Molybdenum carbonyl grafted onto silicate intercalated cobalt-aluminum hydrotalcite: A new potential catalyst for the hydroformylation of octene

Article abstract of DOI:10.1016/j.catcom.2015.02.024

We present the first example of molybdenum carbonyl grafted on diaminosiloxane-functionalized cobalt-aluminum hydrotalcite (CA-HTSi-DA-Mo) as a promising catalyst for the hydroformylation of olefins. The catalyst showed 80% conversion with selective formation of branched aldehyde. About 70% of the catalytic activity retains even after three cycles.

Full text of DOI:10.1016/j.catcom.2015.02.024

Molybdenum carbonyl grafted onto silicate intercalated cobalt-aluminum
hydrotalcite: A new potential catalyst for the hydroformylation of octene
Ayyamperumal Sakthivel, Nihar Ranjan Mahato, Thangaraj Baskaran,
Jayaraj Christopher
PII:
DOI:
Reference:
S1566-7367(15)00089-8
doi: 10.1016/j.catcom.2015.02.024
CATCOM 4241
To appear in:
Catalysis Communications
Received date:
Revised date:
Accepted date:
17 October 2014
16 February 2015
20 February 2015
Please cite this article as: Ayyamperumal Sakthivel, Nihar Ranjan Mahato, Thangaraj
Baskaran, Jayaraj Christopher, Molybdenum carbonyl grafted onto silicate intercalated
cobalt-aluminum hydrotalcite: A new potential catalyst for the hydroformylation of
octene, Catalysis Communications (2015), doi: 10.1016/j.catcom.2015.02.024
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ACCEPTED MANUSCRIPT
Molybdenum carbonyl grafted onto silicate intercalated cobalt-
aluminum hydrotalcite: A new potential catalyst for the
hydroformylation of octene
Ayyamperumal Sakthivel,*a Nihar Ranjan Mahatoa¥ Thangaraj Baskaran,a¥ Jayaraj Christopher,b
a Department of Chemistry, Inorganic Materials and Catalysis Laboratory, University of Delhi, Delhi
110007. bIndian Oil Corporation Ltd, R&D Centre, Faridabad-121007.
Email: sakthiveldu@gmail.com / asakthivel@chemistry.du.ac.in
Abstract
We present the first example of molybdenum carbonyl grafted on diaminosiloxane-functionalized
cobalt-aluminum hydrotalcite (CA-HTSi-DA-Mo) as a promising catalyst for the hydroformylation of
olefins. The catalyst showed 80 % conversion with selective formation of branched aldehyde. About 70
% of the catalytic activity retains even after three cycles.
Keywords: Molybdenum carbonyl, Hydroformylation, Hydrotalcite, Olefin
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1. Introduction
Molybdenum hexacarbonyl (Mo(CO)6) has shown as potential catalyst in various processes such
as olefin metathesis [1,2], olefin hydrogenation [3], ketone hydrosilylation and hydrogenation [4,5].
Furthermore, molybdenum carbonyl complexes used as precursors to get molybdenum (VI) oxo
catalysts, which have been reported to be efficient agents for the epoxidation of olefins, and have been
extensively studied [6-14]. Importantly, Mo(CO)6 has the ability to exchange one or more CO ligands
with other donor ligands. The dehydroxylated environment zero-valent Mo in Mo(CO)6 provides
active sites for hydrogenation; thus, it is used as a catalyst for hydrogenation and hydrosilyation
reactions [15-16]. Mo species in zero-valent and higher oxidation states have a high affinity for olefin
groups and are thus able to catalyze hydrogenation, hydrosilylation, oxidation, and metathesis
processes. Larhed et al. used Mo(CO)6 as source of CO for carbonylation in the presence of palladium
catalysts [17-18]. Furthermore, it has been shown that hetero-bimetallic H-bonded Rh-Mo complexes
show cooperative activity in the hydroformylation of cycopentene [19].
Hydroformylation is an important industrial process for the production of aldehydes from alkenes
[20], and is generally carried out industrially using a cobalt tetracarbonylhydride [HCo(CO)4]-based
catalyst [21-23], or with rhodium-based catalysts [24]. However, cobalt-based catalysts are limited
owing to the high syn-gas pressure required in their use; rhodium-based catalysts are relatively
expensive.
Thus, the development of alternative catalyst that requires less extreme conditions and is less
expensive with attractive prospect [19]. Mo(CO)6 possesses good thermal stability and shows excellent
catalytic activity and selectivity for hydroformylation when it is combined with other metal carbonyl
species [25]. Furthermore, heterogeneous and supported catalysts show improved activity in Fischer-
Tropsch (FT) and oxo processes with better catalyst life and selectivity. Consequently, numerous
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support materials have been utilized for the immobilization of homogeneous catalysts, and their
application in hydroformylation has been studied. Among these various supports, hydrotalcites have
gained substantial attention owing to their excellent anion-exchange properties and controllable
textural features, allowing the intercalation of various organometallic complexes into the interlayer.
Hydrotalcite have been shown as promising catalytic supports for several organic reactions [26-32]. It
is speculated that the introduction of (Mo(CO)6) into a silicate intercalated cobalt aluminum
hydrotalcite (CA-HTSi) support could result in an active species of Mo in the zero-valent state, and the
cobalt species present in the HT framework might generate a new class of heterogeneous cooperative
catalysis for the olefin hydroformylation. To the best of our knowledge, the utilization of Mo(CO)6
alone as a catalyst for the hydroformylation of olefin, either in homogeneous or supported forms, has
not been reported.
The object of the present work is to gain insight into the use of HT-supported molybdenum
carbonyl catalysts in the hydroformylation of olefins. We report the first example of Mo(CO)6
incorporation into a diaminosilane-functionalized CA-HTSi support and shown as promising catalyst
for the hydroformylation of olefins.
2. Experimental Section
2.1. Preparation protocol
All the catalyst preparation and grafting procedure were carried out using standard Schlenk
techniques under nitrogen atmosphere. Solvents were dried by standard procedures (THF, toluene with
Na/benzophenone ketyl; CH2Cl2 with CaH2), distilled under nitrogen and kept over 4 Å molecular
sieves. Silicate intercalated cobalt-aluminum hydrotalcite (CA-HTSi) material was synthesis as per
procedure described in literature [30].
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The grafting of molybdenum carbonyl was carried out by treating an as-prepared CA-HTSi sample
with N-[3-(trimethoxysilyl) propyl]ethylenediamine, followed by reaction with Mo(CO)6 [33].
Different amount of molybdenum carbonyl grafted on silicate intercalated cobalt aluminium
hydrotalcite (CoAl-HTSi) was in-situ carried out by two-step procedure. First, CoAl-HTSi support (1
o
g) was pre-activated at 110 C for overnight under vacuum in a Schlenk round bottom flask, then it
was cooled to room temperature and introduced calculated amount (4 mmol) of N-[3-
(Trimethoxysilyl) propyl] ethylenediamine using dry toluene (30 ml/g support) refluxed for 24 h in
nitrogen atmosphere. Then the reaction mixture was cooled down to room temperature and toluene
was removed by vacuum filtration. The excess diamine was removed by washing with
dichloromethane for several times and the solid was dried using vacuum pump and represented as CA-
HTSi-DA. The various quantity such as 1, 2, 3 and 4 mmol of Mo(CO)6 was introduced [33] in toluene
/ THF on the surface of above prepared CA-HTSi-DA materials to get molybdenum carbonyl grafted
o
materials. The resultant mixture was allowed to stir at 80 C for 4h. The final materials were filter in
N2 atmosphere, washed in dichloromethane and dried in vacuum.
A pictorial representation of the immobilization of Mo(CO)6 on diaminosilane-modified CA-HTSi
(CA-HTSi-DA) is shown in Scheme 1. The samples obtained from the reactions of 1, 2, 3, and 4 mmol
of Mo(CO)6 with 1 g of support are represented as CA-HTSi-DA-1Mo, CA-HTSi-DA-2Mo, CA-
HTSi-DA-3Mo, and CA-HTSi-DA-4Mo, respectively.
2.2. Characterization
Powder XRD was performed to determine the bulk crystalline phases of the materials using a 8 KW
XRD Rigaku, Japan with Cu-Kα radiation (λ = 1.54184 Å). The diffraction patterns were recorded in
the 2θ range 3-15 and 5–70°, with a scan speed and step size of 0.5°/min and 0.02°, respectively. FT-
IR spectra were obtained in the range the range 400–4000 cm-1 using KBr pellets (BRUKER,
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TENSOR 27 FT-IR Spectrometer). The textural properties (BET surface area, micropore area (t-plot
method), BJH average pore volume) of the samples were derived from N2 adsorption–desorption
measurements carried out at −196 °C out using an automatic micropore physisorption analyzer
(Micrometrics ASAP 2020, USA) after the samples were degassed at 110 °C for at least 8 h under 10-
3Torr pressure prior to each run. The solid-state NMR experiment was carried out on a Bruker
AVANCE 400 narrow bore magnet spectrometer equipped with a superconducting magnet with a field
of 9.4 T using a 4 mm double resonance cross-polarized magic angle spinning (CP-MAS) probe
operating at resonating frequencies of 79.4 MHz. The sample was packed in 4 mm zirconia rotors and
subjected to a spinning speed of 5kHz: single pulse experiment with pulse duration of 4 s and a
relaxation delay time of 5 s were used with 2000 number of scans. The chemical shift values are
expressed with respect to TMS. Thermogravimetry-analysis (TGA) was carried out in a Thermal
Analyzer (Model-2950, TA Instruments, and USA). About 5–10 mg of the sample was taken in the
o
-1
o
platinum pan and heated in air at the heating rate of 10 C min up to 800 C. The amount of
molybdenum content in the sample was determined by inductively coupled plasma – atomic emission
spectroscopy (ICP – AES; Model: Optima 8300, Make: Perkin Elmer). The sample was obtained by
digesting CA-HTSi-DA-Mo materials with equal volume (6 ml) mixture containing H2O2, ammonium
hydroxide and ethanol. The resultant mixture was filter by whatman filter paper and the filtrate was
made into 100 ml. The solution was aspirated into plasma of ICP-AES equipment and concentration of
Mo in the samples was obtained with respect to standard solution of Mo (Emerck, Germany).
2.3. Catalytic study
The hydroformylation reactions were performed in 100 ml stainless steel autoclave (Amar
Equipment India Pvt. Ltd). In a typical experiment, required amount of catalyst (0.15 gm), 1-octene
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(0.0191 M; 3 ml) and solvent (3 ml) were charged into the reactor under nitrogen atmosphere and the
stirrer was adjusted to (250) rpm. The reactor was purged with CO and H2 (1:1) mixture with desired
pressure and the temperature reached to preferred temperature with constant stirring. After the reaction
completion, the stirrer was stopped, reactor was cooled to room temperature with water circulation,
depressurized and the product was collected and were analyzed using gas chromatography equipped
with FID (Agilent 7890A Series) connected to a HP-5 capillary column (30 m; HP-5). Further, the
different products such as isomerized, hydrogenated and hydroformylated (Scheme 2) were confirmed
using GC-MS (Agilent). Conversion of 1-octene and also the selectivity of the products were
calculated based on the following formula
Oi + OH + OCHO + OOH
Conversion of 1-octene =
O1 + Oi + OH + OCHO + OOH
OCHO
Selectivity of aldehyde products =
Oi + OH + OCHO + OOH
Where O1, Oi, OH, OCHO, and OOH are mole of unreacted 1-octene, octene isomers (excluding 1-
octene), hydrogenated octene, hydroformylated octene and alcohol in the products respectively.
3. Results and Discussion
Powder XRD patterns of pure CA-HTSi and the Mo(CO)6 grafted samples viz., CA-HTSi-DA-
1Mo and CA-HTSi-DA-3Mo are shown in Fig. 1. All the samples exhibit broad reflections around 2θ
of 10°–16° and 25°–32°, characteristic of the (003) and (006) planes of an HT-layered structure [26-
32]. The parent CoAl-HT shows an additional peak (Fig. 1a) which is characteristic of (0 0 1) plane
and it disappeared upon the introduction of bulk diammine functional group and Mo(CO)6, owing to
filling of guest molecules in the interlayer space. The presence of diaminosilane and Mo(CO)6
between the interlayer of CoAl-HT clearly evident from decrease in unit cell parameter along “c” axis
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(Table 1). Further, the broadening of the XRD reflections in the molybdenum-grafted samples is due to
the orientation of the interlayer species and the presence of siloxane functionality on the external
surface of the layered HT [26-32]. The absence of any XRD reflection corresponding to Mo(CO)6
even under maximum loading indicates the uniform distribution of grafted active molybdenum species
onto the diamino functionality present on the surface of hydrotalcite. The broadening of the XRD
reflection may also be due to the decrease in the particle sizes of the support owing to the presence of
a bulk silicate host on the interlayer [29-32].
FT-IR spectra of CA-HTSi, and molybdenum carbonyl grafted samples are depicted in Fig. 2. All
samples showed vibrational bands around 1081 and 800 cm‒ 1 due to asymmetric and symmetric
vibrations of interlayer silicate species. Absence of band around 1370 cm-1 corresponds carbonate ion
for the CA-HTSi-DA-Mo samples clearly evidence that the interlayer are completely filled with
silicate anions and silane linker which in turn connected on this interlayer silicate [29-31]. A shoulder
peak appearing at approximately 2850 cm‒ 1in the spectrum of the CA-HTSi-DA sample is due to the
ethane (C2H4) functionality present between (NH) groups. The CA-HTSi-DA-Mo samples showed a
new weak broad band around 2010, 1986, and 1930 cm‒ 1 respectively, which can be assigned to the
(CO) group vibrations of the in situ grafted molybdenum carbonyl species on the surface of CA-HTSi-
DA [6,11,12]. The relative intensity of the above vibrational band increases with increase in
molybdenum carbonyl loading.
29
In order to confirm the heterogenization of molybdenum carbonyl on CA-HTSi, SiMAS-NMR
analysis was performed on CA-HTSi-DA-3Mo, and the result is displayed in Fig. 3. CA-HTSi-DA-
3Mo showed resonance peaks at -101.6, -90.8, and -82 ppm, corresponding to the presence of silicon
in different environments on the hydrotalcite framework, such as Q3, Q2, and Q1 sites, respectively
[Qn= Si(OSi)n(OM)4‒ n, where M = H, Al, or Co]. The additional broad shoulder peaks evident around
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the region varying from -45 to -25 ppm correspond to organosilica species, which come from N-[3-
(trimethoxysilyl) propyl]ethylenediamine ligands connected to the surface silica species present on the
interlayer of HT. The textural properties of CA-HTSi and the Mo(CO)6-grafted samples are
summarized in Table 1. The BET surface areas of ligand-modified hydrotalcite and Mo(CO)6-grafted
samples are found to be lesser than the parent cobalt-aluminum hydrotalcite. The grafting of
molybdenum carbonyl through the diamine linker on the HT surface results in decreases the surface
area and pore volume [11, 12]. However, the interparticle pore size remains intact, indicating that the
support is stable even after high loading with Mo(CO)6. The estimated molybdenum content in various
CA-HTSi-DA-Mo samples by ICP-AES analysis is shown in Table 1. It is clear from the table that all
the samples shows similar Mo content to that of theoretical value indicates the molybdenum species
effectively anchored on the surface of diammine.
Hydroformylation of 1-octene using CA-HTSi-DA-Mo materials were systematically evaluated in
the liquid phase medium and the results are summarized in Table 2. The pure support CA-HTSi
showed about 40 % conversion. Though, the hydroformylated product had poor selectivity because the
olefin undergoes polymerization on the support surface. The introduction of diamine functionality on
the CoAlHT materials inhibits the hydroformylation, however, it favored the formation of olefin
isomerized product alone. On the other hand, the introduction of Mo(CO)6 moiety at lower
concentration (1mmol per gram of support) improves the octene conversion. The selectivity of
aldehyde was poor and a considerable amount of hydrogenated side-product was also observed. This
could be due to the presence of isolated molybdenum species on the catalyst has the ability to abstract
hydrogen and favour the formation of considerable amount of hydrogenated product [34-35]. Upon
increasing of the Mo(CO)6 loading increase in conversion of octene and reaches the maximum of
about 87–90%. The concentration of Mo(CO)6 loading in the range of 3–4 mmol per gram of support
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favors the maximum selectivity of hydroformylated products. The increase in loading of Mo(CO)6 on
the support favors the presence of active Mo species in the vicinity of divalent cobalt ions present in
the layer HT, which cooperatively help on enhance the selectivity of hydroformylation products (see
Scheme 3).
Importantly pure Mo(CO)6 doesn’t show any hydroformylation activity. Thus it supports the co-
operative mechanism between cobalt species present in hydrotalcite framework and molybdenum
carbonyl present on the surface diammine, which may lead to the formation of the hydroformylated
product with 75–80 % of selectivity and about 8–9 % of alcohol side-product which appeared in all
cases. Linear aldehyde was obtained in about 20 % selectivity and the major products were identified
as branched aldehydes. In order to understand the co-operative mechanism, the reaction was studied
using physical mixture of CoAl-HT and Mo(CO)6, which doesn’t show any hydroformylated product,
rather it yield olefin isomerized and hydrogenated products. The presence of surface hydroxyl group
on CoAl-HT destabilize Mo(CO)6 and favored the formation of olefin isomerized and hydrogenated
products [34-35] by hydrogen abstraction.
Inorder to improve the hydroformylation product, the reaction was studied by varying the catalyst
amount (CoAl-HT-DA-3Mo) and the results are provided in Table 3. The increase in catalyst loading
increases the 1-octene conversion with the formation of exclusive hydroformylated products.
However, the product distribution of linear and branched aldehyde remains constant. The effect of
reaction time on 1-octene conversion, hydroformylated product selectivity and aldehyde distribution
over CoAl-HT-DA-3Mo are shown in Figure 4. In initial hours considerable amounts of olefin
isomerized products were formed. However, 1-octene conversion and hydroformylated products
increased steadily with increase in reaction time and reaches maximum around 7-8 h (Fig. 4 a).
Although the formation of linear aldehyde is predominant at initial hour, the branched aldehyde
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selectivity increases with the course of time (Fig. 4b). The decrease in pressure and temperature also
results in drastic decrease in hydroformylation of 1-octene were evident (Table 3).
The recyclability of the catalysts was studied under optimized conditions (T = 200 oC, P = 90 bar, 1-
octene (3 ml), CoAl-HT-DA-3Mo = 0.15 gm, t = 8 h), and the results are summarized in Table 4. It is
clear from the table that catalytic activity decreases drastically and reaches a minimum conversion of
about 16 % with the aldehyde selectivity of 6 %, after four cycles, which is due to the conversion of
molybdenum carbonyl species into oxo species when exposed to the atmosphere during the recycle
process. In order to preserve the active sites, attempts were made using dry toluene as solvent, and a
similar initial activity was observed. Importantly, the catalytic activity was about 77 % preserved even
after four cycles (see Table 4) with selective formation of hydroformylated products. The observed
decrease in the catalytic activity is due to the adsorption of reactant / product molecules on active sites
of the catalysts during the reaction. This is supported from TG-DTA analysis of spent catalyst (Fig. 5),
which showed about 35 % weight loss derived from decomposition of diammine functional group and
chemisorbed organics present on the surface. In addition N2 sorption analysis of used catalyst (Table 1)
further supports the above fact, where a drastic decrease in surface area and pore volume occurred
owing to accumulated organic, which accounts the observed decrease in conversion on recycle
catalyst.
Conclusion
The current study reveals that the Mo(CO)6 supported catalyst can be prospective alternative
hydroformylation catalyst when it is supported on cobalt based hydrotalcite materials. To the best of
our knowledge, this is the first report of a Mo(CO)6 based supported catalyst for the hydroformylation
of an olefin. Further details on mechanistic aspects and their importance for various olefins is the
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subject of interest will be explored.
Authors contributions
¥Authors Nihar Ranjan Mahato and Thangaraj Baskaran, contributed equally.
Acknowledgments
Authors extend their sincere thanks to CSIR (Project No: 01(2516)/11/EMR-II), India for the financial
supports. Authors also thank equipment grant by Humboldt Foundation and DU-PU/OBC
grant/Chemistry/2013/1993 on FT-IR facility. We thank Dr. T. Mohan das for his valuable scientific
discussion.
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Scheme 1. Pictorial representation of Mo(CO)6 grafted on diaminosiloxane-functionalized hydrotalcite
(CA-HTSi-DA).
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Scheme 2. Schematic representation of various products derived on CA-HTSi-DA-Mo catalysts.
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Scheme 3. Schematic representation of various products derived on CA-HTSi-DA-Mo catalysts.
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Figure Caption
Fig. 1. XRD patterns of CA-HTSi and molybdenum carbonyl grafted CA-HTSi materials (a) Lower
and (b) Wider angle pattern.
Fig. 2. FT-IR spectra of (a) CA-HTSi, (b) CA-HTSi-DA-1Mo, (c) CA-HTSi-DA-3Mo and (d) CA-
HTSi-DA-3Mo recycled.
Fig. 3.29SiMAS-NMR spectrum of CA-HTSi-DA-3Mo.
Fig. 4. Effect of reaction time on (a) 1-octene conversion and product selectivies on CA-HTSi-DA-
3Mo and (b) distribution of aldehyde on CA-HTSi-DA-3Mo
Fig. 5. TGA profile of (a) recycled CA-HTSi-DA-3Mo and (b) DTA profile of recycled CA-HTSi-DA-
3Mo.
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Fig. 1.Sakthivel et al.
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Fig. 2.Sakthivel et al.
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Fig. 3.Sakthivel et al.
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Fig. 4. Sakthivel et al.
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Fig. 5.Sakthivel et al.
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Table 1.Textural properties of CA-HTSi and CA-HTSi-DA-Mo materials.
BET
Surface
area
Mo
Unit Cell
parametres (A˚)
Pore
volume
(cm3 g‒ 1)
Inter
particules
size (nm)
content
(wt. %)‡
S. No.
Sample details
a
c
(m2g‒ 1)
332.1
210.7
213.4
162.2
166.7
1
2
3
4
5
CA-HTSi
1.23
0.95
0.80
0.70
0.66
13.3
13.8
13.7
13.6
13.2
--
--
2.50
--
24.3
--
CA-HTSi-DA
CA-HTSi-DA-1Mo
CA-HTSi-DA-2Mo
CA-HTSi-DA-3Mo
8
2.48
2.48
2.47
--
17.8
17.0
16.3
--
--
28
27
CA-HTSi-DA-3Mo-
recycled
6
17.3
0.07
0.73
10.3
12.3
7
CA-HTSi-DA-4Mo
205.2
32
--
--
‡ Calcuated based on ICP-AES analysis
23

ACCEPTED MANUSCRIPT
Table 2.Hydroformylation of 1-octene on CA-HTSi-DA-Mo catalysts.
Selectivity of products (%)‡
Distribution of
aldehyde (%)
Catalysts
Conv. (%)
H#
CHO#
OH#
linear
Branched
CA-HTSi
40.0
0.5
5.7
0.5
20
32
0.0
9.7
0.0
0.0
33.6
00.0
03.5
67.4
00.0
96.5
CA-HTSi-DA
CA-HTSi-DA-1Mo
51.0
21.3
CA-HTSi-DA-2Mo
CA-HTSi-DA-3Mo
CA-HTSi-DA-4Mo
82.0
87.0
91.0
2.3
0.0
0.8
71
85
81
8.7
7.5
9.6
22.5
20.3
20.5
77.5
79.7
79.5
†
Reaction conditions: Temperature = 200 oC; Pressure = 90 bar, 1-octene: 0.0191mole (3 ml), catalyst: 0.15 gm, time = 8 h.
#
#
#H = Hydrogenated product, CHO = Hydroformylated products, OH = Alcohol products; Remaining products are 1-
‡
octene isomerized products and trace amount of polymer.
Table 3.Effect of catalyst amount and temperature on hydroformylation of 1-octene on CoAl-HT-DA-
3Mo.
Temperature
Pressure
(bar)
Selectivity of products (%)
Distribution of
aldehyde (%)
(oC)
Catalyst
amount
(g)
Conv.
(%)
H#
CHO#
OH#
linear Branched
0.15
0.15
0.15
0.21
0.3
200
190
200
200
200
55.4
24.0
82.0
89.0
91.0
70
90
90
90
90
--
--
--
--
--
100
90.7
94.5
98.3
100
--
29.7
37.0
15.2
13.0
15.6
70.3
63.0
84.8
87.0
84.4
9.3
4.6
1.7
--
†
o
#
Reaction conditions: Temperature = 200 C; 1-octene: 0.0191mole (3 ml), time = 8 h, Solvent = Toluene (3 ml). H =
Hydrogenated product, CHO = Hydroformylated products, OH = Alcohol products.
24

ACCEPTED MANUSCRIPT
Table 4.Effect of solvent and recyclability of CA-HTSi-DA-Mo catalysts for Hydroformylation of 1-
octene.
Selectivity of products (%)‡
Distribution of
aldehyde (%)
Catalysts
Conv. (%)
H#
CHO#
OH#
linear
20.3
24.0
28.9
15.2
18.7
29.7
Branched
79.7
CA-HTSi-DA-3Mo‡
2nd cycle‡
87.0
40.8
16.0
82.0
76.2
63.2
0.0
2.0
8.7
--
85.0
94.0
5.8
7.5
4.0
1.3
4.6
3.8
0.0
76.0
4th cycle‡
71.1
CA-HTSi-DA-3Moγ
2nd cycleγ
94.5
96.2
100
84.8
--
81.3
4th cycleγ
--
70.3
†
Reaction conditions: Temperature = 200 oC; Pressure = 90 bar, 1-octene: 0.0191mole (3 ml), catalyst: 0.15 gm, time = 8 h,
Reaction carried out without solvent. H = Hydrogenated product, CHO = Hydroformylated products, OH = Alcohol
‡
#
products. γ Reaction studied in presence of toluene as solvent (3 ml). ‡ Remaining products are 1-octene isomerized products and
trace amount of polymer.
25

ACCEPTED MANUSCRIPT
Molybdenum carbonyl grafted onto silicate intercalated cobalt-
aluminum hydrotalcite: A new potential catalyst for the
hydroformylation of octene
Ayyamperumal Sakthivel,*a Nihar Ranjan Mahatoa Thangaraj Baskaran,a Jayaraj Christopher,b
a Department of Chemistry, Inorganic Materials and Catalysis Laboratory, University of Delhi, Delhi
b
110007. Indian Oil Corporation Ltd, R&D Centre, Faridabad-121007.
Email: sakthiveldu@gmail.com / asakthivel@chemistry.du.ac.in
First example of molybdenum carbonyl grafted on cobalt aluminum hydrotalcite (CA-HTSi-DA-Mo)
support is shown as promising catalyst for the hydroformylation of olefins.
Graphical abstract
26

ACCEPTED MANUSCRIPT
Molybdenum carbonyl grafted onto silicate intercalated cobalt-
aluminum hydrotalcite: A new potential catalyst for the
hydroformylation of octene
Ayyamperumal Sakthivel,*a Nihar Ranjan Mahatoa Thangaraj Baskaran,a Jayaraj Christopher,b
aDepartment of Chemistry, Inorganic Materials and Catalysis Laboratory, University of Delhi, Delhi
110007. bIndian Oil Corporation Ltd, R&D Centre, Faridabad-121007.
Email: sakthiveldu@gmail.com / asakthivel@chemistry.du.ac.in
Highlights
 First example of molybdenum carbonyl based catalyst for hydroformylation.
 Introduction of Mo(CO)6 on CoAl-HT help on cooperative mechanism.
 Heterogenization evident from 29Si MAS-NMR and FT-IR
 Catalyst showed 80 % olefin conversion and branched aldehyde selectivity.
27