*3.5. Propylene Partial Oxidation Reaction Kinetics Validation*

Reaction kinetics for the partial oxidation of propylene over a bismuth molybdate catalyst were extracted from Redlingshofer et al. [6]. Acrolein oxidation to formaldehyde was considered negligible due to the low range of selectivities i.e. 0.73–0.78% [16]. The redox reaction mechanism for acrolein formation proceeds via two steps: reduction and oxidation reactions. Models such as the Mars–van-Krevelen and Langmuir–Hinshelwood rate expressions account for the crossover from oxidation to reduction reactions in a single expression. However, the power law reduction reaction was favored since the α-bismuth molybdate catalyst selected, which has a high selectivity to acrolein of 88%–95%, operates optimally in a temperature range of 623–723 K [6]. The kinetics were determined by statistical parameter estimation using experimental data from isothermal investigations and were valid over a temperature range of 633–703 K. The kinetic parameters proved to be statistically significant as represented by their standard deviations, thereby validating the reaction kinetics presented. Further kinetic validations were conducted on Aspen Plus® (AspenTech, Bedford, MA, USA) to determine the feasibility of scaling up the lab-scale kinetics. The yield, conversion and selectivity profiles extracted from Redlingshofer et al. [16] correlated with the Aspen Plus® (AspenTech, Bedford, MA, USA) simulation results illustrated in Table 1, thereby validating the use of these kinetics in the design of an industrial-sized reactor as well as reinforcing the ease of scale-up with multitubular reactors.


