CLEERS Teleconference: Prof. Raj Gounder, Purdue University

Title: Influence of zeolite framework on Cu ion mobility and the kinetics of NOx SCR with ammonia.

Prof. Raj Gounder
Purdue University

Abstract:

Isolated copper ions exchanged onto zeolites catalyze the selective reduction (SCR) of nitrogen oxides (NOx) with ammonia in the presence of excess dioxygen. At low temperatures (<523 K), copper ions are fully coordinated and solvated by ammonia, and most abundant surface intermediates are cationic copper-amine complexes bonded ionically to anionic aluminum centers in zeolite frameworks. Such ionic tethering provides a mechanism for the dynamic and reversible formation of binuclear copper complexes to activate dioxygen during oxidation half-cycles. We will discuss our recent work to study this phenomenon in different zeolite frameworks, in order to understand the influence of pore connectivity on Cu ion mobility and NOx SCR kinetics. We use a combined experimental and computational approach focused on in operando interrogation of the catalyst under widely varying operating conditions, including those well beyond those typical of commercial operation. The effects of Cu ion mobility are preeminent on low temperature NOx SCR catalytic reactivity, and lead to differences in kinetic behavior among Cu-zeolites of different topology.