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| Naji, M. |
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| Motta, Antonella |
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| Aletan, Dirar |
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| Mohamed, Tarek |
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| Ertürk, Emre |
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| Taccardi, Nicola |
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| Kononenko, Denys |
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| Petrov, R. H. | Madrid |
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| Alshaaer, Mazen | Brussels |
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| Bih, L. |
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| Casati, R. |
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| Muller, Hermance |
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| Kočí, Jan | Prague |
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| Šuljagić, Marija |
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| Kalteremidou, Kalliopi-Artemi | Brussels |
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| Azam, Siraj |
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| Ospanova, Alyiya |
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| Blanpain, Bart |
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| Ali, M. A. |
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| Popa, V. |
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| Rančić, M. |
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| Ollier, Nadège |
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| Azevedo, Nuno Monteiro |
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| Landes, Michael |
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| Rignanese, Gian-Marco |
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Høj, Martin
Technical University of Denmark
in Cooperation with on an Cooperation-Score of 37%
Topics
Publications (7/7 displayed)
- 2022Zinc Based High Temperature Methanol Synthesis Catalysts Enabling Direct Synthesis of Olefins and Aromatics from CO2
- 2022Zinc Based High Temperature Methanol Synthesis Catalysts Enabling Direct Synthesis of Olefins and Aromatics from CO 2
- 2020Structural dynamics of an iron molybdate catalyst under redox cycling conditions studied with in situ multi edge XAS and XRDcitations
- 2019Modeling of the molybdenum loss in iron molybdate catalyst pellets for selective oxidation of methanol to formaldehydecitations
- 2019Catalytic Hydropyrolysis of Biomass using Molybdenum Sulfide Based Catalyst. Effect of Promoterscitations
- 2018Hydrogen assisted catalytic biomass pyrolysis for green fuels. Effect of cata-lyst in the fluid bed
- 2011Flame spray synthesis of CoMo/Al2O3 hydrotreating catalystscitations
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article
Modeling of the molybdenum loss in iron molybdate catalyst pellets for selective oxidation of methanol to formaldehyde
Abstract
The loss of molybdenum from industrial iron molybdate (Fe<sub>2</sub>(MoO<sub>4</sub>)<sub>3</sub>) catalyst pellets with an excess of molybdenum oxide was studied during selective oxidation of methanol to formaldehyde for up to about 10 days on stream at varying reaction conditions (MeOH = 1.6–4.5%, O2 = 2.5–10%, H<sub>2</sub>O = 0–10.2 vol% in N<sub>2</sub> and temperature = 250, 300 and 350 °C). The changing morphology and the local elemental composition in the pellets were followed for increasing time on stream. Molybdenum was shown to volatilize, leaving a depleted zone starting at the pellet surface and moving inwards with time. For temperatures ≤ 300 °C only volatilization of the excess MoO<sub>3</sub> phase was observed. Increasing concentration of MeOH and temperature enhanced the rate of volatilization, the oxygen concentration had negligible effect, while increasing the H<sub>2</sub>O concentration decreased the volatilization rate. At 350 °C (MeOH = 4.5%, O2 = 10%, H<sub>2</sub>O = 0% in N<sub>2</sub>) Mo in the Fe<sub>2</sub>(MoO<sub>4</sub>)<sub>3</sub> phase was furthermore volatilized leading to the formation of the reduced ferrous molybdate (FeMoO<sub>4</sub>). A dynamic 1D mathematical model for a single pellet, in which methanol oxidation to formaldehyde and simultaneous volatilization of free MoO<sub>3</sub> takes place, was developed. The model parameters were fitted using experimental data of the pellet weight loss while the evolution of the MoO<sub>3 </sub>depletion layer thickness was used to validate the model. The model describes the data well and additionally predicts that deposition of MoO<sub>3</sub> behind the depletion layer front occurs under certain conditions, leading to a MoO<sub>3</sub> deposition layer, which was verified by scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectroscopy (EDS). Simulations with the model show that the overall loss of molybdenum is significantly slower for large pellets compared to small pellets, which is a key parameter for the success of the industrial process.