Aqueous-phase hydrogenolysis of glycerol to 1,3-propanediol over Pt-H 4SiW12O40/SiO2

Article abstract of DOI:10.1007/s10562-011-0757-1

Hydrogenolysis of glycerol to 1,3-propanediol in aqueous-phase was investigated over Pt-H₄SiW₁₂O₄₀/SiO₂ bi-functional catalysts with different H₄SiW₁₂O ₄₀ (HSiW) loading. Among them, Pt-15HSiW/SiO₂ showed superior performance due to the good dispersion of Pt and appropriate acidity. It is found that Bronsted acid sites facilitate to produce 1,3-PDO selectively confirmed by Py-IR. The effects of weight hourly space velocity, reaction temperature and hydrogen pressure were also examined. The optimized Pt-HSiW/SiO₂ catalyst showed a 31.4% yield of 1,3-propanediol with glycerol conversion of 81.2% at 200 °C and 6 MPa. Graphical Abstract: [Figure not available: see fulltext.].

Full text of DOI:10.1007/s10562-011-0757-1

Catal Lett (2012) 142:267–274
DOI 10.1007/s10562-011-0757-1
Aqueous-Phase Hydrogenolysis of Glycerol to 1,3-propanediol
Over Pt-H4SiW12O40/SiO2
•
Shanhui Zhu Yulei Zhu Shunli Hao
•
•
•
Lungang Chen Bin Zhang Yongwang Li
•
Received: 30 September 2011 / Accepted: 5 December 2011 / Published online: 20 December 2011
Ó Springer Science+Business Media, LLC 2011
Abstract Hydrogenolysis of glycerol to 1,3-propanediol
in aqueous-phase was investigated over Pt-H4SiW12O40/
SiO2 bi-functional catalysts with different H4SiW12O40
(HSiW) loading. Among them, Pt-15HSiW/SiO2 showed
superior performance due to the good dispersion of Pt and
appropriate acidity. It is found that Brønsted acid sites
facilitate to produce 1,3-PDO selectively confirmed by
Py-IR. The effects of weight hourly space velocity, reaction
temperature and hydrogen pressure were also examined.
The optimized Pt-HSiW/SiO2 catalyst showed a 31.4% yield
of 1,3-propanediol with glycerol conversion of 81.2% at
200 °C and 6 MPa.
and reduce the CO2 emission [1–4]. In this context, bio-
mass-derived polyols emerge as promising building blocks
for liquid fuels and valuable commodity chemicals [5–10].
Among them, glycerol is especially attractive because it
can be converted to a wide range of value-added chemicals
by catalytic processes such as reforming, oxidation,
dehydration, esterification, etherification, hydrogenolysis,
polymerization and so on [1, 6, 9, 11]. In addition, glycerol
is a by-product in a large amount from the production of
biodiesel by transesterification of plant and animal oils
with methanol [1, 6]. Therefore, it is essential for the
sustainable development of biodiesel industry to effec-
tively utilize the renewable glycerol.
Keywords Glycerol ꢀ Hydrogenolysis ꢀ 1,3-propanediol ꢀ
Hydrogenolysis of glycerol to 1,2-propanediol (1,2-
PDO) and 1,3-propanediol (1,3-PDO) is a noticeable
pathway for the production of renewable value-added
chemicals. 1,3-PDO owes much higher economical value
than 1,2-PDO, in particular, as an important monomer in
the synthesis of polyester fibers [1, 6, 11]. Industrial pro-
duction of 1,3-PDO is currently based on chemical syn-
thesis via hydration of acrolein or hydroformylation of
ethylene oxide [12]. In comparison with petroleum-derived
acrolein and ethylene oxide, glycerol is not only renewable,
but also structurally analogous to 1,3-PDO. These features
render glycerol to be preferential feedstorks, in terms of
sustainability and energy efficiency, for the synthesis of
1,3-PDO by catalytic hydrogenolysis.
Silicotungstic acid
1 Introduction
The conversion and utilization of renewable biomass pro-
vide a facile route to alleviate the shortage of fossil fuels
S. Zhu ꢀ Y. Zhu (&) ꢀ L. Chen ꢀ B. Zhang ꢀ Y. Li
State Key Laboratory of Coal Conversion, Institute of Coal
Chemistry, Chinese Academy of Sciences, 030001 Taiyuan,
People’s Republic of China
Conversion of glycerol to 1,2-PDO has been extensively
studied in recent years, and high yields have been obtained
in previous reports [8, 9, 13–22]. In contrast, direct hy-
drogenolysis of glycerol to 1,3-PDO is still a challenge.
Several patents and papers have disclosed 1,3-PDO pro-
duction by the catalytic hydrogenolysis of glycerol in the
presence of homogeneous or heterogeneous catalysts. Che
[23] found that glycerol can be hydrogenolyzed to 1,3-PDO
e-mail: zhuyulei@sxicc.ac.cn
S. Zhu ꢀ L. Chen ꢀ B. Zhang
Graduate University of Chinese Academy of Sciences,
100039 Beijing, People’s Republic of China
S. Hao
Synfuels China Co. Ltd, 030032 Taiyuan,
People’s Republic of China
123

268
S. Zhu et al.
and 1,2-PDO in yields of 21 and 23%, respectively, at
200 °C and 32 MPa syngas in 1-methyl-2-pyrolidinone on
a homogeneous rhodium complexes catalyst Rh(CO)2
(acac) with H2WO4 as a promoter. Chaminand et al. [24]
reported that hydrogenolysis of glycerol to 1,3-PDO on Rh/
SiO2 catalyst achieved 4% yield in the presence of H2WO4
at 200 °C and 8.0 MPa. Kurosaka et al. [25] obtained 24%
yield of 1,3-PDO from glycerol in 1,3-dimethyl-2-imida-
zolidinone over Pt/WO3/ZrO2 at 170 °C and 8.0 MPa.
Tomishige et al. [26, 27] reported that the yield of 1,3-PDO
reached 38% over Ir-ReOx/SiO2 catalyst with H2SO4 as an
additive in a batch reactor. Additionally, other effective
hydrogenolysis processes that have been reported recently
employed Rh-ReOx/SiO2 [8], Pt/WO3/TiO2/SiO2 [28],
bimetallic Pt–Re [29], and Pt/WO3/ZrO2 [30] as hetero-
geneous catalysts.
2 Experimental
2.1 Catalyst Preparation
The Pt/SiO2 catalysts were prepared by impregnation of
silica support (Qingdao Haiyang Chemical Co., Ltd, 20–40
mesh, 374 m2/g) with an aqueous solution H2PtCl6ꢀ6H2O
(AR, SCRC). Impregnated samples were dried overnight at
110 °C and then calcined in static air at 400 °C for 4 h.
The Pt-HSiW/SiO2 catalysts were prepared by impregna-
tion of Pt/SiO2 catalysts with aqueous solutions containing
the desired amount of HSiW (AR, SCRC). After impreg-
nation, samples were dried overnight at 110 °C and then
calcined in static air at 350 °C for 4 h. The actual HSiW
and Pt loadings were evaluated by ICP. The difference
between nominal and measured mass ratio is minor. Thus
the samples are hereafter referred by their nominal com-
positions. The catalysts are generally labeled as Pt-xHSiW/
SiO2, in which x stands for the nominal weight loading of
HSiW. The loading of Pt were fixed at 2 wt% in all cata-
lysts. Additionally, 10Cu-15HSiW/SiO2 was prepared as a
reference sample according to the method described pre-
viously [31].
These previous efforts have demonstrated the feasibil-
ity of the direct hydrogenolysis route in the synthesis of
1,3-PDO. However, these studies also remain several
problems. Most of the previous studies have been per-
formed in organic solvent, which will greatly reduce the
environmental and economical viability. Another disad-
vantage arises from use of liquid acids, e.g., H2WO4,
H2SO4, which will cause problems in terms of catalyst
separation, reactor corrosion and environmental protec-
tion. Furthermore, the previous processes are mainly
discontinuous, leading to difficulty in catalyst and product
separation.
2.2 Catalyst Characterization
N2 adsorption–desorption isotherms were recorded at
-196 °C on a Micromeritics ASAP 2420 instrument. Prior
to the measurement, each sample was degassed under
vacuum at 300 °C for 8 h.
The development of a novel catalyst system for this
environmentally friendly reaction has attracted consider-
able attention. Alhanash et al. [17] reported that 5%
Rh/Cs2.5H0.5[PW12O40] catalyst gave 7.1% selectivity of
1,3-PDO in liquid phase. We have previously investi-
gated vapor-phase hydrogenolysis of glycerol over
Cu-HSiW/SiO2 without employing solvent in a fixed-bed
reactor [31]. Replacement of liquid acid catalysts with
supported HSiW would remove energy-consuming sepa-
ration steps and reduce disposal needs for corrosive liq-
uids, which makes our process more environmentally
friendly and energy-saving. It is well known that crude
glycerol from biodiesel production contains water
unavoidably and water is also a product of the reaction
sequence, which makes water the desired solvent for
glycerol hydrogenolysis from the standpoint of environ-
mental and economical viability. In this work, we reported
a detailed study of continuous hydrogenolysis of glycerol
over Pt-HSiW/SiO2 bi-functional catalysts in aqueous
medium. We examined the effects of HSiW content,
reaction temperature, hydrogen pressure, weight hourly
space velocity (WHSV) on the catalytic performance.
Furthermore, a comparison between the performance of
Cu-HSiW/SiO2 and Pt-HSiW/SiO2 under identical condi-
tions was presented later.
Powder X-ray diffraction (XRD) patterns were recorded
on a D2/max-RA X-ray diffractometer (Bruker, Germany),
using Cu Ka radiation at 30 kV and 10 mA. The X-ray
patterns were recorded in 2h values ranging from 7° to 80°.
CO chemisorption was carried out in Auto Chem.II2920
equipment (Mircromeritics, USA). In a typical run, about
0.2 g sample was filled in a U-shaped quartz tube. The
sample was first reduced by H2 at 300 °C for 2 h, flushed
with He at the same temperature for 1 h and then cooled
down to 50 °C. The CO chemisorption was operated by
pulse injection of pure CO at 50 °C. The Pt particle size
was calculated by assuming an adsorption of one CO
molecule per surface platinum atom.
NH3-TPD was carried out in the same apparatus as
above. In a typical experiment about 0.2 g sample was
loaded in a U-shaped quartz tube. Prior to each run, the
catalyst sample was pretreated in He at 350 °C for 1 h,
then cooled to 100 °C and was saturated with pure NH3 for
30 min. After being purged with He for 30 min, the sample
was heated to 700 °C at a heating rate of 10 °C/min and the
NH3 desorption was monitored with a TCD detector. All
the detected TPD peaks were deconvoluted at different
maxima peak temperatures with a Gaussian function for
123

Aqueous-phase Hydrogenolysis of Glycerol
269
fitting, and the peak areas were calculated. The peak area
can be correlated with the amount of adsorbed NH3 on the
basis of the pulsed NH3 injection experiment.
amounted to 24 h. The catalyst activity within this time
period was rather stable.
The liquid products were analyzed by a gas chromatog-
raphy (Ruihong chromatogram analysis Co., Ltd, China)
with a flame ionization detector and a capillary column
(DB-WAX, 30 m 9 0.32 mm). The tail gas was off-line
analyzed using a gas chromatograph (Huaai chromatogram
analysis Co., Ltd, China) equipped with a column (OV-101,
60 m 9 0.25 mm) and a thermal conductivity detector. The
products were identified by GC–MS analysis.
Raman spectra were recorded with a LabRAM HR800
System equipped with a CCD detector at room tempera-
ture. The 325 nm of the He-Cd laser was used as the
exciting source with a power of 30 MW.
ICP optical emission spectroscopy (Optima2100DV,
PerkinElmer) was used to analyze the chemical composi-
tion of the catalysts.
IR spectra of adsorbed pyridine (Py-IR) were measured
with VERTEX70 (Bruker) FT-IR spectrophotometer,
equipped with a deuterium triglycine sulphate (DTGS)
detector. The samples were degassed in a vacuum at 300 °C
for 1 h, and then exposed to the pyridine vapor after cooling
down to 30 °C. The Py-IR spectra were then recorded at 100
and 200 °C after applying vacuum for 30 min.
The mass balances for liquid products accounted for
93–98% and the selectivity of gas products never exceeded
2%. The identified products were 1,3-PDO, 1,2-PDO,
1-propanol (1-PO), 2-propanol (2-PO), ethanol, propion-
aldehyde, acetone, propionic acid, acetic acid, acetol, acro-
lein, ethylene glycol, propane, methane, CO2 and traces of
unknown products such as cyclic acetals. The conversion of
glycerol, selectivity and yield of products were calculated as
follows:
2.3 Catalytic Tests
Conversionð%Þ
The catalytic reaction of glycerol was performed in a down
flow fixed-bed reactor (i.d. 12 mm, length 600 mm) with
an ice-water trap. In a typical run, 4.0 g catalyst (20–40
mesh) was charged in the constant temperature section of
the reactor, with quartz sand packed in both ends. Prior to
the test, the catalyst sample was in situ reduced in a stream
of pure H2 (100 mL/min) at 300 °C for 2 h. After reduc-
tion, a 10 wt% glycerol aqueous solution and H2 were fed
into the reactor through a preheating zone which was
maintained at 120 °C. The liquid and gas products were
cooled and collected in a gas–liquid separator immersed in
an ice-water trap and then three samples were obtained to
collect representative dada for each set-point. Activity and
product distributions calculated from the samples showed
negligible differences. Total time-on-steam typically
moles of glycerol ðinÞ ꢁ moles of glycerol ðoutÞ
¼
ꢂ 100
moles of glycerol ðinÞ
moles of one product
Selectivity ð%Þ ¼
ꢂ 100
moles of all liquid products
moles of one product
Yield ð%Þ ¼
ꢂ 100
moles of glycerol ðinÞ
3 Results and Discussion
3.1 Catalyst Characterization
Table 1 lists the physicochemical properties for the
as-prepared samples. As can be seen, there is a decrease of
Table 1 Physicochemical properties and acidities of Pt/SiO2 and Pt-HSiW/SiO2 with different HSiW loadings
Catalysts
Surface area Pore size Pore volume Dispersion (%)
(m2g-1
NH3-TPD peak Acid amount Total acidity
position (°C)
(mmol NH3/gcat.) (mmol NH3/gcat.)
)
(nm)
(cm3g-1
)
CO
chemisorption
XRD
Pt/SiO2
369.2
353.4
7.7
7.5
0.95
0.89
11.0
13.8
10
12
179
166
448
168
455
166
450
163
457
168
424
0.11 (105–281 °C) 0.11
0.20 (121–380 °C) 1.06
0.86 (380–540 °C)
0.12 (117–359 °C) 1.32
1.20 (359–597 °C)
0.10 (124–374 °C) 1.57
1.47 (374–608 °C)
0.09 (130–333 °C) 1.69
1.60 (333–592 °C)
Pt-5HSiW/SiO2
Pt-10HSiW/SiO2 333.2
Pt-15HSiW/SiO2 323.9
Pt-20HSiW/SiO2 279.9
Pt-30HSiW/SiO2 266.4
8.0
7.9
7.7
8.4
0.85
0.81
0.72
0.68
15.7
19.1
14.6
9.5
14
–
–
–
0.15 (135–350 °C) 1.95
1.80 (350–534 °C)
123

270
S. Zhu et al.
998
HSiW
HSiW
Pt
977
HSiW
890
1/4
Pt-30HSiW/SiO2
Pt-20HSiW/SiO2
Pt-15HSiW/SiO2
Pt-10HSiW/SiO2
Pt-5HSiW/SiO2
Pt-30HSiW/SiO2
Pt-20HSiW/SiO2
Pt-15HSiW/SiO2
Pt-10HSiW/SiO2
Pt-5HSiW/SiO2
Pt/SiO2
SiO2
200
400
600
800
1000
1200
20
30
40
50
60
70
80
-1
(o)
Raman shift (cm )
2
Fig. 2 Raman spectra of Pt-HSiW/SiO2 with different loadings of
HSiW
Fig. 1 XRD patterns of Pt-HSiW/SiO2 with different loadings of
HSiW
998, 977 and 890 cm-1 which are assigned to W=O sym-
metric and asymmetric vibrations and W–O–W asymmet-
ric stretching vibration of bulk HSiW, respectively [32]. As
shown in Fig. 2, these peaks shown up and the intensity
increased with the increasing of HSiW content, confirming
the presence of Keggin structure in the as-prepared sam-
ples. Compared to bulk HSiW, the slight shifts in the peaks
could be attributed to the interaction of HSiW with silica
support.
surface area and pore volume with increasing HSiW con-
tent, as previously reported over Ni-HSiW/SiO2 [32]. This
decrease is even more pronounced for Pt-30HSiW/SiO2,
perhaps due to pore blockage.
The XRD patterns of reduced Pt-HSiW/SiO2 catalysts
with different HSiW loadings are illustrated in Fig. 1. It is
clear that no characteristic peak for HSiW crystallites
(20.5°, 25.4°, 29.4°, 34.6°, and 53.3°) was detected for all
the samples, implying the fine dispersion of HSiW on the
support surface. This was well consistent with previous
results [32] that the diffraction peaks of HSiW appeared at
HSiW content above 50% on silica. The three peaks at
39.8°, 46.2° and 67.5° are assigned to the reflection of
metallic Pt [28]. The intensity of peaks became weaker
with increasing HSiW loading, and then disappeared when
HSiW loading were above 10%, indicating that HSiW can
improve the dispersion of Pt on the support surface to some
extent. As shown in Table 1, the dispersion calculated by
XRD increased with the increasing HSiW loading.
It has been suggested that appropriate acidity is essential
for the selective hydrogenolysis of glycerol to 1,3-PDO due
to the bi-functional process [14, 16, 17, 20, 35]. 1,3-PDO
cannot be formed selectively over those supported metal
catalysts such as Pt/C and Rh/SiO2 without the presence of
an effective acidic component. Thus, the acidic properties
of the as-prepared samples were examined by NH3-TPD
and Py-IR. The strength of acid sites as determined by the
NH3 desorption temperature is generally classified as three
types, weak (150–300 °C), medium (300–500 °C), and
strong (500–650 °C) [34]. In Fig. 3, a small peak around
179 °C was observed over Pt/SiO2, indicating that Pt/SiO2
only had weak strength acid sites. In contrast, Pt-HSiW/
SiO2 showed much larger peaks at around 170 and 450 °C,
indicating that it has more acidic sites with weak and
medium acid strength. As shown in Table 1, the acid
amount of medium acid sites was much higher than that of
weak acid sites, suggesting that more medium acid sites
were formed due to addition HSiW to Pt/SiO2. The amount
of acid sites increased gradually with increasing HSiW
content.
The CO chemisorption on the reduced catalysts was
employed to calculate dispersion of surface Pt atoms and
the results are also presented in Table 1. This dispersion
firstly increased to a maximum and then decreased rapidly
as the HSiW loading increased. It is assumed that HSiW
can promote Pt dispersion at lower HSiW content, whereas
the low dispersion at higher HSiW content is because of
partial covering of the surface Pt metal with HSiW. Similar
phenomenon has been reported in the case of Pd-HSiW/
SiO2 [33] and Ir-ReOx/SiO2 [26]. This partial covering
effect can decrease surface Pt active sites and affect the
activity of glycerol hydrogenolysis.
Py-IR spectra of Pt/SiO2 and Pt-15HSiW/SiO2 catalysts
at 100 and 200 °C are displayed in Fig. 4. The bands at
1,450 and 1,540 cm-1 are attributed to the pyridine
adsorbed on the Lewis acid and Brønsted acid sites,
Raman spectroscopy is known to be well suited for
observation of Keggin structure to verify the integrity of
HSiW structure [34]. The Raman spectrum gives bands at
123

Aqueous-phase Hydrogenolysis of Glycerol
271
Table 2 Amount of acid sites determined by Py-IR on Pt/SiO2 and
Pt-15HSiW/SiO2
f
Catalysts
Acid sites (mmol/g)
Lewis Brønsted
100 °C 200 °C 100 °C 200 °C 100 °C 200 °C
L/(B ? L) ratio
e
Pt/SiO2
0.0424 0.0180 0.0116 0.0112 0.79
0.62
0.29
d
c
Pt-15HSiW/ 0.0653 0.0571 0.1406 0.1385 0.32
SiO2
b
a
50
40
30
20
10
0
Conversion
Selectivity
60
50
40
30
20
10
0
100
200
300
400
500
600
700
Temperature (oC)
Fig. 3 NH3-TPD profiles of a Pt/SiO2;
c Pt-10HSiW/SiO2; d Pt-15HSiW/SiO2; e Pt-20HSiW/SiO2; f Pt-30HSiW/
b
Pt-5HSiW/SiO2;
SiO2
L
B
0
5
10
15
20
25
30
HSiW loading (%)
Fig. 5 Effect of HSiW loading on the conversion of glycerol and
selectivity to 1,3-PDO over Pt-HSiW/SiO2. Reaction conditions:
200 °C, 5.0 MPa, 4.0 g catalysts; 10 wt% glycerol aqueous solution,
H2/glycerol = 137:1 (molar ratio), WHSV = 0.045 h-1
d
c
b
3.2 Influence of HSiW Loading
a
Figure 5 shows the effect of HSiW loading on glycerol
hydrogenolysis over Pt-HSiW/SiO2. Over the Pt/SiO2 cat-
alyst, the conversion and selectivity to 1,3-PDO were only
19.3 and 5.0%, respectively. Compared with Pt/SiO2, the
activity and selectivity to 1,3-PDO over Pt-5HSiW/SiO2
increased sharply. With increasing HSiW content, both
conversion and 1,3-PDO selectivity increased linearly, but
further increase led to the decrease of activity and 1,3-PDO
selectivity. The optimal loading of HSiW was 15%, in
which case glycerol conversion and 1,3-PDO selectivity
attained maxima: 63.8 and 34.5%, respectively. It is sug-
gested that HSiW can affect the reactivity of glycerol
hydrogenolysis significantly.
1400
1450
1500
1550
1600
1650
1700
-1
Wavenumber (cm )
Fig. 4 Py-IR spectra of a 200 °C, Pt/SiO2; b 100 °C, Pt/SiO2;
c 200 °C, Pt-15HSiW/SiO2; d 100 °C, Pt-15HSiW/SiO2
respectively [16]. The concentrations of Lewis (L) acid and
Brønsted (B) acid sites are obtained from the bands at
1,450 and 1,540 cm-1 [36] and the calculated L/(L ? B)
ratios are listed in Table 2. The results show that both the
amount and ratio of Brønsted acid sites increase remark-
ably by doping HSiW on Pt/SiO2. Concurrently, the
decrease of L/(L ? B) ratios with the increase of evacua-
tion temperature indicates that Brønsted acid sites are
stronger than Lewis acid sites. Thus, HSiW is responsible
for inducing the presence of Brønsted acid sites, consistent
with the previous reports [32, 37].
Concerning the activity of the catalysts, Pt-15HSiW/
SiO2 was most active, probably due to the good dispersion
of Pt and suitable acidity. The CO chemisorption results
suggest that the Pt-15HSiW/SiO2 catalyst exhibited the
highest dispersion (Table 1). On the other hand, 15 wt%
HSiW loading seemed to provide sufficient acidity to
123

272
S. Zhu et al.
obtain high activity and further increase of HSiW loading
resulted in a negative effect on the catalytic performance of
the catalyst, which might be a result of the unsuitable
metal/acid ratios.
Table 3 Influence of WHSV on glycerol hydrogenolysis over Pt-
15HSiW/SiO2
WHSV Conversion Selectivity (%)a
(h-1
)
(%)
1,3-PDO 1,2-PDO n-PO i-PO Othersb
Compared to Pt/SiO2, the selectivity to 1,3-PDO over
Pt-HSiW/SiO2 enhanced remarkably. According to the
literatures [38, 39], Brønsted acid sites played a key role in
the dehydration of glycerol to 3-hydroxypropionaldehyde,
which subsequently hydrogenated to form 1,3-PDO or
further dehydrated to produce acrolein. These results lead
to the proposition that Brønsted acid sites were more
advantageous than Lewis acid sites for the selective
hydrogenolysis of glycerol to 1,3-PDO. Thus, it is obvious
that Brønsted acid sites are indispensable in order to pro-
duce 1,3-PDO selectively.
0.03
88.5
63.8
24.2
9.4
27.2
34.5
37.7
40.1
24.8
17.6
24.1
30.9
36.9 5.5
35.6 5.2
27.5 1.6
23.7 1.2
5.6
7.1
9.1
4.1
0.045
0.075
0.15
Reaction conditions: 200 °C, 5.0 MPa, 4.0 g catalysts; 10 wt%
glycerol aqueous solution; H2/glycerol = 137:1 (molar ratio)
a
1,3-PDO: 1,3-propanediol, 1,2-PDO: 1,2-propanediol, 1-PO:
1-propanol, 2-PO: 1-propanol
b
Others include ethanol, methanol, acetone, acetol, propane, etc
Additionally, in order to explore the role of metal Pt for
glycerol hydrogenolysis, we conducted the reaction with
HSiW/SiO2 under the same condition as other catalysts.
For the HSiW/SiO2 catalyst, the conversion and selectivity
to 1,3-PDO was very poor (5.8 and 3.2%, respectively) and
large amounts of dehydration products such as acrolein and
acetol were formed, indicating that the hydrogenation sites
of Pt are also essential to form 1,3-PDO. In summary, it can
be concluded that efficient catalytic reactivity in glycerol
hydrogenolysis to 1,3-PDO are realized by the combination
of Brønsted acid sites of HSiW and active hydrogen spe-
cies of Pt.
Conversion
1,3-PDO
1,2-PDO
1-PO
100
80
60
40
20
0
2-PO
The above results reveal that Brønsted acid sites was
favorable to produce 1,3-PDO selectively. Additionally,
the high loading of HSiW led to the decrease of 1,3-PDO
selectivity. Thus, the balance between acidic sites and
active hydrogen species played a key role in formation
1,3-PDO effectively. Since the Pt-15HSiW/SiO2 sample
exhibited the highest performance, the following investi-
gations conducted on this sample.
180
190
200
210
Temperature (oC )
Fig. 6 Effect of reaction temperature on glycerol hydrogenolysis
over Pt-15HSiW/SiO2. Reaction conditions: 5.0 MPa, 4.0 g catalysts;
10 wt% glycerol aqueous solution, H2/glycerol = 137:1 (molar ratio),
WHSV = 0.045 h-1
3.3 Influence of Weight Hourly Space Velocity
The WHSV dependence of glycerol hydrogenolysis over
Pt-15HSiW/SiO2 is noted in Table 3. Conversion of glyc-
erol decreased remarkably with increasing WHSV because
residence time shortened correspondingly. Simultaneously,
the selectivity to 1,3-PDO increased along with the
decrease of 1-PO, indicating that the short residence time
favored to suppress 1,3-PDO overhydrogenolysis to 1-PO.
180 °C to 17.1% at 210 °C. In contrast, the increase of
temperature positively affected 1,2-PDO selectivity,
because it may be easier to activate terminal hydroxyl
groups of glycerol at high temperature [28]. Concurrently,
1-PO selectivity increased linearly with the increasing
temperature as high temperature facilitated to overhydro-
genolysis of propanediols [30]. The optimum reaction
temperature lies between 180 and 200 °C due to the high
selectivity to desired 1,3-PDO with reasonable conversion.
3.4 Influence of Temperature
Figure 6 shows the effect of reaction temperature on
glycerol hydrogenolysis over Pt-15HSiW/SiO2. As expec-
ted, glycerol conversion increased monotonically from
16.3 to 99.4% with increasing temperature from 180 to
210 °C. The selectivity to 1,3-PDO dropped from 41.7% at
3.5 Influence of Hydrogen Pressure
Figure 7 shows the effect of H2 pressure on glycerol
hydrogenolysis over Pt-15HSiW/SiO2 at 200 °C. Glycerol
123

Aqueous-phase Hydrogenolysis of Glycerol
273
4 Conclusions
Conversion
80
1,3-PDO
1,2-PDO
1-PO
Our present work has demonstrated that glycerol can be
effectively and selectively converted to 1,3-PDO in aque-
ous medium over Pt-HSiW/SiO2 bifunctional catalysts.
Brønsted acid sites with appropriate acid strength was
related to form 1,3-PDO selectively. The content of HSiW
affected the performance of glycerol hydrogenolysis sig-
nificantly, indicating that a well balance between Brønsted
acid sites and active hydrogen species is responsible for the
good yield of 1,3-PDO. Finally, the conversion of glycerol
and the selectivity to 1,3-PDO greatly depend on the
WHSV, temperature and hydrogen pressure.
2-PO
60
40
20
0
Acknowledgments The authors gratefully acknowledge the finan-
cial support of the Natural Science Foundation of China (No.
20976185). This work was also supported by the Major State Basic
Research Development Program of China (973 Program) (No.
2012CB215305).
3
4
5
6
Hydrogen pressure (MPa)
Fig. 7 Effect of H2 pressure on glycerol hydrogenolysis over
Pt-15HSiW/SiO2. Reaction conditions: 200 °C, 4.0 g catalysts;
10 wt% glycerol aqueous solution, H2/glycerol = 137:1 (molar ratio),
WHSV = 0.045 h-1
References
1. Behr A, Eilting J, Irawadi K, Leschinski J, Lindner F (2008)
Green Chem 10:13
2. Huber GW, Iborra S, Corma A (2006) Chem Rev 106:4044
3. Corma A, Iborra S, Velty A (2007) Chem Rev 107:2411
4. Alonso DM, Bond JQ, Dumesic JA (2010) Green Chem 12:1493
conversion improved significantly with increasing H2
pressure from 3.0 to 6.0 MPa. The yield of 1,3-PDO
increased with H2 pressure and maximal yield of 1,3-PDO
(31.4%) was achieved at 6.0 MPa and 200 °C. Concur-
rently, the selectivity to 1,2-PDO decreased gradually with
increasing H2 pressure except the high pressure range
([5 MPa). In summary, as reported previously [31], the
increase of hydrogen pressure is favorable to form 1,3-
PDO, which might be due to the increase in the active
hydrogen species formed from hydrogen on Pt-15HSiW/
SiO2.
5. Amada Y, Koso S, Nakagawa Y, Tomishige
ChemSusChem 3:728
K (2010)
6. Zhou CHC, Beltramini JN, Fan YX, Lu GQM (2008) Chem Soc
Rev 37:527
7. Ryneveld E, Mahomed A, Heerden P, Friedrich H (2011) Catal
Lett 141:958
8. Shinmi Y, Koso S, Kubota T, Nakagawa Y, Tomishige K (2009)
Appl Catal B 94:318
9. Balaraju M, Rekha V, Prasad PSS, Prasad RBN, Lingaiah N
(2008) Catal Lett 126:119
10. Sun J, Liu H (2011) Green Chem 13:135
11. Behr A, Eilting J, Irawadi K, Leschinski J, Lindner F (2008)
Chim Oggi 26:32
12. Kraus GA (2008) Clean Soil Air Water 36:648
13. Akiyama M, Sato S, Takahashi R, Inui K, Yokota M (2009) Appl
Catal A 371:60
14. Balaraju M, Rekha V, Prasad PSS, Devi BLAP, Prasad RBN,
Lingaiah N (2009) Appl Catal A 354:82
15. Miyazawa T, Koso S, Kunimori K, Tomishige K (2007) Appl
Catal A 329:30
16. Gandarias I, Arias PL, Requies J, Guemez MB, Fierro JLG
(2010) Appl Catal B 97:248
17. Alhanash A, Kozhevnikova EF, Kozhevnikov IV (2008) Catal
Lett 120:307
18. Zhao J, Yu WQ, Chen C, Miao H, Ma H, Xu J (2010) Catal Lett
134:184
19. Mane RB, Hengne AM, Ghalwadkar AA, Vijayanand S, Mohite
PH, Potdar HS, Rode CV (2010) Catal Lett 135:141
20. Miyazawa T, Kusunoki Y, Kunimori K, Tomishige K (2006)
J Catal 240:213
Previously we have investigated vapor-phase hydrog-
enolysis of glycerol to 1,3-PDO over 10Cu-15HSiW/SiO2
[31]. Under the optimized conditions, the glycerol con-
version and 1,3-PDO selectivity achieved 83.4 and 32.1%,
respectively. Since the evaporation of glycerol was
energy-consuming, the liquid phase catalytic process was
more suitable and conducted in this article. Additionally, a
comparison between the performances of 10Cu-15HSiW/
SiO2 and Pt-15HSiW/SiO2 under identical conditions was
made. Thus, hydrogenolysis of glycerol over 10Cu-
15HSiW/SiO2 was examined in aqueous-phase at 200 °C
and 6.0 MPa. The conversion of glycerol and selectivity to
1,3-PDO were only 9.1 and 8.9% over 10Cu-15HSiW/
SiO2, respectively. Compared to 10Cu-15HSiW/SiO2, the
yield of Pt-15HSiW/SiO2 increased remarkably (conver-
sion 81.2%, 1,3-PDO selectivity 38.7%). On the other
hand, in comparison with the literature [31], the great
discrepancy of performance over 10Cu-15HSiW/SiO2 was
mainly due to the different hydrogenolysis process.
21. Huang L, Zhu YL, Zheng HY, Li YW, Zeng ZY (2008) J Chem
Technol Biotechnol 83:1670
22. Vasiliadou ES, Heracleous E, Vasalos IA, Lemonidou AA (2009)
Appl Catal B 92:90
123

274
S. Zhu et al.
23. Che TM (1987) US Patent 4,642,394, Celanese Corp
24. Chaminand J, Djakovitch L, Gallezot P, Marion P, Pinel C,
Rosier C (2004) Green Chem 6:359
25. Kurosaka T, Maruyama H, Naribayashi I, Sasaki Y (2008) Catal
Commun 9:1360
32. Jin H, Yi X, Sun X, Qiu B, Fang W, Weng W, Wan H (2010)
Fuel 89:1953
33. Kawakami T, Ooka Y, Hattori H, Chu W, Kamiya Y, Okuhara T
(2008) Appl Catal A 350:103
34. Atia H, Armbruster U, Martin A (2008) J Catal 258:71
35. Wawrzetz A, Peng B, Hrabar A, Jentys A, Lemonidou AA,
Lercher JA (2010) J Catal 269:411
26. Amada Y, Shinmi Y, Koso S, Kubota T, Nakagawa Y, Tomishige
K (2011) Appl Catal B 105:117
27. Nakagawa Y, Shinmi Y, Koso S, Tomishige K (2010) J Catal
272:191
28. Gong L, Lu Y, Ding Y, Lin R, Li J, Dong W, Wang T, Chen W
(2010) Appl Catal A 390:119
36. Emeis CA (1993) J Catal 141:347
37. Xu S, Wang L, Chu W, Yang W (2009) J Mol Catal A 310:138
38. Alhanash A, Kozhevnikova EF, Kozhevnikov IV (2010) Appl
Catal A 378:11
29. Daniel OM, DeLaRiva A, Kunkes EL, Datye AK, Dumesic JA,
Davis RJ (2010) ChemCatChem 2:1107
39. Cavani F, Guidetti S, Marinelli L, Piccinini M, Ghedini E,
Signoretto M (2010) Appl Catal B 100:197
30. Qin LZ, Song MJ, Chen CL (2010) Green Chem 12:1466
31. Huang L, Zhu YL, Zheng HY, Ding GQ, Li YW (2009) Catal
Lett 131:312
123