The Catalyst Review - April 2015 - 16

EXPERIMENTAl
as adsorbents for gas separations. Herein the authors report a new system, HOF-3, constructed from a new triangular organic linker
containing three hydrogen-bonding motifs of 2,4-diaminotriazinyl (DAT) as shown in Figure 1a. It can be readily synthesized in 84%
yield by the reaction of the corresponding nitrile with dicyandiamide.
Unlike previously reported HOFs whose porous structures were built from discrete building units, HOF-3 appears to be the first
example of HOFs constructed from one-dimensional rod-packing units exhibiting the srs topology (parallel threefold helical rods
linked by additional 3-C nodes into a 3-D net). Of greater significance is the fact that its C2H2/CO2 separation selectivities are
systematically higher than those found in the well-established MOF materials as seen in Figure 2. The C2H2 uptakes at ambient
temperature and pressure are systematically about twice as high as for CO2 under the same conditions. The preferential adsorption
of HOF-3 for acetylene over carbon dioxide is attributed to its unique pockets and pore surfaces. Source: Li P, He Y, Zhao Y, et al.
(2015). Angew. Chem. Int. Ed. 54: 574-577.
figure 1. X-ray crystal structure of HOf-3 featuring a) the
basic organic building block in which the centers of central
benzene ring (green balls) and centers of three 1,3,5-triazine
rings (magenta balls) act as nodes; b) The H-bonded link
between DAT groups showing that each is joined to two other
DAT groups; c) The net of 3-c branch points as it occurs in the
crystal structure; and d) three-dimensional packing showing
the 1D hexagonal channels of about 7.0 in diameter
along the c axis (C gray, H white, N pink).

figure 2. a) Sorption isotherms of C2H2 and CO2 of HOf-3a at 296 K; b)
comparison of the heats of adsorption of C2H2 in HOf-3a and various MOfs; c)
IAST adsorption selectivities of C2H2/CO2 in equimolar mixture in HOf-3a and
various MOfs at 296 K; and d) experimental column breakthrough curve for
an equimolar C2H2/CO2 mixture (296 K, 1 bar) in an adsorber bed packed with
HOf-3a.

Design of a Hierarchical Meso/Macroporous Zeolite-Supported Cobalt
Catalyst for the Enhanced Direct Synthesis of Isoparaffins from
Syngas...
Currently, many groups across the globe are focused on achieving the direct synthesis of middle isoparaffins (the main components
of gasoline) from syngas via the use of the Fischer-Tropsch synthesis (FTS) combined with hydrocracking/isomerization catalysts
(acidic zeolites). In order to overcome random selectivity resulting in low yields of the desired product, zeolites with microporous and
meso/macroporous structures (hierarchical pores) appear to hold promise because they facilitate enhanced diffusion of reactants
and products.
Previously, the authors had developed series of nanoparticle-modified SiO2 supports, such as SiO2-SiO2, Al2O3-SiO2, and ZrO2-SiO2
systems which have large pore sizes (meso/macropores) and high BET surface areas, resulting in improved dispersion of active sites
and acceleration the diffusion rate of reactants/products. Herein, they describe the development of hierarchical meso/macroporous
13-zeolite using a combination of a steam-assisted crystallization (SAC) method and an alumina-modified SiO2 system (AS). The asprepared zeolite was then impregnated with Co to prepare the hierarchical porous zeolite catalyst Co/ASB illustrated in Scheme 1.
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The Catalyst Review

April 2015

The Catalyst Review - April 2015

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