Kinetics of oxidation of acrolein on a vanadium-molybdenum oxide catalyst

Mechanistic Study on the Selective Oxidation of Acrolein to Acrylic Acid: Identification of the Rate‐Limiting Step via Perdeuterated Acrolein

“…In this connection, the primary KIE in the α‐H/D‐abstraction results in the lower activity of ACR‐D 4 compared to that of ACR (Figure ). At this point, the experimental results of this work are not in line with those of Tichy et al., who observed no activity change due to deuteration . Anyway, we have to keep in mind that the experimental conditions and especially the used catalyst differ in these two studies (Table ).…”

“…Moreover, if the desorption of the surface acrylate is relatively slow compared to the formation of surface acrylate by the ACR oxidation, the thermodynamic adsorption equilibrium of AA (Scheme ) is not adjusted. In this case, the desorption of the surface acrylate can be rate‐determining and a secondary KIE is assigned to this desorption since in the nucleophile substitution of the surface acrylate by gaseous water no cleavage of a C−H bond occurs . However, in this case, a less pronounced effect on the activity would be expected…”

“…A comparison between the feed composition 4 vol.% CH 2 =CHCHO, 7 vol.% O 2 , 17 vol.% H 2 O with 4 vol.% CH 2 =CHCDO, 7 vol.% O 2 , 17 vol.% D 2 O (balance: N 2 ; catalyst: Mo 9.4 V 2 O x coated on aerosol) shows no difference in the reaction rates or no KIE, respectively. This leads the authors to the conclusion that the cleavage of the C−H or C−D bond is not involved in the RDS and the re‐oxidation of the catalyst by molecular O 2 was identified as rate‐determining . Nevertheless, other works point to the desorption of the acrylate as the RDS .…”

“…This leads the authors to the conclusion that the cleavage of the CÀ H or CÀ D bond is not involved in the RDS and the reoxidation of the catalyst by molecular O 2 was identified as ratedetermining. [50] Nevertheless, other works point to the desorption of the acrylate as the RDS. [16,23] Therefore, no consensus conclusion has been reached on the RDS of the acrolein oxidation reaction.…”

Activity Hysteresis during Cyclic Temperature‐Programmed Reactions in the Partial Oxidation of Acrolein to Acrylic Acid

“…The role of bulk oxygen in the catalytic mechanism has already been discussed in previous works [14,26,28,30,48,50,[52][53][54]. This participation is considered by a reversible reaction between bulk and surface and, thus, is directly related to the concentration of reduced bulk and surface sites or to the bulk and surface degree of reduction, respectively.…”