Stability of Iron-Molybdate Catalysts for Selective Oxidation of Methanol to Formaldehyde: Influence of Preparation Method

Raun, Kristian Viegaard; Lundegaard, L. F.; Beato, Pablo; Appel, C.C.; Agersted, Karsten; Thorhauge, Max; Schumann, Max; Jensen, Anker Degn; Grunwaldt, Jan‐Dierk; Høj, Martin

doi:10.1007/s10562-019-03034-9

Cited by 17 publications

(16 citation statements)

References 33 publications

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“…This phenomenon is quite usual in commercial MoO 3 -containing catalysts, such as the ferric-molybdatebased catalyst for methanol selective oxidation to formaldehyde. 52 In the case of spent Mo5S, FE-SEM data (Fig. 13) confirm the presence of Mo-rich particles, well visible in BSE micrograph, even though their dimensions are far smaller and they had partially lost the evidenced acicular form of the fresh material showing a more rounded shape in the exhaust material.…”

Section: Catalytic Activity In Ethanol Conversion In the Presence Of Oxygensteady-state Experimentsmentioning

confidence: 58%

A study of molybdena catalysts in ethanol oxidation. Part 1. Unsupported and silica‐supported MoO₃

Pampararo

Garbarino

Ardoino

et al. 2021

J of Chemical Tech & Biotech

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Background: Acetaldehyde is a main organic intermediate for manifold chemical products. In the near future, its production using renewable raw materials is rapidly becoming highly desirable. In this paper, investigations on pure and silica-supported molybdenum oxide (MoO 3 ) as catalysts for the ethanol oxidative dehydrogenation process to acetaldehyde are reported.Results: Acicular pure ⊍-MoO 3 crystals and silica-gel supported MoO 3 (1, 5 and 12% wt MoO3 /wt support ) were prepared by the thermal decomposition method and by incipient wetness impregnation, respectively. Catalysts were studied and extensively characterized assessing structural, morphological and chemical properties. The samples were tested in ethanol oxidative dehydrogenation through Temperature Programmed Surface Reaction (TPSR) and steady-state measurements. MoO 3 /SiO 2 samples were constituted by MoO 3 particles weakly interacting with the support, but also by some molybdate species entering the silica framework and significantly modifying the silica morphology. High catalyst acidity limits oxydehydrogenation yield, catalyzing the competitive dehydration reaction to ethylene. Thus, the highest obtained acetaldehyde yield was ≈60%. Molybdenum loss by MoO 3 volatilization was found on MoO 3 /SiO 2 . Conclusion:The produced and characterized catalysts are active, and allow quite a high yield to acetaldehyde. Slight deactivation was observed and also investigated.

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Section: Catalytic Activity In Ethanol Conversion In the Presence Of Oxygensteady-state Experimentsmentioning

confidence: 58%

A study of molybdena catalysts in ethanol oxidation. Part 1. Unsupported and silica‐supported MoO₃

Pampararo

Garbarino

Ardoino

et al. 2021

J of Chemical Tech & Biotech

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“…The findings of Ivanov and Dimitrov [82] and Andersson [20] were also substantiated in the studies by Raun et al [43,87,88] utilizing Raman spectroscopy, XRD, XPS, SEM, and STEM on powder samples used at 384-416 • C for up to 600 h on stream. Excess MoO 3 evaporated (within 10 h), then Fe 2 (MoO 4 ) 3 was reduced to the Mo depleted phases FeMoO 4 (10-250 h on stream) and Fe 2 O 3 (observed after 600 h on stream) due to the loss of Mo during operation.…”

Section: Deactivationmentioning

confidence: 59%

A Review and Experimental Revisit of Alternative Catalysts for Selective Oxidation of Methanol to Formaldehyde

et al. 2021

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The selective oxidation of methanol to formaldehyde is a growing million-dollar industry, and has been commercial for close to a century. The Formox process, which is the largest production process today, utilizes an iron molybdate catalyst, which is highly selective, but has a short lifetime of 6 months due to volatilization of the active molybdenum oxide. Improvements of the process’s lifetime is, thus, desirable. This paper provides an overview of the efforts reported in the scientific literature to find alternative catalysts for the Formox process and critically assess these alternatives for their industrial potential. The catalysts can be grouped into three main categories: Mo containing, V containing, and those not containing Mo or V. Furthermore, selected interesting catalysts were synthesized, tested for their performance in the title reaction, and the results critically compared with previously published results. Lastly, an outlook on the progress for finding new catalytic materials is provided as well as suggestions for the future focus of Formox catalyst research.

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“…It is necessary for the oxygen vacancy to be reoxidized in time for the activity and selectivity to remain constant in the long term. Raun [31] also found that the Mo structure could influence the stability of Mo-Fe catalysts. A lower rate of catalyst deactivation was observed for the large h-MoO 3 compared with α-MoO 3 .…”

Section: Temperature (℃)mentioning

confidence: 99%

Effect of Mo Dispersion on the Catalytic Properties and Stability of Mo–Fe Catalysts for the Partial Oxidation of Methanol

Zhang

Han

2020

Molecules

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Mo–Fe catalysts with different Mo dispersions were synthesized with fast (Cat-FS, 600 r·min−1) or slow stirring speed (Cat-SS, 30 r·min−1) by the coprecipitation method. Improving the stirring speed strengthened the mixing of the solution and increased the dispersion of particles in the catalyst, which exhibited favorable activity and selectivity. The byproduct (dimethyl ether (DME)) selectivity increased from 2.3% to 2.8% with Cat-SS, while it remained unchanged with Cat-FS in a stability test. The aggregation of particles and thin Mo-enriched surface layer decreased the catalyst surface area and slowed down the reoxidation of reduced active sites with Cat-SS, leaving more oxygen vacancies which promoted the formation of DME by the nonoxidative channel.

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Stability of Iron-Molybdate Catalysts for Selective Oxidation of Methanol to Formaldehyde: Influence of Preparation Method

Cited by 17 publications

References 33 publications

A study of molybdena catalysts in ethanol oxidation. Part 1. Unsupported and silica‐supported MoO₃

A study of molybdena catalysts in ethanol oxidation. Part 1. Unsupported and silica‐supported MoO₃

A Review and Experimental Revisit of Alternative Catalysts for Selective Oxidation of Methanol to Formaldehyde

Effect of Mo Dispersion on the Catalytic Properties and Stability of Mo–Fe Catalysts for the Partial Oxidation of Methanol

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Stability of Iron-Molybdate Catalysts for Selective Oxidation of Methanol to Formaldehyde: Influence of Preparation Method

Cited by 17 publications

References 33 publications

A study of molybdena catalysts in ethanol oxidation. Part 1. Unsupported and silica‐supported MoO3

A study of molybdena catalysts in ethanol oxidation. Part 1. Unsupported and silica‐supported MoO3

A Review and Experimental Revisit of Alternative Catalysts for Selective Oxidation of Methanol to Formaldehyde

Effect of Mo Dispersion on the Catalytic Properties and Stability of Mo–Fe Catalysts for the Partial Oxidation of Methanol

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A study of molybdena catalysts in ethanol oxidation. Part 1. Unsupported and silica‐supported MoO₃

A study of molybdena catalysts in ethanol oxidation. Part 1. Unsupported and silica‐supported MoO₃