Dynamic evolution of catalytic active sites within zeolite catalysis

Abstract

Zeolites with Brønsted acid and cation-exchanged sites are extremely effective single-site heterogeneous catalysts and are routinely employed in various industrially important processes such as MTH and SCR. However it is now generally accepted that these sites of catalytic activity are not necessarily statically fixed to the zeolite architecture, but are more dynamic in nature and can mobilize within the pores & cages of the respective zeolites at operando conditions. Herein, an overview of the state of understanding of the mobility of (i) protons in pristine BAS-zeolites, (ii) aluminum ions in the process of framework decomposition, and (iii) metal sites in TM-exchanged zeolites is presented. In turn, the state of play of computationally probing active-site mobility will then be discussed, whereby enhanced sampling techniques is highlighted in particular as an emerging and promising method for probing active site mobility. Finally, a selection of case studies are highlighted, in which enhanced sampling techniques were employed to elucidate the mobility of catalytic sites in zeolites.