(621dr) Reducing Internal Mass-Transport Limitations of One-Dimensional Nanoporous Zeolites

Reducing Internal Mass-Transport
Limitations of One-dimensional Nanoporous Zeolites

Rui Liand Jeffrey D. Rimer

Department of Chemical and Biomolecular Engineering, University
of Houston, 4800 Calhoun Road, Houston,
TX, 77204, jrimer@central.uh.edu

Zeolites possess well-defined pores that provide
desired shape selectivity for chemical reactions, which is one essential
advantage of their use as catalysts in commercial applications. The ability to
tune the geometry and dimensions of internal pores can influence diffusion,
adsorption, and catalytic performance. Here, we will discuss methods of
tailoring the synthesis of one-dimensional (1D) zeolites, which impose
significant mass transfer limitations for internal diffusion. Several 1D
zeolites are promising catalysts for reactions such as methanol-to-hydrocarbons,^1,2 isomerization, and cracking; however, large internal diffusion
pathlengths attributed to poorly engineered crystal size and habit often lead
to rapid coking, which imposes restraints for commercial applications. We will present
methods to rationally design 1D zeolites with tailored size and morphology. To
this end, we examine pathways of crystal nucleation and growth, which
predominantly involve non-classical mechanisms associated with precursors
(e.g., primary particles and/or bulk amorphous phases). These pathways can be altered
through the judicious selection of synthesis parameters. Moreover, we have
shown that zeolite growth modifiers (ZGMs)³ are an effective method to selectively alter the properties
of zeolite crystals. The advantages of ZGMs are their versatility and low cost,
which make them an attractive method of catalyst preparation. Here, we will also
discuss how a synergistic combination of synthesis parameters and ZGMs can be
used to improve the mass transport properties of 1D zeolites for energy
conversion and the production of chemicals.⁴

(1) Wang,
Q.; Cui, Z.-M.; Cao, C.-Y.; Song, W.-G. Journal of Physical Chemistry C 2011,
115, 24987.

(2) Teketel,
S.; Olsbye, U.; Lillerud, K.-P.; Beato, P.; Svelle, S. Microporous and Mesoporous
Materials 2010, 136, 33.

(3) Lupulescu,
A. I.; Kumar, M.; Rimer, J. D. Journal of the American Chemical Society 2013,
135, 6608.

(4) Teketel,
S.; Skistad, W.; Benard, S.; Olsbye, U.; Lillerud, K. P.; Beato, P.; Svelle, S.
ACS Catalysis 2012, 2, 26.