Dynamic Release-Immobilization of a Homogeneous Rhodium Hydroformylation Catalyst by a Polyoxometalate Metal-Organic Framework Composite

Article abstract of DOI:10.1002/cctc.201500330

Thermal treatment of phosphotungstic acid (PTA)-MIL-101(Cr) composites in the presence of hydroformylation catalyst RhH(CO)(PPh₃)₃ leads to immobilization of the homogeneous Rh complex within the metal-organic framework (MOF) scaffold by coordination of PTA-Rh. The Rh complex-containing MOFs are tested in the hydroformylation of 1-octene in which PTA competes with CO during ligand association. In the presence of the carbonyl ligand, the Rh complex is released from the MOF and behaves as a homogeneous catalyst. Therefore, the product spectra and selectivities of the Rh complex-containing MOFs are similar to those of RhH(CO)(PPh₃)₃. Upon CO evacuation, Rh recoordinates to PTA, allowing for easy recycling of this new pseudo-heterogeneous catalyst.

Full text of DOI:10.1002/cctc.201500330

DOI: 10.1002/cctc.201500330
Communications
Dynamic Release–Immobilization of a Homogeneous
Rhodium Hydroformylation Catalyst by a Polyoxometalate
Metal–Organic Framework Composite
[
a, b]
[a]
[a]
[a]
[b]
Sina Sartipi,*[
Maria Jose Valero Romero, Elena Rozhko, Zhenyang Que, Hans A. Stil,
b]
[a]
[a]
Jan de With, Freek Kapteijn, and Jorge Gascon*
[
6]
Thermal treatment of phosphotungstic acid (PTA)-MIL-101(Cr)
composites in the presence of hydroformylation catalyst
RhH(CO)(PPh ) leads to immobilization of the homogeneous
MIL-101 family. MIL-101(Cr) is a stable MOF that consists of
approximately 30 Š diameter cavities with openings of 12 and
[
7]
16 Š. Polyoxometalate MOF composites based on MIL-101
3
3
[
6,8]
Rh complex within the metal–organic framework (MOF) scaf-
fold by coordination of PTA-Rh. The Rh complex-containing
MOFs are tested in the hydroformylation of 1-octene in which
PTA competes with CO during ligand association. In the pres-
ence of the carbonyl ligand, the Rh complex is released from
the MOF and behaves as a homogeneous catalyst. Therefore,
the product spectra and selectivities of the Rh complex-con-
taining MOFs are similar to those of RhH(CO)(PPh ) . Upon CO
have already been synthesized and used in catalysis.
Polyoxometalates are known to act as mild coordinating li-
gands in homogeneous catalysis, with a coordination strength
[
9]
lower than that of CO. Therefore, use of a phosphotungstic
acid (PTA)-MOF composite is considered for the dynamic coor-
dination of the RhH(CO)(PPh3)3 hydroformylation catalyst.
Indeed, the objective of this study, rather than immobilization
in its conventional sense, is to utilize MOFs as scaffolds for
handling and recycling the Rh-based hydroformylation catalyst
and to control its release in the reaction environment by CO
coordination: in the absence of CO the catalysts would stay co-
ordinated to the PTA-MOF solid but, at high CO pressure, the
homogenous complex would detach from the MOF. Removal
of CO from the environment should result in recoordination of
the catalyst to the PTA-MOF composite and enable recycling.
MIL-101(Cr) was prepared by hydrothermal synthesis. Two
PTA-MIL-101(Cr) composites were synthesized according to the
3
3
evacuation, Rh recoordinates to PTA, allowing for easy recy-
cling of this new pseudo-heterogeneous catalyst.
The hydroformylation reaction is largely applied in industry to
the production of aldehydes and other bulk chemical plat-
[
1]
forms. Although the state-of-the-art reaction is homogene-
ously catalyzed, many attempts have been made to immobilize
organometallic complexes for heterogeneous processes. To
this end, various organic and inorganic materials (e.g., SiO2,
Al O , polymers, activated carbon, and zeolites) have been
[
8a]
approach reported by Juan-AlcaÇiz et al. (Table 1). 70–75%
2
3
[2]
studied and functionalized in many ways. Although promis-
ing examples are reported with respect to catalyst per-
formance and recyclability, metal leaching is a common chal-
lenge to overcome in these systems. Moreover, dynamics of
the complex in terms of ligand dissociation–association and
Table 1. Textural and chemical properties of MIL-101(Cr) and PTA-MIL-
101(Cr) composites.
[a]
3
À1
[d]
Sample
S
V [m g
]
PTA
2
À1
[b]
[c]
[m g
]
total
micro
[wt%]
[3]
flexibility may be affected upon immobilization.
[e]
MIL-101(Cr)
15PTA@MIL-101(Cr)
30PTA@MIL-101(Cr)
2750
2100
1970
1.31
0.95
0.94
1.09
0.82
0.76
n.a.
15
30
Metal–organic frameworks (MOFs) hold unbeatable internal
volumes and adsorption capacities. Moreover, they can be uti-
lized as catalysts by various approaches, one being the use of
[
a] BET surface area calculated between relative pressures of 0.05 and
0.15; [b] Total pore volume calculated at 0.95 relative pressure; [c] Micro-
pore volume obtained from the t plot applied to the N isotherm; [d] PTA
[
4]
their empty space, often referred to as encapsulation. Al-
ready, a few examples have been reported in the literature on
2
[5]
loading calculated based on wt% W, obtained from inductively coupled
plasma optical emission spectrometry; [e] Not applicable.
the utilization of MOFs as hydroformylation catalysts. Encap-
sulation is more feasible in cage-type structures such as the
[
a] Dr. S. Sartipi, Dr. M. J. Valero Romero, Dr. E. Rozhko, Z. Que,
Prof. Dr. F. Kapteijn, Prof. Dr. J. Gascon
of surface area and the pore volume of MIL-101(Cr) were pre-
served after PTA introduction (Table 1 and Figure S3). XRD anal-
ysis confirmed the crystalline structure of MIL-101 (Figure S4).
Furthermore, the morphology of all samples was similar, as ob-
served in SEM micrographs (Figure S5). Energy-dispersive X-ray
spectroscopic mapping illustrated the homogeneous distribu-
tion of W in nPTA@MIL-101(Cr) (Figure S6; n=wt% PTA). As
Catalysis Engineering, Chemical Engineering Department
Delft University of Technology
Julianalaan 136, 2628BL, Delft (The Netherlands)
E-mail: j.gascon@tudelft.nl
[
b] Dr. S. Sartipi, Dr. H. A. Stil, Dr. J. de With
Shell Global Solutions International BV
Shell Technology Center Amsterdam
Grasweg 31, 1031 HW Amsterdam (The Netherlands)
[
8,10]
demonstrated previously
and in line with these characteri-
Supporting Information for this article is available on the WWW under
http://dx.doi.org/10.1002/cctc.201500330.
zation results, the employed synthesis approach led to a molec-
ChemCatChem 2015, 7, 3243 – 3247
3243
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Communications
ular distribution of Keggin units within the cavities of nPTA@-
MIL-101(Cr).
To immobilize RhH(CO)(PPh ) within the cavities of PTA-con-
3
3
taining MIL-101(Cr), 15PTA@MIL-101(Cr) and 30PTA@MIL-
À3
1
01(Cr) were heated in solutions of approximately 0.5”10
À3
and 1.5”10 m RhH(CO)(PPh3)3 in toluene, respectively, at
3
43 K. After filtration, weakly adsorbed Rh complex was re-
moved from the MOFs by two successive washing steps at the
same temperature. The RhH(CO)(PPh ) solution had a yellowish
3
3
color, characteristic of a Rh-PPh complex, as shown in Fig-
3
ure S1a. Although heating the solution at 343 K for 18 h did
not affect its appearance (not shown), it became colorless after
similar treatment in the presence of nPTA@MIL-101(Cr) and fil-
tration (Figure S1b). Inductively coupled plasma optical emis-
sion spectrometry revealed 0.25 and 0.88 wt% Rh in Rh-
Figure 2. X1-octene and product selectivities towards olefinic C8 isomers, nona-
nal (l-aldehyde), and branched (b)-aldehyde(s) vs. reaction time with
1
5PTA@MIL-101(Cr) and Rh-30PTA@MIL-101(Cr), respectively.
RhH(CO)(PPh
pressure, H
3 3
) catalyst. Reaction conditions: T=343 K, p=40 bar gauge
These values indicated full uptake from the precursor solu-
tions. The above-mentioned procedure led to 1.10 wt% Rh in
Rh@MIL-101(Cr).
3
3
2
/CO molar ratio=1, Vtoluene =14 cm , V1-octene =6 cm , n1-octe-
3
À1
ne =38.2 mmol, 1-octene/Rh=9.9”10 molmol , and agitation
speed=1000 rpm.
Diffuse-reflectance infrared Fourier transform (DRIFT) spectra
of MIL-101(Cr), nPTA@MIL-101(Cr), Rh-nPTA@MIL-101(Cr), and
RhH(CO)(PPh ) are shown in Figure 1. Characteristic IR vibra-
Under the conditions applied to the homogeneous system,
3
3
X1-octene reaches 100% after 4 h in absence of the MOF
(
Figure 2). The major reaction products are olefinic C8 isomers,
nonanal, 1-methyloctanal, and other branched C9 aldehydes.
After full conversion of the substrate, olefinic C8 isomers
convert into branched aldehydes. Therefore, with long reaction
times (Figure 2) and/or higher RhH(CO)(PPh ) concentrations
3
3
(
Figure S7), the linear-to-branched aldehyde ratio decreases.
The initial linear-to-branched aldehyde ratio with
RhH(CO)(PPh ) is 2.4–2.5, within the range reported for this
3
3
catalyst if no excess PPh ligand is added to the reaction mix-
3
[
9d,11]
ture.
The product spectra and selectivities of Rh-nPTA@-
MIL-101(Cr) are very similar to those of RhH(CO)(PPh ) at iso-
3
3
conversion conditions (entries 1 vs. 11 and 3 vs. 13, Table 2, for
Rh-30PTA@MIL-101(Cr) and RhH(CO)(PPh ) , respectively). Re-
3
3
covery of Rh-nPTA@MIL-101(Cr) after the first reaction run and
its reuse in a second cycle involves no significant loss of activi-
ty or change in selectivity (entries 7 and 8 for Rh-15PTA@MIL-
1
01(Cr) and entries 11 and 12 for Rh-30PTA@MIL-101(Cr)).
However, the reaction mixture, which was initially colorless,
turned slightly yellowish after the first run. This color change,
in addition to a product spectrum identical to that of
Figure 1. DRIFT spectra of MIL-101(Cr) (1), Rh@MIL-101(Cr) (2), 15PTA@MIL-
1
3
01(Cr) (3), Rh-15PTA@MIL-101(Cr) (4), 30PTA@MIL-101(Cr) (5), Rh-
0PTA@MIL-101(Cr) (6), and RhH(CO)(PPh (7). Samples 1, 3, and 5 were
RhH(CO)(PPh ) , pointed to leaching of the Rh complex during
3
)
3
3 3
treated at 473 K in a He atmosphere prior to collection of the DRIFT spectra
at RT.
the course of reaction. To verify this, the filtrate after separa-
tion of the used Rh-15PTA@MIL-101(Cr) (entry 7) was subjected
to hydroformylation reaction conditions similar to those in the
first run. Such a hot filtration experiment led to further conver-
sion of 1-octene (15%, entry 9).
À1
tional bands associated with PTA (e.g., 1083 cm , assigned to
À1
PÀO) and the Rh complex (1119 and 1973 cm ) are clearly visi-
ble in samples containing these elements. In the case of Rh-
It is well known that hydroformylation is initiated by ligand
À1
[3]
1
5PTA@MIL-101(Cr), the band at 1973 cm is hardly visible, at-
dissociation. In this case, PTA that is primarily coordinated to
tributed to the low Rh loading of this sample. On the other
Rh dissociates from the metal and must compete with CO for
ligand association in the reaction cycle. As Rh-carbonyl coordi-
nation is stronger, the Rh complex may be released from the
MOF after coordination with CO. Once CO is evacuated from
the reaction medium, the Rh complex recoordinates to the
PTA. This situation is feasible at the process termination step
À1
hand, MIL-101(Cr) bands at 1020 and 1163 cm , assigned to
the CrÀO vibration, are detected for all samples, indicating
conservation of the MOF structure.
1
-Octene conversion (X1-octene) and selectivities towards major
reaction products are presented in Figures 2 and S7, Table 2.
ChemCatChem 2015, 7, 3243 – 3247
www.chemcatchem.org
3244
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Communications
[a]
Table 2. Hydroformylation of 1-octene with different catalytic systems.
[e]
Entry
Catalytic
system
1-octene/Rh
[10 molmol
Reuse
[cycle no.]
X
[%]
1-octene
S [%]
l/b
3
À1
]
[b]
[c]
[d]
C8 olefins
l-aldehyde
b-aldehyde(s)
1
2
3
4
5
6
7
8
9
RhH(CO)(PPh
RhH(CO)(PPh
RhH(CO)(PPh
RhH(CO)(PPh
Rh@MIL101(Cr)
Rh@MIL101(Cr)
Rh-15PTA@MIL-101(Cr)
Rh-15PTA@MIL-101(Cr)
filtrate after 1st run
filtrate after 1st run
Rh-30PTA@MIL-101(Cr)
Rh-30PTA@MIL-101(Cr)
Rh-30PTA@MIL-101(Cr)
Rh-30PTA@MIL-101(Cr)
Rh-30PTA@MIL-101(Cr)
Rh-30PTA@MIL-101(Cr)
Rh-30PTA@MIL-101(Cr)
Rh-30PTA@MIL-101(Cr)
Rh-30PTA@MIL-101(Cr)
3
3
3
3
)
)
)
)
3
3
3
3
17.4
9.8
8.7
5.0
4.4
4.4
9.7
9.7
n.d.
n.d.
5.6
5.6
2.8
2.9
2.9
2.9
2.9
2.9
2.9
–
–
–
–
1
2
1
2
n.a.
n.a.
1
2
–
1
2
3
4
5
6
30
58
66
99
37
4
20
24
15
3
34
32
70
69
70
71
67
63
65
41
39
40
31
5
36
38
38
41
61
n.d.
33
38
40
34
40
36
43
37
25
26
28
30
30
15
15
15
19
22
n.d.
14
16
16
14
17
15
17
15
11
11
12
13
13
2.5
2.5
2.5
2.2
2.7
[f]
n.d.
40
n.d.
2.4
2.4
2.4
2.1
2.4
2.4
2.6
2.5
2.3
2.3
2.3
2.3
2.3
43
52
51
43
40
37
40
54
50
51
46
43
[
g]
[h]
[
i]
1
0
1
1
1
1
1
1
1
1
1
1
2
3
4
5
6
7
8
9
3
3
[
a] Reaction conditions: T=343 K, p=40 bar, t=2 h, H
2
/CO molar ratio=1, Vtoluene =14 cm , V1-octene =6 cm , n1-octene =38.2 mmol, and agitation speed=
1
000 rpm. [b] Olefinic C8 isomers; [c] Nonanal; [d] Branched aldehyde(s); [e] Linear-to-branched aldehyde ratio; [f] Not determined; [g] Before treating the
used MOF in the reaction mixture at 343 K for 18 h in an inert atmosphere (see the Experimental Section); [h] Not applicable; [i] After treating the used
MOF in the reaction mixture at 343 K for 18 h in an inert atmosphere (see the Experimental Section).
by substitution of syngas with inert gas. Moreover, complex
immobilization by nPTA@MIL-101(Cr) can be promoted by re-
heating the system at 343 K, immediately after the hydrofor-
mylation reaction in the same reactor. After such a process ter-
mination protocol (see the Experimental Section), the filtrate
after catalyst separation becomes colorless and gives negligi-
ble conversion upon exposure to hydroformylation reaction
conditions (entry 10, Table 2). To further confirm this hypothe-
sis, Rh-30PTA@MIL-101(Cr) catalyst was tested in successive hy-
droformylation reactions (entries 14–19 and Figure 3). Al-
though the regioselectivity decreased slightly after the first
cycle, both conversion and selectivity remained constant after
at least six reutilizations of the catalyst. These results indicated
that the Rh complex was recoordinated to the PTA after each
Figure 3. X1-octene and product selectivities towards olefinic C8 isomers, non-
anal (l-aldehyde), and (b)-branched aldehyde(s) vs. number of cycles with
hydroformylation reaction and CO evacuation, proving the re-
cyclability of this Rh complex-containing MOF.
Rh-30PTA@MIL-101(Cr) catalyst. Reaction conditions: T=343 K, p=40 bar,
t=2 h, H /CO molar ratio=1, n1-octene =38.2 mmol, 1-octene/
Rh=2.9”10 molmol , and agitation speed=1000 rpm.
Heteropolyacids are known to coordinate to Rh by their ter-
minal O atoms and thus can be employed as ligands for hydro-
2
3
À1
[9]
formylation catalysts. To further confirm that PTA acts as an
anchoring agent for complex immobilization in the PTA-MOF
composite, Rh@MIL-101(Cr) was studied in the hydroformyla-
tion reaction.
101(Cr) (entries 1–3, Table S1). At similar 1-octene/Rh ratios,
X1-octene is lower with Rh-nPTA@MIL-101(Cr) than with
RhH(CO)(PPh ) (entries 2 and 7, Table 2, respectively).
Compared to other systems, selectivity towards olefinic C8
isomers over Rh@MIL-101(Cr) is lower by a factor of 10
3
3
On the other hand, addition of MIL-101(Cr) or Cr(NO ) to
3
3
(
entry 5, Table 2). In spite of this improvement, which already
the reaction mixture with RhH(CO)(PPh ) results in the loss of
3 3
points to electronic modifications of Rh, conversion drops dra-
matically from 37% in the first reaction run to less than 5% on
reuse of Rh@MIL-101(Cr) in the second cycle (entries 5 and 6,
respectively). Therefore, the Rh complex is not strongly anch-
ored in MIL-101(Cr) if PTA is absent. Notably, 1-octene is con-
verted in blank runs over neither MIL-101(Cr) nor nPTA@MIL-
catalytic activity (the effect of Cr(NO ) addition is much stron-
3 3
ger; entries 4 and 5, Table S1 and entry 4, Table 2). Approxi-
mately one third of Cr atoms in MIL-101(Cr) are unsaturated.
Hence, it is speculated that unsaturated Cr sites are responsi-
ble for lowering X1-octene if Rh complex-containing MIL-101 is
used. Due to interactions with the WÀO moiety, the concentra-
ChemCatChem 2015, 7, 3243 – 3247
www.chemcatchem.org
3245
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Communications
tion of such free Cr sites decreases in PTA-MOF composites.
HF(aq); see the MSDS.) The autoclave was then heated to 493 K over
À1
0
.75 h and kept at this temperature for 8 h in an oven under rotary
Indeed, the 1-octene turnover number [mol1-octene molRh ] for
conditions. After cooling to RT, the crystallized product was filtered
and washed overnight with boiling ethanol (96%) under reflux.
The powder was then filtered and dried overnight at 433 K under
static air conditions. The synthesis yield was approximately 30%.
PTA-MIL-101(Cr) composites were synthesized by following the
above procedure, except that PTA (0.2 or 0.4 g) was added to the
mixture with Cr(NO ) ·9H O and terephthalic acid. PTA-MIL-101(Cr)
Rh@MIL-101(Cr) is lower than those obtained for Rh-
1
1
5PTA@MIL-101(Cr) and Rh-30PTA@MIL-101(Cr) (1.6 vs.
3
À1
.9 10 mol1
molRh , respectively, entries 5, 7, and 11,
-octene
Table 2). These results further indicate that, although mobile,
the Rh complex closely interacts with the MOF structure.
Thermogravimetric analysis shows that both MIL-101(Cr) and
PTA-MOF composites are thermally stable up to 600 K (Fig-
ure S8), which is much higher than the typical hydroformyla-
tion reaction temperatures of 333–473 K. Comparing the XRD
pattern of MIL-101(Cr) after 2 h exposure to the reaction envi-
ronment with that after 24 h shows no changes in the MOF
pattern (Figure 4).
3
3
2
composites were denoted nPTA@MIL-101(Cr), in which n indicates
wt% PTA. For the immobilization of the hydroformylation catalyst,
RhH(CO)(PPh
)
(0.02 g) and 15PTA@MIL-101(Cr) (0.5 g) or
3
3
RhH(CO)(PPh3)3 (0.055 g) and 30PTA@MIL-101(Cr) (0.5 g) were
3
mixed with toluene (40 cm ) inside an autoclave Teflon liner Teflon-
lined autoclave. The autoclave was heated at 343 K for 18 h in an
oven under rotary conditions. The mixture was then filtered
3
through a cannula, mixed with 1-octene/toluene (3:10, 40 cm )
inside the autoclave, and heated at 343 K for 18 h in the rotary
oven for washing. The washing step was repeated twice to remove
the weakly adsorbed Rh complex, with pure toluene used in the
second step (Figure S1). The powder was then filtered and dried at
3
43 K in an Ar atmosphere. To avoid exposure to air,
RhH(CO)(PPh ) -containing samples and solutions were handled in
3
3
a glove box during the whole procedure unless isolated from the
environment by means of a sealed autoclave or flask. Rh complex-
containing MOFs were denoted Rh-nPTA@MIL-101(Cr), in which n
indicates wt% PTA in the MOF before complex immobilization. For
comparison, the above procedure was repeated with
RhH(CO)(PPh3)3 (0.055 g) and MIL-101(Cr) (0.5 g) and this sample
denoted Rh@MIL-101(Cr).
Figure 4. XRD patterns (CoK
after use in hydroformylation experiments for different durations. Reaction
conditions: T=343 K, p=40 bar gauge pressure (MIL-101(Cr)) or 15 bar
a
) of MIL-101(Cr) and Rh-15PTA@MIL-101(Cr)
Hydroformylation experiments were performed in a Parr 5000 Multi
Reactor Stirrer System under constant syngas pressure (semi-batch
conditions). The reaction vessels (autoclaves) had a volume of
gauge pressure (Rh-15PTA@MIL-101(Cr)), H
2
/CO molar ratio=1,
3
4
5 cm and stirring was performed by suspended magnetic bars to
3
3
V
toluene =14 cm , V1-octene =6 cm , m=0.08 g (MIL-101(Cr)) or 0.16 g (Rh-
avoid grinding the catalyst particles (Figure S2a). Autoclaves were
1
5PTA@MIL-101(Cr)), and agitation speed=1000 rpm.
3
transferred to the glove box and filled with toluene (14 cm ) as sol-
3
vent, 1-octene (6 cm ) as substrate, and RhH(CO)(PPh ) or Rh com-
3
3
plex-containing MOFs (0.08 or 0.16 g). The reaction medium was
isolated from the environment by using a shut-off valve mounted
on top of the autoclaves (Figure S2b) when disconnected from the
experimental unit.
In summary, the phosphotungstic acid-MIL-101(Cr) compo-
site is thermally and chemically stable in a hydroformylation re-
action environment. Phosphotungstic acid coordinates to Rh
as a ligand and is used as an anchoring agent for complex im-
mobilization in the PTA-MOF composite. In the course of hy-
droformylation, CO competes with phosphotungstic acid, thus,
the Rh complex is released from the metal–organic framework
and behaves as a homogeneous catalyst. Once CO is removed
from the reaction environment, Rh recoordinates to phospho-
tungstic acid and reallocates relocates within the metal–organ-
ic framework cavities, allowing easy recycling of the homoge-
neous catalyst. This new approach for the controlled release
and immobilization of organometallic complexes allows the
full recycling of homogeneous catalysts and enables the use of
related composites in other catalytic applications.
Before starting the reaction, traces of air in the opened connec-
tions were removed by consecutively pressurizing and depressuriz-
ing the system with He. Syngas was then introduced to the auto-
claves by consecutively pressurizing and depressurizing the system
with an equimolar mixture of H and CO. Subsequently, the syngas
2
pressure was stabilized at 40 bar gauge pressure (1 bar=100 kPa)
À1
and autoclaves were heated to 343 K at a heating rate of 2 Kmin
and kept at this temperature for a targeted duration. After the re-
action time had elapsed, reactors were depressurized immediately,
syngas was replaced by consecutively pressurizing and depressuriz-
ing the system with He, and the vessels were cooled. The auto-
claves were then transferred to the glove box for GC sampling.
After liquid sampling, the autoclaves were resealed, reconnected
to the experimental unit, and flushed with He. The used MOF was
À1
heated in the reaction mixture at 343 K (2 Kmin ) for 18 h under
Experimental Section
a 5 bar gauge pressure of He. Finally, the powder was separated
from the solution by using a cannula in the glove box. Occasional-
ly, the filtrate before or after the latter step was subjected to the
hydroformylation reaction conditions described above. This al-
lowed for the measurement and comparison of the homogeneous
conversion of unreacted substrate before and after the final treat-
MIL-101(Cr) was prepared by hydrothermal synthesis:
Cr(NO ) ·9H O (1.63 g) and terephthalic acid (0.7 g) were dissolved
3
3
2
in distilled H O (20 g) inside an autoclave Teflon liner Teflon-lined
2
autoclave. Acid concentration HF(aq) (0.15 g) was added to the mix-
ture. (Warning: Special precautions must be taken on handling
ChemCatChem 2015, 7, 3243 – 3247
www.chemcatchem.org
3246
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Communications
ment step. Additionally, the Rh complex-loaded MOFs were recov-
ered and tested in successive cycles.
2013, 177, 135–142; c) C. Hou, G. Zhao, Y. Ji, Z. Niu, D. Wang, Y. Li,
Nano Res. 2014, 7, 1364–1369.
6] J. Juan-AlcaÇiz, J. Gascon, F. Kapteijn, J. Mater. Chem. 2012, 22, 10102–
[
[
[
10119.
7] G. FØrey, C. Mellot-Draznieks, C. Serre, F. Millange, J. Dutour, S. SurblØ, I.
Margiolaki, Science 2005, 309, 2040–2042.
8] a) J. Juan-AlcaÇiz, E. V. Ramos-Fernandez, U. Lafont, J. Gascon, F. Kap-
teijn, J. Catal. 2010, 269, 229–241; b) E. V. Ramos-Fernandez, C. Pieters,
B. Van Der Linden, J. Juan-AlcaÇiz, P. Serra-Crespo, M. W. G. M. Verho-
even, H. Niemantsverdriet, J. Gascon, F. Kapteijn, J. Catal. 2012, 289,
Acknowledgements
The authors would like to thank Shell Global Solutions Interna-
tional BV for supporting this research (contract number:
PT31176).
4
2–52.
9] a) R. Augustine, S. Tanielyan, S. Anderson, H. Yang, Chem. Commun.
999, 1257–1258; b) R. L. Augustine, S. K. Tanielyan, S. Anderson, H.
[
1
Keywords: heterogeneous catalysis
·
heterogenization
·
Yang, Y. Gao in Studies in Surface Science and Catalysis, Vol. 130 D, 2000,
pp. 3351–3356; c) R. L. Augustine, S. K. Tanielyan, N. Mahata, Y. Gao, A.
Zsigmond, H. Yang, Appl. Catal. A 2003, 256, 69–76; d) K. Mukhopad-
hyay, R. V. Chaudhari, J. Catal. 2003, 213, 73–77; e) R. L. Augustine, P.
Goel, N. Mahata, C. Reyes, S. K. Tanielyan, J. Mol. Catal. A 2004, 216,
hydroformylation · metal–organic frameworks · rhodium
[
[
1] R. Franke, D. Selent, A. Bçrner, Chem. Rev. 2012, 112, 5675–5732.
2] ff. C. B. Neves, M. J. F. Calvete, T. M. V. D. Pinho E Melo, M. M. Pereira, Eur.
J. Org. Chem. 2012, 6309–6320.
189–197; f) S. K. Tanielyan, R. L. Augustine, N. Marin, G. Alvez, ACS Catal.
[
[
3] P. W. N. M. van Leeuwen, C. Claver, Rhodium Catalyzed Hydroformyla-
tion, Springer, Netherlands, 2002.
4] a) F. X. LlabrØs i Xamena, J. Gascon, Metal Organic Frameworks as Heter-
ogeneous Catalysts, The Royal Society of Chemistry, United Kingdom,
2011, 1, 159–169; g) M. N. Sokolov, S. A. Adonin, E. V. Peresypkina, P. A.
Abramov, A. I. Smolentsev, D. I. Potemkin, P. V. Snytnikov, V. P. Fedin,
Inorg. Chim. Acta 2013, 394, 656–662.
[
[
10] J. Juan-AlcaÇiz, M. G. Goesten, E. V. Ramos-Fernandez, J. Gascon, F. Kap-
teijn, New J. Chem. 2012, 36, 977–987.
11] L. Huang, Y. He, S. Kawi, J. Mol. Catal. A 2004, 213, 241–249.
2013; b) J. Gascon, A. Corma, F. Kapteijn, F. X. LlabrØs I Xamena, ACS
Catal. 2014, 4, 361–378.
[
5] a) T. Van Vu, H. Kosslick, A. Schulz, J. Harloff, E. Paetzold, M. Schneider, J.
Radnik, N. Steinfeldt, G. Fulda, U. Kragl, Appl. Catal. A 2013, 468, 410–
4
17; b) T. Van Vu, H. Kosslick, A. Schulz, J. Harloff, E. Paetzold, J. Radnik,
Received: March 27, 2015
U. Kragl, G. Fulda, C. Janiak, N. D. Tuyen, Microporous Mesoporous Mater.
Published online on August 12, 2015
ChemCatChem 2015, 7, 3243 – 3247
www.chemcatchem.org
3247
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim