Hydrothermal Liquefaction of Algae to Produce
Bio-Oil and Subsequent Catalytic
Deoxygenation to Hydrocarbon
Chao Miao
10.01.2014
Outline
 Sequential hydrothermal liquefaction of algae to produce bio-oil
 Hydrothermal catalytic deoxygenation of fatty acid to produce hydrocarbon
 Conclusion
Hydrothermal Liquefaction
Hydrothermal Liquefaction (HTL)
Reaction media: hot compressed water
Advantages of microbial biomass hydrothermal liquefaction
Combination of cell wall disruption and bio-oil extraction in one step
No organic solvents Requirement
No dewatering step
Easy separation
Mature and commercialized thermo-conversion process
(A Peterson et al. 2008)
Technical Gaps
Current gaps of direct hydrothermal liquefaction (DHTL) process
to produce bio-oil
(1) Protein and carbohydrate are mostly transformed into bio-char;
(2) Bio-char will decrease the bio-oil separation efficiency;
(3) Sulfur and nitrogen in protein will transformed into bio-oil, bringing environmental issues;
(4) How to recover the valuable co-products, e.g. sugar, polysaccharide, protein, and amino acid.
Hypothesis and Concept
Two-step sequential hydrothermal liquefaction to produce bio-oil
Low temperature (160-180C)
Sugar,
Polysaccharide,
Amino acid.
High temperature (240-300C)
Bio-oil,
Bio-char,
Water extractives (WEs).
Low temperature water (150-220°C)
Hydrolyze cell wall of algae
Above 200 °C
Hemicellulose
Starch
Protein
C5 sugar
Glucose
Amino acid
Furfural, 5-HMF
Organic acid
Ammonia, Pyrrol, Indole
Bio-char
N, S in bio-oil
Experiment of SEQHTL
140-200C
220-300C
240 °C
Results of 1st step SEQHTL (Algae)
70
100
(a)
80
60
Yield (Wt%)
60
Yield (Wt%)
Polysaccharides
WEs
Dry Treated Algae
(b)
Polysaccharides
WEs
Dry Treated Algae
40
50
40
20
30
0
20
130
140
150
160
170
180
190
200
210
(c)
60
15
20
25
30
35
40
45
Polysaccharides
WEs
Dry Treated Algae
 The polysaccharide could be separated with 1:9
algae/water ratio at 160C, within 20min, which is
optimal condition for 1st step of SEQHTL in the
studied condition
50
Yield (Wt%)
10
Residence Time(min)
Temperature(C)
70
5
40
30
20
10
1:6
1:9
Biomass/Water Ratio(w/w)
1:12
SEQHTL Vs DHTL
40
SEQHTL
DHTL
(a)
50
(b)
SEQHTL
DHTL
40
Bio-char Yield (wt%)
Bio-oil Yield (wt%)
30
20
30
20
10
10
0
0
220
240
260
300
Temperature (C)
20
(c)
SEQHTL
DHTL
WEs Yield (wt%)
10
5
0
240
260
Temperature (C)
240
260
300
Temperature (C)
15
220
220
300
 Bio-oil produced through SEQHTL showed a
higher yield than DHTL.
 For bio-oil production through SEQHTL, the
optimal condition is suggested at 240C, with 1:6
biomass/water ratio within 30min.
 Bio-char and WEs produced through SEQHTL
showed a significant lower yield than DHTL.
 The lower yield is attributed to the
prior removal of polysacchride and sugar in the
first step of SEQHTL.
Fatty Acids Composition in Bio-oil
Fatty acid
Structure
Palmitic
Hexadecenoic
Hexadecadienoic
Stearic
Oleic
Linoleic
Linolenic
Others
Total Fat
C16:0
C16:1n9
C16:2n6
C18:0
C18:1n9
C18:2n6
C18:3n3
DHTL
220˚C
mg/g
190.79
44.93
23.18
17.81
167.67
213.50
28.34
77.01
763.23
SEQHTL
220˚C
mg/g
242.44
55.93
28.15
22.42
241.34
262.66
32.12
59.81
944.87
DHTL
240˚C
mg/g
198.14
46.22
23.13
19.24
202.23
213.83
25.18
64.16
792.13
SEQHTL
240˚C
mg/g
217.97
49.08
24.02
20.50
221.82
228.13
26.41
60.57
848.50
DHTL
300˚C
mg/g
191.71
33.50
8.11
19.77
136.97
65.61
3.96
213.16
672.79
SEQHT
L 300˚C
mg/g
192.70
41.37
12.22
20.24
200.97
101.81
3.45
131.3
704.06
Percentage of Fatty Acids in Bio-oil (Wt%)
100
SEQHTL
DHTL
80
 Bio-oil produced through SEQHTL showed
higher fatty acid content than DHTL.
 The major components in bio-oil are
palmitic, oleic, linoleic acid.
60
40
20
0
220
240
Temperature (C)
300
Upgrading of Bio-oil
Issues of bio-oil produced by hydrothermal liquefaction
High melting point
High pour and cloud point
High viscosity
Fatty acid
Acylglyceride
High oxygen content
Deoxygenation
Hydrodeoxygenation (HDO)
 High pressure of H2
 Moderate temperature (250-350C)
 Metal-based catalyst.
(1) Noble metals supported on metal oxide, or
zeolite;
(2) Sulfide metals supported on alumina.
Decarboxylation/decarbonylation (DeCOx)
 Decarboxylation does not require H2
 Decarbonylation requires small amount of H2
 Temperature (300-400C)
 Metal-based catalyst.
(1) Metal site: Pd, Pt, Ni.
(2) Support: activated carbon, metal oxide,.
Deoxygenation
Technical issues
1. High cost of noble metal (Pd, Pt) used as industrial scale catalyst
2. Low fatty acid conversion over Ni-based catalyst under no external H2
Our concept
 Hydrothermal catalytic deoxygenation of fatty acid to produce hydrocarbon with in-situ
formed H2 from fatty acid
1. Hydrogen can be produce by reforming and water-gas shift reaction
2. It is potential to integrate SEQHTL process with hydrothermal catalytic doxygenation
process to produce hydrocarbon.
Catalyst-Ni/ZrO2
Why Ni/ZrO2:
Ni and ZrO2 are low cost catalysts compared with noble metal
ZrO2 is a very good support providing oxygen vacancy
ZrO2 is a very stable and catalytic active in subcritical water phase (<350C)
Deoxygenation activity:
Pd>Pt>Ni>Rh>Ir>Ru>Os
Effect of Reaction Temperature
 Increased temperature improved fatty acid
conversion and paraffin yield.
Yield of products
Liquid Products (%)
Total liquid paraffins
(%)
Gas Products (%)
Total Hydrocarbon
(%)
T (°C)
C15
C16
C8-C14
C8-C19
CH4
CO2
C2H4
C1-C19
250
2.8
0.0
0.0
2.8
0.1
0.0
0.0
2.9
270
18.9
0.8
0.0
26.9
0.2
0.0
0.0
27.1
290
34.6
4.0
21.4
60.5
18.6
5.5
0.1
79.1
300
30.2
2.8
26.0
59.5
27.6
5.1
0.3
87.1
Effect of Water on Reaction
 Presence of water increased fatty acid
conversion and paraffin yield
 Presence of water suppress side reactions:
(a) ketonization and (b) esterification
Hydrothermal Deoxygenation with In-situ H2
 Fatty acid conversion and paraffin
yield were increased with the reaction
time.
 Hydrogen was in-situ produced at 2-5
mole per mole of fatty acid
Conversion of SA or Yield of paraffin
100
Conversion
Paraffins yield
80
60
 Oxygen Balance
40
Before (mol)
After (mol)
0.0035
0.0058
20
0
0
2
4
6
8
Reaction Time (h)
10
12
14
 Oxygen is increased by ~60% after the
reaction.
Reaction Pathway-Liquid Phase
(a)
+C15H31COOH Ketonization
C15H31COC15H31
-H2O, -CO2
+H2 Decarbonylation
-H2O, -CO
Decarboxylation
-CO2
C15H32
+H2, Hydrogenolysis
-CH4
C15H31COOH
+2H2
-H2O
C16H33OH
+H2
-H2O
Esterification
-H2O
Aqueous reforming
-CO2, -H2
C16H34
C15H31COOC16H33
C8-C14 Paraffins
Conclusion
 A two-step sequential hydrothermal liquefaction method was developed to produce bio-oil,
carbohydrate, and protein from algae.
 Comparing SEHQTL with DHTL, The amount of bio-char was reduced >50% after
removing carbohydrate and protein. The removed WEs could be used as carbon and nitrogen
nutrients.
 The removal of carbohydrate and protein did not significantly influence the quality and
quantity of bio-oil. On the contrary, SEQHTL bio-oil extracted at lower temperature seemed
to have higher fatty acid contents.
 The produced bio-oil from SEQHTL process can be upgraded through hydrothermal catalytic
deoxygenation to directly produce hydrocarbon.
 Compared with traditional deoxygenation process (in the absence of water but presence of
H2), hydrothermal catalytic deoxygenation method is able to remove oxygen from bio-oil
with no external H2
 Decarbonylation is the major deoxygenation route over Ni/ZrO2 catalyst. Hydrothermal
reforming and water-gas shift reaction are the main reactions for the formation of in-situ H2.
Thank you