Synergistic effect between Pd and Re on Pd-Re/SBA-15 catalysts and their catalytic behavior in glycerol hydrogenolysis

Article abstract of DOI:10.1039/c6ra02758j

Pd-Re/SBA-15 catalysts were prepared by the impregnation method. The influence of the interaction between Pd and Re in the Pd-Re catalysts on glycerol hydrogenolysis was investigated. Pd and Re had interaction which was confirmed by H₂-TPR, XPS and EXAFS. In the Pd-Re catalysts, Re showed a higher oxidation state compared with that of the mono-component Re catalyst. The mechanically mixed Pd + Re catalysts showed a lower glycerol conversion than that of the bi-component Pd-Re catalysts, which suggested that the interaction of Pd and Re was very important in glycerol hydrogenolysis.

Full text of DOI:10.1039/c6ra02758j

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ARTICLE TYPE
Synergistic effect between Pd and Re on Pd-Re/SBA-15 catalysts and
their catalytic behavior in glycerol hydrogenolysis
Yuming Li,a Huimin Liu,a Lan Maa,b and Dehua He*a
Received (in XXX, XXX) Xth XXXXXXXXX 20XX, Accepted Xth XXXXXXXXX 20XX
5
DOI: 10.1039/b000000x
PdꢀRe/SBAꢀ15 catalysts were prepared by impregnation method. The influence of interaction between Pd and Re in PdꢀRe catalysts on
glycerol hydrogenolysis was investigated. Pd and Re had interaction which was confirmed by H2ꢀTPR, XPS and EXAFS. In PdꢀRe
catalysts, Re showed higher oxidation state compared with monoꢀcomponent Re catalyst. The mechanical mixed Pd+Re catalysts showed
lower glycerol conversion than biꢀcomponent PdꢀRe catalysts which suggested that the interaction of Pd and Re was very important in
10 glycerol hydrogenolysis.
the conversions of glycerol from 6ꢀ32% to 50ꢀ60%, and the
yields to 1,2ꢀPD also increased. In this study, Re was added into
Pd/SBAꢀ15. And the addition of Re could increase the activity of
Pd. As the content of Re increased, the conversion of glycerol
50 also increased. Re and Pd may have an interaction and increase
the activity of CꢀO bond cleavage. The preparation and reaction
conditions were varied and the influences on the properties of Pdꢀ
Re catalysts were studied.
Introduction
In recent years, as the consumption of fossil fuels like coal, oil
and natural gas growing rapidly, renewable and environmental
15 friendly resources are eagerly to be developed [1]. Biodiesol
which could offer great potential is one of these kinds of
resources. It was produced by transesterification of vegetable oil
or fatty acid esters with methanol or ethanol. The demand of
biodiesel would increase to 100ꢀ300 EJ/y by 2050 [2]. At
20 meantime, during the production of biodiesel, glycerol is formed
as a byꢀproduct. But the traditional usage cannot satisfy the high
accumulation, new ways should be found for this platꢀform
molecule material [3]. Hydrogenolysis of glycerol can produce
1,2ꢀpropanediol (1,2ꢀPD) and 1,3ꢀpropanediol (1,3ꢀPD) which are
25 all highꢀvalue added chemicals. At present, 1,2ꢀPD is produced
mainly by hydrolysis of epoxypropane in petrochemical industry.
It can be used in synthesis polyethers, unsaturated polyester
resins and antifreeze products, as well as in food industry. On the
other hand, 1,3ꢀPD has highest value among the products of
30 glycerol hydrogenolysis. Nowadays, it’s usually produced by
petrochemical routes from ethylene oxide or acrolein. 1,3ꢀPD is
mainly used to produce a kind of fiber PTT (polytrimethyleneꢀ
terephꢀthalate) which is widely used in industry. Meanwhile, it’s
also important in pharmaceuticals industry as a kind of drug
35 intermediates. [4-5]
Experiments
55 Materials
PdCl2 was purchased from Shenyang Nonferrous Metal Institute.
HReO4 (75ꢀ80% aqueous solution) was purchased from Alfa
Aesar. P123 (EO20PO70EO20, Mw=5800) was purchased from
SigmaꢀAldrich. Other materials (analytical reagents) were all
60 bought from Beijing Chemical Reagent Company.
Catalyst preparation
SBAꢀ15 was prepared with the method as references [17-18]. P123
was dissolved in HCl aqueous solution and the TEOS
(tetraethylorthosilicate) was added and hydrolyzed for 20 h. After
65 filtration, washed with deionized water until neutral and dried,
the sample was calcined at 500 oC for 6 h to remove the template.
PdꢀRe catalysts were all prepared by impregnation method.
SBAꢀ15 was impregnated with PdCl2 which was dissolved in HCl
aqueous solution, and HReO4 aqueous solution at room
70 temperature for 10 h with continuously stirring. After removing
water by evaporation and drying at 110 oC overnight, the samples
Many researches have been published for glycerol
hydrogenolysis. Z. Xiao et al used CuCr2O4 as catalyst in this
reaction. 45.2% of glycerol conversion and 99.6% of selectivity
to 1,2ꢀPD were obtained under 130 C and 2 MPa H2 pressure.
[6]
o
o
were directly reduced by pure hydrogen at 250 C for 2 h. The
40 But most of nonꢀnoble metal Cu or Ni catalysts had no 1,3ꢀPD
obtained catalysts are denoted as xPdꢀyRe/SBAꢀ15, where x and
y meant the content of Pd and Re (quality content wt%),
75 respectively. With the ICP analysis, the actual contents of Pd and
Re in the fresh catalysts are nearly to their theoretical ones. With
5Pdꢀ5Re/SBAꢀ15 catalyst as an example, the actual content of Pd
was 5.0 wt%, and the actual content of Re was 5.1 wt%.
[11]
production [7-8]. For noble metals, Ru [9], Pt [10] and Pd
were
always used. In these noble metal based catalysts, 1,3ꢀPD could
[12-
be obtained. And from our previous studies and other papers
16], the addition of Re could increase the activities of noble
[15-16]
45 metals. For RuꢀRe
catalysts, the addition of Re increased
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For mechanical mixed Pd+Re catalysts, 10Pd/SBAꢀ15 and
10Re/SBAꢀ15 were reduced respectively and then mixed together
by mechanical mixing (denoted as 10Pd+10Re). Another
mechanical mixed catalyst (denoted as 5Pd+5Re) was prepared
by the method the same as 10Pd+10Re (using 5Pd/SBAꢀ15 and
5Re/SBAꢀ15).
of all samples was calibrated with C 1s peak (284.6 eV).
Re L3ꢀedge extended Xꢀray absorption fine structure
(EXAFS) was characterized on Beijing Synchrotron Radiation
Facility (BSRF) 1W1B station.
5
55
Hydrogenolysis of glycerol
Glycerol hydrogenolysis was carried out in a 100 mL of stainless
steel autoclave with a magnetic stirrer. For a typical reaction,
0.15 g Pd catalyst and 40 % glycerol aqueous solution were
Catalyst Characterization
The structure properties of the catalysts, including pore volume,
10 size distribution and specific surface area were characterized by 60 added into the autoclave. After sealing up the autoclave, 8MPa H2
N2 adsorption/desorption with BET and BJH methods on a
Micromeritics ASAP 2010C analyser. All samples were degassed
at 300 oC before the characterization.
The crystall structures of all samples were characterized by
15 Xꢀray diffraction (XRD) on a Rigaku D/maxꢀRB diffractometer 65 reaction, the autoclave was cooled down to 5 oC and then the gas
was purged to check leakage. Then 3 MPa H2 was used to purge
air for 3 times to remove the air in the autoclave. The autoclave
was heated to 200 oC, and 8MPa H2 was charged. Then the stirrer
was started, and the reaction was carried on for 18 h. After
(powered at 40 kV and 200 mA).
was decompressed. The gas phase products were analyzed by
TCD gas chromatograph (Beijing WeisifuꢀGC 6890) and liquid
phase products were analyzed by FID gas chromatograph (Lunanꢀ
SP 6890).
The conversion of glycerol and the selectivity to products
were calculated based on following equations. The carbon
balances of all reactions were maintained at 95±5%.
The acidity of the catalysts were characterized by NH3ꢀTPD
with Quantachrome CHEMꢀ300 chemsorption instrument
equipped with a quadrupolemassꢀspectrometer detector (Ametek
20 Dymaxion, DM300 M Gas Analyser). 0.1 g of the sample was
firstly treated at 250 oC with pure He gas (99.999%) for 2 h, and
70
o
then cooled down to 100 C to adsorb NH3 with 2%NH3/He gas
o
o
at 100 C for 0.5 h. After flowing in pure He gas at 100 C for
another 0.5 h to move the physical adsorption of NH3, the
25 temperature was increased from 100 oC to 750 oC at the rate of 15
oC/min.
Sumof Cmol of all products
Conversion(%) =
×100%
Added glycerol before reaction (Cmol)
C mol of each product
Selctivity(%) =
×100%
Sum of C mol of all products
The reduction behaviors of the catalysts were also
characterized with H2ꢀTPR method on Quantachrome CHEMꢀ300
chemsorption instrument. In a typical H2ꢀTPR, 0.1 g of the
30 sample was firstly treated at 250 oC in pure Ar gas (99.999%) for
75
o
Results and discussion
2 h. After the sample was cooled down to 30 C, the Ar gas was
switched into byꢀpass and changed into 5%H2/Ar. The TCD
detector was stabilized in 5%H2/Ar at 30 C, and then the gas
The structure properties of xPd-5Re/SBA-15 catalysts
o
The structure properties of xPdꢀ5Re/SBAꢀ15 catalysts after
reduced at 250 oC were measured by N2 adsorptionꢀdesorption
switched into the sample tube again. During this process, the
35 reduction peak of palladium at 30 oC would combine with a peak
which caused by the residual pure Ar gas in the sample tube. This
80 method. Fig. 1 (a) shows the the N2 adsorptionꢀdesorption
isotherms of xPdꢀ5Re/SBAꢀ15. All catalysts had type IV
isotherms, which meant the mesoporous structure of SBAꢀ15 had
been maintained. The pore size distributions of xPdꢀ5Re/SBAꢀ15
are shown in Fig. 1 (b). All the catalysts had similar pore size
85 distribution with SBAꢀ15. The specific surface areas, pore
volumes and average pore sizes of the samples are shown in
Table 1. After impregnation and reduction, the specific surface
area of xPdꢀ5Re/SBAꢀ15 became lower than that of SBAꢀ15.
1Pdꢀ5Re/SBAꢀ15 had the largest specific surface area (784 m2/g),
90 while 10Pdꢀ5Re/SBAꢀ15 had the smallest (610 m2/g). All
catalysts had similar pore volume and average pore size.
o
was recorded as Step I. After the TCD was stabled at 30 C, the
Step II of H2ꢀTPR was recorded by increasing the temperature
from 30 oC into 500 oC at the rate of 15 oC/min.
40
The dispersion of Pd in PdꢀRe catalysts was characterized by
CO chemisorption. In a typical measurement, 0.1 g of the sample
o
was reduced with 5%H2/Ar at 250 C for 2 h, and then cooled
down to 30 oC in 99.999% He gas. After stabilized at 30 oC for 30
min, CO was pulsed for several times for the chemisorption and
45 dispersion of Pd was calculated.
The high resolution transmission electron microscopy (HRꢀ
TEM) of the catalysts was taken on JEMꢀ2010 JEOL with an
energy dispersive spectrometer (EDS).
The Xꢀray photoelectron spectroscopy (XPS) was recorded
50 by PHI Quantera SXM of ULVACꢀPHI Inc. The binding energy
95
2
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Table 1 Structure properties, dispersions and H2 consumption of xPdꢀ5Re/SBAꢀ15
Dispersion of Step I H2
Step II H2
(mmol)b
Total H2
(mmol)b
SBET(m2/g)
V (cm3/g)
DBJH (nm)
Pd (%)a
(mmol)b
SBAꢀ15
856
784
730
618
638
610
670
705
0.71
0.66
0.61
0.53
0.55
0.53
0.53
0.59
5.7
5.6
5.7
5.4
5.6
5.6
5.4
5.4
ꢀ
ꢀ
ꢀ
ꢀ
1Pdꢀ5Re/SBAꢀ15
3Pdꢀ5Re/SBAꢀ15
5Pdꢀ5Re/SBAꢀ15
8Pdꢀ5Re/SBAꢀ15
10Pdꢀ5Re/SBAꢀ15
5Pd/SBAꢀ15*
31.7
19.6
13.7
11.1
9.8
ꢀ0.001
0.047
0.063
0.109
0.139
0.025
ꢀ0.001
0.076
0.059
0.055
0.039
0.043
0.013
0.097
0.075
0.105
0.118
0.149
0.181
0.037
0.096
17.3
ꢀ
5Re/SBAꢀ15*
a: calculated from CO chemsorption
b: calculated from H2ꢀTPR
5
*: results from our previous paper [24]
(a)
(a)
10Pd-5Re/SBA-15
10Pd-5Re/SBA15
8Pd-5Re/SBA-15
5Pd-5Re/SBA-15
8Pd-5Re/SBA15
5Pd-5Re/SBA15
3Pd-5Re/SBA15
1Pd-5Re/SBA15
3Pd-5Re/SBA-15
1Pd-5Re/SBA-15
SBA-15
1.0
1.5
2.0
2.5
3.0
0.0
0.2
0.4
0.6
0.8
1.0
o
p/p
2
θ
( )
0
Pd (111)
Pd (200)
Pd (220)
ꢁ
Φ
ꢁ
ꢀ
(b)
(b)
ꢀ
10Pd-5Re/SBA-15
10Pd-5Re/SBA15
Φ
8Pd-5Re/SBA-15
5Pd-5Re/SBA-15
8Pd-5Re/SBA15
5Pd-5Re/SBA15
3Pd-5Re/SBA15
1Pd-5Re/SBA15
3Pd-5Re/SBA-15
1Pd-5Re/SBA-15
SBA-15
10
20
30
40
50
(o)
60
70
80
0
2
4
6
8
10 12 14 16 18 20
2
θ
Pore size (nm)
25
Fig. 2 (a) Small XRD patterns and (b) wide XRD patterns of xPdꢀ
5Re/SBAꢀ15
10 Fig. 1 (a) N2 adsorptionꢀdesorption isotherms and (b) pore size
distribution of xPdꢀ5Re/SBAꢀ15
The reduction behaviors of xPd-5Re/SBA-15 catalysts
The structures and dispersions of xPd-5Re/SBA-15 catalysts
30 The H2ꢀTPR profiles of xPdꢀ5Re/SBAꢀ15 are shown in Fig. 3,
and the H2 consumption results are listed in Table 1. It can be
seen that the Step I of H2ꢀTPR of 1Pdꢀ5Re/SBAꢀ15 was same as
that of SBAꢀ15 blank indicating that there was nearly no Pd was
From the small angle XRD patterns of xPdꢀ5Re/SBAꢀ15 in Fig. 2
15 (a), it can be seen that all catalysts maintained the mesoporous
structure of SBAꢀ15. From the wide angle XRD patterns (Fig. 2
(b)), when the content of Pd was low (1%), the diffraction peaks
o
reduced at 30 C and all Pd might be interacted with Re for this
of Pd0 were not clearly. As the content of Pd increased, the 35 sample. Other xPdꢀ5Re/SBAꢀ15 samples all showed higher
diffraction peaks of Pd(111) at 2θ = 40 o, Pd(200) at 2θ = 46 o and
consumption of H2 than that of SBAꢀ15 blank at 30 C. For Step
II of H2ꢀTPR, 1Pdꢀ5Re/SBAꢀ15 showed two broad reduction
peaks at 150 oC and 200 oC, and it had no obviously
o
o
20 Pd(220) at 2θ = 68 were observed [19-21]. As the content of Pd
increased from 1% to 10%, the dispersion of Pd decreased from
31.7% to 9.8%, which might be caused by the agglomeration of
Pd at higher loading (Table 1).
o
decomposition peak of PdH at 100 C [22-23]. As the content of Pd
40 in xPdꢀ5Re/SBAꢀ15 increased to 3~10%, the peak at 150 oC
shifted to lower temperature and the intensity of the peak became
higher. For 3Pdꢀ5Re/SBAꢀ15 and 5Pdꢀ5Re/SBAꢀ15, the
o
o
reduction peaks appeared at 130 C and 220 C, while for 8Pdꢀ
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5Re/SBAꢀ15 and 10Pdꢀ5Re/SBAꢀ15, the reduction peaks became 35 reduction had mixed oxidation states in the range of 0~7+. The
a broad peak in a wide temperature of 100~200 oC. The change of
reduction behaviors of the catalysts might result in the change of
the activity of PdꢀRe catalysts. From the TPR results, it can be
seen that all the catalysts (except 1Pdꢀ5Re/SBAꢀ15) had the
peak at 40.5 eV (Re0) of the sample was very clearly, indicating
that part of ReOx was reduced to Re0. But for the reduced 5Pdꢀ
5Re/SBAꢀ15, as reported in our previous study [24], the XPS
spectrum (Re 4f: 46.0 eV and 43.1 eV) of Re in the biꢀcomponent
5
o
o
reducible species that could be reduced at 30 C and 130 C (or 40 catalyst was very different from that of reduced monoꢀcomponent
150 oC). As the content of Pd increased, the reduction
temperature of the PdꢀRe species decreased. Combining with the
results of our group reported previously [24], the reduction species
10 at 30 C and 130 C might be favourable the CꢀO bond cleavage
and promoting the reaction. From H2ꢀTPR, the sum of H2 45 mainly in the range of 4+~7+. From XPS results of the samples,
5Re/SBAꢀ15 catalyst. The Re 4f peaks of the reduced 5Pdꢀ
5Re/SBAꢀ15 were mainly at 46.0 eV and 43.1 eV, while the peak
intensity of Re0 at 40.4 eV was very low [24]. This means the
oxidation states of Re in 5Pdꢀ5Re/SBAꢀ15 after reduction were
o
o
consumption of 5Re/SBAꢀ15 and 5Pd/SBAꢀ15 (0.133 mmol) was
higher than that of 5Pdꢀ5Re/SBAꢀ15 (0.118 mmol). It could be
inferred that the oxidation state of Re in 5Pdꢀ5Re/SBAꢀ15 was
15 different from that of Re in 5Re/SBAꢀ15. XPS and EXAFS were
introduced to characterize the oxidation state of Re in Pdꢀ
Re/SBAꢀ15.
after reduction, the oxidation states of Re in biꢀcomponent
catalyst were higher than that of Re in monoꢀcomponent
Re/SBAꢀ15 catalyst. This result agreed with H2ꢀTPR results as
discussed above.
(a) 5Re/SBA-15 calcination
46.8 eV
Re 4f
5Re/SBA-15
48.9 eV
(a) Step I
10Pd-5Re/SBA-15
8Pd-5Re/SBA-15
5Pd-5Re/SBA-15
3Pd-5Re/SBA-15
1Pd-5Re/SBA-15
55
50
45
40
5Pd/SBA-15*
SBA-15
BE (eV)
50
(b) 5Re/SBA-15(H2-250)
0
200
400
600
Time (s)
800
1000
1200
46.3 eV
Re 4f
(b) Step II
5Re/SBA-15
48.9 eV
Intensity*0.5
43.3 eV
10Pd-5Re/SBA-15
40.5 eV
8Pd-5Re/SBA-15
5Pd-5Re/SBA-15
3Pd-5Re/SBA-15
1Pd-5Re/SBA-15
5Pd/SBA-15*
55
50
45
40
SBA-15
BE (eV)
Fig. 4 XPS spectra of 5Re/SBAꢀ15(a) after calcination at 500 oC
and (b) after reduction at 250 oC
100
200
300
400
500
Temp (oC)
20
55
Fig. 3 (a) H2ꢀTPR profiles (Step I) and (b) H2ꢀTPR profiles (Step
II) of xPdꢀ5Re/SBAꢀ15 (*: from our previous paper [24])
In order to confirm the oxidation states of Re, XANES
technique was also used for measuring PdꢀRe catalysts. Re L3ꢀ
Edge was also analyzed by Xꢀray Absorption Fine Spectrum.
Commercial samples of Re0 and ReO3 were also used as
The oxidation states of Re in xPd-5Re/SBA-15 catalysts
60 comparison. From XANES spectra, the edge shift values of all
samples were calculated and the results are shown in Table 2.
From these results, it could be conferred that the valences of Re
in 5Re/SBAꢀ15 after reduction were between 0~6+, while the
valence of Re in 5Pdꢀ5Re/SBAꢀ15 after reduction was a little
65 higher than 6+. From k3ꢀWeighted EXAFS oscillations of Re L3ꢀ
Edge EXAFS results (Fig. 5 (a)), the different intensity and
frequency meant that the Re in 5Re/SBAꢀ15 had different
coordination environment compared with Re in 5Pdꢀ5Re/SBAꢀ
15. The Fourier transform of k3ꢀWeighted Re L3ꢀEdge EXAFS
25 With XPS analysis, the oxidation state of Re was characterized.
All the results were calibrated by C 1s signal at 284.6 eV. Fig. 4
o
shows the XPS results of 5Re/SBAꢀ15 after 500 C calcination
o
and after 250 C reduction, respectively. For 5Re/SBAꢀ15 after
calcination in air, the binding energies (BE values) of Re were
30 mainly at 48.9 eV and 46.8 eV, which means that the oxidation
states of Re were in the range of 6+~7+ [25-26]. After reduction at
250 oC, the XPS spectrum changed a lot, and four peaks appeared
in this sample. The BE values of Re were at 48.9 eV, 46.3 eV,
43.3 eV and 40.5 eV, indicating Re in 5Re/SBAꢀ15 after
4
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(Fig. 5 (b)) results showed that there were two coordination peaks
respectively, while the selectivity to 1ꢀPO increased from
between 0.1~0.3 nm for Re in 5Re/SBAꢀ15, while there was only 30 20~30% to 45.5%. From these results, it was suggested that there
one peak at 0.15 nm for Re in 5Pdꢀ5Re/SBAꢀ15. These
differences meant the different coordination environments and
local structures of Re in monoꢀcomponent Re and biꢀcomponent
PdꢀRe catalysts.
was an interaction between Pd and Re, which could influence not
only the conversion of glycerol, but also the distribution of the
products.
5
On the other hand, the spent 5Pdꢀ5Re/SBAꢀ15 catalyst was
35 also recycled, and the recycle results of the catalyst in glycerol
hydrogenolysis are listed in Table S1. It can be seen that from the
results, the activity of the spent catalyst decreased a lot, and only
9.3%, compared with that of fresh one (40.7%). However, by
Table 2 The edge shift values of Re L3ꢀEdge
edge shift (eV)
o
calcining the spent catalyst at 500 C and then reducing it at 250
Re
ꢀ1.93
40 oC in flowing H2/N2, the conversion of glycerol over regenerated
5Pdꢀ5Re/SBAꢀ15 was 28.8%, which was higher than that of
unregenerated one (9.3%), and the product distribution was
similar with the fresh one.
ReO3
ꢀ4.66
ꢀ3.32
ꢀ4.69
5Re/SBAꢀ15(H2ꢀ250)
5Pdꢀ5Re/SBAꢀ15(H2ꢀ250)
10
The spent 5Pdꢀ5Re/SBAꢀ15 catalyst was also characterized
45 with XRD, TEM, TPH and TPO. From the small angle XRD
patterns (Fig. S1 (a)), the spent 5Pdꢀ5Re/SBAꢀ15 still maintained
the ordered mesoporous structure of SBAꢀ15, but the intensity of
SiO2(111) peak decreased somewhat. From wide angle XRD
(a)
5Pd-5Re/SBA-15(H -250)
2
o
pattern (Fig. S1 (b)), the peak of Pd(111) at 2θ = 40 became a
5Re/SBA-15
(
H -250
2
)
50 little higher after reaction, which meant the particle size of Pd
increased somewhat. From TEM images in Fig. S2, the average
particle sizes of 5Pdꢀ5Re/SBAꢀ15 catalyst before and after
reaction were 5.1 nm and 5.0 nm, respectively. While the particle
size distribution of spent catalyst was 3~8 nm, this meant that
55 some larger PdꢀRe particles might be formed during the reaction.
From Table S1, the spent catalyst lost activity after glycerol
hydrogenolysis reaction. However, after the calcination and
reduction, the activity of the spent catalyst could be recovered to
a certain extent. From this, it could be suspected that some
60 organic species or carbon species might block the pores of the
catalysts. TPH and TPO were used to characterize the carbon
deposition in the spent catalyst, which are shown in Fig. S3 and
S4.
0
2
4
6
k
8
10
12
14
16
( )
10 nm-1
(b)
5Pd-5Re/SBA-15
(
H -250
)
2
5Re/SBA-15(H -250)
2
From the results of TPH and TPO, it was suggested that the
65 spent 5Pdꢀ5Re/SBAꢀ15 catalyst might be partly covered by some
kinds of carbon deposition species after the reaction, which
would cause the deactivation of the catalyst. But the calcination
0
1
2
3
4
5
6
R
(0.1 nm)
o
Fig. 5 (a) k3ꢀWeighted EXAFS oscillations of Re L3ꢀEdge
EXAFS and (b) the Fourier transform of k3ꢀWeighted Re L3ꢀEdge
EXAFS of PdꢀRe catalysts
of the spent catalyst at 500 C could remove the organic species
deposition and recover the activity to the catalyst.
15
70 The effect of reduction temperatures on the catalytic
performance and properties of 5Pd-5Re/SBA-15
From results mentioned above, Re in 5Pdꢀ5Re/SBAꢀ15 after
o
The catalytic performance of xPd-5Re/SBA-15 catalysts in
glycerol hydrogenolysis
reduction at 250 C could still maintain at high oxidation state,
and this might be due to the interaction of Pd and Re.
75 Considering the reduction behaviors of 5Pdꢀ5Re/SBAꢀ15 in H2ꢀ
TPR, it could be suggested that the different reduction
temperatures might lead to different activities. Therefore, the
effect of different reduction temperatures on the activity of 5Pdꢀ
5Re/SBAꢀ15 was checked, and results are shown in Table 4.
80 From the results, it is clearly shown that when the 5Pdꢀ5Re/SBAꢀ
15 was only dried at 110 C without reduction, the conversion of
glycerol was very low (only 7.2%). But the selectivity to 1,3ꢀPD
was the highest (21.3%). When 5Pdꢀ5Re/SBAꢀ15 was reduced
20 The catalytic performance of PdꢀRe catalysts with different
amounts of Pd is shown in Table 3. For monoꢀcomponent Pd or
Re catalyst, the conversion of glycerol was very low (1~3 %). For
the biꢀcomponent PdꢀRe catalysts, as the content of Pd increased
from 1% to 8%, the conversion of glycerol increased from 15.0%
25 to 72.2%. As the content of Pd further increased to 10%, the
conversion of glycerol decreased somewhat (70.8%). With the
increase of Pd amount, the selectivity to 1,2ꢀPD and 1,3ꢀPD
decreased from 50~60% and 12.1% to 37.0% and 4.2%,
o
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with H2 at room temperature, the conversion of glycerol increased
to 19.1% and the distribution of the products was similar to that
Re species at 30 oC was completely reduced, and other PdꢀRe
oxide that was only reduced at above 130 C was maintained as
o
of only dried 5Pdꢀ5Re/SBAꢀ15. As the reduction temperature 20 oxides. This perhaps related to relatively lower activity of 5Pdꢀ
increased into 150 oC, the conversion of glycerol got its
maximum (50.7%) and the selectivity to 1,3ꢀPD decreased to
8.3%. At the same time, the selectivities to 1,2ꢀPD and 1ꢀPO
increased from about 30% to 45~55%. As the reduction
5Re/SBAꢀ15. From XRD patterns in Fig. 6, 5Pdꢀ5Re/SBAꢀ15
without reduction showed no clearly diffraction peaks. When the
catalyst was reduced at 25 oC, the diffraction peaks of Pd became
5
o
clearly. When the reduction temperature increased to 150 C, the
temperature increased from 150 C to 250 C, the conversion of 25 reducible species in PdꢀRe/SBAꢀ15 below 130 oC could be totally
o
o
glycerol decreased to 40.7% and the selectivity to 1,2ꢀPD
reduced and the conversion of glycerol was the highest. Further
increasing reduction temperature from 150 to 550 C, the XRD
diffraction peaks of Pd had nearly no changed (Fig. 6). After the
reduction temperature increased to 750 oC, the conversion of
o
10 increased to 59.9%. When the reduction temperatures were in the
range of 250~550 oC, the glycerol conversions over 5Pdꢀ
5Re/SBAꢀ15 and the dispersions of products were quite similar. If
the reduction temperature continually increased to 650~750 oC, 30 glycerol decreased a lot, and from XRD pattern, the diffraction
the conversions of glycerol sharply decreased from about 40%
15 into about 21%.
peaks of Pd disappeared and PdꢀSi crystal component could be
detected [27]
.
From the H2ꢀTPR, it could be supposed that when the
o
reduction temperature was below 130 C, only the reducible Pdꢀ
Table 3 Catalytic performance of xPdꢀ5Re/SBAꢀ15 in glycerol hydrogenolysis
35
Select. (%)
Conv. (%)
CH4
0.0
1.1
1.4
2.0
1.6
1.8
0.0
C1~2ꢀOH
2.8
EG
5.3
0.9
1.1
1.8
0.6
0.9
1.7
1ꢀPO
14.6
25.0
25.9
24.6
42.6
45.5
38.7
2ꢀPO
0.7
1.8
2.2
2.1
6.3
7.8
1.5
1,2ꢀPD
72.2
58.3
58.8
59.9
41.6
37.0
49.6
1,3ꢀPD
4.4
12.1
9.8
8.2
4.6
5Pd/SBAꢀ15
1Pdꢀ5Re/SBAꢀ15
3Pdꢀ5Re/SBAꢀ15
5Pdꢀ5Re/SBAꢀ15
8Pdꢀ5Re/SBAꢀ15
10Pdꢀ5Re/SBAꢀ15
5Re/SBAꢀ15
1.5
15.0
33.5
40.7
72.2
70.8
3.1
0.8
0.9
1.4
2.7
2.8
1.7
4.2
6.7
Reaction Conditions
1~2ꢀOH: methanol and ethanol, EG: glycol, PO: propanol, PD: propanediols.
：
0.15 g Pd catalyst, 40% Glycerol aqueous 10 mL, 200 oC, 8 MPa H2, 18 h, 700 rpm.
C
40
Table 4 The effect of reduction temperatures on catalytic performance of 5Pdꢀ5Re/SBAꢀ15 in glycerol hydrogenolysis
Select. (%)
Treatment conditions
Conv. (%)
(oC)
CH4
0.3
0.8
0.9
0.9
1.4
2.0
1.4
0.9
1.8
2.1
1.7
2.2
C1~2ꢀOH
1.1
EG 1ꢀPO
2ꢀPO
0.8
1.4
1.4
2.7
3.6
2.1
2.8
3.5
3.5
3.9
2.5
1.4
1,2ꢀPD
29.2
29.6
41.7
46.5
45.6
59.9
61.0
62.9
57.0
60.9
65.0
66.9
1,3ꢀPD
21.3
16.0
12.9
9.5
Dry only (110)
H2ꢀ25
7.2
19.1
23.5
40.2
50.7
40.7
42.2
41.7
41.4
39.9
30.6
21.3
1.1
0.6
0.6
0.9
0.9
1.8
1.2
1.5
1.4
2.1
2.7
3.8
46.3
50.9
41.6
38.4
39.0
24.6
24.8
22.0
25.3
22.1
18.8
15.3
0.6
H2ꢀ50
0.8
H2ꢀ110
H2ꢀ150
H2ꢀ250
H2ꢀ350
H2ꢀ450
H2ꢀ500
H2ꢀ550
H2ꢀ650
H2ꢀ750
1.1
1.2
8.3
1.4
8.2
1.3
7.5
1.6
7.7
1.5
9.5
2.1
6.9
1.7
7.6
1.0
9.4
Reaction Conditions: 0.15 g Pd catalyst, 40% Glycerol aqueous 10 mL, 200 oC, 8 MPa H2, 18 h, 700 rpm.
6
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(b)
5Pd-5Re/SBA-15-H2-750
5Pd-5Re/SBA-15-H2-650
5Pd-5Re/SBA-15-H2-500
5Pd-5Re/SBA-15-H2-350
5Pd-5Re/SBA-15-H2-250
5Pd-5Re/SBA-15-H2-150
5Pd-5Re/SBA-15-H2-RT
5Pd-5Re/SBA-15-Dry-110
10
20
30
40
50
60
70
80
o
2θ
( )
Fig. 6 XRD patterns of 5Pdꢀ5Re/SBAꢀ15 with different reduction
temperatures
Fig. 7 TEM images of 5Pdꢀ5Re/SBAꢀ15 (a) reduced at 25 oC and
(b) reduced at 750 oC
25
5
From the characterization results of H2ꢀTPR, XRD and TEM
of 5Pdꢀ5Re/SBAꢀ15 catalyst, when the reduction temperatures
were below 110 C, part of the PdꢀRe oxide species could not be
In order to confirm the morphology of 5Pdꢀ5Re/SBAꢀ15
prepared by different reduction temperatures, HRꢀTEM
characterization was introduced. From TEM image of 5Pdꢀ
5Re/SBAꢀ15 reduced at 25 oC (Fig. 7 (a)), the PdꢀRe particles
10 were all ballꢀlike and the average particle size was 5 nm. With
EDX analysis, both Pd and Re elements were confirmed in these
particles. For 5Pdꢀ5Re/SBAꢀ15 reduced at 250 oC, the average
o
30 reduced and the activity of the catalyst was relatively low. The
reducible species of PdꢀRe could be fully reduced when the
reduction temperatures were in the range of 150~550 oC. With the
temperature variation in this range, the activities of 5Pdꢀ
5Re/SBAꢀ15 were relatively high. However, when the reduction
35 temperature became too high, the interaction between Pd and Re
would be weakened and PdꢀSi species was formed. This led the
activity of 5Pdꢀ5Re/SBAꢀ15 became lower.
particle size was also 5 nm, but the particles grew along the
[24]
channel of SBAꢀ15
and showed rodꢀlike shapes. When the
o
15 reduction temperature increased to 750 C, the TEM image (Fig.
7 (b)) showed a very different morphology from others. PdꢀRe
particles agglomerated into large and nonuniform particles with
5~16 nm scale, and the average particle size was 9.8 nm.
Meanwhile, most of these particles stayed outside of SBAꢀ15
20 channels.
The effect of Pd and Re interaction on the catalytic
performance of 5Pd-5Re/SBA-15 in glycerol hydrogenolysis
40 From the results mentioned above, Pd and Re in 5Pdꢀ5Re/SBAꢀ
15 might have some interaction. To make sure the importance of
Pd and Re interaction in glycerol hydrogenolysis, some
mechanical mixing catalysts were prepared by mixing
10Pd/SBAꢀ15 and 10Re/SBAꢀ15 or 5Pd/SBAꢀ15 and 5Re/SBAꢀ
45 15. The reaction results with these mechanical mixed catalysts are
shown in Table 5. From these results, it can be seen that for
10Pd/SBAꢀ15+10Re/SBAꢀ15 and 5Pd/SBAꢀ15+5Re/SBAꢀ15
(a)
o
reduced at 250 C, the conversions of glycerol were 12.8% and
20.7%, respectively. These conversions were much lower than
50 that over 5Pdꢀ5Re/SBAꢀ15 prepared by coꢀimpregnation method
(40.7%). When the reduction temperature increased to 500 oC, the
conversions of glycerol over two mechanical mixed catalysts
decreased to 7.7% and 10.1%, respectively, and these were also
much lower than that over coꢀimpregnation 5Pdꢀ5Re/SBAꢀ15
o
55 reduced at 500 C (41.4%). But the mechanical mixed catalysts
still showed higher activities compared with monoꢀcomponent Pd
or Re catalyst (see Table 3). To study further, the sample of
10Pd/SBAꢀ15+10Re/SBAꢀ15 (denoted as 10Pd+10Re) was
characterized by H2ꢀTPR and XRD.
60
From H2ꢀTPR profiles in Fig. 8, except PdH desorption peak
at 100 C, the reduction peaks of 10Pd+10Re were mainly at 30
o
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o
oC and 350 C, which were different from 5Pdꢀ5Re/SBAꢀ15. It
results (Table 6) showed that when the reduction temperature was
was much like the overlap of TPR profiles of 5Pd/SBAꢀ15 and 35 250 oC, the conversion of glycerol increased from 6.5% to 40.1%
5Re/SBAꢀ15 (Fig. 3). From this, it could be inferred that Pd and
Re in mechanical mixed 10Pd+10Re catalyst had nearly no
interaction.
as the content of Re increased from 1% to 10%. For the
distribution of the products, the selectivity to 1,2ꢀPD decreased
from 77.2% to 38.9%, while the selectivity to 1ꢀPO and 1,3ꢀPD
increased from 7.6% and 7.2% to 45.5% and 10.1%, respectively.
5
Fig. 9 shows the XRD patterns of 10Pd+10Re catalyst and
o
other catalysts. For 10Pd+10Re reduced at 250 C, the intensity 40 When the reduction temperature increased from 250 oC to 500 oC,
of diffraction peak of Pd0 was a little higher than that of Pd0 on
5Pdꢀ5Re/SBAꢀ15, and the diffraction peaks of Re0 could be
the activities of 1PdꢀxRe/SBAꢀ15 catalysts changed a lot. For
1Pdꢀ1Re/SBAꢀ15 and 1Pdꢀ5Re/SBAꢀ15 catalysts, the increase of
reduction temperature had little effect on the conversion of
glycerol and the products distribution. But for 1Pdꢀ10Re/SBAꢀ15
10 clearly observed. After reduced at 500 oC, the intensity of
diffraction peaks of Pd0 increased a lot, which meant that higher
reduction temperatures would lead to bigger Pd particles. 45 and 1Pdꢀ15Re/SBAꢀ15 catalysts, the increase of reduction
Meanwhile, the diffraction peaks of Re0 were also very clearly.
These were different from 5Pdꢀ5Re/SBAꢀ15. As the reduction
temperature made the conversion of glycerol decrease from
38.8% and 40.1% to 21.5% and 25.8%, respectively. For the
products distribution, the selectivity to 1,2ꢀPD maintained at
about 50% which was higher than that of 250 oC reduced catalyst.
o
15 temperature of 5Pdꢀ5Re/SBAꢀ15 increased from 250 C to 500
oC, the intensity of Pd0 diffraction peaks changed a little, and
there was no obvious diffraction peak of Re0. It is suggested from
XRD patterns that Pd and Re components in the mechanical
mixed catalysts had no interaction, while ReOx on the
20 mechanical mixed catalysts could be easily reduced.
50
Therefore, with the comparison of PdꢀRe catalysts and
mechanical mixed Pd+Re catalysts, it can be seen that the Pd and
Re interaction was very important in glycerol hydrogenolysis.
With this interaction, PdꢀRe biꢀcomponent catalysts could have
25 higher activities. To make sure this speculation, 1PdꢀxRe/SBAꢀ15
catalysts with different Re amounts were also prepared, and
reduced in H2 at 250 oC or 500 oC before using in the reaction.
From the TPR profiles in Fig. 10, it can be seen that the
reduction properties of 1PdꢀxRe/SBAꢀ15 were different from that
30 of monoꢀcomponent Pd or Re catalyst. The two main reduction
peaks of each catalysts appeared between 100~250 oC. This
suggested that even when the content of Re increased to 15%, Pd
and Re in 1PdꢀxRe/SBAꢀ15 still had interaction. The reaction
5Pd-5Re/SBA-15
10Pd/SBA-15+10Re/SBA-15
100
200
300
400
500
Temp ( )
oC
Fig. 8 Comparison of H2ꢀTPR profiles of PdꢀRe/SBAꢀ15 with
Pd/SBAꢀ15 + Re/SBAꢀ15
55
Table 5 Comparison of the catalytic performance of PdꢀRe/SBAꢀ15 with mechanical mixed Pd/SBAꢀ15 + Re/SBAꢀ15
catalysts in glycerol hydrogenolysis
60
Select. (%)
Reduction
Conv. (%)
Temp (oC)
CH4
C1~2ꢀOH
EG
1ꢀPO
2ꢀPO
1,2ꢀPD
1,3ꢀPD
5Pdꢀ5Re/SBAꢀ15a
5Pd/SBAꢀ15+5Re/SBAꢀ15b
10Pd/SBAꢀ15+10Re/SBAꢀ15c
5Pdꢀ5Re/SBAꢀ15a
250
250
250
500
500
500
40.7
20.7
12.8
41.4
10.1
7.7
2.0
1.5
1.5
1.8
1.3
1.2
1.4
1.6
1.6
1.5
1.5
1.0
1.8
3.0
1.4
1.4
4.4
3.4
24.6
24.9
22.6
25.3
24.8
12.1
2.1
3.9
4.0
3.5
3.9
2.2
59.9
61.0
59.4
57.0
59.6
72.9
8.2
4.0
9.5
9.5
4.6
7.2
5Pd/SBAꢀ15+5Re/SBAꢀ15b
10Pd/SBAꢀ15+10Re/SBAꢀ15c
Reaction Conditions:
(a) 0.15 g Pd catalyst, 40% Glycerol aqueous 10 mL, 200 oC, 8 MPa H2, 18 h, 700 rpm.
(b) 0.15 g Pd+0.15 g Re catalysts, 40% Glycerol aqueous 10 mL, 200 oC, 8 MPa H2, 18 h, 700 rpm.
(c) 0.075 g Pd+0.075 g Re catalysts, 40% Glycerol aqueous 10 mL, 200 oC, 8 MPa H2, 18 h, 700 rpm.
65
8
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XRD patterns of 1PdꢀxRe/SBAꢀ15 reduced at 250 oC and
500 oC are shown in Fig. 11. It clearly shows that when the
reduction temperature was 250 oC, there were no obvious
15 diffraction peaks of Pd and Re, even when the content of Re was
15%. This indicated that for 1PdꢀxRe/SBAꢀ15 reduced at 250 oC,
Pd and Re had some interaction. When the reduction temperature
(a)
5Pd-5Re/SBA-15(H -250)
2
10Pd/SBA-15
(
(
H -250
)
+
2
10Re/SBA-15
H2-250
)
10Re/SBA-15(H -250)
2
o
o
increased from 250 C to 500 C, for 1Pdꢀ1Re/SBAꢀ15 and 1Pdꢀ
5Re/SBAꢀ15, there were still no Pd and Re diffraction peaks.
20 This suggested that the interaction between Pd and Re was still
maintained and the conversion of glycerol over these two
catalysts had little changes compared with those of 250 oC
reduced samples. But for 1Pdꢀ10Re/SBAꢀ15 and 1Pdꢀ15Re/SBAꢀ
10Pd/SBA-15
(
H -250)
2
10
20
30
40
50
60
70
80
(o)
2θ
o
15, reduction temperature at 500 C made ReOx being reduced
(b)
5Pd-5Re/SBA-15(H -500)
2
o
o
25 into Re0 (2θ = 40.5 and 42.9 , as shown in Fig. 11), which
could be observed from the XRD patterns. The appearance of Re0
also meant that the Pd and Re interaction was partly weakened,
which made the conversion of glycerol decreased. From above,
Pd and Re interaction in biꢀcomponent catalysts played an
30 important role in glycerol hydrogenolysis.
10Pd/SBA-15(H -500)+
2
10Re/SBA-15
(
H2-500)
10Re/SBA-15(H -500)
2
Intensity
*0.5
10Pd/SBA-15(H -500)
2
The effect of Pd and Re interaction on glycerol dehydration
and acetol hydrogenation
10
20
30
40
50
60
70
80
(o)
From references [28-29], there are two main steps in glycerol
hydrogenolysis, including glycerol dehydration to acetol and
35 acetol hydrogenation to 1,2ꢀPD. For researching the behaviors of
PdꢀRe catalysts in the dehydration and hydrogenation, 5Pdꢀ
5Re/SBAꢀ15, 5Pd/SBAꢀ15 and 5Re/SBAꢀ15 catalysts were used
in these two reactions. The results are listed in Table 7. For
glycerol dehydration, the conversions of glycerol over monoꢀ
40 component Pd and Re catalysts were 7.0% and 5.6%,
respectively. Meanwhile, the conversion of glycerol over 5Pdꢀ
5Re/SBAꢀ15 was 26.5%, which was higher than that of monoꢀ
component Pd or Re catalyst. In glycerol dehydration, the main
product was acetol. For 5Pd/SBAꢀ15 and 5Re/SBAꢀ15, the
45 selectivity to acetol was 74.4% and 89.0%, respectively. For 5Pdꢀ
5Re/SBAꢀ15, the selectivity to acetol was only 59.2%, which was
lower than that of monoꢀcomponent Pd or Re catalyst. While, the
selectivity to 1,2ꢀPD (25.3%) was higher than that of 5Pd/SBAꢀ
15 (16.4%) or 5Re/SBAꢀ15 (5.8%).
2θ
Fig. 9 Comparison of XRD patterns of PdꢀRe/SBAꢀ15 with
Pd/SBAꢀ15 + Re/SBAꢀ15
5
(a) reduced at 250 oC, (b) reduced at 500 oC
1Pd-15Re/SBA-15
1Pd-10Re/SBA-15
1Pd-5Re/SBA-15
Intensity * 8
1Pd-1Re/SBA-15
100
200
300
400
500
Temp
Fig. 10 H2ꢀTPR profiles of 1PdꢀxRe/SBAꢀ15
( )
oC
50
10
Table 6 The catalytic performance of 1PdꢀxRe/SBAꢀ15 in glycerol hydrogenolysis
Select. (%)
Conv. (%)
CH4
0.9
1.1
1.2
1.3
0.0
1.3
0.5
0.9
C1~2ꢀOH
0.8
0.8
0.6
0.6
1.1
1.0
0.8
EG
5.4
0.9
0.4
0.9
4.0
2.9
2.1
0.8
1ꢀPO
7.6
2ꢀPO
1,2ꢀPD
77.2
58.3
45.5
38.9
75.4
57.3
51.4
51.3
1,3ꢀPD
7.2
12.1
10.3
10.1
6.6
10.5
10.2
9.6
1Pdꢀ1Re/SBAꢀ15(H2ꢀ250)
1Pdꢀ5Re/SBAꢀ15(H2ꢀ250)
1Pdꢀ10Re/SBAꢀ15(H2ꢀ250)
1Pdꢀ15Re/SBAꢀ15(H2ꢀ250)
1Pdꢀ1Re/SBAꢀ15(H2ꢀ500)
1Pdꢀ5Re/SBAꢀ15(H2ꢀ500)
1Pdꢀ10Re/SBAꢀ15(H2ꢀ500)
1Pdꢀ15Re/SBAꢀ15(H2ꢀ500)
6.5
15.0
38.8
40.1
5.6
15.2
21.5
25.8
0.8
1.8
2.5
2.6
1.4
2.0
2.2
2.3
25.0
39.5
45.5
11.5
24.9
32.8
34.4
0.7
Reaction Conditions: 0.15 g Pd catalyst, 40% Glycerol aqueous 10 mL, 200 oC, 8 MPa H2, 18 h, 700 rpm.
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From these results, biꢀcomponent PdꢀRe catalysts showed
higher performance in both glycerol dehydration and acetol
15 hydrogenation reactions. These results were in accordance with
the higher performance of PdꢀRe catalysts in glycerol
hydrogenolysis. Besides, the mechanical Pd+Re had a better
activity than monoꢀcomponent Pd catalyst. This might be caused
by the acidity of ReOx, which could promote the dehydration
20 step [24]. From above, the synergism of Pd and Re interaction and
acidity of ReOx lead PdꢀRe biꢀcomponent catalysts more
effective in glycerol hydrogenolysis.
1Pd-15Re/SBA-15
1Pd-10Re/SBA-15
1Pd-5Re/SBA-15 H2-500
(
H2-500
)
(
H2-500
)
(
)
1Pd-1Re/SBA-15
1Pd-15Re/SBA-15
1Pd-10Re/SBA-15
1Pd-5Re/SBA-15
(
H2-500
H2-250
H2-250
H2-250
)
(
)
(
)
(
)
1Pd-1Re/SBA-15
(
H2-250
)
10
20
30
40
50 60
70
80
o
( )
2θ
Fig. 11 XRD patterns of 1PdꢀxRe/SBAꢀ15 with different
Conclusions
reduction temperatures
Biꢀcomponent PdꢀRe catalysts had higher activity than monoꢀ
25 component Pd or Re catalyst. With the addition of Re component,
Pd particles were grown along the SBAꢀ15 channels and the
average particle size became smaller. Meanwhile, with the
existence of Pd component, ReOx could maintain at higher
oxidation state. Pd and Re interaction play an important role in
30 glycerol hydrogenolysis and could promote both glycerol
dehydration and acetol hydrogenation steps.
5
For acetol hydrogenation reaction, the biꢀcomponent 5Pdꢀ
5Re/SBAꢀ15 also showed high conversion. For 5Pd/SBAꢀ15, the
conversion of acetol was the lowest (3.8%). And 21.3% of acetol
conversion was got over 5Re/SBAꢀ15, which was a little higher
than that of 5Pd/SBAꢀ15. For biꢀcomponent 5Pdꢀ5Re/SBAꢀ15,
10 the conversion of acetol reached 86.0%. This was the highest
among the three catalysts. For all catalysts, the selectivities to
1,2ꢀPD were all higher than 90%.
Table 7 The results of glycerol dehydration over PdꢀRe catalysts
Select. (%)
Conv.
(%)
Reaction
C1~2ꢀOH 1ꢀPO 2ꢀPO 1,2ꢀPD 1,3ꢀPD Acetol
5Pd/SBAꢀ15
Glycerol dehydrationa
7.0
26.5
5.6
n.d.
3.8
86.0
21.3
1.0
6.7
6.3
2.5
2.0
8.0
1.7
0.0
0.1
0.2
16.4
25.3
5.8
0.5
1.1
0.7
74.4
59.2
89.0
5Pdꢀ5Re/SBAꢀ15 Glycerol dehydrationa
5Re/SBAꢀ15
SBAꢀ15
5Pd/SBAꢀ15
Glycerol dehydrationa
Glycerol dehydrationa
Acetol hydrogenationb
ꢀ
2.4
0.5
0.7
1.5
1.9
2.4
0.9
2.5
1.3
5.5
0.2
4.5
94.4
91.6
98.3
91.5
0.0
0.0
0.0
0.0
ꢀ
ꢀ
ꢀ
ꢀ
5Pdꢀ5Re/SBAꢀ15 Acetol hydrogenationb
5Re/SBAꢀ15
SBAꢀ15
Acetol hydrogenationb
Acetol hydrogenationb
35
Reaction Conditions a: 0.15 g Pd or 0.15 g Re catalyst, 40% Glycerol aqueous 10 mL, 200 oC, 8 MPa N2, 18 h, 700 rpm.
Reaction Conditions b: 0.15 g Pd or 0.15 g Re catalyst, 40% Glycerol aqueous 10 mL, 200 oC, 8 MPa H2, 1 h, 700 rpm
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40 Foundation of China (No. 21033004, 20973098).
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Graphical abstract
OH
50
40
30
20
10
0
H2-TPR
HO
OH
5Pd-5Re/SBA-15
HO
OH
HO
OH
-H2O +H2
10Pd/SBA-15+
10Re/SBA-15
Pd-ReOx
Support
100
200
Temp
300
400
500
o
( )
C