New insights in the understanding of the behaviour and performances of bismuth molybdate catalysts in the oxygen-assisted dehydration of 2-butanol

Synthesis and Monitoring of α‐Bi2Mo3O12 Catalyst Formation using Thermo‐Raman Spectroscopy

“…2%) of other phases, have been reported. [27] Thus, monitoring of the preparation process is important to obtain selectively a single phase. This should enable a clarification of the roles and stabilities of individual bismuth molybdate phases during selective oxidations.…”

Synergy effects in mixed Bi2O3, MoO3 and V2O5 catalysts for selective oxidation of propylene

“…Thus, the minor synergy effect in the mechanical mixtures of Bi 2 O 3 and MoO 3 is probably due to the intimate presence of both Bi and Mo components although there was not yet any chemical bonding between them. In contrast, the synergy effect in the mixtures of bismuth molybdates, as reported in the literature [5,8,[14][15][16], was due to two active bismuth molybdate phases (gamma and beta and/or alpha phases) being present exhibiting a high ability to abstract the alpha hydrogen by the beta or alpha phase and a high ability to replenish lattice oxygen by the gamma phase, which has a higher electrical conductivity [16].…”

“…The increase in catalytic activities for the selective oxidation of propylene to acrolein has been observed in mixtures of bismuth molybdates [8,14,15] and in the bismuth vanado molybdate which is a compound with the same structure as bismuth vanadate but with Mo cations replaced by V cations forming cation vacancies in the compound [4,19]. It can be remarked that the original components of these mixtures The origin of these increases in the catalytic activity must be different.…”

“…The catalytic activities of the three main phases of bismuth molybdate (a, b, c) decrease in the following generally accepted order: Bi 2 Mo 2 O 9 (b) C Bi 2 Mo 3 O 12 (a) [ Bi 2 MoO 6 (c). Although this order has been reported by many authors [6][7][8][9][10], there are some papers in which the opposite trend is stated: c C b [ a [11] or b [ (a = c) [12] or a [ b [ c [13].…”

“…The synergy effects between the three phases of bismuth molybdate have been described in the literature but are still under debate [8,14,15]. This synergy effect is expressed as the enhancement of the catalytic activity when two or three phases are present in the catalyst.…”