(481g) Kinetic Description of Site Ensembles on Catalytic Surfaces
AIChE Annual Meeting
2021
2021 Annual Meeting
Catalysis and Reaction Engineering Division
Fundamentals of Catalysis and Surface Science I: Single Atoms & Alloys
Wednesday, November 10, 2021 - 1:42pm to 2:00pm
The Hinshelwood approximation, however, crucially neglects the propensity of multi-site elementary steps (e.g. two-site A*âB* â *â* + AB) to engender (i) aggregation (μij >> 1) of slowly-consumed ensembles and (ii) partitioning (μij << 1) of rapidly-consumed ensembles. Accurate description of partitioning and clustering phenomena requires derivation of higher-order, ensemble-specific rate terms which (i) quantify the unique kinetic influence each ensemble exerts on each elementary step and (ii) explicate the effect of partitioning/clustering to engender profound changes in rates, selectivities, and identities of rate-determining steps unidentifiable in the Langmuir-Hinshelwood formalism â as we demonstrate in the context of (i) the A + ½B2 â AB reaction and (ii) the industrially-relevant ammonia synthesis reaction for which we predict kinetically-relevant clustering of N*âN* pairs (μN*âN* ~ 105) resultant from the well-known difficulty of activating Nâ¡N triple bonds in rate-determining N2adsorption.