Water-promoted hydrogenation of levulinic acid to γ-valerolactone on supported ruthenium catalyst

Article abstract of DOI:10.1002/cctc.201402834

A highly efficient and green process for the hydrogenation of biomass-derived levulinic acid (LA) to γ-valerolactone (GVL) has been developed. GVL was obtained in a yield of 99.9mol-% with a turnover frequency as high as 7676h^-1 in aqueous medium by using a Ru/TiO₂ catalyst under mild reaction conditions (70-°C). The strong interaction between Ru and TiO₂ facilitated both the dispersion of Ru nanoparticles and the stability of the catalyst. In addition, as solvent, water participated in the hydrogenation of LA, which was confirmed by an isotope- labeling experiment with D (D₂O). Specifically, the H atom(s) in water took part in the hydrogenation of the C=O group of LA, which promoted the catalytic activity and GVL yield remarkably. Water of catalysis: Water promotes the hydrogenation of levulinic acid to γ-valerolactone on a supported ruthenium catalyst with a γ-valerolactone yield of 99.9mol-% at 70-°C.

Full text of DOI:10.1002/cctc.201402834

Supporting Information
ꢀ Copyright Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, 2014
Water-Promoted Hydrogenation of Levulinic Acid to
g-Valerolactone on Supported Ruthenium Catalyst
Jingjing Tan,[a, b] Jinglei Cui,[a, b] Tiansheng Deng,[a] Xiaojing Cui,[a] Guoqiang Ding,[c]
Yulei Zhu,*[a, c] and Yongwang Li[a, c]
cctc_201402834_sm_miscellaneous_information.pdf

Table of Contents
1. Materials and Methods
2. Experiments
3. Results and discussion
4. The solubility of H2 in different solvents
5. 1HMNR and 13CMNR of GVL
6. Mass spectrum of GVL
7. The effect of temperature on the hydrogenation reaction
8. Reusability study of Ru/TiO2 catalyst
9. The effect of agitation rate on the conversion of LA
10. The typical GC chart of hydrogenation of LA to GVL
1

1. Materials
Levulinic acid (LA, 98%) and D2O (99.9%) were purchased from Aladdin;
methanol, ethanol, 1, 4-dioxane and γ-valerolactone (GVL, 98%) were purchased
from Sinopharm Chemical Reagent Co., Ltd.. All the above agents were utilized
without further purification. RuCl3·3H2O, γ-Al2O3, SiO2, ZrO2, and TiO2 (P25
Degussa) were purchased from Sinopharm Chemical Reagent Co., Ltd.; Organic
solvent-water mixtures were obtained by diluting 1 g deionized water with 9 g
alcohols or 1,4-dioxane.
2. Experiments
2.1 The computational formula
The conversion of LA and the selectivity of the products (GVL) were quantified
according to the following equations:
moles of LA(inlet) ̶ moles of LA(outlet)
Conversion =
Selectivity =
×100%
moles of LA(inlet)
moles of one product
×100%
moles of all products
Turnover frequency (TOF) was calculated on the basis of surface Ru atoms,
which is estimated with the total loadings of Ru.
number of LA molecular converted
TOF =
(number of surface Ru atoms)(reaction time,h)
2.2 Catalyst characterization
2.2.1 X-ray diffraction (XRD) measurements Figure S2.
Powder X-ray diffraction (XRD) patterns were obtained on a D2/max-RA X-ray
diffractometer (Bruker, Germany), with Cu Kα radiation at 30 kV and 10 mA. The
X-ray patterns were recorded in 2θ values ranging from 5° to 80° with a scanning
speed of 4 º/min.
2

2.2.2 Transmission electron microscope (TEM) Figure S3.
TEM measurements were performed with a field-emission transmission electron
microscopy (FETEM, JEM-2011F) operating at 200 kV voltages. The reduced
samples were suspended in ethanol with an ultrasonic dispersion for 30 min and
deposited on copper grids coated with amorphous carbon films.
2.2.3 Temperature-programmed reduction (TPR) FigureS4.
Hydrogen temperature-programmed reduction (H2-TPR) experiments were carried
out on a micro automatic chemical adsorption instrument TP5080 with a TCD
detector. Before the measurement, 20 mg catalyst (20-40 mesh) was loaded to a
fixed-bed quartz microreactor (i.d.=4 mm) and pretreated in an N2 flow of 30mL
o
min-1 at 200 C for 0.5 h. After being cooled at the same atmosphere to room
temperature (RT), the pretreated sample was exposed to a flow (30 mL/min) of 10
vol% H2/N2 mixture and heated from RT to 630 oC at a ramp of 10 oC /min.
2.2.4 1H and 13C nuclear magnetic resonance (1HNMR and 13CNMR) Figure S5.
Liquid-state NMR experiments were performed on a Bruker AVANCE III 400 MHz
spectrometer operating at 400-MHz 1H and 100-MHz 13C frequencies.
2.2.5 Gas chromatograph-Mass spectrometer (GC-MS) Figure S6.
The liquid product was collected and analyzed by an Agilent GC-MS (6890 series
GC with a 5973 MS detector) equipped with DB-WAX capillary(30 m×0.32 μm×
0.5 μm) by the external standard method. Identification of the products was achieved
with a spectral library (NIST MS Search 2005).
3

3. Results and discussion
Table S1 the TOF values of the Ru-based catalyst under 70oC
Entry
catalyst
Ru/Al2O3
Ru/SiO2
Ru/ZrO2
LA con.%
7.3
TOF/ h-1
1275
t/ min
15
T/ oC
70
1
2
3
19.1
3330
15
70
21.6
3773
15
70
4
Ru/TiO2
44.0
7676
15
70
Reaction conditions: LA (5 g, 43.1mmol), 10 g water; H2 (4 MPa); Ru (1 wt%)/support (0.1 g,
0.0099 mmol of Ru)
100
80
60
40
20
0
0
50
100
150
200
250
300
350
Reaction time / min
Figure S1 the kinetics profiles of LA hydrogenation to GVL
Reaction conditions: LA (5 g, 43.1mmol), 10 g water; H2 (4 MPa); Ru (1 wt%)/TiO2 (0.1 g,
0.0099 mmol of Ru) 70 oC
4

3.1 XRD patterns of Ru-based catalysts
Ru/TiO
2
Ru/ZrO2
Ru/SiO
2
Ru/Al O
2 3
RuO
2
10
20
30
40
2θ / degree
Figure S2. (a) XRD patterns of Ru-based catalysts with different supports and the patterns of pure
RuO2 ( RuO2 TiO2 ZrO2)
50
60
70
80
1200
1000
800
Ru/SiO2
Ru/Al2O3
600
400
10
20
30
40
50
60
2θ / degree
Figure S2. (b) XRD patterns of Ru/SiO2 and Ru/Al2O3 ( RuO2)
The XRD patterns of as-prepared Ru-based catalysts loaded on the different
supports were displayed in Figure S2 (a). The diffraction peaks at around 28.0°, 35.2°,
37.3°, 40.3°，54.4° are assigned to RuO2 phase. [1] The diffraction peaks represented
anatase (2θ = 25.5°, 38.1°, 48.2°, and 54°) and rutile (2θ = 27.6° and 36.3°).[2] The
5

diffraction peaks at 34.3°, 50.2° and 60.1° are associated with the tetragonal-ZrO2.
Other diffraction peaks (24.1°, 28.3°, 31.6 °and 40.8°) reveal the monoclinic-ZrO2.[3]
No diffraction peaks of RuO2 appeared on the catalyst of Ru/ZrO2 or Ru/TiO2. As can
be seen in Figure S2 (b) some diffraction peaks of RuO2 on the supports of Al2O3 or
SiO2 were detected.
6

3.2 TEM image of Ru-based catalyst
Figure S3. TEM image of supported catalyst of Ru/metal oxide after reduction (a) Ru/Al2O3
(b) Ru/SiO2 (c) Ru/ZrO2 (d) Ru/TiO2, (e, f) HRTEM image of supported catalyst of Ru/TiO2
7

3.3 TPR profiles of the supported Ru catalysts
Ru/Al O
2 3
Ru/TiO
2
Ru/ZrO
2
Ru/SiO
2
RuO
2
100
150
200
250
300
Temperature /oC
Figure S4. H2-TPR profiles of the supported Ru catalysts
8

4. The solubility of H2 in different solvents
The hydrogen solubility in the solvent, can be evaluated by the level of Henry
constant of H2 (KH) that is calculated from Henry's law (the equation 1).
XA=PA/KH
(1)
Where XA represents the mole fraction of the solute gas in the liquid phase at the
partial pressure of the solute gas at PA
PA- the equilibrium partial pressure
KH-the Henry constant
According to equation (1), once the equilibrium pressure PA is determined, the mole
fraction of the solute gas in the liquid phase XA is inversely proportional to the Henry
constant KH. Under the condition of room temperature and 0.3~2.0 MPa, the KH value
of hydrogen in water is 7500 MPa, while those in methanol and ethanol are 596 and
452 MPa respectively.[4]
Table S2 The hydrogen solubility in the different solvents
P (MPa)
Entry
solvent
ΔPa
-
Pure H2 (P1)
Solvent + LA (P2)
Solvent+LA+H2 (P3)
1
2
3
4
5
none
water
5.55
-
-
-
-
-
-
0.12
0.10
0.68
0.50
5.50
5.30
5.75
5.45
0.17
0.35
0.48
0.60
1,4-dioxane
methanol
ethanol
Conditions: 130 oC, 4 MPa H2 (Room temperature), 10 g of solvent, 5 g of LA, balance time =20 min; a:
ΔP=P1+P2-P3.
At present, experimental results about hydrogen solubility in different solvents that
are helpful to validate the aforementioned equation are scarce. However, a feasible
comparison can be made for LA hydrogenation to GVL using the data measured by
ΔP as shown in Table S2. In comparison with other organic solvent system, a
minimum ΔP is seen in water system which confirmed that the lowest hydrogen
solubility in water.
9

5. 1HMNR and 13CMNR of GVL
SX-5-20140909-CNMR
SX-5-20140909-CNMR
8000
7500
7000
6500
6000
5500
5000
4500
4000
3500
3000
2500
2000
1500
1000
500
4
7
3
5
O
H C
3
O
6
1
5
2
7
4
3
2
0
-500
210
200
190
180
170
160
150
140
130
120
110
100
90
80
70
60
50
40
30
20
10
0
-10
f1 (ppm)
Figure S5. (a) The 13C NMR spectroscopy of GVL standard sample
13C NMR (101 MHz, D2O) δ 179.96 (s), 79.38 – 78.53 (m), 30.97 – 29.46 (m), 29.32 (d, J = 25.3 Hz),
21.01 (d, J = 18.6 Hz), 20.71 (s).
SX-4-20140909-CNMR
SX-4-20140909-CNMR
10000
3
4
9000
8000
O
H
O
6
3C
1
7000
6000
5000
4000
3000
2000
1000
0
5
2
7
7
4
3
5
2
-1000
210
200
190
180
170
160
150
140
130
120
110
100
90
80
70
60
50
40
30
20
10
0
-10
f1 (ppm)
Figure S5. (b) The 13C NMR spectroscopy of GVL produced from the hydrogenation of LA in the
solvent of D2O
13C NMR (101 MHz, D2O) δ 181.56 (d, J = 1.6 Hz), 178.04 (s), 79.79 – 79.23 (m), 79.07 (d, J = 4.5
Hz), 66.84 (d, J = 4.9 Hz), 33.29 (d, J = 12.0 Hz), 30.58 – 30.13 (m), 29.35 (d, J = 9.5 Hz), 29.28 –
28.05 (m), 22.06 (dd, J = 13.2, 2.9 Hz), 20.36 – 19.13 (m).
10

SX-5-20140909-HNMR
SX-5-20140909-HNMR
7500
7000
6500
6000
5500
5000
4500
4000
3500
3000
2500
2000
1500
1000
500
7
O
H
O
3C
1
5
2
7
6
3
4
3
5
4
4
0
-500
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
-1
-2
-3
-4
f1 (ppm)
Figure S5. (c)The 1H NMR spectroscopy of GVL standard sample
1H NMR (400 MHz, D2O) δ 5.24 – 5.06 (m, 1H), 3.11 – 2.90 (m, 2H), 2.87 – 2.75 (m, 1H), 2.29 (dtd, J
= 12.6, 9.3, 8.0 Hz, 1H), 1.82 (d, J = 6.4 Hz, 3H).
SX-4-20140909-HNMR
SX-4-20140909-HNMR
55000
50000
45000
40000
35000
O
H
O
C
30000
25000
20000
15000
10000
5000
0
1
3
5
2
7
6
4
3
7
3
4
4
5
-5000
10.5
10.0
9.5
9.0
8.5
8.0
7.5
7.0
6.5
6.0
5.5
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
f1 (ppm)
Figure S5. (d) The 1H NMR spectroscopy of GVL produced from the hydrogenation of LA in the
solvent of D2O
1H NMR (400 MHz, D2O) δ 4.86 – 4.66 (m, 197H), 4.41 (s, 9H), 2.87 – 2.52 (m, 51H), 2.52 – 2.32 (m,
22H), 1.97 – 1.81 (m, 19H), 1.81 – 1.62 (m, 2H), 1.59 – 1.29 (m, 69H), 1.29 – 1.11 (m, 3H).
11

Compared with the 13CNMR spectroscopy of GVL standard sample, 13CNMR
spectroscopy of GVL produced from the hydrogenation of LA in the solvent of D2O
yielded many split peaks (as can be seen the C5, C3, C4 and C7 in Figure S5 a and b),
which implied that a part of D were on these carbons or on the adjacent carbons.
1
Generally, in HNMR, the ratio of the integral value of H peak is approximately
equivalent to the ratio of the number of H atoms on each C atom. The ratio of integral
value (C5: C3: C4: C7=1.11:4.55:3.73:6.13=0.488:2:1.64:2.69) in GVL produced
from the hydrogenation of LA in the solvent of D2O changed significantly by
comparison to the ratio of integral value (C5: C3: C4: C7=1.0:2.08:2.06:3.13) in
standard GVL sample (Figure S5 c and d), indicating that some of H was replaced by
D in the hydrogenation process. Particularly, the D on C5 came from D2O via
hydrogenation of the C=O group of LA.
12

6. Mass spectrum of GVL
56
a
41
85
43
28
O
O
100
15
b
56
γ-valerolactone(GVL)
85
41
43
28
100
15
0
20
40
60
m / z
80
100
120
Figure S6. (a)The Mass spectrum of GVL standard sample (b) the Mass spectrum of GVL
after mixing with D2O
Compared with the Mass spectrum of GVL standard sample, it can be observed that
there is no change for the m/z ratio of GVL produced from mixing with D2O,
implying that no D atom in GVL.
13

7. The effect of the temperature on the hydrogenation reaction
Reaction time / h
LA conversion / %
15
100
80
60
14
4
40
3
2
20
1
0
0
40
50
60
70
80
90 100 110 120 130 140
Reaction temperature /oC
Figure S7. Influence of the temperature on the conversion of LA and the reaction time. Reaction
conditions: LA (5 g, 43.1mmol), 10 g water; H2 (4 MPa); Ru (1 wt%)/TiO2 (0.1 g, 0.0099 mmol
of Ru)
14

8. Reusability study of Ru/TiO2 catalyst
Figure S8. TEM image of supported catalyst of Ru/TiO2 (a) fresh catalyst (b) catalyst spent for
seven runs
15

9. The effect of agitation rate on the conversion of LA
60
45
70 oC
130oC
30
15
0
300 350 400 450 500 550 600 650 700
rpm / n
Figure S9. Conversion of LA at different agitation rates over 1wt% Ru/TiO2
Reaction conditions: LA 5 g, water 10 g, H2 4 MPa, a) catalyst 0.1 g, 70 oC, t=1 h; b) catalyst 30
mg, 130 oC, t=30 min.
16

10. The typical GC chart of hydrogenation of LA to GVL
前部信号 (140507A\140501 2014-05-07 20-19-12\112F0301.D)
FID1 A,
归一化
250
200
150
100
50
O
O
O
OH
O
Levulinic acid(LA)
γ-valerolactone(GVL)
0
5
10
15
20
25
min
Figure S10. The typical GC chart of hydrogenation of LA to GVL
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17