Post on 12-Mar-2018
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
(A Peterson et al. 2008)
Hydrothermal Liquefaction (HTL)
Reaction media: hot compressed water
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
Advantages of microbial biomass hydrothermal liquefaction
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.
Technical Gaps
Hypothesis and Concept
Two-step sequential hydrothermal liquefaction to produce bio-oil
Hemicellulose
Starch
Protein
C5 sugar
Glucose
Amino acid
Furfural, 5-HMF
Organic acid
Ammonia, Pyrrol, Indole
Low temperature (160-180C)
Sugar,
Polysaccharide,
Amino acid.
High temperature (240-300C)
Bio-oil,
Bio-char,
Water extractives (WEs).
Above 200 °C
Bio-char
N, S in bio-oil
Low temperature water (150-220°C)
Hydrolyze cell wall of algae
Experiment of SEQHTL
240 °C240 °C140-200C 220-300C
Temperature(C)
130 140 150 160 170 180 190 200 210
Yie
ld (
Wt%
)
0
20
40
60
80
100Polysaccharides
WEs
Dry Treated Algae
(a)
Residence Time(min)
5 10 15 20 25 30 35 40 45
Yie
ld (
Wt%
)
20
30
40
50
60
70Polysaccharides
WEs
Dry Treated Algae
(b)
Biomass/Water Ratio(w/w)
1:6 1:9 1:12
Yie
ld (
Wt%
)
10
20
30
40
50
60
70Polysaccharides
WEs
Dry Treated Algae
(c)
Results of 1st step SEQHTL (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
SEQHTL Vs DHTL
Temperature (C)
220 240 260 300
Bio
-oil
Yie
ld (
wt%
)
0
10
20
30
40 SEQHTL
DHTL(a)
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.
Temperature (C)
220 240 260 300
Bio
-ch
ar Y
ield
(w
t%)
0
10
20
30
40
50
SEQHTL
DHTL
(b)
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.Temperature (C)
220 240 260 300
WE
s Y
ield
(w
t%)
0
5
10
15
20
SEQHTL
DHTL
(c)
Fatty Acids Composition in Bio-oil
Bio-oil produced through SEQHTL showed
higher fatty acid content than DHTL.
The major components in bio-oil are
palmitic, oleic, linoleic acid.
Temperature (C)
220 240 300
Perc
en
tag
e o
f F
att
y A
cid
s in
Bio
-oil (
Wt%
)
0
20
40
60
80
100
SEQHTL
DHTL
Fatty acid Structure DHTL
220˚C
mg/g
SEQHTL
220˚C
mg/g
DHTL
240˚C
mg/g
SEQHTL
240˚C
mg/g
DHTL
300˚C
mg/g
SEQHT
L 300˚C
mg/g
Palmitic C16:0 190.79 242.44 198.14 217.97 191.71 192.70
Hexadecenoic C16:1n9 44.93 55.93 46.22 49.08 33.50 41.37
Hexadecadienoic C16:2n6 23.18 28.15 23.13 24.02 8.11 12.22
Stearic C18:0 17.81 22.42 19.24 20.50 19.77 20.24
Oleic C18:1n9 167.67 241.34 202.23 221.82 136.97 200.97
Linoleic C18:2n6 213.50 262.66 213.83 228.13 65.61 101.81
Linolenic C18:3n3 28.34 32.12 25.18 26.41 3.96 3.45
Others 77.01 59.81 64.16 60.57 213.16 131.3
Total Fat 763.23 944.87 792.13 848.50 672.79 704.06
Upgrading of Bio-oil
Issues of bio-oil produced by hydrothermal liquefaction
High melting point
High pour and cloud point
High viscosity
Fatty acid
AcylglycerideHigh oxygen content
Deoxygenation
Hydrodeoxygenation (HDO)
Decarboxylation/decarbonylation (DeCOx)
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 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
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.
Our concept
Hydrothermal catalytic deoxygenation of fatty acid to produce hydrocarbon with in-situ
formed H2 from fatty acid
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
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
Increased temperature improved fatty acid
conversion and paraffin yield.
Yield of products
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
Oxygen is increased by ~60% after the
reaction.
Before (mol) After (mol)
0.0035 0.0058 Oxygen Balance
Reaction Time (h)
0 2 4 6 8 10 12 14
Co
nve
rsio
n o
f S
A o
r Y
ield
of p
ara
ffin
0
20
40
60
80
100
Conversion
Paraffins yield
Reaction Pathway-Liquid Phase
C15H31COOH
C15H32
C16H34C16H33OH
C15H31COOC16H33
+H2
-H2O, -CO
Decarbonylation
Decarboxylation
-CO2
+2H2
-H2O
+H2
-H2O
-H2O
Esterification
+H2, Hydrogenolysis
-CH4
C8-C14 ParaffinsAqueous reforming
-CO2, -H2
C15H31COC15H31-H2O, -CO2
Ketonization+C15H31COOH
(a)
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