(617u) Crystallization of One-Dimensional Zeolites: Elucidating Nonclassical Mechanisms of Growth and the Role of Structure Direction
AIChE Annual Meeting
2016
2016 AIChE Annual Meeting
Catalysis and Reaction Engineering Division
Poster Session: Catalysis and Reaction Engineering (CRE) Division
Wednesday, November 16, 2016 - 6:00pm to 8:00pm
Crystallization of One-dimensional
Zeolites: Elucidating Nonclassical Mechanisms of Growth and the Role of
Structure Direction
Rui Liand Jeffrey D. Rimer
Department of Chemical and Biomolecular Engineering, University
of Houston, 4726 Calhoun Road, Houston,
TX, 77204, jrimer@central.uh.edu
Zeolites possess well-defined
pore systems that give rise to shape selectivity for chemical reactions, thus
providing an essential advantage for their use as catalysts in commercial applications.
The performance of zeolites (i.e., activity and lifetime) is closely aligned with
the selection of internal pore geometry and dimensions, which can influence diffusion,
adsorption, and reaction pathways. Design of optimized zeolite catalysts a
priori is challenging owing to the complexity of synthesis that is derived
in part from the unknown role of amorphous precursors, organic
structure-directing agents (OSDAs), and the pathways of crystallization. Previous
studies have demonstrated that one-dimensional (1D) 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 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 and the
resulting physicochemical properties of the materials.5 One interesting phenomenon regarding nonclassical
crystallization of zeolites is the existence of WLPs, which are common to many
different framework types.1 Here, we will discuss how two widely-used 1D zeolites,6,7 LTL and
TON, crystallize from similar growth solutions that comprised of amorphous WLP precursors.
Despite the similarity of their precursor solutions, we will show how these two
structures involve distinct growth pathways that can be manipulated by the
judicious selection of synthesis parameters (e.g., temperature, alkaline
content, OSDA, etc.). We will present our work on the design of OSDAs for
zeolite TON crystallization. Moreover, we will discuss mechanisms of LTL and
TON crystallization and demonstrate how facile, economically-viable methods can
be used to produce zeolites with improved properties for a wide range of
industrial applications.
References
(1) Kumar, M.; Li, R.et al., Chemistry
of Materials, 2016, 28, 1714-1727.
(2) Politi, Y.; Arad, T.et al., Science,
2004, 306, 1161-1164.
(3) Penn, R. L.; Banfield, J. F.
Science, 1998, 281, 969-971.
(4) Lupulescu, A. I.; Rimer, J.
D. Science, 2014, 344, 729-732.
(5) De Yoreo, J. J.; Gilbert, P.
U. P. A.et al., Science, 2015, 349.
(6) Nacamuli, G. J.,US6143166 A,
2000.