Solid State Reactions in Fe-Mo Oxide Catalysts for Methanol Oxidation During Aging in Industrial Plants.

Burriesci, N.; Garbassi, F.; Petrera, M.; Petrini, G.; Pernicone, N.

doi:10.1016/s0167-2991(08)65224-6

Cited by 30 publications

(32 citation statements)

References 4 publications

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“…Catalyst deactivation by solid-state diffusion and reaction appears to be an important mechanism for degradation of complex multicomponent catalysts in dehydrogenation, synthesis, partial oxidation, and total oxidation reactions [8,[149][150][151][152][153][154][155][156][157][158][159][160]. However, it is difficult in most of these reactions to know the extent to which the solid-state processes, such as diffusion and solid-state reaction, are affected by surface reactions.…”

Section: Solid-state Reactionsmentioning

confidence: 99%

Heterogeneous Catalyst Deactivation and Regeneration: A Review

2015

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Deactivation of heterogeneous catalysts is a ubiquitous problem that causes loss of catalytic rate with time. This review on deactivation and regeneration of heterogeneous catalysts classifies deactivation by type (chemical, thermal, and mechanical) and by mechanism (poisoning, fouling, thermal degradation, vapor formation, vapor-solid and solid-solid reactions, and attrition/crushing). The key features and considerations for each of these deactivation types is reviewed in detail with reference to the latest literature reports in these areas. Two case studies on the deactivation mechanisms of catalysts used for cobalt Fischer-Tropsch and selective catalytic reduction are considered to provide additional depth in the topics of sintering, coking, poisoning, and fouling. Regeneration considerations and options are also briefly discussed for each deactivation mechanism.

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Section: Solid-state Reactionsmentioning

confidence: 99%

Heterogeneous Catalyst Deactivation and Regeneration: A Review

2015

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“…However, under these conditions sublimation of molybdenum can occur, particularly at reactor hot spots and, if there is not sufficient excess molybdenum in the catalyst (i.e. if Mo/Fe is not greater than 1.5), breakdown to oxides occurs [13,[15][16][17][18]: Many authors believe the redox process occurs via a Mars-Van Krevelen type mechanism, [14,[19][20][21]. This mechanism is supported by kinetic studies and experimental works indicating rapid diffusion of bulk oxygen to the catalyst surface [22][23][24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

A Combined Multi-Technique In Situ Approach Used to Probe the Stability of Iron Molybdate Catalysts During Redox Cycling

et al. 2009

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A setup combining a number of techniques (WAXS, XANES and UV-Vis) has been used to probe the stability of an iron molybdate catalyst during redox cycling. The catalyst was first reduced under anaerobic methanol/ helium conditions, producing formaldehyde and then regenerated using air. Although in this test-case the catalyst and conditions differ from that of a commercial catalyst bed we demonstrate how such a setup can reveal new information on catalyst materials.

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“…In practice it varies between 8 and 18 months depending on the operating conditions and tolerances. By now, it is well established that the catalyst deactivates because it looses Mo during operation due to the formation of volatile species [9][10][11][12][13], causing lower activity and selectivity as well as increased pressure drop as molybdena needles condense in the lower part of the reactor. Another deactivation cause is sintering of the catalyst in the hot spot [11,14,15].…”

Section: Introductionmentioning

confidence: 99%

“…By now, it is well established that the catalyst deactivates because it looses Mo during operation due to the formation of volatile species [9][10][11][12][13], causing lower activity and selectivity as well as increased pressure drop as molybdena needles condense in the lower part of the reactor. Another deactivation cause is sintering of the catalyst in the hot spot [11,14,15]. The deactivated catalyst consists mainly of Fe 2 (MoO 4 ) 3 , but contains as well the worse performing Fe 2 O 3 and FeMoO 4 phases [9,11,13,16,17].…”

Section: Introductionmentioning

confidence: 99%

On the Synergy Effect in MoO3–Fe2(MoO4)3 Catalysts for Methanol Oxidation to Formaldehyde

et al. 2008

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Methanol oxidation to formaldehyde was studied over a series of Fe-Mo-O catalysts with various Mo/Fe atomic ratio and the end compositions Fe 2 O 3 and MoO 3 . The activity data show that the specific activity passes through a maximum with increase of the Mo content and is the highest for Fe 2 (MoO 4 ) 3 . The selectivity to formaldehyde, on the other hand, increases with the Mo content in the catalyst. A synergy effect is observed in that a catalyst with the Mo/Fe ratio 2.2 is almost as active as Fe 2 (MoO 4 ) 3 and as selective as MoO 3 . Imaging of a MoO 3 / Fe 2 (MoO 4 ) 3 catalyst by SEM and TEM shows that the two phases form separate crystals, and HRTEM reveals the presence of an amorphous overlayer on the Fe 2 (MoO 4 ) 3 crystals. EDS line-scan analysis in STEM mode demonstrates that the Mo/Fe ratio in the amorphous layer is *2.

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Solid State Reactions in Fe-Mo Oxide Catalysts for Methanol Oxidation During Aging in Industrial Plants.

Cited by 30 publications

References 4 publications

Heterogeneous Catalyst Deactivation and Regeneration: A Review

Heterogeneous Catalyst Deactivation and Regeneration: A Review

A Combined Multi-Technique In Situ Approach Used to Probe the Stability of Iron Molybdate Catalysts During Redox Cycling

On the Synergy Effect in MoO3–Fe2(MoO4)3 Catalysts for Methanol Oxidation to Formaldehyde

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