Full Papers
The activity of MIL-100 (Fe) can be enhanced by postsynthe-
by dissolving ZrCl
4
(0.053 g, 0.227 mmol) and 1,4-benzenedicarbox-
ylic acid (H BDC; 0.034 g, 0.227 mmol) in DMF (24.9 g, 340 mmol)
sis treatment to give MIL-100 (Fe)-NH F, which can be recycled.
2
4
at RT. The obtained mixture was sealed and placed in a preheated
oven at 1208C for 24 h. Crystallization was performed under static
conditions. After cooling in air to RT, the resulting solid was collect-
ed by filtration, washed repeatedly with DMF, and dried at RT.
An excellent scope of the MIL-100 (Fe)-NH F catalyst has
4
been found for aliphatic, unsaturated, and aromatic aldoximes.
Experimental Section
Synthesis of zeolites
Synthesis of mixed oxides derived from hydrotalcites
Ultrastable HY zeolite with a Si/Al ratio of 2.6 was purchased from
PQ Zeolites B. V. HY-Fe zeolite was prepared following the method
Al/Mg Hydrotalcite was prepared by following a procedure report-
ed previously. Mg-Al hydrotalcite was prepared from gels pro-
[62]
[59]
described in the literature. Typically, the commercially available
HY zeolite (Si/Al=2.6; 0.7 g) was stirred at RT with a 0.2m aqueous
solution of Fe(NO ) (7 mL) at pH 3. After ion exchange, the solid
duced with a Mg/Al ratio of 3. The gels were produced by mixing
two solutions: solution A that contained Mg(NO ) (2.25 mol) and
3
2
À1
3
3
Al(NO ) (0.75 mol) in an Al+Mg concentration of 1.5 molL for an
3 3
was collected by filtration, washed exhaustively with milliQ water,
and dried at 1008C overnight. The HY-Fe zeolite was dehydrated at
atomic ratio of Al/Al+Mg=0.25 and solution B that contained
Na CO (2 mol) and NaOH (6.75 mol) dissolved in the same volume
2
3
1
508C under reduced pressure. ICP analysis showed that the cata-
of solution A. Both solutions were added simultaneously at a rate
lyst contained 5.3 wt% of Fe. HY-Na was prepared using an ion-ex-
change method that consisted of the treatment of commercially
À1
of 1 mLmin under vigorous mechanical stirring at RT. The resul-
tant gel was left for 18 h at 608C, and then the solid was collected
by filtration and washed until pH 7. The hydrotalcite was calcined
at 4508C under dry nitrogen for 6 h to obtain the corresponding
available CBV100 (NaY) with aq. 2.5m NH Cl at 808C for 1 h under
4
stirring. The catalyst was collected by filtration and washed exhaus-
tively with water. Finally, it was calcined at 5808C to obtain HY-Na
2
À1
Al/Mg mixed oxide (HTc) with a surface area of 267 m g .
(
2.8 wt% Na measured by ICP).
The hydrotalcite that contained Fe (Al/Mg/Fe-HTc) was prepared
by the coprecipitation method at constant pH controlled by the
slow addition of two solutions A and B in a single container. To
The samples of Sn-Beta (2 wt%) and Zr-Beta (1 wt%) were pre-
[42,43]
pared following the methods described in the literature
and
calcined at 5808C in air for 3 h before use.
synthesize HT-Fe (4.4 wt% Fe)
a solution A that contained
MgCl ·6H O (0.05 mol), AlCl ·6H O (0.0025 mol), FeCl ·6H O
2
2
3
2
3
2
The mesoporous material MCM-41 (Si/Al=15) was prepared ac-
À1
[60]
(0.0041 mol), and water (58 mL) was mixed at 60 mLh under vig-
orous stirring with solution B prepared by dissolving Na CO
cording to the literature. The 2D layered ITQ-2 (Si/Al=15) cata-
lyst was prepared by the expansion and subsequent exfoliation of
the corresponding laminar precursors of the MWW structure by fol-
lowing the method in Ref. [61]. The zeolites and mesoporous ma-
terials were calcined in air at 5808C for 3 h before use.
2
3
(
27.54 g) and NaOH (5.28 g) in water (78 g). The precipitated solid
was aged at 608C for 24 h. Finally, the precipitate was collected by
filtration and washed to eliminate the alkali metals and nitrate ions
until the pH of the washing water was 7. The solid was then dried
[63]
at 608C for 12 h. The sample was calcined at 4508C first in air
(7 h) and then in N (16 h) to obtain the corresponding mixed
oxide (Al/Mg/Fe-HTc).
MOFs
2
Fe(BTC) under the name of Basolite F 300 and Cu (BTC) under the
3
2
Al/Mg/Cu-HTc was synthesized following a procedure described in
name of Basolite C 300 were purchased from Sigma Aldrich as well
as other chemicals used in this work. The sample of MIL-100 (Fe)
was synthesized by a microwave-assisted hydrothermal method as
[64]
the literature. The Cu was loaded onto the synthesized hydrotal-
cite (4 g) by wet impregnation with an aqueous solution of copper
acetate (0.042m, 40 mL) under stirring for 24 h at RT. The Cu-im-
pregnated hydrotalcite was washed with distilled water (450 mL)
to remove free Cu and acetate ions and then dried at 708C for
[47]
reported by Mµrquez et al.
Typically, iron(III) chloride hexahy-
drate (2.43 g, 9 mmol) was dissolved in distilled water (30 mL) with
stirring. Trimesic acid (0.84 g, 4 mmol) was added to the solution,
which was heated in microwave to 1308C over 1 min (1400 W) and
maintained at this temperature for 5.5 min. The reaction mixture
was cooled to RT and centrifuged at 10500 rpm for 25 min. An
orange solid (2.5 g) was obtained that was washed first with dis-
tilled water (30 mL) at 708C under stirring for 3 h and then with
ethanol at 658C for 3 h. The catalyst was dried in an oven at 1008C
overnight.
1
2 h. The sample was calcined at 4508C first in air (7 h) and then in
N (16 h) to obtain the mixed oxide (Al/Mg/Cu-HTc) with a 5 wt%
2
Cu content.
Characterization
The Brønsted and Lewis acidity of the zeolites and mesoporous
catalyst were measured by IR spectroscopy of pyridine adsorption–
desorption at different temperatures. The IR spectra of pyridine on
the solid acid catalysts were obtained by using a Nicolet 750 FTIR
The sample of MIL-100 (Fe)-NH F was synthesized by the micro-
4
wave-assisted solvothermal method (see above) and then was
modified by postsynthesis purification. After centrifugation at
2
1
0500 rpm for 25 min, the orange solid (2.5 g) was washed first
spectrophotometer from self-supporting wafers of 10 mgcm treat-
À4
À5
with distilled water (30 mL) at 708C under stirring for 3 h and then
with ethanol at 658C for 3 h. The catalyst was dried in the oven at
ed overnight under vacuum (10 –10 Pa) at 4008C. After equili-
bration with pyridine, the samples were degassed for 1 h at in-
creasing temperatures (150, 250, and 3508C). After each desorption
step, a spectrum was recorded at RT and the background was sub-
tracted.
1
(
008C overnight and was then treated with a solution of NH4F
38 mm, 20 mL) at 708C for 3 h. After cooling, the precipitate was
collected by filtration and washed with hot water (608C, 5
[47]
2
00 mL) to remove traces of NH4F.
IR spectra of adsorbed benzaldehyde oxime were recorded by
using a Bruker Vertex 70 FTIR spectrometer using a detector at
UiO-66 (Zr) was synthesized following a procedure described in the
[38]
À1
literature. The standard synthesis of Zr-BDC MOF was performed
4 cm resolution. An IR cell that allowed in situ treatment in con-
ChemSusChem 2015, 8, 3270 – 3282
3280
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim