(627b) Crystallization of One-Dimensional Zeolites: Elucidating Mechanisms of Growth and the Role of Structure Direction

            Crystallization
of One-dimensional Zeolites: Elucidating 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.

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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.

(7) Perego, C.;
Carati, A. Zeolites and zeolite-like materials in industrial catalysis;
In Zeolites: From Model Materials to Industrial Catalysts; Čejka, J.,
Per¨¦z-Pariente, J., Eds.; Transworld Research Network: 2008, p 357-389.