(179e) Rate Analysis of a Curious Case of (Side) Product Inhibition
AIChE Annual Meeting
2022
2022 Annual Meeting
Catalysis and Reaction Engineering Division
Fundamentals of Catalysis and Surface Science III: Kinetics of surface reactions
Monday, November 14, 2022 - 4:50pm to 5:10pm
Product co-feed experiments generating differential beds when used to develop Mars-van Krevelen based kinetic models for ethane partial and total oxidation are insufficient to explain integral data at low residence times that probe lower ranges of hydroxyl/carbonate coverages than those prevalent in differential co-feed experiments (Figure 1). Measured (average) rates deviate from true ones even at conversions as low as 0.1%, with apparent rates being more sensitive to residence time at low, rather than high conversions. Estimation of rate parameters and mechanisms over non-stoichiometric oxygen-containing nickel oxide requires consideration of inhibitory effects of both water and CO2, unlike those over niobium-doped nickel oxides that exclusively carry lattice oxygens recalcitrant to carbonate formation, and hence strong product inhibition. A mathematical analysis of product inhibitory effects on apparent reaction orders and activation energies is also presented. The study captures commonly encountered pitfalls when using rate parameters from low conversion kinetic data in inferring mechanistic features for reaction systems of interest in heterogeneous catalysis applications.