J. Phys. Chem. B 1999, 103, 197-202
197
On the Structural, Acidic and Catalytic Properties of Zeolite SUZ-4
Dmitri B. Lukyanov,*,| Vladimir L. Zholobenko,†, John Dwyer, Sami A. I. Barri,§, and
Warren J. Smith∇
UMIST Centre for Microporous Materials and Departments of Chemical Engineering and Chemistry, UMIST,
P.O. Box 88, Manchester M60 1QD, U.K., and British Petroleum Chemicals, Research and Engineering,
Sunbury on Thames, Middlesex TW16 7LL, U.K.
ReceiVed: August 24, 1998; In Final Form: NoVember 2, 1998
Highly crystalline SUZ-4 zeolite was synthesized and its acidic and catalytic properties were investigated
using FTIR spectroscopy and n-hexane conversion. Based on the analysis of the published crystallographic
data, it is concluded that SUZ-4 zeolite has a three-dimensional pore system that includes ten-membered ring
channels parallel to unit cell c-axis which are intersected by two arrays of eight-membered ring channels
running in the plane [001]. Experimental results reported here support this conclusion. About 45% of acid
sites (bridging hydroxyls) are located in the large channels of SUZ-4 zeolite, while the remaining sites occupy
positions in nonplanar double eight-membered rings. The bridging hydroxyls in SUZ-4 zeolite are more
accessible for guest molecules (n-hexane and isobutane) than those in ferrierite. Both zeolites show similar
strength of acid sites and have similar protolytic cracking activity. The hydrogen transfer activity of ferrierite
is observed to be higher than that of the SUZ-4 zeolite. These results indicate that SUZ-4 zeolite has potential
as a catalyst and may display unusual shape-selective properties in comparison with other zeolites.
Introduction
two-, or three-dimensional pore system. In addition, it appears
that no information has yet been published on the acidic and
SUZ-4 is a new synthetic zeolite patented by the British
Petroleum Company.1 XRD studies of this material show2 that
SUZ-4 framework topology is related to that of ferrierite which,
in turn, is structurally related to the mineral wollastonite.2,3 The
structure of ferrierite is well-known,4 and its two-dimensional
pore system consists of ten-membered ring channels parallel to
[001] interconnected with eight-membered ring channels parallel
to [010]. Additionally, small channels formed by six-membered
rings are present. Both the ten- and eight-membered ring
channels in ferrierite are elliptical in shape with dimensions of
4.2 × 5.4 Å and 3.5 × 4.8 Å, respectively.4 The proposed2
SUZ-4 framework consists of five-, six-, eight-, and ten-
membered rings. According to Lawton et al.,2 the pore system
of this zeolite includes straight ten-membered ring channels and
small cages linked through the double six-membered rings. The
minimum and maximum dimensions of the ten-membered rings
are 4.6 and 5.2 Å, respectively, which are very similar to those
in ferrierite.
catalytic properties of SUZ-4 zeolite.
The work described in this paper was undertaken in order to
clarify acidic and catalytic properties of the new SUZ-4 zeolite
in relation to its structure and to indicate the potential of this
zeolite as a catalyst in hydrocarbon reactions. The results of a
detailed FTIR characterization of acid sites in SUZ-4 zeolite in
comparison with ferrierite are discussed in a different paper.6
Experimental Section
Materials. Two zeolites, namely, SUZ-4 and ferrierite, were
used in this study. A template synthesized ferrierite was provided
by BP Chemicals. Zeolite SUZ-4 was synthesized at UMIST
according to the procedure described in the patent literature (ref
1b, example 6).
In a typical preparation, 3.5 g of potassium hydroxide and
2.0 g of sodium aluminate (BDH Grade; 40 wt % Al2O3, 30 wt
% Na2O, and the rest water) were dissolved in 75 g of distilled
water. Tetraethylammonium hydroxide (5.0 g) solution (40 wt
% in water) was then added to the solution followed by the
addition of 20 g of Ludox AS40 colloidal silica (BDH Grade;
40 wt % SiO2 in water). The resultant gel was stirred for 1 h
and then heated in a revolving autoclave at 180 °C for 96 h.
After this period, the product was removed from the autoclave
and the content was filtered. The solid was washed with distilled
water, dried overnight at 120 °C, and then calcined at 550 °C
in air for 12 h. XRD analysis revealed the solid to be highly
crystalline SUZ-4 zeolite (see Results and Discussion section).
The chemical composition of the calcined SUZ-4 zeolite,
expressed as a unit cell, was K4.6Na0.4Al5.0Si31.0O72 (Si:Al )
6.2) which was very similar to that of the calcined ferrierite:
Consequently, on structural consideration, it might be ex-
pected that SUZ-4 zeolite would display catalytic properties
similar to ferrierite which is reported5 to be an excellent catalyst
for isomerization of n-butene into isobutene. However, the data
published in ref 2 do not make immediately clear the nature of
the channel system in SUZ-4. For instance, it is not evident
from the representation given2 whether this zeolite has a one-,
* To whom correspondence should be addressed at the Department of
Chemical Engineering, UMIST, E-mail: MCDSTDBL@fs1.ch.umist.ac.uk,
Fax: (44-161) 200-4399.
† Present address: Dept. of Chemistry, Keele University, Keele, Stafford-
shire ST5 5BG, UK.
§ Present address: Dept. of Chemistry, KFUPM, P.O.Box 122, Dhahran
31261, Saudi Arabia.
K4.3Na0.6Al4.9Si31.1O72 (Si:Al ) 6.3). The NH4-forms of SUZ-4
| Department of Chemical Engineering.
and ferrierite were obtained by contacting the calcined zeolite
(4.0 g) with 1.0 M ammonium nitrate solution (80 mL) at 60
Department of Chemistry.
∇ British Petroleum Chemicals.
10.1021/jp983468l CCC: $18.00 © 1999 American Chemical Society
Published on Web 12/17/1998