduction of iron molybdate (Mo:Fe = 2.2:1) with methanol feedstock under anaerobic conditions was adopted.…”

Section: Initial Investigations Into the Mechanism And Reaction Site mentioning

confidence: 99%

“…Mo under this oxidation state is deemed crucial to optimal catalyst performance. Confirmation derives from experiments carried out to determine the activity profile of the other main oxidation state of Mo, which is Mo (IV) [22,24]. During reaction, the active Mo (VI) briefly exists as reduced Mo (IV), which can readily use gas phase oxygen to re-oxidise back to Mo (VI).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Catalysts for the Selective Oxidation of Methanol

2016

Self Cite

View full text Add to dashboard Cite

Abstract:In industry, one of the main catalysts typically employed for the selective oxidation of methanol to formaldehyde is a multi-component oxide containing both bulk Fe 2 (MoO 4 ) 3 and excess MoO 3 . It is thought that the excess MoO 3 primarily acts to replace any molybdenum lost through sublimation at elevated temperatures, therefore preventing the formation of an unselective Fe 2 O 3 phase. With both oxide phases present however, debate has arisen regarding the active component of the catalyst. Work here highlights how catalyst surfaces are significantly different from bulk structures, a difference crucial for catalyst performance. Specifically, Mo has been isolated at the surface as the active surface species. This leaves the role of the Fe in the catalyst enigmatic, with many theories postulated for its requirement. It has been suggested that the supporting Fe molybdate phase enables lattice oxygen transfer to the surface, to help prevent the selectivity loss which would occur in the resulting oxygen deficit environment. To assess this phenomenon in further detail, anaerobic reaction with methanol has been adopted to evaluate the performance of the catalyst under reducing conditions.

show abstract

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

et al. 2021

View full text Add to dashboard Cite

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.

show abstract

The Selective Oxidation of Methanol on Iron Molybdate Catalysts

Cited by 40 publications

References 20 publications

VOx/Fe2O3 Shell–Core Catalysts for the Selective Oxidation of Methanol to Formaldehyde

VOx/Fe2O3 Shell–Core Catalysts for the Selective Oxidation of Methanol to Formaldehyde

Catalysts for the Selective Oxidation of Methanol

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

Contact Info

Product

Resources

About