Transcript PowerPoint Template - Wayne State University

Shuli Yan
2007-11
My Research in Sichuan University
 Ph.D ----- ”An Investigation of Ca- and Zn-based Oxide
Catalysts Used in the Transesterification of Oil with
Methanol”
 M.S. ----- ” Growth of Carbon Nanotubes from Methane by
a Catalytic Chemical Vapor Decomposition Method”
My Research in Sichuan University
My dissertation
Publicataions:
One Patent and five
papers
 Using supported CaO catalysts for
transesterfication (solid base catalyst)
 Using ZnO and Al2O3 binary metal oxide catalysts
for transesterification (solid acid catalyst)
Publications:
One patent and three
papers, and further more
are in process
Supported CaO Catalysts Used in
the Transesterification of
Rapeseed Oil for the Purpose of
Biodiesel Production
Published on Energy and Fuel, DOI: 10.1021/ef070105o
Introduction
 Biodiesel
O
O
H2 C O C R1
O
HC O C R2
O
H2 C O C R3
H3C
O
C
H2C OH
R1
O
+ 3 CH 3OH
H3C
O
C
R2
+
HC OH
O
H3C
O
C
R3
H2C OH
Fig.1 The transesterification of triglyceride with methanol
(1)
Introduction
Fats and oils have quite big
molecules with a spinal of glycerol
on which are bond three fatty acid
rests.
By the transesterification, the fatty
acid rests are removed from the
glycerol and each is bond with
methanol.
The products are one mole glycerol
and three mole of fatty acid methyl
ester.
Various Catalysts used in Biodiesel
Production
Homogenous
• Base Catalysts: NaOH, KOH, NaMeO
• Acid Catalysts: H2SO4, PTSA, MSA, H3PO4,
Typical base concentrations are :
NaOH/KOH –-- 0.3 to 1.5 %
Na MeO –-- 0.5 % or less
Heterogeneous
• Sulfated Zeolites & Clays
• Hetro-poly acids
• Metal Oxides, Sulfates
• Composite materials
Introduction
Benefits - Heterogeneous Catalyst
• Catalyst
Regeneration
–
Decrease
of
Catalyst Cost
• Simplification of separation process –
Decrease of production cost
• Decrease of wastewater – Development of
environmental friendly process
• Utilization of lower quality feed stocks for
biodiesel production
Introduction
 Literatures
Ca-based catalysts
 Goal
Supporting CaO onto carriers
 Content
Experimental Section
 Oil refining process
Crude oil (water degummed)
Caustic soda
Water
Bleaching
earth
Sulfuric acid
Neutralization
Separation of soapstock
Soap splitting
Washing
Fatty acid
Drying
Waste water
Bleaching
Used
bleaching
earth
Neutralized, degummed and
bleached oil
Fig. 2 Chemical refining process for raw oils
Experimental Section
Catalyst Samples
• MgO, CaO, SrO and BaO
• Samples 1–4 denote the catalysts using
MgO, SiO2, Al2O3, and HY particles as
carriers.
• Samples 5–9 denote the catalysts obtained
by impregnation withdifferent
concentrations of lime acetate solution.
Catalyst Characterization
XRD, TPD, TG, BET, AAS, XPS
Experimental Section
Transesterification Process
Experimental Section
The FAME phase was analyzed by the gas
chromatography method using GC9790
equipped with a column DEXIL-300 Japan
Frontier.
The glycerol phase was analyzed by a
chemical method according to the Chinese
State Standard GB/T 13216.6-91.
Catalytic Activities of Alkaline Earth
Metal Oxides.
Table 1. Catalytic activities of some alkaline earth metal oxides
and NaOH in the transesterification
Pretreatment
Reaction
temperatu
re oC
Catalyst
dosage
%
Methanol Reaction
to oil ratio time hr
Oil
conversio
n %
MgO
700 oC, N2, 2 hr
64.5
10
18 : 1
3.5
<5
CaO
700 oC, N2, 2 hr
64.5
10
18 : 1
3.5
58
SrO
700 oC, N2, 2 hr
64.5
10
18 : 1
3.5
60
BaO
700 oC, N2, 2 hr
64.5
10
18 : 1
3.5
86
NaOH
\
64.5
0.5
6:1
0.5
97
Catalyst
Catalytic activity of supported
calcium oxide
Table 2. Catalytic activity of supported calcium oxide
Pretreatment
Reaction
temperat
ure oC
Catalyst
dosage
%
Methanol
to oil
ratio
Reaction
time hr
Oil
conversio
n %
NaOH
\
64.5
0.5
6:1
0.5
97
Sample 1
700 oC, N2, 2 hr
64.5
2
18 : 1
3.5
92
Sample 2
700 oC, N2, 2 hr
64.5
2
18 : 1
6
60
Sample 3
700 oC, N2, 2 hr
64.5
2
18 : 1
6
36
Sample 4
700 oC, N2, 2 hr
64.5
2
18 : 1
6
23
Catalyst
Characterization of supported
calcium oxide
Table 3. Physicochemical properties of some metal oxides
Sample
SBET
m2/g
X-ray
structure
CaO content
(wt)%
Alkalinity
umol/m-2
sample 1
6.6
Ca(OH)2,
MgO
16.5
29
CaO
1.5
CaO,
Ca(OH)2
100
23
MgO
43.5
MgO,
Mg(OH)2
\
15.5
Transesterification catalyzed by
CaO/MgO
100
Conversion %
80
60
40
20
0
-2
0
2
4
6
8
10
12
14
16
Time hr
NaOH
Sample 6
1
CaO
MgO
Figure 4. Catalytic activities of homogeneous catalyst NaOH a, CaO b, MgO b
and a binary alkaline earth metal oxides Sample 1 c.
Effect of Ca loading on catalyst
activity
Table 5. Effect of Ca loading on catalyst activity
Catalyst
sample 5
sample 6
sample 7
sample 8
sample 9
CaO content (wt)% 3.9
8.3
9.5
16.5
20.4
Average crystal size 8
of Ca(OH)2 nm a
14
14
16
34
Oil conversion % b, 62
75
80
92
80
c
a All
samples showed the mixture of Ca(OH)2 and MgO. Average crystal size was calculated from Xray line broadening at 34.09 2θ angles for (0, 1, 1) plane of Ca(OH)2.
b Pretreatment: 700 oC, N , 2 hr
2
c Experiment condition: 64.5 oC, 18:1molar ratio of methanol/oil, 2 % catalyst dosage, 3.5 hr.
Effect of calcine temperature on
CaO/MgO catalyst
TG curve
DTG curve
0
200
400
600
Temperature
o
800
C
Figure 6. TG and DTG curves of sample 10.
1000
Table 7. Effects of calcination temperatures on the CaO/MgO catalyst
Catalyst samples
11
12
13
14
15
16
120
200
300
450
700
900
CaO content (wt) %
9.6
9.7
11.5
13.6
16.5
16.4
X-ray structure
MgO,
Mg(OH)2
MgO,
Mg(OH)2
MgO,
Mg(OH)2
MgO,
CaCO3
MgO,
Ca(OH)2
MgO,
Ca(OH)2
SBET m2/g
31.0
29.6
20.3
10.1
6.6
1.4
Oil conversion % a, b
<5
<5
<5
11
92
46
Calcine temperature
a
oC
Pretreatment: calcine temperature, N2, 2 hr
Experiment conditions: 64.5 oC, 18:1molar ratio of methanol/oil, 2 % catalyst dosage, 3.5
hr.
b
Effects of storage and pretreatment
conditions on CaO/MgO catalyst
Table 8. Effects of storage conditions and pretreatment conditions on the
catalytic activity of sample 15
Catalyst
Pretreatment
conditions
Oil conversiond
%
\
<5
N2 flow a for 5 hr
700 oC, N2, 2 hr
89
N2 flow b for 5 hr
\
8
N2 flow b for 5 hr
700 oC, N2, 2 hr
84
N2 flow c for 5 hr
\
14
N2 flow c for 5 hr
700 oC, N2, 2 hr
81
air for 24 hr
\
<5
air for 24 hr
100 oC, N2, 2 hr
<5
air for 24 hr
200 oC, N2, 2 hr
16
air for 24 hr
500 oC, N2, 2 hr
43
air for 24 hr
700 oC, N2, 2 hr
91
Storage
conditions
Sample 15 N2 flow a for 5 hr
a
N2 flow with
21 (vol) % O2
b N flow with
2
10 (vol) % CO2
c N flow with
2
4 (vol) % H2O
d Experiment
conditions:
64.5 oC,
18:1molar ratio
of
methanol/oil, 2
% catalyst
dosage, 3.5 hr.
70
1086
50
Transmittance
1794
2515
60
2839
2912
2338
40
3425
1617
30
3633
20
880
10
0
3708
4000
1440
3000
2000
Wavenumber cm
1000
0
-1
Fig. 9 IR spectrum of the poisoned sample 15
Effects of reaction conditions
Table 6. Effect of reaction temperature on transesterification
Reaction temperatures
oC
Rapeseed oil conversion %
25
35
45
55
64.5
70
<5
8
23
42
84
72
Pretreatment: 700 oC, N2, 2 h
Reaction conditions: 12 hr, 1g of sample 1, 12 : 1 molar ratio, 50 g oils.
Table 7. Effect of mole ratio of methanol/oil on transesterification
Mole ratio of methanol/oil
3:1
6:1
12 : 1
18 : 1
36 : 1
42 : 1
Rapeseed oil conversion %
13
49
84
92
92
92
Pretreatment: 700 oC, N2, 2 hr
Reaction conditions: 12 hr, 1g of sample 1, 64.5 oC, 50 g oils.
Effects of reaction conditions
Table 8. Effect of catalyst dosage on transesterification
Catalyst dosage
1
1.5
2
3
4
5
Rapeseed oil conversion %
70
74
84
82
81
82
Pretreatment: 700 oC, N2, 2 hr
Reaction conditions: 12 hr, 64.5 oC , 12 : 1 molar ratio, 50 g oils.
Table 9. Effect of stirring speed on transesterification
Stirring speed r/min
100
280
440
720
950
1130
Rapeseed oil conversion
%
51
80
89
89
92
91
Pretreatment: 700 oC, N2, 2 hr
Reaction conditions: 6 hr, 1g of sample 1, 64.5 oC , 18 : 1 molar ratio, 50 g oils.
Effects of water and FFA in oil
Acid value mgKOH/g
2
4
6
8
10
100
100
80
80
60
60
40
40
20
20
0
0
-1
0
1
2
3
4
5
6
7
Oil conversion %
Oil conversion %
0
8
Water content %
water
FFA
Figure 10. Effects of water and FFA on the equilibrium conversion ratio
Pretreatment conditions: 700 oC, N2, 2 hr.
Reaction conditions: 64.5 oC, 12:1molar ratio of rapeseed oil to methanol, sample 1, 2 % catalyst
dosage, 8hr .
100
100
80
80
Oil conversion %
Oil conversion %
Effects of water and FFA in oil
60
40
0.5% water addition
20
without water additon
0
60
40
acid value 2mg/g
20
without FFA addition
0
-20
0
20
40
60
80
100
120
140
160
180
200
Reaction time min
-20
0
20
40
60
80
100
120
140
160
180
200
Reaction time min
2
1
Figure 11. Conversions against reaction time.
1: 0.5 (wt) % water addition;
2: FFA addition with acid value 2 mgKOH/g
Pretreatment conditions: 700 oC, N2, 2 hr.
Reaction conditions: 64.5 oC, 12:1molar ratio of rapeseed oil to methanol, sample 1, 2
% catalyst dosage.
Effects of water and FFA in oil
100
Oil conversion %
80
Figure 12.
Transesterification of some
commercial oils
60
40
Pretreatment conditions: 700
oC, N , 2 hr.
2
20
0
0
1
2
3
Reaction time hr
Industrial lard
Industrial coconut oil
Crude rapeseed oil
Crude peanut oil
4
Reaction conditions: 64.5 oC,
18:1molar ratio of oil to
methanol, sample 1, 2 %
catalyst dosage, 8hr .
Refined rapeseed oil
Refined rapeseed oil with 0.5% water addition and 2 mgKOH/g acid value
Stability and regeneration of
CaO/MgO catalyst
100
Oil conversion %
80
Figure 13. Reusability of
CaO/MgO catalyst.
60
Pretreatment conditions: 700
oC, N , 2 hr.
2
40
Reaction conditions: 64.5 oC,
12:1molar ratio of rapeseed oil
to methanol, sample 1, 2 %
catalyst dosage, 1.8 hr.
20
0
cycle 3
cycle 1
cycle 2
Regeneration 1
cycle 4
Regeneration 2
Entry
Active sites on the surface of CaO
crystal
（0 0 1）
（1 1 1）
Ca
O
（-1 1 0）
Fig.14 Particle of cubic CaO, exhibiting three
crystallographics surfaces.
Active sites on the surface of CaO
crystal
Oxygen vacancy
H
O
Mg
H
H
C O
O
C
H
Ca
O
Mg
O C
O
Fig.15 Active sites on the (110) surface of CaO minicrystal. Mg2＋ replacing sites,
oxygen vacancies, and CO2, H2O, O2 displacing oxygen vacancies.
Active sites on the surface of CaO
crystal
Fig. 16 Methanol molecular was actived on the surface of CaO crystal.
Mechanism of CaO-catalyzed transesterification
of triglyceride with methanol
CaO
+
CH 3OH
CH 3OCaOH
+
CH 3OCaOH
CH 3OH
(1)
Ca(CH3 O) 2
+
(2)
H2O
Ç¿¼îλ
O
H2C O C R1
O
H2C O C R1
-
O
HC O C R2
+
-
O
2+
H3 C
O CH3
O
O
Ca
CH3
O
-
CH3
(3)
O
H2C O C R3
H2C
O
C
2+
Ca
HC O C R2
O
H2C O C R3
R1
-
O
Ca O CH3
O
O
CH3
+
(4)
HC O C R2
O
H2C O C R3
H 2C O H
H2C O Ca O CH3
O
H3C
OH
+
HC O C R2
O
H 2C O C R 3
O
H3C
-
O
Ca
2+
O
-
CH3
+
HC O C R2
O
H 2C O C R 3
(5)
Fig. 17
Mechanism of
CaO-catalyzed
transesterifica
tion of
triglyceride
with methanol
Conclusion
 Supported CaO catalysts are active in the
transesterification reaction for biodiesel production.
 The basic carrier MgO, a Ca loading of 16.5 (wt)%
and a calcination temperature of 700 oC
 pretreatment before use is important
 When the CaO/MgO catalyst was operated at the
boiling temperature of methanol, 64.5 oC, with an
18:1 molar ratio of methanol/oil and 1 g catalyst, the
conversion of rapeseed oil reached 92 %.
 High content of water and FFA in oil could inhibit its
transesterification.
Shuli Yan
Using solid acid catalysts in oil
transesterification
4
100
1
8
NaOH
1
6
H2SO4
Oil conversion %
80
2
5
60
40
no catalyst
3
no catalyst
4
sample 1
5
sample 2
6
sample 3
7
sample 4
8
2
20
3
7
0
-50
0
50
100
150
200
Time min
-1
250
300
350
400
Fig. 6－7 Comparison of
the transesterification
processes in presence of
samples 1, 2, 3, 4, NaOH,
H2SO4 and in absence of
catalyst respectively.
Reaction conditions:
1. 50 g refined rapeseed oil,
10 g methanol, NaOH 1.2 (wt)
%, atmosphere, 64.5 oC;
2. H2SO4 2 (wt) %, others are
the same as 1;
3. 70 g refined rapeseed oil,
100 g methanol, no catalyst,
3.4MPa, 200oC;
4. 42:1 molar ratio of
methanol to rapeseed oil, no
catalyst, 43 MPa, 350 oC [35];
5. Sample 1, 1.4 (wt) %, 3.3
MPa, others are the same as 3;
6. Sample 2, 1.4 (wt) %,
others are the same as 5;
7. Sample 3, 1.4 (wt) %,
others are the same as 5;
8. Sample 9, 1.4 (wt) %,
others are the same as 5;
Using solid acid catalysts in oil
transesterification
Fig. 6－8 Effect of
reaction temperature
on oil conversion
Reaction conditions:
1. 70 g refined rapeseed
oil, 100 g methanol, ZnO,
1.4 (wt)%, 2hr;
2. 70 g refined rapeseed
oil, 100 g methanol, ZnAl-LDO, 1.4 (wt)%, 1hr;
3. 70 g refined rapeseed
oil, 100 g methanol, no
catalyst, 1hr;
Using solid acid catalysts in oil
transesterification
90
Oil conversion %
75
ZnO
1
H2SO4
2
NaOH
3
60
45
30
15
0
-2
0
2
4
6
8
10
12
14
16
18
FFA content %
Fig. 3 Effects of FFA content on oil conversions.
Reaction conditions:
〇1. 50 g refined rapeseed oil, 10 g methanol, 1.2 (wt) % g NaOH catalyst/g oil, atmosphere, 64.5 oC, 1 hr;
█2. 70 g refined rapeseed oil, 100 g methanol, 1.4 (wt) % g ZnO catalyst/g oil, 3.3 MPa, 200 oC, 6 hr;
▲3. 50 g refined rapeseed oil, 39 g methanol, 2 (wt) % g H2SO4 catalyst/g oil, atmosphere, 64.5oC, 90 hr.
Using solid acid catalysts in oil
transesterification
90
ZnO
1
Oil conversion %
75
60
45
NaOH
2
H2SO4
3
30
15
0
0
5
10
15
20
Water content %
Fig. 4 Effects of water content on oil conversions.
Reaction conditions:
〇1. 50 g refined rapeseed oil, 10 g methanol, 1.2 (wt) % g NaOH catalyst/g oil, atmosphere, 64.5 oC, 1 hr;
█2. 70 g refined rapeseed oil, 100 g methanol, 1.4 (wt) % g ZnO catalyst/g oil, 3.3 MPa, 200 oC, 6 hr;
▲3. 50 g refined rapeseed oil, 39 g methanol, 2 (wt) % g H2SO4 catalyst/g oil, atmosphere, 64.5oC, 90 hr.
Using solid acid catalysts in oil
transesterification
Crude Oils
Triglyceride
Transesterification
Water
Hydrolysis
FFA
Esterification
Hydrolysis
Fatty acid methyl esters
Fig. 8-10 Three reactions involved in the treatment of oils with
methanol containing some water and FFA.
Using solid acid catalysts in oil
transesterification
（1）
（2）
ZnO
ZnOx
+
ZnOx
+
O
CH 3OH
Zn(CH 3O) 2
+
H2O
O
H2C O C R1
O
HC O C R2
O
H2C O C R1
+
O
H3 C
O CH3
O
O
Zn
CH3
O
CH3
O
H2C O C R3
H2C
O
C
Zn
HC O C R2
O
H2C O C R3
R1
-
O
Zn O CH3
O
O
CH3
+
HC O C R2
O
H2C O C R3
H 2C O H
H2C O Zn O CH3
O
H3C OH
+
HC O C R2
O
H 2C O C R 3
O
H3 C
O
O
Zn
CH3
+
HC O C R2
O
H 2C O C R 3
Fig. 6－13
Mechanism of
ZnO-catalyzed
transesterificatio
n of triglyceride
with methanol