Synthesis, characterization and insights into stable and well organized hexagonal mesoporous zinc-doped alumina as promising metathesis catalysts carrier

Article abstract of DOI:10.1039/c4dt03630a

A series of highly ordered hexagonal mesoporous alumina and zinc-modified mesoporous alumina samples are synthesized via a sol-gel method through an evaporation-induced self-assembly process using Pluronic F127 as nonionic templating agent and several aluminum precursors. The process was mediated using several carboxylic acids along with hydrochloric acid in ethanol. Successful impregnation of ZnCl₂ was achieved while maintaining the ordered structure. The surface and textural properties of the materials were investigated. N₂-physisorption analysis revealed a BET surface area of 394 m² g^-1 and a pore volume around 0.55 cm³ g^-1. Moreover, small-angle XRD diffraction patterns highlighted the well-organized hexagonal structure even upon the incorporation of zinc chloride. The organized-structure arrangement was further confirmed by transmission electron microscopy (TEM) analysis. The Zn/Al composition of the final materials was confirmed by EDX and XPS analysis, and the zinc amount incorporated was analyzed by ICP. Furthermore, the surface modification with zinc chloride impregnation was analyzed by XPS, ¹H and ²⁷Al MAS-NMR and FTIR spectroscopic techniques. In addition, the effects of synthesis conditions and the mechanism of the mesostructure formation were explored. The catalytic activity of several methyltrioxorhenium (MTO)-based catalysts supported on these hexagonal mesoporous alumina materials was tested for methyl oleate self-metathesis. The results showed improved kinetics using hexagonal alumina in comparison to those using wormhole-like alumina counterparts. This behavior could be attributed to better mass transfer features of hexagonal mesoporous alumina. The prepared materials with desirable pore size and structure are suitable candidates as catalyst supports for metathesis of bulky functionalized olefins and other catalytic transformations due to their enhanced Lewis acidity and more uniform pore networks favoring enhanced and selective mass transfer phenomena.

Full text of DOI:10.1039/c4dt03630a

View Article Online
View Journal
Dalton
Transactions
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: A. Abidli, S.
Hamoudi and K. Belkacemi, Dalton Trans., 2015, DOI: 10.1039/C4DT03630A.
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
Accepted Manuscripts are published online shortly after
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. We will replace this Accepted Manuscript with the edited
and formatted Advance Article as soon as it is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the Ethical guidelines still
apply. In no event shall the Royal Society of Chemistry be held
responsible for any errors or omissions in this Accepted Manuscript
or any consequences arising from the use of any information it
contains.
www.rsc.org/dalton

Page 1 of 16
Dalton Transactions
Dynamic Article Links ►
Journal Name
View Article Online
DOI: 10.1039/C4DT03630A
Cite this: DOI: 10.1039/c0xx00000x
www.rsc.org/xxxxxx
ARTICLE TYPE
Synthesis, characterization and insights into stable and well organized
hexagonal mesoporous zinc-doped alumina as promising metathesis
catalysts carrier
a,b
a,b
a,b
Abdelnasser Abidli, Safia Hamoudi, and Khaled Belkacemi*
5
Received (in XXX, XXX) Xth XXXXXXXXX 20XX, Accepted Xth XXXXXXXXX 20XX
DOI: 10.1039/b000000x
A series of highly ordered hexagonal mesoporous alumina and zincꢀmodified mesoporous alumina are synthesized via a solꢀgel method
through an evaporationꢀinduced selfꢀassembly process using Pluronic F127 as nonionic templating agent and several aluminum
precursors. The process was mediated using several carboxylic acids along with hydrochloric acid in ethanol. Successful impregnation of
1
1
2
0
5
0
ZnCl was achieved while maintaining the ordered structure. The surface and textural properties of the materials have been investigated.
2
2
3
N ꢀphysisorption analysis revealed a BET surface area of 394 m /g and a pore volume around 0.55 cm /g. Moreover, smallꢀangle XRD
2
diffraction patterns highlighted the wellꢀorganized hexagonal structure even upon the incorporation of zinc chloride. The organizedꢀ
structure arrangement was further confirmed by transmission electron microscopy (TEM) analysis. The Zn/Al composition of the final
materials was confirmed by EDX and XPS analysis, and the zinc amount incorporated was analyzed by ICP. Furthermore, the surface
1
27
modification with zinc chloride impregnation was analyzed by XPS, Hꢀ and Al MASꢀNMR and FTIR spectroscopy techniques. In
addition, the effects of synthetic conditions and the mechanism of the mesostructure formation was explored. The catalytic activity of
several methyltrioxorhenium (MTO)ꢀbased catalysts supported on these hexagonal mesoporous alumina materials was tested for methyl
oleate selfꢀmetathesis. The results showed improved kinetics using hexagonal alumina in comparison to those using wormholeꢀlike
alumina counterparts. This behavior could be attributed to better mass transfer features of hexagonal mesoporous alumina. The prepared
materials with desirable pore size and structure are suitable candidates as catalyst supports for metathesis of bulky functionalized olefins
and other catalytic transformations due to their enhanced Lewis acidity and more uniform pore networks favoring enhanced and selective
mass transfer phenomena.
Introduction
research topic. Indeed, various organized mesoporous siliceous
and nonꢀsiliceous materials were targeted, among them; cubic
MCMꢀ41and MCMꢀ48, SBAꢀ15 and KITꢀ6, in addition to
Ordered materials attracted an enormous attention of many
research groups focusing on the enhancement of several
heterogeneous catalysts activities and selectivity. This was carried
out by the improvement of the surface organization and porous
network uniformity of these materials. These textural aspects
offered advantageous alternatives towards desired shapeꢀselective
catalysis which are governed by mass transfer phenomena. These
phenomena can be tuned by controlling the porosity and the
12
11
13
5
5
6
0
5
0
2
3
3
5
14, 15
16, 17
ordered mesoporous carbon (CMKꢀ1 and CMKꢀ3),
nobia,
17
17
18
titania, zirconia, tantalum oxide and other several nonꢀ
siliceous interesting ordered mesoporous metal oxides and
19
1
ꢀ7
20
hybrid materials.
Ordered mesoporous alumina (OMA) has been one of the
0
21, 22
challenging nonꢀsiliceous organized materials to synthesize.
23
Niesz et al. reported a Pluronic P123ꢀtemplated solꢀgel synthesis
8
surface homogeneity. Moreover, this key point is more critical
of OMA where the synthesis was performed at 40 °C affording
when selectivity is an issue, dealing with bulky molecules that
undergo both intraꢀ and interꢀmolecular reactions. Despite the
increasing progress that has been achieved since the first synthesis
of hexagonally ordered mesoporous silica,
ordered materials for catalytic applications still remains as a hot
24
high BET surface and narrow pore size distribution. Liu et al.
reported a nanocasting synthesis templated by mesoporous CMKꢀ
5
3
carbon. A Pluronic F127ꢀtemplated synthesis of OMA was also
9
ꢀ11
the synthesis of
25
26
reported by Yuan et al. Recently, Wu et al. reported an
efficient OMA synthesis using inexpensive aluminum nitrate at 30
°
C. OMA with relatively large mesopores have been obtained
a
Department of Soil Sciences and Agri-Food Engineering, Laval 65 using a swelling agent in a Pluronic P123ꢀtemplated synthesis.
4
4
0
5
University. G1V 0A6, Quebec city, Quebec, Canada. Fax: (418) 656 3723;
Along with high surface area and pore size and uniform
mesoporous network, great efforts have been also focused on
achieving thermally and hydrothermally stable crystalline
framework walls of OMA.
Tel: (418) 656 2131 ext: 6511; E-mail: khaled.belkacemi@fsaa.ulaval.ca
b
Centre in Green Chemistry and Catalysis (CGCC). H3A 0B8, Montreal,
Quebec, Canada.
†
4, 24, 25
Moreover this feature can help
Electronic Supplementary Information (ESI) available:
See DOI: 10.1039/b000000x/
70 the material to maintain large surface area even after thermal
treatment at high temperatures.
27
This journal is © The Royal Society of Chemistry [year]
[journal], [year], [vol], 00–00 | 1

Dalton Transactions
Page 2 of 16
View Article Online
DOI: 10.1039/C4DT03630A
In order to establish a versatile and costꢀeffective preparation of
OMA materials, many approaches have been investigated. These 60 compounds of nonꢀtransition metals like Al and Sn.
catalysts which are generally Lewis acids or organometallic
50
studies revealed the importance of many keyꢀcontrol factors in
order to overcome limitations over ordered mesoporous network
formation. Therefore, the effect of inorganic precursorsꢀtemplate
Methyl oletate was used as a model molecule for the studies on
metathesis of functionalized bulky olefins contained in vegetable.
The most widely used heterogeneous catalysts for methyl oleate
5
0
5
0
5
0
5
0
5
0
5
8
metathesis were Re
2
O
7
supported on alumina and silicaꢀalumina
ratio was investigated. Furthermore, many process parameters
50, 51
65
materials.
However these catalysts require the use of toxic tinꢀ
were deeply investigated among them, the complexation effect of
anions and hydroꢀcarboxylic acid and organicꢀinorganic interface
based promoters and additives such as Bu Sn to increase the
4
catalyst reactivity. The presence of tin also hinders the catalyst
regeneration due to the deposed SnO2 species on the catalyst
2
5, 27ꢀ30
protectors and templateꢀassistants during aging process,
31
32
1
1
2
2
3
3
4
4
5
5
synthetic routes, swelling agents and coꢀsolvents, saltꢀlike
surface, formed during each recycling process which reacts with
3
3
52
effect of water and acid concentration, the pH of the synthesis 70 the active Re oxide.
2
5, 34
medium and nature of pH adjustor,
temperature.
as well as the calcination
Owing to the above limitations of Re O ꢀbased heterogeneous
2 7
2
5
catalysts, the need for alternative approaches without using toxic
molecules arises. Methyltrioxorhenium (MTO) was found to be an
active organorhenium complex for metathesis catalysis without
The particular acidic properties of the alumina surface attributed
to Lewisꢀacid aluminum species and Brønstedꢀacid hydroxyl
53, 54
groups, promoted significantly the incorporation of several metals 75 the use of toxic promoter.
We have demonstrated recently that
and other metal oxides on alumina. Frequently, OMA
modification and synthesis under high thermal conditions led to
partial or complete loss of the mesoporous hexagonal
zinc chlorideꢀmodified wormholeꢀlike mesoporous alumina
exhibited higher metathesis activity comparing to alumina
55ꢀ57
supports.
structurally organized alumina would be more suitable, expecting
OMA and preserving the wellꢀordered 2Dꢀhexagonal 80 to improve the catalyst performance for the functionalized olefin
Furthermore, we hypothesized that
a
well
3
5
arrangement. Therefore, doping metals and metal oxides on
mesostructure is a challenging procedure. In this perspective,
various elements were supported on OMA and simultaneously
maintaining the organized structure. For instance, Ni, Mg, Fe, Cr,
metathesis reaction.
In the present work, we report the synthesis of wellꢀorganized
hexagonal ZnCl ꢀmodified alumina. The effects of aluminum
2
3
5,
Cu, Ce, La, Y, Ca and Sn were successfully supported on OMA.
precursor and interfacial protectors (CA: carboxylic acids) on
85 mesophase formation were investigated using simple carboxylic
acids to prepare a series of ordered modifiedꢀalumina. A
comprehensive mechanism of mesopores formation using
carboxylic acids is proposed. The catalytic activity for methyl
oleate selfꢀmetathesis using methyltrioxorhenium (MTO)
3
6
37
38, 39
Siꢀ, Ceꢀ, and Zrꢀdoped OMA, Ce–ZrꢀCoꢀdoped OMA,
40
41
Cu/CeꢀOMA, Laꢀdoped OMA and noble metalsꢀdoped OMA
Pt, Ag and Pd) were also prepared. Similarly, OMAꢀsupported
metal oxides such as; MgO, CaO, TiO , and Cr O and ordered
titaniaꢀalumina mixed oxides were also obtained. In addition, to
42
(
3
5
2
2
3
4
3
prevent OMA collapse, the metalꢀmodified OMA were obtained 90 supported on these wellꢀordered Znꢀmodified Al O was
2
3
with uniform metal dispersion. These materials presented high
catalytic activities for various reactions including carbon dioxide
investigated for the first time on this material and comparison
with wormholeꢀlike alumina is also discussed.
4
4
45
42
reforming of methane, hydrogen production, CO oxidation,
4
6
47
thiophene hydrodesulfurization and methanol dehydration.
Experimental section
Catalytic metathesis reaction could be one of these applications
that can benefit from the ordered mesostructure network of
alumina and modifiedꢀalumina, especially when transꢀ or cisꢀ 95 Pluronic F127 (EO1 PO EO106, MW = 12 600), aluminum
Chemicals and reagents
06
i
70
selectivity is critical and highly desired.
isopropoxide Al(OPr )3 (≥98.0%), aluminumꢀtriꢀsecꢀbutoxide
s
Actually, metathesis reaction is an efficient transformation
offering direct access to industrially important products from
oleochemicals in one reaction step. Metathesis of fats and oils is a
Al(OBu )3 (97.0%), citric acid (≥99.5%), Lꢀ(+)ꢀtartaric acid
(≥99.5 %), fumaric acid (≥99.5 %), oxalic acid (˃99.0%), maleic
acid (≥99.0%), acetic acid (≥99.7%) and zinc chloride (ZnCl2,
clean catalytic and atom efficient reaction with no byꢀproduct 100 99.9%) were purchased from SigmaꢀAldrich Canada (Oakville,
48
t
formation.
It is
a
transalkylidenation reaction involving
ON, Canada). Aluminum triꢀtertꢀbutoxide Al(OBu ) (97.0%) was
3
substituents rearrangement of molecules containing C=C bonds
resulting in exchange of alkylidene fragments.
A number of catalysts have been developed for metathesis of
purchased from VWR International (Mississauga, ON, Canada).
Aluminum nitrate nonahydrate Al(NO ) •9H O (99.9%),
3
3
2
hydrochloric acid (HCl, 36.5ꢀ38 wt%) and malonic acid (≥99.0%)
functional olefins. The most active homogeneous catalysts 105 were purchased from Acros Organics (Morris Plains, NJ, USA).
developed are transition metalsꢀbased alkylidene complexes.
Grubbs, HoveydaꢀGrubbs, Schrock catalysts are the most
Cyclohexane (99.9%), hexane (99.0%), and ethanol (99.9%) were
purchased from Fisher Scientific (Ottawa, Ontario, Canada). All
reagents were used as received without further purification. All
gases used were provided by Praxair at a purity of at least
49
successful among them and they are commercially available.
These homogeneous catalysts are active and compatible with a
wide range of functional groups. However, they are expensive and 110 99.995%
often nonꢀreusable. Typical heterogeneous catalysts for metathesis
are based on transition metal complexes in presence of coꢀ
catalysts or promoters. Traditional catalytic systems consist of
metal chlorides, oxides and oxychlorides, often based on Mo, W,
and Re and less commonly based on Os, Ir and Ti with coꢀ
2
| Journal Name, [year], [vol], 00–00
This journal is © The Royal Society of Chemistry [year]

Page 3 of 16
Dalton Transactions
View Article Online
DOI: 10.1039/C4DT03630A
Alumina and modified-alumina synthesis
Synthesis of well-ordered hexagonal mesoporous alumina
60 using Xꢀray photoelectron spectroscopy (XPS), inductively
1
coupled plasma optical emission spectroscopy (ICPꢀOES), H and
2
7
Al magic angle spinning nuclear magnetic resonance (MAS
(
meso-Al O )
2 3
NMR) techniques, as well as Fourier transform infrared (FTIR)
spectroscopy.
5
0
5
0
Highly ordered hexagonal mesoporous alumina (Al O ꢀmeso)
2 3
materials were synthesized through an extended solꢀgel process
associated with nonionic block copolymer as a directing agent, in
65
Powder X-ray diffraction (XRD) measurements
2
5
a similar procedure described by Yuan et al. Their synthesis was
screened under different conditions (carboxylic acid, aluminum
precursor and calcination temperature). Typically, Pluronic F127
The crystal structures of the calcined samples were analyzed by
XRD using a an Ultima III Rigaku monochromatic diffractometer
(Model D/MAXꢀ2200, with CuKα radiation source (λ=1.54059 Å)
operated at a voltage of 40 kV and a current of 44 mA. Small
angle XRD measurements were performed over the 2θ angle
range of 0.6ꢀ6° at a scanning rate of 0.5°/min. The different
crystal phases were identified by wide angle XRD measurements.
The patterns were collected from 10° to 80° at a speed of
1
1
2
70
(2.17 g) was dissolved in anhydrous ethanol (20 mL) under
stirring at room temperature. Then, the investigated carboxylic
acid (2.6 mmol) was added. The pH of the solution was adjusted
below 2 by adding hydrochloric acid (1.0ꢀ1.5 mL), giving a clear
solution. The investigated aluminumꢀprecursor (10 mmol) was
subsequently added under vigorous stirring. The mixture was then
covered with polyethylene film, and left under stirring at room
temperature for 5 h. The solvent was removed slowly in a drying
oven at 60 °C and aged for 48h. The obtained solid was heated
from room temperature to 400 °C with a slow ramping rate (1
75
5
.0°/min.
Brunauer–Emmett–Teller (BET) surface area measurements
80
The textural properties and surface analysis of calcined samples
were performed by nitrogen adsorption/desorption isotherms. The
°
C/min), and calcined for 4 h in air. The obtained Al O –meso
2 3
material was calcined further at higher temperatures (up to 1100
C) at ramping rate of 10 °C/min for 1 h in air (2 h for 600ꢀ
00 °C).
ꢀ
4
samples were initially outꢀgassed under vacuum (10 Torr) at
50ꢀ300 °C during 12 h. Then, the multipoint BET surface area
°
7
2
measurement was carried out using a volumetric adsorption
analyzer (Model Autosorbꢀ1, Quantachrome Instruments, Boyton
Beach, FL) at liquid nitrogen temperature ꢀ196 °C (77 K). The
specific surface area was evaluated using the Brunauer–Emmett–
Teller (BET) method. Total pore volume was estimated from the
2
5
85
Zinc chloride (ZnCl ) modification of ordered alumina (Al O )
2
2
3
The modification of ordered alumina with ZnCl was carried out
2
55ꢀ57
using the procedure reported in our previous works.
In a
amount adsorbed at the relative pressure P/P = 0.990 single point.
3
0
typical synthesis, mesoꢀAl O (2.0 g) was suspended in ethanol
0
2
3
90
Pore size distribution curves were calculated using the desorption
(
20 mL) under stirring at room temperature. Zinc chloride (334
mg, 2.45 mmol) was dissolved in ethanol (10 mL) by applying a
0 s vortex mixing. The addition of ZnCl solution to mesoꢀAl O
branch of the N ꢀadsorption/desorption isotherms and the Barrettꢀ
2
JoynerꢀHalenda (BJH) method as reported in the literature for this
3
2
2
3
58ꢀ60
type of materials.
suspension was carried out drop wise under stirring. The mixture
was kept under stirring at room temperature for 24 h in air,
allowing a complete evaporation of ethanol. The obtained dried
sample was heated from room temperature to 400 °C with a
ramping rate of 2 °C/min, and then calcined for 4 h in air,
providing ZnCl ꢀmodified Al O –meso with optimized Al:Zn
3
5
95
Transmission electron microscopy (TEM) studies
The pore size and morphology were examined by transmission
electron microscopy (TEM). The micrographs were taken from a
JEMꢀ1230 electron microscope (JEOL, Japan) equipped with a
2
2
3
5
5ꢀ57
4
0
molar ratio of 8:1 as reported in our previous works.
1
00 lanthanum hexaboride (LaB6) thermionic emission source,
operated at an acceleration voltage up to 80 kV, using Gatan dualꢀ
view multiscan camera. For TEM observations, the powdered
samples were dispersed in methanol and sonicated for 10 min. A
suspension drop of the obtained solution (5 µL) was then placed
05 uniformly onto a Formvar film coated nickel grid (200 meshes)
and it was allowed to dry in air at room temperature before
analysis.
Catalytic activity evaluation and GC analysis of the reaction
products
4
5
The synthesized catalysts were tested for methyl oleate selfꢀ
metathesis in hexane under controlled dry atmosphere at 45 °C for
1
3
h. Aliquots were taken at different time intervals. The reaction
was monitored by GC analysis using dodecane as internal
standard. The products were identified using pure standards and
5
5ꢀ57
Microstructural characterizations SEM/EDX
10
5
0
GCꢀMS analysis as reported in our previous works.
1
Characterization of the materials and the surface sites
The microstructure, morphology and elemental composition of the
synthesized materials were determined using scanning electron
microscopy (SEM) along with energy dispersive Xꢀray
spectrometry (EDX). Before analysis, powdered samples were
The prepared alumina and zinc chlorideꢀmodified alumina
materials were characterized using Powder Xꢀray diffraction
5
5
(XRD) and N2 physisorption. Also transmission electron 115 dispersed on a copper grid (300 mesh) coated with a Lacey
microscopy (TEM), scanning electron microscopy (SEM) and
Energyꢀdispersive Xꢀray (EDX) spectroscopy measurements were
performed. The synthesized materials were also characterized
amorphous carbon film. The samples were deposited by cathodic
sputtering in vacuum chamber (100 mTorr), using an Au/Pd thin
film to make the surface electrically conductive for better
This journal is © The Royal Society of Chemistry [year]
Journal Name, [year], [vol], 00–00 | 3

Dalton Transactions
Page 4 of 16
View Article Online
DOI: 10.1039/C4DT03630A
1
sensitivity and higher imaging resolution. The characterization 60 H -MAS NMR measurements
was carried out on a JEOL model JSMꢀ840A scanning electron
microscope equipped with an energyꢀdispersive Xꢀray (EDX)
spectrometer operating at an accelerating voltage of 15 kV using
Catalyst framework was investigated by solidꢀstate NMR
spectroscopy. HꢀMAS NMR spectra were recorded on a Bruker
1
ꢀ
6
AVANCE 300 (Bruker BioSpin Ltd.) wide bore NMR
spectrometer equipped with superconducting magnet of 7.1 Tesla
using a conventional 4mmꢀbroadband resonance magic angle
spinning MAS probehead at operating Larmor frequencies of
300.1 MHz. The dehydrated samples were quickly packed into a 4
5
secondary electron mode at high vacuum (10 Torr). EDX spectra
of the particles were collected using a singleꢀpoint quantitative
analysis taken from several random areas of the sample. SEM
images were acquired using OrionTM software at different
magnifications (X 350ꢀ3000). The EDX signals were obtained by
focusing a high energy electron beam on the particles and
65
mmꢀzirconia (ZrO ) rotor, and then the spectra were acquired at
10
2
70
room temperature at a typical spinning rate of 10 kHz at the magic
angle. Single pulse excitation HꢀNMR experiments were
accumulating the spectra within an acquisition time of 60 s using
1
TM
Spirit
Bruker AXS Microanalysis software. Average atomic
ratio of the present elements was calculated from several EDX
spectra at different points of the prepared sample.
performed for Al O ꢀmeso and the ZnCl ꢀmodified Al O ꢀmeso
2 3 2 2 3
using a 90° pulse length of 2.25 µs, an acquisition time of 30 ms,
15
and a recycle delay between scans of 60 s. Eight scans were
Inductively coupled plasma optical emission spectrometry 75 collected for each HꢀMASꢀNMR spectrum. All the corresponding
1
(ICP-OES) analysis
chemical shift values were referenced to tetramethylsilane (TMS)
signal (0.0 ppm in a spinning rotor).
The actual Al/Zn atomic ratio and the Re loading in the prepared
catalyst supports was determined by ICPꢀOES using a Perkinꢀ
Elmer Optima 4300DV ICPꢀemission spectrometer with radial
plasma viewing. For analysis, 10 mg of sample were digested with
2
7
2
0
Al-MAS NMR investigations
80
The form, coordination state and environment of aluminum, as
well as the surface and intrinsic Lewis acidic site concentrations
were studied by means of Al solidꢀstate magicꢀangle spinning
(MAS) NMR spectroscopy measurements. The experiments were
5
mL of aqua regia (nitroꢀhydrochloric acid) solution. After 24 h,
27
the solution was filled up to 50 mL with deionized water for
sample dilution to perform ICP experiments. Measurements from
emission spectra for the dissolved species were conducted using 85 conducted on a Bruker Avance 300 (7.1 T) instrument. AlꢀMASꢀ
25
2
7
calibration curves of a series of Al, Zn and Re standard solutions.
The experimental ICP metal composition values were compared
to the expected Al/Zn atomic ratio for each sample.
NMR spectra were obtained using a highꢀspeed broadband MASꢀ
probe with an outer diameter of 4 mm, and rotated around the
Magic Angle at a rate of 10 kHz controlled within ±2 Hz using a
Bruker MASꢀcontroller, with an acquisition time of 15.4 ms. The
90 system was operated at a resonance frequency of 78.1 MHz for
30
X-ray photoelectron spectroscopy (XPS) measurements
27
Al nuclei. All spectra were obtained at room temperature. For
the 1Dꢀ spectrum measurements, a short single excitation π/10
Identification of material surface species and their
oxidation/coordination states was achieved by means of XPS
analysis. XPS spectra were recorded on an AXIS ULTRA from
Kratos Analytical (Manchester, UK) equipped with a double Xꢀ
ray source for nonꢀmonochromatic AlꢀMg (Kα) Xꢀray irradiation,
a monochromatic Al (Kα) Xꢀray irradiation source (1486.6 eV),
and an electrostatic analyzer of large radius. The base pressure in
2
7
pulse of 0.6 µs was applied. The small flip angle of the Al pulse
was advantageously used to improve signal intensity
35
6
5
95
quantification of the quadrupole nucleus. The relaxation time
2
7
was set at 250 ms, and 2000 scans were recorded. The AlꢀNMR
ppm scale was referenced to Al(NO ) •9H O by adjusting the
3
3
2
66
signal to 0 ppm.
ꢀ
10
40
45
50
55
the UHV XPS chamber was 5 10 Torr. All spectra were
acquired with the Al monochromatic source at room temperature 100 Fourier transform infrared (FTIR) spectroscopy studies
operated at 300 W. The working pressure in the analyzing
ꢀ
7
chamber was less than 10 Torr. The survey spectrum used to
determine the elementary apparent composition was recorded with
pass analyzer energy of 160 eV and an energy step of 1 eV, using
FTIR investigations of the mesophase formation pathway were
carried out in a Nicolet Magna 850 FTIR spectrometer (Thermo
Fisher Scientific Inc.) equipped with a liquid nitrogenꢀcooled
The 105 MCT detector in absorbance mode under static conditions. Before
61, 62
lenses in the hybrid mode, which maximizes sensitivity.
ꢀ
4
detailed spectra were obtained with pass energy of 20 or 40 eV,
and an energy step of 50 or 100 meV. The charge neutralizer was
used for charge compensation of the nonꢀconducting samples. The
binding energies were corrected for charge shifts, with the use of
analysis, the samples were degassed under vacuum (10 Torr) at
250 °C overnight. FTIR spectra were recorded at room
−1
temperature in the midꢀIR spectral range; 400ꢀ4000 cm region at
−1
4 cm resolution accumulating 128 scans. ATRꢀFTIR data
6
3
TM
the C1s set at 285 eV peak as internal reference. The uncertainty 110 acquisition and manipulation were performed with Omnic
in the reported binding energy (BE) values is ±0.1 eV. The survey
spectra were recorded in the binding energy range 0–1150 eV, and
detailed spectra were recorded for O1s, Zn2p, Zn Auger L2M45
M45, Cl2p and Al2p. Curve fitting and deconvolution were
software (v. 6.1) and presented as absorbance. Spectra were
obtained using a 45° troughꢀstyle sample holder with a zinc
selenide (ZnSe) internal reflection element (56 mm×10 mm×3
mm) (PIKE Technologies, Inc) yielding nine internal reflections,
performed using mixed Gaussian/Lorentzian line shapes after a 115 while deconvolution of the IR spectra was carried out using the
Shirleyꢀtype background removal by using the CasaXPS 2.3.15
software.
ORIGIN software (OriginLab Corporation, Northampton, MA).
64
4
| Journal Name, [year], [vol], 00–00
This journal is © The Royal Society of Chemistry [year]

Page 5 of 16
Dalton Transactions
View Article Online
DOI: 10.1039/C4DT03630A
Results and discussion
showing also typical typeꢀIV curves with H1ꢀhysterisis (Figure 2)
characteristic for mesoporous solids.
68
Material characterizations
Table 1 Textural properties of the prepared hexagonally OMA and zinc
Physisorption analysis and material textural properties
chlorideꢀmodified OMA obtained by means of N
isotherms.
2
adsorption–desorption
60
5
Aluminumꢀtriꢀsecꢀbutoxide was used as aluminum precursor for
a
b
c
a
b
c
Alumina Acid
Aluminum
S
BET
2
V
P
D
P
ZnCl
2
ꢀ
S
BET
2
V
P
D
P
the synthesis of conventional wormholeꢀlike alumina as reported
3
3
precursor (m /g)(cm /g)(nm)Modified(m /g)(cm /g)(nm)
5
5ꢀ57
in our previous work.
Therefore, different hexagonal OMA
d
2 3
Al O
materials were prepared using the same precursor in the presence
of several, inexpensive monoꢀ, diꢀ and triꢀcarboxylic acids. Table1
shows the textural properties of these materials.
s
Al
Al
Al
Al
Al
Al
Al
2
2
2
2
2
2
2
O
O
O
O
O
O
O
3
3
3
3
3
3
3
ꢀ1 Citric
Al(OBu )
3
3
3
3
3
3
3
362 0.46 3.4 ZnCl
Al
394 0.49 3.8 ZnCl
Al
313 0.43 3.9 ZnCl
Al
317 0.39 3.8 ZnCl
Al
319 0.31 3.4 ZnCl
Al
298 0.29 3.4 ZnCl
Al
378 0.55 3.8 ZnCl
and Al
.9
300 0.53 5.5 ZnCl
Al
324 0.59 5.6 ZnCl
Al
321 0.24 4.9 ZnCl
Al ꢀ10
2
ꢀ
316 0.44 3.8
154 0.26 3.8
214 0.31 3.8
2
3
O ꢀ1
2
ꢀ
O ꢀ2
3
2
ꢀ
1
0
s
ꢀ2 Tartaric Al(OBu )
2
s
ꢀ3 Fumaric Al(OBu )
2
3
O ꢀ3
s
e
ꢀ4 Oxalic Al(OBu )
2
ꢀ
ND ND ND
2
3
O ꢀ4
s
ꢀ5 Maleic Al(OBu )
2
ꢀ
ND ND ND
ND ND ND
ND ND ND
1
2
2
5
0
5
2
3
O ꢀ5
2
ꢀ
O ꢀ6
3
2
ꢀ
s
ꢀ6 Malonic Al(OBu )
2
s
ꢀ7 Acetic Al(OBu )
2
3
O ꢀ7
4
t
Al
2
2
O
3
3
ꢀ8 Citric
Al(OBu )
3
2
ꢀ
239 0.41 4.9
257 0.44 5.6
2
3
O ꢀ8
2
ꢀ
O ꢀ9
3
t
Al
O
ꢀ9 Tartaric Al(OBu )
3
2
i
Al
2
O
3
ꢀ
Citric
Al(OPr )
3
2
ꢀ
241 0.38 3.8
1
0
2
O
3
and
4.9
i
Al
2
O
3
3
ꢀ
ꢀ
Tartaric Al(OPr )
3
289 0.46 5.6 ZnCl
Al ꢀ11
337 0.30 3.8 ZnCl
Al ꢀ12
2
ꢀ
190 0.39 5.7
1
1
2 3
O
Al
2
O
Citric
Al(NO
•9H
3
)
3
2
ꢀ
139 0.40 3.8
and
1
2
2
O
2 3
O
6
.5
Al
13
2
O
3
ꢀ
Tartaric Al(NO
•9H
3
)
O
3
293 0.58 3.8 ZnCl
2
ꢀ
222 0.46 3.8
3
3
4
0
5
0
2
2 3
Al O ꢀ13
a
2
b
3
BET specific surface area (m /g); BJH pore volume (cm /g) determined
c
d
at P/P
8
0
= 0.997; BJH average pore diameter (nm); Al:Zn atomic ratio of
e
:1 determined by ICPꢀOES analysis; ND: Not determined.
6
5
t
i
However, the OMA prepared with Al(OBu )3 and Al(OPr )
3
afforded larger pore diameters up to 5.6 and 5.7 nm, respectively.
The slight difference observed using distinct aluminum precursors
may be attributed to the different organicꢀinorganic interfaces
Fig. 1 (a) Nitrogen adsorption–desorption isotherms and (b) pore size
distributions of the prepared OMA samples: (1) Al O -tartaric, (2) Al O -
2 3 2 3
fumaric, (3) Al
Al(OBu )
2
O
3
-oxalic and (4) Al
3
and calcined at 400 °C.
O
2 3
-maeilc acid, synthesized using 70 obtained during the templating pathway, allowing distinct
s
chelation between Al atoms, carboxylic acids and Pluronic F127
moiety. It could be also due to different density charge levels at
these interfaces, allowing the selfꢀassembly process in ethanol
prior to the hydrolysis. These pathways are governed by Van der
Waals interactions, covalent and hydrogen bonding.
69
Figure 1 shows the nitrogen adsorptionꢀdesorption isotherms of
hexagonal OMA synthesized using different carboxylic acids. All
isotherms are IVꢀtype and exhibit H1ꢀtype hysteresis loops. These
isotherms display wellꢀknown patterns of organized mesoporous
network containing cylindrical channels. Moderate to relatively
70
1
7
7
8
8
5
0
5
BET analysis of the ZnCl ꢀmodified OMA showed a decreased
2
4
5
5
5
0
5
BET surface area while pore volume and pore distributions are
retained even upon pores filling by zinc chloride (Table 1).
Therefore, it is suggested that this drop in BET surface is mainly
due to additional calcination step (4 h at 400 °C) in comparison to
the original OMA. Moreover, similar shifts were observed using
other aluminum precursors (Table 1; see also Figure S2 in the
Supporting Information).
2
large BET surface area (up to 394 m /g), pore volume (up to 0.55
3
cm /g) and uniform narrow pore distribution with average pore
size of 3.4ꢀ4.9 nm were obtained (Table 1).
No significant difference was observed with the investigated
carboxylic acids (see also Figure S1 in the Supporting
Information) which could be attributed to their similar
coordination abilities with Al centers via monodentate or bridging
67
bidentate modes during the mesophase formation process.
Moreover, similar BET surface area and pore volume were
obtained using different aluminum precursors (See Table 1)
This journal is © The Royal Society of Chemistry [year]
Journal Name, [year], [vol], 00–00 | 5

Dalton Transactions
Page 6 of 16
View Article Online
DOI: 10.1039/C4DT03630A
60
5
0
5
0
5
1
1
2
2
6
5
70
75
3
3
4
0
5
0
Fig. 2 (a) Nitrogen adsorption–desorption isotherms and (b) BJH pore size
distributions curves of the prepared OMA samples using tartaric acid with
different aluminum precursors: (1) Al
2
O
3
-Al(NO
3
)
3
•9H
2
O, (2) Al
2 3
O -
Fig. 3 Small-angle powder X-ray diffraction patterns for the prepared (a)
t
i
Al(OBu )
3
2
and (3) Al O
3 3
- Al(OPr ) . All samples were calcined at 400 °C.
80 ordered mesoporous alumina and (b) the zinc chloride-modified ordered
s
3
mesoporous alumina synthesized using Al(OBu ) and calcined at 400 °C.
XRD analysis
Small angle XRD patterns of ZnCl ꢀmodified OMA, prepared
2
Hexagonally mesostructured materials were successfully obtained
as shown from smallꢀangle XRD results in Figure 3a. The samples
calcined at 400 °C exhibited three diffraction peaks (100, 110 and
using other aluminum precursors exhibited similar diffraction
peaks (Figure 4). However, the main diffraction peak at around
8
9
9
5
0
5
1.0° was slightly shifted to lower angles for the sample prepared
i
2
00) at around 2θ = 1.0, 2.0 and 2.3°, respectively. This confirms
with Al(OPr ) indicating the presence of relatively larger pore
3
71
the hexagonal mesostructure, which can be attributed to the p6mm
size. This suggestion confirms the results of BET analysis.
23, 25
space group.
The formation of wellꢀorganized mesoporous
network is confirmed by the high signalꢀtoꢀnoise ratio in small
angle XRD patterns with narrow width at halfꢀmaximum of the
(100) diffraction peak.
45
50
55
Zinc chloride modification did not result in any ordered
mesostructure collapse, as shown in Figure 3b indicating similar
patterns to those obtained with OMA materials.
1
00
Fig. 4 Small-angle powder X-ray diffraction patterns for the prepared zinc
chloride-modified ordered mesoporous alumina calcined at 400 °C using
tartaric acid with different aluminum precursors.
6
| Journal Name, [year], [vol], 00–00
This journal is © The Royal Society of Chemistry [year]

Page 7 of 16
Dalton Transactions
View Article Online
DOI: 10.1039/C4DT03630A
Wideꢀangle XRD (WAXRD) patterns displayed in Figure 5
reveals the absence of any crystalline Al O phase in the sample
2
3
treated at 400 °C, suggesting that only amorphous network is
formed. Moreover, further annealing at higher temperatures (800
°C) found to be sufficient to crystallize amorphous Al O into the
5
0
5
2
3
6
5
γꢀAl O phase as confirmed by wideꢀangle XRD patterns showing
2
3
wellꢀresolved diffraction peaks (111, 220, 311, 222, 400, 511 and
40) at around 2θ = 20, 34, 37, 39, 47, 62 and 77° . These peaks
are assigned to the presence of γꢀ Al O reflections (JCPDS Card,
4
2
3
1
10ꢀ0425). The presence of single γꢀAl O phase was observed
2 3
with all the screened aluminum precursors. Surprisingly, this γꢀ
Al O phase remains stable even at elevated temperature up to
70
2
3
1
000 °C, demonstrating the high thermal stability of these
materials. However, under higher thermal treatment (1100 °C)
conversion of γꢀAl O phase into αꢀAl O phase (JCPDS Card, 11ꢀ
1
2
3
2
3
0
661) was observed.
7
8
8
5
0
5
2
2
3
0
5
0
Fig. 6 TEM images of the synthesized ordered mesoporous alumina
materials with different carboxylic acids; (a) citric, (c) fumaric, (d)
malonic, (e) tartaric and (f) oxalic acid, viewed along [001] orientation
and (b) maleic acid, viewed along [110] orientation.
90
of different carboxylic acids and several aluminum precursors did
not result in any significant difference in the microstructure of the
prepared OMA (Figures S5 and S6 in the Supporting
Information). The SEM images display also the presence of
microparticles which can be attributed to irregular aggregation of
many nanoscale single crystals under thermal treatment. Moreover
the microstructure observed with OMA was slightly modified
after zinc chloride incorporation as depicted in Figure 7b (see also
3
5
Fig. 5 Wide-angle XRD patterns of OMA samples calcined at different
temperatures, prepared using citric acid with different aluminum
s
t
i
precursors: (a) Al(OBu )
3 3 3 2 3
, (b) Al(OBu ) and (c) Al(OPr ) . Both γ-Al O and
95
α-Al * phase diffraction peaks are indexed.
2 3
O
4
0
TEM analysis
In agreement with XRD measurements, the TEM images confirm
that highly organized selfꢀassembly process was achieved using
the different carboxylic acids (Figure 6), revealing the hexagonal 100 Figure S5 in the Supporting Information). The impregnation
mesostructure and showing clearly the ordered mesoporous
network aligned along [110] direction and arranged along [001]
direction. Similar observations were portrayed in zinc chlorideꢀ
modified OMA samples (see Figures S3 and S4 in the Supporting
process allowed the formation of relatively smaller and less
regular particle morphology and size. This can be observed in
Figure 7b which shows mediumꢀsized particles around 8ꢀ15 µm. It
is believed that the presence of such smaller microparticles could
4
5
Information) in accordance with XRD results, confirming thus the 105 be due to mechanoꢀchemical dislocation effect during the ZnCl
2
maintained organized structure even after zinc chloride
incorporation. It is worth to observe that the mean pore sizes as
evaluated by TEM analysis are in the vicinity of 3 to 6 nm,
confirming the mean pore sizes determined with BET analysis.
incorporation process. The EDX spectrum of OMA sample
displayed in Figure 7c exhibits only a strong signal for O and Al
elements highlighting the evidence for mesoporous Al O
3
5
0
2
formation. Whilst, Au/Pd and C were also detected deriving from
10 Au/Pd thin film used to enhance the sample surface electrical
conductivity for better improved detection purpose and from the
carbon film used for samples deposition, respectively. EDX
analysis of ZnCl ꢀmodified Al O samples depicted in Figure 7d
1
SEM analysis
5
5
The SEM images displayed in Figure 7a highlight the
microstructure of the nonꢀuniform plateꢀshaped particles of the
obtained OMA after template removal and crystal growth. The use
2
2
3
shows also the presence of O and Al elements belonging to Al O
2
3
115 material. In addition, it shows the presence of both Zn and Cl
elements owing to the impregnation of ZnCl2 into to Al O
materials.
2
3
6
0
This journal is © The Royal Society of Chemistry [year]
Journal Name, [year], [vol], 00–00 | 7

Dalton Transactions
Page 8 of 16
View Article Online
DOI: 10.1039/C4DT03630A
material, the Al2p binding energy increased from 74.3 to 74.7 eV.
This small shift could be attributed to the Al environment
changes, especially surface hydroxyl groups that are modified
6
6
7
0
5
0
72
with ZnCl2. However, this nonꢀsignificant shift implies that all
5
Al species on both OMA and ZnCl ꢀOMA exhibit the same Lewis
2
acidic properties.
On the other hand, similar O1s XPS spectrum was obtained for
ZnCl ꢀOMA samples (Figure 8c) without a significant shift, whilst
2
Fig. 7 Representative SEM images obtained for (a) OMA and (b) ZnCl
modified OMA microparticles prepared using oxalic acid with Al(OBu )
2
-
lower intensities were observed for AlꢀOꢀH and H O signals. The
2
estimated ratio of oxygen intensity in AlꢀOꢀAl over the oxygen in
AlꢀOꢀH increased from ~ 2 (hexagonal mesoporous alumina) to ~
s
10
3
.
Energy dispersive X-ray (EDX) spectra of (c) OMA and (d) ZnCl -modified
2
s
3
OMA samples prepared using oxalic acid-Al(OBu ) .
3 (ZnCl ꢀtreated hexagonal mesoporous alumina). This may be
2
XPS analysis
due to the formation of ZnꢀO bonding as a consequence of ZnCl
interactions with AlꢀOꢀH species. Therefore, the occurrence of
these species decreased after ZnCl treatment of OMA. It is worth
to note that was also suggested to be assigned to the formation of
alumina stoichiometry having an Al:O atoms ratio close to 2:3. 75 ZnO species resulted from the interaction of Zn with surface
2
The XPS measurements of OMA samples confirmed the presence
of only Al and O elements as depicted in the survey spectrum
15
20
25
30
35
40
45
50
2
(Figure S7a in the Supporting Information) with the desired
74
Al2p spectrum displayed in Figure 8a shows a strong signal at
4.3 eV binding energy, which is assigned to the Al element from
hydroxyl. The H O low intensity signal is simply attributed to
2
the second thermal treatment which helped to remove significant
amount of moisture compared to bulk OMA.
7
7
2
the anhydrous amorphous alumina phase. Moreover, all Al
73
species (IV, V and VI) contribute to form the Al2p peak. The
The XPS analysis of ZnCl ꢀpromoted Al O revealed the presence
2 2 3
deconvolution of O1s XPS spectrum of OMA samples reveals the 80 of Zn and Cl elements in addition to Al and O (Figure S7b in the
presence of three different oxygen species on the bulk alumina
Figure 8b). The hidden signals were detected at 530.9, 532.1 and
533.1 eV, which are assigned to bulk oxygen from Al O crystal
Supporting Information). The expected nominal Al:Zn ratio of 8:1
is confirmed by ICPꢀOES analysis. However, the atomic element
calculations resulted in Zn/Cl stoichiometry around 1.6 to 1.8.
(
2
3
matrix (AlꢀOꢀAl), the surface hydroxyl groups (AlꢀOꢀH) and the
This statement could indicate that further to ZnCl
, other ZnꢀCl
2
6
0, 72
strongly adsorbed H O molecules, respectively.
The presence 85 species are dispersed on the OMA surface as pointed out
2
55, 56
of such moisture traces could be the reason behind the slight shift
in the Al O stoichiometry.
previously by Pillai et al.
Regarding the zinc element, Zn2p3/2 XPS spectra displayed a
2
3
Figure 8d depicts the spectrum of Al2p peak of ZnCl ꢀmodified
OMA at 74.7 eV. In comparison to the peak obtained for OMA
unique signal at 1022.5 eV (Figure 8e). However, it is difficult to
2
2+
distinguish between different Zn species since the presence of
2+
90
Zn signal at this binding energy could be attributed to ZnO
75
76
species (1022.5 eV) , ZnCl (1022.5 ±0.2 eV) or Zn(OH)2
2
95
1
1
1
00
05
10
55
115
Fig. 8 XPS spectra of (a) Al2p and (b) O1s of the prepared OMA and (c) O1s and (d) Al2p (e) Zn2p3/2 and (f) Cl2p3/2 and Cl2p1/2 of the zinc chloride
modified OMA.
8
| Journal Name, [year], [vol], 00–00
This journal is © The Royal Society of Chemistry [year]

Page 9 of 16
Dalton Transactions
View Article Online
DOI: 10.1039/C4DT03630A
7
7
(
1022.6 eV). Nonetheless, it could be hardly assigned to a
60
65
70
7
4
spinel ZnAl O phase (1022.0 eV). Therefore, the chlorine XPS
2
4
2+
spectra are necessary to confirm the nature of the related Zn
species. XPS spectrum of chlorine ions displayed in Figure 8f
exhibits two signals at 199.3 and 200.9 eV for Cl2p3/2 and Cl2p1/2
respectively after peak deconvolution process. These signals are
assigned to Cl bonded to Zn. The ZnꢀCl species were also
confirmed as ZnꢀCl2p3/2 with binding energy of 199.1 ± 0.2ꢀ0.9
and ZnꢀCl2p1/2 with a binding energy of 200.6 ± 0.2ꢀ1.462 eV.
Moreover, the ZnꢀCl2p3/2 is suggested to be bonded to the alumina
surface via OH groups as AlꢀOꢀZnꢀCl. The calculated low Zn/Cl
stoichiometry compared to the incorporated ZnCl2 could be
attributed to a partial removal of chlorine from the support surface
upon zinc chloride decomposition under thermal treatment (400
5
,
1
0
7
8
7
9
1
5
°C) as reported recently by Schmidt et al.
75
1
27
H and Al –MAS-NMR Analyses
1
To confirm the presence of ZnꢀOꢀAl bond, HꢀMASꢀNMR
analysis was conducted investigating the possible interaction of
2
0
ZnCl with the surface hydroxyl groups and the possible types of
2
Zn/Cl species which can be obtained upon alumina modification.
Recently, it was suggested that the incorporation of ZnCl2 to
alumina may lead to the formation of mixed Zn/O/Cl species, but 80 Fig. 9 H-MAS-NMR spectra of (a) OMA prepared with oxalic acid-
1
Al(OBus) . Zinc chloride modified alumina prepared with (b) oxalic acid-
3
the possible presence of bulk ZnCl or elemental zinc is
2
s
t
i
7
9
3 3 3
Al(OBu ) , (c) tartaric acid-Al(OBu ) and citric acid-Al(OPr ) . All samples
2
3
3
4
4
5
5
5
0
5
0
5
0
5
completely eliminated.
were calcined at 400 °C.
1
First of all, the HꢀMASꢀNMR was conducted on OMA only and
the results are depicted in Figure 9a which exhibit two main
the terminal hydroxyl signals and decrease in bridging hydroxyl
peaks observed at 1.7 and 3.8 ppm. These peaks can be assigned 85 signals in the modifiedꢀwormholeꢀlike alumina samples spectra in
to the basic terminal hydroxyl groups and the acidic bridging
hydroxyl groups of intermediate strength, respectively as it was
previously reported by Decanio et al. In contrast, strong acidic
comparison to the initially analyzed wormholeꢀlike alumina.
Figure 10 shows the AlꢀMASꢀNMR spectra of asꢀprepared dried
27
8
0
OMA and OMA calcined at 400 °C as well as ZnCl ꢀmodified
2
and basic hydroxyl groups were detected using wormholeꢀlike
OMA. Several carboxylic acids and aluminum precursors were
5
5, 56
27
alumina as reported in our previous work,
as well as in other 90 screened for the preparation of these materials. The AlꢀMASꢀ
8
1
published results. An additional peak was also observed at 4.3
ppm for OMA sample, which is assigned to hydrogen bonded
NMR spectra of the nonꢀcalcined (dried) samples exhibit a single
peak centered at around δ = 0 ppm which can be assigned to the
8
0, 82
77
water physisorbed on alumina surface.
Afterwards, the ZnCl2ꢀ
octahedral Alꢀsymmetry. This was ascribed to the AlOOH
83
modified OMA were analyzed and the results are reported in
intermediate phase. The spectra of calcined materials exhibit tree
Figures 9bꢀ9d. As depicted in these figures, the HꢀMASꢀNMR 95 major signals at around δ = 5, 35 and 62 ppm compared to the asꢀ
1
spectra reveal the elimination of the peak at 1.7 ppm. These
observations suggest that the basic terminal hydroxyl groups are
neutralized upon ZnCl2 addition. It is believed that ZnCl2 is
bonded to the alumina surface via this type of hydroxyl groups
prepared OMA, which are assigned to sixꢀ, fiveꢀ and fourꢀ
3+
84
coordinated aluminum centers (Al ), respectively. This was
attributed to the enhanced dehydration and dehydroxylation upon
58
calcination process. All these peaks appear for both calcined and
forming various AlꢀOꢀZnꢀCl species; this was confirmed by 100 zinc chlorideꢀmodified OMA. However, compared to asꢀ
1
combining the HꢀMASꢀNMR results with those obtained by XPS
analysis. This neutralization leads to a drop in Brønsted acidity,
and as a result an enhanced Lewis acidity of the catalyst support is
obtained. The peak attributed to hydrogen bonded water
synthesized dried samples, calcined samples exhibit two new
signals with high intensity for peaks at δ = 35 (AlO ) and 62.0
5
ppm (AlO ) and lower intensity for the peak at 5.6 ppm (AlO ).
4
6
The origin of the observed conversion of octahedral Alꢀsymmetry
physisorbed on alumina was observed also with ZnCl ꢀmodified 105 to pentahedral and tetrahedral ones could be due to the partial
2
alumina (Figure 9b). This peak was eliminated in other samples
(Figures 9cꢀ9d) which may be due to water trace removal via the
second calcination process upon alumina modification.
substitution of oxygen ions by hydroxyl groups in octahedral Alꢀ
85, 86
centers during the template removal.
Furthermore, the spectra
of calcined OMA samples exhibit a relatively strong signal for Al
Distinct shapes of the main signal were observed along with
pentaꢀcoordinated indicating higher content of AlO centers. Fu et
5
87
variation of carboxylic acid and aluminum precursors used for 110 al. related this phenomenon to the oxygen deficiency and
8
0
OMA and ZnCl ꢀOMA synthesis. Decanio et al. suggested that
distorted AlꢀO inside the alumina framework, as well as the
substantial defects induced by relatively large surface area of the
2
1
1
this signal broadening can be attributed to the strong Hꢀ H
8
8, 89
dipolar interactions of the neighboring hydroxyl groups or
mesoporous networks.
No significant difference on the
1
physisorbed H O molecules. These HꢀMASꢀNMR results are
distribution environment of Al centers was observed when using
2
supported by the DRIFT analysis reported previously by Tovar et 115 distinct aluminum precursors.
8
1
55, 56
al. and in our previous work
describing the disappearance of
This journal is © The Royal Society of Chemistry [year]
Journal Name, [year], [vol], 00–00 |
9

Dalton Transactions
Page 10 of 16
View Article Online
DOI: 10.1039/C4DT03630A
5
0
5
0
6
6
7
7
0
5
0
5
1
1
2
25
80
27
Fig. 11 Al-MAS-NMR spectra of zinc chloride modified alumina
i
2
7
synthesized using (a) citric acid-Al(OPr ) , (b) citric acid-Al(OBut) , (c)
3
3
Fig. 10 Al-MAS-NMR spectra of as-made OMA prepared using (a) citric
acid-Al(OPri) and (b) citric acid-Al(OBut) , and calcined OMA samples
prepared using (c) citric acid-Al(OPr )
i t s)
, (d) tartaric acid-Al(OBu )
tartaric acid-Al(OPr )
85 and (f) tartaric acid-Al(OBu )
3
3
, (e) oxalic acid-Al(OBu
3
3
3
s
i
t
3
. All samples were calcined at 400 °C.
30
3
t
, (d) citric acid-Al(OBu )
3
, (e) tartaric
, (g) oxalic acid-Al(OBus) and (h)
. All samples were calcined at 400 °C.
i
acid-Al(OPr )
tartaric acid-Al(OBu )
3
, (f) tartaric acid-Al(OBu )
3
3
s
3
Mechanism of OMA and ZnCl -modified OMA formation
2
On the other hand, performing the synthesis in the presence of
different carboxylic acids did not affect the Al coordination
distribution for all OMA samples. In the case of zinc chlorideꢀ
In order to simplify the mechanistic pathway for the mesophase
formation and based on wellꢀestablished mechanisms and
35
40
45
50
55
9, 10, 25, 89, 90
modified OMA, regardless of the Al precursor used, and for the 90 theories,
we propose herein a comprehensive
samples using tartaric acid, the AlO and AlO distributions were
conserved after zinc chloride incorporation (Figure 11). However,
mechanism for OMA synthesis and zinc chloride modification as
schematically illustrated in Figure 12. In this mechanism, it is
shown that the uniform aggregation of liquidꢀcrystal phase of
surfactant micelles is the main factor to be controlled in order to
5
6
lower signal of AlO was observed when citric acid was used.
6
Surprisingly, this distribution was not observed with the
corresponding unmodified OMA. It is believed that the triꢀ 95 obtain such organized mesostructure. This agglomeration is
carboxylic acid (citric) led to higher amount of AlO on OMA
obtained after a selfꢀassembly process mediated by complexation
effect of carboxylic acids with Al cations, as well as the nonionic
surfactant (F127) via Van der Waals forces and hydrogen
6
surface compared to the one prepared using the diꢀcarboxylic acid
(
tartaric). This can be ascribed to the relative difference in the
complexation ability of these acids with the Al precursors and
bonding to the template before calcination process. It is then 100 protectors to prevent chlorine ions from complexation with Al
25
bonding Therefore, carboxylic acids are used as interfacial
ꢀ
suggested that the difference on the exposed amount of AlO can
atoms. Cl anions can coordinate strongly with Al species leading
6
only be observed after zinc chloride incorporation upon
the organized assemblies to collapse during the evaporation
25
interaction of Zn atoms preferably with AlO coordination sites.
process.
Finally, the templating agent is removed upon
6
Moreover, such selective doping was previously reported when
calcination under 400 °C, providing the hexagonally structured
Cuꢀdoped Al O was investigated showing high Cu atoms 105 mesoporous network.
2
3
8
7
preference towards AlO sites. Therefore, the synthesized Al O3
5
2
materials with high pentaꢀcoordinated aluminum distribution
8
7, 88
centers are highly desirable for heterogeneous catalysis.
1
0
| Journal Name, [year], [vol], 00–00
This journal is © The Royal Society of Chemistry [year]

Page 11 of 16
Dalton Transactions
View Article Online
DOI: 10.1039/C4DT03630A
6
6
7
7
0
5
0
5
5
1
0
1
5
Fig. 12 Proposed mechanistic scheme for the formation of organized
mesoporous alumina and zinc chloride-modified OMA.
2
0
ATR-FTIR analysis
ATRꢀFTIR measurements were conducted to verify and support
the proposed mechanism involving the carboxylic acidꢀmediated
mesophase formation and its interaction with aluminum metal
centers. Figure 13 shows the ATRꢀFTIR spectra of both pure
carboxylic acids and asꢀprepared alumina samples synthesized
using different carboxylic acids and aluminum precursors. Pure
citric and tartaric acid samples exhibit wellꢀresolved signals at
80
Fig. 13 ATR-FTIR absorbance spectra of (a) citric and (d) tartaric acid
2
3
3
4
4
5
5
5
0
5
0
5
0
5
samples, and the as-prepared alumina samples synthesized using (b) citric
t
i
t
acid-Al(OBu )
3
, (c) citric acid-Al(OPr )
3
, (e) tartaric acid-Al(OBu )
3
and (f)
i
85
tartaric acid-Al(OPr )
3
.
ꢀ
1
around 1728 and 1709 cm , respectively. These bands are
assigned to the carbonyl stretching vibration υ (C=O) of the free
carboxylic acids. Moreover, for both acids, their spectra exhibit a
Catalytic activity for methyl oleate self-metathesis over
heterogeneous MTO-based catalysts supported on organized
mesoporous alumina
ꢀ
1
second band at around 1677 and 1686 cm , respectively. This
band can be assigned to the Hꢀbonded carbonyl stretching
In order to evaluate the performance of the synthesized hexagonal
mesoporous alumina materials as catalytic supports, some of the
formulated MTOꢀbased catalysts supported on these materials
have been tested for their catalytic activity conducted on methyl
oleate selfꢀmetathesis (See Scheme 1). The obtained results were
also compared to those acquired using MTO catalyst supported on
wormholeꢀlike mesoporous alumina for the same reaction under
90
vibration υ (C=O) of the free carboxylic acids. Also, symmetric
ꢀ
stretching vibrations υ (COO ) for free citric and tartaric acid are
s
ꢀ
1
91
detected at around 1416 and 1443 cm , respectively. In the case
of the asꢀsynthesized alumina samples, they exhibit two new
signals in addition to those observed for free citric acid, while the
95
ꢀ
1
signal at around 1720ꢀ1740 cm decreases, indicating the
identical reaction conditions (45 °C, 90 min of reaction time) as
2
5
neutralization of citrate ions by Al atoms. The newly appeared
signals are assigned to the aluminumꢀcoordinated citrate and
tartrate groups: the increased signals at around 1438 and 1450
cm are assigned υ (C=O) due to the monodentate coordination of
citrate and tartrate groups to aluminum centers, respectively. In
addition, the spectra exhibit wellꢀresolved bands at around 1590
55, 56
optimized previously by Pillai et al.
These results are
summarized in Table 2.
As already reported, the selfꢀmetathesis of methyl oleate with the
00 MTO/ZnCl ꢀAl O ꢀmeso catalyst gave the primary metathesis
ꢀ
1
1
1
1
2
2
3
92
products 9ꢀoctadecene and dimethylꢀ9ꢀoctadeceneꢀ1,18ꢀdioate in
both cis and trans isomers. Methyl elaidate, which is the transꢀ
isomer of methyl oleate, is also formed during the reaction. This
ꢀ
1
and 1618 cm , which are assigned to the asymmetric stretching
ꢀ
91
vibrations υa (COO ) complexed to Al atoms. These results
demonstrate the evidence of carboxylic acidꢀAl coordination
pathway leading to the mesophase formation and growth. These
interactions are not tightly dependent on the nature of the
carboxylic acid or the aluminum precursor.
product was obtained from the nonꢀproductive or degenerate
55, 56, 93
05 metathesis as previously described.
It is worth to observe
that when 3 wt% MTO supported on mesoporous alumina,
unmodified with ZnCl was used as catalyst, only weak methyl
2
oleate conversion of 2.4% was reached after 3 h of reaction,
testifying the poor catalyst performance: The yield of total
10 metathesis products was 2.4% where only 43% of this yield is
ascribed to the desired metathesis products (1
selectivity towards the desired products is in the vicinity of ~
2%. The same catalyst modified with ZnCl markedly boosted
, 2, 4 and 5). The
4
2
the conversion up to ~ 87% after the same reaction time where the
This journal is © The Royal Society of Chemistry [year]
Journal Name, [year], [vol], 00–00 | 11

Dalton Transactions
Page 12 of 16
View Article Online
DOI: 10.1039/C4DT03630A
total metathesis product yield attained 86.7% with 52% attributed
to the desired metathesis products. This catalyst yielded also ~
5
5, 56
3
4% of methyl elaidate as reported in our previous work.
The MTOꢀbased catalysts supported on some hexagonal alumina
such as Al O ꢀ2 and ꢀ11 (Cata #2 and Cata #3, respectively)
exhibited somewhat similar activity compared to the MTOꢀbased
catalyst supported on wormholeꢀlike alumina. They reached
comparable conversion. It is interesting to note that almost all
5
5
6
0
5
0
2
3
5
these ZnCl ꢀmodified mesoporous alumina materials when they
2
were tested as catalyst supports for methyl oleate selfꢀmetathesis,
displayed almost similar conversion around 87 to 88% at identical
reactions conditions. These catalysts were fairly more selective
towards desired metathesis products. Their yield of desired
products was slightly higher. This was reflected in somewhat
lowering the nonꢀproductive metathesis product (methyl elaidate),
indicating thus, a better selectivity towards the formation of the
desired products. This statement is verified also in the next section
treating the kinetics of the reaction.
1
1
2
0
5
0
Kinetic profiles of methyl oleate self-metathesis over MTO-
6
5
based catalysts supported on ZnCl -modified mesoporous
2
Al O3
2
The activity and the products distribution yields of methyl oleate
selfꢀmetathesis over MTOꢀbased catalysts as shown in Table 2
were reached after 90 min of reaction. This long reaction time is
considered sufficient to reach the chemical and thermodynamic
reaction equilibria of methyl oleate selfꢀmetathesis. However, it is
possible that this time would be finally shorter than can really
appear in order to achieve such equilibria. In fact, for similar
reaction conditions, this equilibrium time is dependent on how
quick is the reaction for a given catalyst. This cannot be
confirmed if a kinetic study is not carried out. For that purpose,
the selfꢀmetathesis of methyl oleate is kinetically evaluated at the
7
7
8
8
9
9
0
5
0
5
0
5
25
Scheme 1 Reaction pathway of methyl oleate self-metathesis.
Catalytic activity for methyl oleate selfꢀmetathesis over
heterogeneous MTOꢀbased catalysts supported on organized or wormholeꢀ
like mesoporous alumina.
o
investigated temperature of 45 C as depicted in Figure 14. It is
clearly shown that the metathesis equilibrium was reached early
far from 90 min of reaction for MTOꢀbased catalysts supported on
Table
2
30
both types of ZnCl ꢀmodified mesoporous alumina where high
2
methyl oleate conversions were obtained.
d
a
a
a
a
a
b
c
Catalyst
1
2
3
4
5
Conv DMP References
Cata #1 15.5 14.3 35.0 9.1 4.3 78.2
Cata #2 29.3 8.5 32.9 12.9 4.6 88.2
Cata #3 31.8 8.9 30.2 14.1 2.4 87.4
Cata #4 24.4 8.3 34.3 16.2 3.6 86.7
43.2 This work
55.3 This work
57.2 This work
52.4 Pillai et al.
1.0 Pillai et al.
5
5, 56
5, 56
5
Cata #5 0.2 0.3 1.4 0.2 0.3
2.4
a
The numbers appearing for the metathesis products
1
,
2
,
3
,
4
, and
5
are
expressed in terms of individual product yield (Yield
%) [Product ]/([Methyl oleate] –[Methyl oleate]
[Product ] is the molar concentration of the product i =1 to 5, and [Methyl
oleate] and [Methyl oleate]
i
), defined as: Yield
i
(
=
i
0
t
)*100, where
35
40
45
i
0
t
are the molar concentrations of methyl oleate
b
initially and at a given time t, respectively. Conv: Conversion, expressed
as Conv (%) = ([Methyl oleate]
0
–[Methyl oleate]
t
)/Methyl oleate]
yield which is
and
0
*100;
c
DMP: Desired metathesis products
(1+2+4+5)
represented by the summation of the individuals yields of
1
,
2
,
4
5;
d
The investigated catalysts were 3 wt% MTO/ZnCl
and Aluminaꢀ11 in the case of Cata #1, Cata #2 and Cata #3,
respectively. Cata #4 consisted of 3 wt% MTO on ZnCl ꢀmodified
2
ꢀAluminaꢀ1, Aluminaꢀ
Fig. 14 Time-course profiles of methyl oleate self-metathesis over 3 wt%
2
1
00 MTO/ZnCl
like mesoporous Al
oleate; Desired metathesis products;
2
-Al
2
O
3
catalysts using highly ordered hexagonal and wormhole-
. Symbols: For ordered hexagonal Al : ■ Methyl
Methyl elaidate. For
2 3
O : □ Methyl oleate; ∆ Desired metathesis products; ○
2
2
O
3
2 3
O
▲
●
wormholeꢀlike mesoporous alumina, while Cata #5 was 3 wt% MTO on
wormholeꢀlike mesoporous alumina only.
wormhole-like Al
Methyl elaidate.
1
2
| Journal Name, [year], [vol], 00–00
This journal is © The Royal Society of Chemistry [year]

Page 13 of 16
Dalton Transactions
View Article Online
DOI: 10.1039/C4DT03630A
At the beginning of these equilibria, the yield of desired
metathesis products attained 54% and 47% after 60 min of
regular hexagonal pores obtained with highly organized
mesoporous alumina where the reactant and products diffusion
reaction when the catalysts were supported on hexagonal and 50 inside the porous network, in addition to reactant adsorption on
wormholeꢀlike mesoporous alumina, respectively. Moreover, with
hexagonal alumina, the MTOꢀbased catalyst seemed to be more
selective towards desired metathesis products where only 30% of
methyl elaidate, a nonꢀproductive metathesis product, was
the catalyst sites and desorption of the products from the catalyst
could be much easier and faster. The kinetics could be tightly
dependent on the textural mesoporosity available for transporting
substrates to the surface catalytic active sites. This suggestion
5
0
5
0
94
generated. Nevertheless, the time where the reaction begins to 55 corroborates that reported by Pauly et al. when they studied the
reach its equilibrium (onset equilibrium time) is much smaller
(~10 min) when hexagonal alumina was used in comparison to
wormholeꢀlike structured alumina (30 to 40 min), indicating a
huge activity of the MTOꢀbased catalyst supported on
hexagonally structured alumina which kinetically outperformed
the MTOꢀbased catalyst supported on wormholeꢀlike structured
alumina. Consequently, the new catalyst is more selective towards
the desired products. Indeed, the products 1, 2, 4, and 5 were
formed via productive metathesis pathway, whereas the product 3
was formed via nonꢀproductive metathesis pathway which is a
parallel unwanted side reaction. Frequently, the selectivity (S) can
be defined as the yield of desired products over the yield of all
undesired products. Then for the selfꢀmetathesis reaction, S can be
evaluated by:
effect the textural mesoporosity and the catalytic activity of
mesoporous molecular sieves with wormhole framework
structures.
1
1
2
Conclusions
6
0
A successful preparation of hexagonal wellꢀordered mesoporous
alumina and ZnCl ꢀmodified alumina in a simple, versatile, and
2
reproducible process was carried out by a bottomꢀup approach
through an evaporationꢀinduced selfꢀassembly technique, using
Pluronic F127 and different carboxylic acids and aluminum
precursors.
The synthesis allowed the formation of wellꢀorganized
mesoporous alumina materials with moderate to relatively large
BET surface areas and pore volumes, as well as interestingly
uniform mesoporous network. Carboxylic acid and aluminum
70 precursor choices are controlling parameters in this solꢀgel
synthesis. The complexation ability of carboxylic acids with Al
centers is the key factor, leading to successful wellꢀordered
assembly process. Zinc chloride enhanced greatly Lewis acidity of
the supports, while mainly AlꢀOꢀZnꢀCl species are formed on the
65
Yieldꢁofꢁdesiredꢁmetathesisꢁproductsꢁꢂꢃ, ꢄ, ꢅꢁandꢁꢆꢇ
Yieldꢁofꢁtheꢁꢁundesiredꢁꢁmetathesisꢁproductꢁꢂꢈꢇ
ꢀ
ꢁ =
ꢁ
Table 3 summarizes this selectivity for both MTOꢀbased catalysts
using hexagonal and wormholeꢀlike mesoporous aluminas.
2
5
7
8
8
5
0
5
surface as illustrated with XPS and MAS NMR analysis. Theses
ordered materials are potential candidates as catalysts supports for
selective heterogeneous catalytic reactions, such as metathesis of
functionalized bulky fatty molecules. The hexagonal alumina
exhibited faster kinetics than those obtained with wormholeꢀlike
alumina counterpart. This behavior could be attributed to better
mass transfer features of hexagonal mesoporous alumina. These
finding and the synthesis reported herein are key points to
Table 3 Selectivity towards the desired metathesis products for the
heterogeneous MTOꢀbased catalysts supported on hexagonal or
wormholeꢀlike mesoporous aluminas.
S
Catalysts
Cata #1
Cata #2
Cata #3
Cata #4
Cata #5
1.234
1.681
1.894
1.531
0.714
elaborate
a
promising strategy for the synthesis and
functionalization of various novel metalꢀdoped organized
supports. Moreover, they can pave the way to explore
opportunities for the largeꢀscale production of wide range of these
interesting organized modifiedꢀmesoporous materials as catalytic
supports.
3
3
4
4
0
5
0
5
Therefore, it is evident that the MTOꢀbased catalyst using
hexagonal mesoporous alumina is more selective towards the
desired metathesis products than that using wormholeꢀlike
alumina.
Even if the activity levels reached with both types of mesoporous
alumina materials were quite similar, the kinetics was drastically
improved with hexagonal mesoporous alumina compared to
wormhole like alumina. In our opinion this could be attributed to
the difference in the porous network structure of both alumina
materials which greatly influenced the mass transfer phenomena,
adsorption/desorption kinetics of the reactant (methyl oleate) as
well as the desorption of the reaction products. In other words, in
the case of wormholeꢀlike structure, the reactant will take much
9
0
Acknowledgments
The authors gratefully acknowledge the Natural Sciences and
Engineering Research Council of Canada (NSERC) and Canadian
Foundation for Innovation (CFI) who provided funds for this
research. Alain Adnot, Pierre Audet and Richard Janvier are
acknowledged for XPS characterization, MAS NMR analysis and
TEM measurements, respectively. The authors thank Dr. K. T.
Venkateswara Rao for his technical advices and for his kind
suggestions during the early stages of this project.
9
5
more time to adsorb and react on the catalytic sites as well as the 100
products to desorb from the catalyst pores. This is due to the
irregular and interconnected porous network characterizing a
wormholeꢀlike framework structure, in comparison to the more
This journal is © The Royal Society of Chemistry [year]
Journal Name, [year], [vol], 00–00 | 13

Dalton Transactions
Page 14 of 16
View Article Online
DOI: 10.1039/C4DT03630A
3
4.
S. M. Grant, A. Vinu, S. Pikus and M. Jaroniec, Colloids Surf.,
A, 2011, 385, 121ꢀ125.
Notes and references
1
2
3
4
.
.
.
.
C. Márquez‐Alvarez, N. Žilková, J. Pérez‐Pariente and J.
Čejka, Catal. Rev., 2008, 50, 222ꢀ286.
X. Jiang, N. Suzuki, B. P. Bastakoti, K. C. W. Wu and Y.
Yamauchi, Chem. Asian J., 2012, 7, 1713ꢀ1718.
B. P. Bastakoti, S. Ishihara, S.ꢀY. Leo, K. Ariga, K. C. W. Wu
and Y. Yamauchi, Langmuir, 2014, 30, 651ꢀ659.
X. Jiang, H. Oveisi, Y. Nemoto, N. Suzuki, K. C. W. Wu and
Y. Yamauchi, Dalton Trans., 2011, 40, 10851ꢀ10856.
A. Taguchi and F. Schüth, Microporous Mesoporous Mater.,
75 35.
36.
S. M. Morris, P. F. Fulvio and M. Jaroniec, J. Am. Chem. Soc.,
2008, 130, 15210ꢀ15216.
W. Cai, J. Yu, C. Anand, A. Vinu and M. Jaroniec, Chem.
Mater., 2011, 23, 1147ꢀ1157.
X. Zhao, Y. Zheng, Y. Zheng, Y. Zhan and X. Zheng, RSC
Adv., 2014, 4, 12497ꢀ12505.
Q. Sun, Y. Zheng, Z. Li, Y. Zheng, Y. Xiao, G. Cai and K.
Wei, Phys. Chem. Chem. Phys., 2013, 15, 5670ꢀ5676.
F. Huang, Y. Zheng, Z. Li, Y. Xiao, Y. Zheng, G. Cai and K.
Wei, Chem. Commun., 2011, 47, 5247ꢀ5249.
E. Moretti, M. Lenarda, L. Storaro, A. Talon, R. Frattini, S.
Polizzi, E. RodríguezꢀCastellón and A. JiménezꢀLópez, Appl.
Catal., B, 2007, 72, 149ꢀ156.
5
0
5
0
5
0
5
0
5
0
5
0
5
0
37.
80
38.
1
1
2
2
3
3
4
4
5
5
6
6
7
5.
39.
2
005, 77, 1ꢀ45.
W. Li, Q. Yue, Y. Deng and D. Zhao, Adv. Mater., 2013, 25,
129ꢀ5152.
6
7
.
.
85 40.
5
D. Zhao, Y. Wan and W. Zhou, in Ordered Mesoporous
Materials, WileyꢀVCH Verlag GmbH & Co. KGaA, 2013, pp.
41.
90 42.
43.
Q. Sun, Y. Zheng, Y. Zheng, Y. Xiao, G. Cai and K. Wei,
Scripta Mater., 2011, 65, 1026ꢀ1029.
5
ꢀ54.
8
.
L. Calvillo, V. Celorrio, R. Moliner, P. L. Cabot, I. Esparbé
and M. J. Lázaro, Microporous Mesoporous Mater., 2008, 116,
Z.ꢀX. Li, F.ꢀB. Shi, L.ꢀL. Li, T. Zhang and C.ꢀH. Yan, Phys.
Chem. Chem. Phys., 2011, 13, 2488ꢀ2491.
H. Oveisi, A. Beitollahi, M. Imura, C.ꢀW. Wu and Y.
Yamauchi, Microporous Mesoporous Mater., 2010, 134, 150ꢀ
156.
L. Xu, H. Zhao, H. Song and L. Chou, Int. J. Hydrogen
Energy, 2012, 37, 7497ꢀ7511.
Y. Bang, S. J. Han, J. G. Seo, M. H. Youn, J. H. Song and I. K.
Song, Int. J. Hydrogen Energy, 2012, 37, 17967ꢀ17977.
L. Kaluža, M. Zdražil, N. Žilková and J. Čejka, Catal.
Commun., 2002, 3, 151ꢀ157.
T. Xiu, J. Wang and Q. Liu, Microporous Mesoporous Mater.,
2011, 143, 362ꢀ367.
M. A. R. Meier, J. O. Metzger and U. S. Schubert, Chem. Soc.
Rev., 2007, 36, 1788ꢀ1802.
A. H. Hoveyda and A. R. Zhugralin, Nature, 2007, 450, 243ꢀ
251.
J. C. Mol, Green Chemistry, 2002, 4, 5ꢀ13.
R. H. A. Bosma, G. C. N. Van Den Aardweg and J. C. Mol, J.
Organomet. Chem., 1983, 255, 159ꢀ171.
R. Spronk and J. C. Mol, Appl. Catal., 1991, 76, 143ꢀ152.
R. Buffon, A. Choplin, M. Leconte, J. M. Basset, R. Touroude
and W. A. Herrmann, J. Mol. Catal., 1992, 72, L7ꢀL10.
R. Buffon, A. Auroux, F. Lefebvre, M. Leconte, A. Choplin, J.
M. Basset and W. A. Herrmann, J. Mol. Catal., 1992, 76, 287ꢀ
295.
S. K. Pillai, S. Hamoudi and K. Belkacemi, Appl. Catal., A,
2013, 455, 155ꢀ163.
S. K. Pillai, S. Hamoudi and K. Belkacemi, Fuel, 2013, 110,
32ꢀ39.
2
92ꢀ298.
9.
C. T. Kresge, M. E. Leonowicz, W. J. Roth, J. C. Vartuli and J.
S. Beck, Nature, 1992, 359, 710ꢀ712.
1
0.
J. S. Beck, J. C. Vartuli, W. J. Roth, M. E. Leonowicz, C. T.
Kresge, K. D. Schmitt, C. T. W. Chu, D. H. Olson and E. W.
Sheppard, J. Am. Chem. Soc., 1992, 114, 10834ꢀ10843.
D. Zhao, J. Feng, Q. Huo, N. Melosh, G. H. Fredrickson, B. F.
Chmelka and G. D. Stucky, Science, 1998, 279, 548ꢀ552.
R. Schmidt, M. Stöcker and O. Henrik Ellestad, in Studies in
Surface Science and Catalysis, eds. B. Laurent and K. Serge,
Elsevier, 1995, vol. Volume 97, pp. 149ꢀ156.
95 44.
45.
11.
46.
1
2.
100
47.
48.
13.
F. Kleitz, S. Hei Choi and R. Ryoo, Chem. Commun., 2003,
2
136ꢀ2137.
R. Ryoo, S. H. Joo, M. Kruk and M. Jaroniec, Adv. Mater.,
001, 13, 677ꢀ681.
1
1
4.
5.
105 49.
2
S. Jun, S. H. Joo, R. Ryoo, M. Kruk, M. Jaroniec, Z. Liu, T.
Ohsuna and O. Terasaki, J. Am. Chem. Soc., 2000, 122, 10712ꢀ
50.
51.
1
0713.
1
6.
P. Yang, T. Deng, D. Zhao, P. Feng, D. Pine, B. F. Chmelka,
G. M. Whitesides and G. D. Stucky, Science, 1998, 282, 2244ꢀ
110 52.
53.
2
246.
17.
P. Yang, D. Zhao, D. I. Margolese, B. F. Chmelka and G. D.
Stucky, Nature, 1998, 396, 152ꢀ155.
Y. Noda, B. Lee, K. Domen and J. N. Kondo, Chem. Mater.,
54.
1
1
2
2
8.
9.
0.
1.
115
2
008, 20, 5361ꢀ5367.
55.
G. J. d. A. A. SolerꢀIllia, C. Sanchez, B. Lebeau and J. Patarin,
Chem. Rev., 2002, 102, 4093ꢀ4138.
S. Inagaki, S. Guan, T. Ohsuna and O. Terasaki, Nature, 2002,
56.
120 57.
58.
4
16, 304ꢀ307.
Y. Yamauchi, N. Suzuki and T. Kimura, Chem. Commun.,
009, 5689ꢀ5691.
S. K. Pillai, A. Abidli and K. Belkacemi, Appl. Catal., A, 2014,
479, 121ꢀ133.
E. P. Barrett, L. G. Joyner and P. P. Halenda, J. Am. Chem.
Soc., 1951, 73, 373ꢀ380.
2
22.
H. Oveisi, X. Jiang, M. Imura, Y. Nemoto, Y. Sakamoto and Y.
Yamauchi, Angew. Chem. Int. Ed., 2011, 50, 7410ꢀ7413.
K. Niesz, P. Yang and G. A. Somorjai, Chem. Commun., 2005,
59.
125 60.
61.
R. B. Anderson, J. Catal., 1964, 3, 50ꢀ56.
2
2
2
3.
4.
5.
B. C. Lippens and J. H. de Boer, J. Catal., 1965, 4, 319ꢀ323.
J. T. Kloprogge, L. V. Duong, B. J. Wood and R. L. Frost, J.
Colloid Interface Sci., 2006, 296, 572ꢀ576.
J. F. Moulder, W. F. Stickle, P. E. Sobol and K. D. Bomben,
Handbook of X-ray Photoelectron Spectroscopy: A Reference
Book of Standard Spectra for Identification and Interpretation
of XPS Data, Physical Electronics, PerkinꢀElmer Corp, 1992.
D. Briggs and P. Seah, Practical Surface Analysis: Auger and
X-ray photoelectron spectroscopy, John Wiley & Sons, first
edition 1983, second edition 1990.
D. A. Shirley, Phys. Rev. B: Condens. Matter Mater. Phys.,
1972, 5, 4709ꢀ4714.
D. Fenzke, D. Freude, T. Fröhlich and J. Haase, Chem. Phys.
Lett., 1984, 111, 171ꢀ175.
S. Hayashi and K. Hayamizu, Bull. Chem. Soc. Jpn., 1989, 62,
2429ꢀ2430.
R. J. Motekaitis and A. E. Martell, Inorg. Chem., 1984, 23, 18ꢀ
23.
1
986ꢀ1987.
Q. Liu, A. Wang, J. Xu, Y. Zhang, X. Wang and T. Zhang,
Microporous Mesoporous Mater., 2008, 116, 461ꢀ468.
Q. Yuan, A.ꢀX. Yin, C. Luo, L.ꢀD. Sun, Y.ꢀW. Zhang, W.ꢀT.
Duan, H.ꢀC. Liu and C.ꢀH. Yan, J. Am. Chem. Soc., 2008, 130,
62.
130
3
465ꢀ3472.
2
2
2
6.
7.
8.
Q. Wu, F. Zhang, J. Yang, Q. Li, B. Tu and D. Zhao,
Microporous Mesoporous Mater., 2011, 143, 406ꢀ412.
F. Huang, Y. Zheng, G. Cai, Y. Zheng, Y. Xiao and K. Wei,
Scripta Mater., 2010, 63, 339ꢀ342.
F. Huang, Y. Zheng, Y. Xiao, Y. Zheng, G. Cai and K. Wei,
Mater. Lett., 2011, 65, 244ꢀ246.
Q. Sun, Y. Zheng, Z. Li, Y. Zheng, Y. Xiao and G. Cai, Mater.
Lett., 2012, 84, 44ꢀ47.
X.ꢀL. Zheng, Q.ꢀP. Sun, F. Liu, Y. Zheng and J.ꢀB. Weng, J.
Porous Mater., 2014, 21, 819ꢀ825.
63.
135 64.
65.
29.
66.
140
3
0.
67.
3
1.
Z. Ramli and R. Saleh, AIP Conf. Proc., 2009, 1136, 26ꢀ30.
S. M. Grant and M. Jaroniec, J. Colloid Interface Sci., 2012,
32.
3.
68.
69.
M. Kruk and M. Jaroniec, Chem. Mater., 2001, 13, 3169ꢀ3183.
G. J. d. A. A. SolerꢀIllia and C. Sanchez, New J. Chem., 2000,
24, 493ꢀ499.
3
67, 129ꢀ134.
3
S. M. Grant and M. Jaroniec, J. Mater. Chem., 2012, 22, 86ꢀ92.
145
1
4
| Journal Name, [year], [vol], 00–00
This journal is © The Royal Society of Chemistry [year]

Page 15 of 16
Dalton Transactions
View Article Online
DOI: 10.1039/C4DT03630A
7
0.
Q. Huo, D. I. Margolese, U. Ciesla, P. Feng, T. E. Gier, P.
Sieger, R. Leon, P. M. Petroff, F. Schuth and G. D. Stucky,
Nature, 1994, 368, 317ꢀ321.
7
7
7
1.
2.
3.
T. Seki and M. Onaka, in Advanced Nanomaterials, Wileyꢀ
VCH Verlag GmbH & Co. KGaA, 2010, pp. 481ꢀ521.
J. van den Brand, P. C. Snijders, W. G. Sloof, H. Terryn and J.
H. W. de Wit, J. Phys. Chem. B, 2004, 108, 6017ꢀ6024.
R. Lizárraga, E. Holmström, S. C. Parker and C. Arrouvel,
Phys. Rev. B: Condens. Matter Mater. Phys., 2011, 83, 094201.
B. R. Strohmeier and D. M. Hercules, J. Catal., 1984, 86, 266ꢀ
5
0
5
0
5
0
5
0
5
0
1
1
2
2
3
3
4
4
5
74.
2
79.
S. W. Gaarenstroom and N. Winograd, J. Chem. Phys., 1977,
7, 3500ꢀ3506.
7
7
7
7
5.
6.
7.
8.
6
R. D. Seals, R. Alexander, L. T. Taylor and J. G. Dillard,
Inorg. Chem., 1973, 12, 2485ꢀ2487.
L. S. Dake, D. R. Baer and J. M. Zachara, Surf. Interface Anal.,
1
989, 14, 71ꢀ75.
G. E. Muilenbenger, Handbook of X-Ray Photoelectron
Spectroscopy: Perkin-Elmer Corporation Minnesota, 1979.
S. A. Schmidt, N. Kumar, A. Shchukarev, K. Eränen, J.ꢀP.
Mikkola, D. Y. Murzin and T. Salmi, Appl. Catal., A, 2013,
79.
4
68, 120ꢀ134.
E. C. Decanio, J. C. Edwards and J. W. Bruno, J. Catal., 1994,
48, 76ꢀ83.
T. Tovar, S. M. Stewart and S. Scott, Top. Catal., 2012, 55,
30ꢀ537.
8
0.
1
81.
5
8
8
2.
3.
C. E. Bronnimann, I. S. Chuang, B. L. Hawkins and G. E.
Maciel, J. Am. Chem. Soc., 1987, 109, 1562ꢀ1564.
C. Boissière, L. Nicole, C. Gervais, F. Babonneau, M.
Antonietti, H. Amenitsch, C. Sanchez and D. Grosso, Chem.
Mater., 2006, 18, 5238ꢀ5243.
8
4.
J. F. Stebbins, Handbook of Physical Constants, V. 2; Ahrens,
T. J., Ed.; American Geophysical Union: Washington DC,
1
995.
85.
J. A. Wang, X. Bokhimi, A. Morales, O. Novaro, T. López and
R. Gómez, J. Phys. Chem. B, 1998, 103, 299ꢀ303.
J. Čejka, Appl. Catal., A, 2003, 254, 327ꢀ338.
8
8
6.
7.
L. Fu, X. Li, M. Liu and H. Yang, J. Mater. Chem. A, 2013, 1,
1
4592ꢀ14605.
H. J. Kim, H. C. Lee and J. S. Lee, J. Phys. Chem. C, 2007,
11, 1579ꢀ1583.
88.
1
8
9
9.
0.
M. Liu and H. Yang, Colloids Surf., A, 2010, 371, 126ꢀ130.
J.ꢀL. Blin, A. Léonard, Z.ꢀY. Yuan, L. Gigot, A. Vantomme, A.
K. Cheetham and B.ꢀL. Su, Angew. Chem. Int. Ed., 2003, 42,
2872ꢀ2875.
P. C. Hidber, T. J. Graule and L. J. Gauckler, J. Am. Ceram.
Soc., 1996, 79, 1857ꢀ1867.
D. A. Thornton, Coord. Chem. Rev., 1990, 104, 173ꢀ249.
A. Salameh, A. Baudouin, J.ꢀM. Basset and C. Copéret, Angew.
Chem. Int. Ed., 2008, 47, 2117ꢀ2120.
9
1.
9
9
2.
3.
9
4.
T. R. Pauly, Y. Liu, T. J. Pinnavaia, S. J. L. Billinge and T. P.
Rieker, J. Am. Chem. Soc., 1999, 121, 8835ꢀ8842.
This journal is © The Royal Society of Chemistry [year]
Journal Name, [year], [vol], 00–00 | 15

Dalton Transactions
Page 16 of 16
View Article Online
DOI: 10.1039/C4DT03630A
Graphical Abstract
Synthesis, characterization and insights into stable and well organized hexagonal
mesoporous zinc-doped alumina as promising metathesis catalysts carrier
a,b
a,b
a,b
Abdelnasser Abidli, Safia Hamoudi and Khaled Belkacemi*
ZnCl -modified hexagonal mesoporous alumina was successfully synthesized, yielding
2
Al-O-Zn-Cl species with promising properties for supporting MTO towards methyl oleate
self-metathesis.