(337c) Structure-Property Relationships for Unidimensional, Large and Extra-Large Pore Zeolites Using Alkane Hydrocracking and Hydroisomerization As Probe Reactions

Structure-Property
Relationships for Unidimensional, Large and Extra-Large Pore Zeolites Using
Alkane Hydrocracking and Hydroisomerization as Probe Reactions

Viktor
J. Cybulskis¹, Stacey I. Zones², Tracy M.
Davis², Cong-Yan Chen², Michael W. Deem³ and
Mark E. Davis¹

¹Chemical
Engineering, California Institute of Technology, Pasadena, CA 91125, USA

²Chevron
Energy Technology Company, Richmond, CA 94802, USA

³Bioengineering,
Rice University, Houston, TX 77005 USA

High-silica
zeolites (Si/Al > 30) are versatile catalytic materials in petroleum
refining processes due to their thermal stability, shape selectivity, and
chemical functionality. However, of the 232 known [1] and more than 330,000
predicted [2] zeolite structures, the global refining market is dominated by
five main frameworks: FAU, MOR, MFI, *BEA and FER [3]. While these zeolites
often deliver satisfactory commercial performance, the development of materials
with improved function or entirely new structures for future applications requires
a deeper understanding of how specific properties, such as composition,
framework topology, and acid site function, can influence the product
distribution for a given reaction.

For
the present study, large and extra-large pore zeolites were prepared from the corresponding
structure-directing agents (SDAs) shown in Table 1 to investigate the effects
of the organo-cation guest molecules and synthesis
conditions on zeolite crystallinity, microporosity, and heteroatom incorporation.
Unidimensional (1D) structures were chosen so that the zeolite pore opening could
be used to adequately describe the confining size. Hydrocracking and
hydroisomerization of n-hexane (nC₆) and n-decane (nC₁₀)
were used as probe reactions on these Pt-exchanged, 12- and 14-membered ring
(MR) zeolites to examine the effect of pore structure on shape selectivity by
comparing the distributions and yields of branched C₆ and C₁₀
isomers. Elucidation of these structure-property relations support de novo computational design efforts to predict
chemically-synthesizable SDAs and produce a novel, 1D zeolite framework with tailored
catalytic properties.

Table 1. 1D,
12- and 14-MR zeolites synthesized from the corresponding SDAs

References:

[1]       C. Baerlocher and L.B. McCusker, Database
of Zeolite Structures, http://www.iza-structure.org/databases/. Accessed March 27,
2017 (2017).

[2]       R. Pophale, P.A. Cheeseman and M.W. Deem, Phys. Chem. Chem. Phys. 13, 12407 (2011).

[3]       W. Vermeiren and J.P. Gilson, Top. Catal. 52, 1131 (2009).