(582bk) Zeolite Catalyst Design and Optimization: Impact of Synthesis Parameters on Crystal Properties
James Sutjianto, Rui Li, and Jeffrey D. Rimer*
Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX, 77204
Zeolites possess well-defined networks of pores that give rise to shape selectivity as catalysts for chemical reactions and provide an essential advantage for their use as sieves and sorbents in commercial applications. The performance of zeolite catalysts (i.e., their activity and lifetime) is closely aligned with their physicochemical properties, which include (but are not limited to) shape, size, and composition. The design of zeolite catalysts a priori is challenging owing to the complexity of their synthesis that is derived from the multiple growth units and pathways of crystallization. Previous studies have demonstrated that zeolites, such as zeolite L (LTL type), grow via nonclassical mechanisms involving the assembly of so-called worm-like particles (WLPs), which are bulk amorphous precursors that serve as putative growth units during crystallization.1 Evidence of crystallization by particle attachment (or CPA) is mounting for a range of materials that include biominerals2, metal oxides,3 and zeolites.4 In this relatively new area of research, there are many knowledge gaps between the design of synthesis conditions, the resultant precursors, and the final physicochemical properties of the zeolite products. Here, we will discuss how the judicious selection of synthesis parameters, such as reagent sources, alkalinity, and supersaturation, alter the morphology and structure of crystalline products. Our findings reveal the involvement of diverse precursors and multifaceted pathways of crystal growth. The results presented here provide a generalized platform for rational design towards the development of optimal zeolite catalysts through facile, commercially-viable synthesis approaches that bridge fundamental research with practical applications.
(1) Kumar, M.; Li, R.; Rimer, J. D.; Chem. Mater. 28 (2016) 1714-1727
(2) Politi, Y.; Arad, T.; Klein, E.; Weiner, S.; Addadi, L.; Science. 306 (2004) 1161-1164
(3) Penn, R. L.; Banfield, J. F.; Science. 281 (1998) 969-971
(4) Lupulescu, A. I.; Rimer, J. D.; Science. 344 (2014) 729-732