Direct hydrothermal liquefaction (HTL) of high-moisture

lignite under subcritical and supercritical water conditions

Krzysztof Kapusta, Krzysztof Stańczyk

Central Mining Institute (GIG)

Clean Coal Technology Centre

Poland

Berlin, 4th June 2018

1

9th International Freiberg Conference on IGCC & XtL Technologies

2

Hydrothermal technologies: In brief

Hydrothermal technologies are defined as

chemical and physical transformations of

carbon containing feedstock in high-

temperature (200–600°C), high-pressure (5–40

MPa) liquid or supercritical water

• Hydrothermal carbonization (HTC): <250°C

• Hydrothermal liquefaction (HTL): 250–400°C

• Hydrtothermal gasification (HTG): >400°C

Source: Peterson, A.A., Vogel, F., Lachance, R.P., Fröling, M., Antal Jr., M.J.,

Tester, J.W., 2008.Thermochemical biofuel production in hydrothermal media: a

review of subandsupercritical water technologies. Energy Environ. Sci. 1, 32–65.

carb

oniz

ation

t=374⁰C, p=22.1 MPa

Critical point

3

Hydrothermal liquefaction (HTL): Overview

Carbon feedstock

Water High-pressure reactor

Liquid product

„Heavy Oil ”

HTL char

Aquous phase

Thermal decomposition of carbon feedstocks at moderate temperature: 250 – 4000C

which produce liquid products, often called “bio-oil”, “bio-crude” or „heavy oil”

Water as reaction medium and reagent (source of hydrogen)

Well suited for the processing of high-moisture materials (water as reaction environment)

The HTL process can be carried out with or without catalyst

Catalyst

4

HTL of high-moisture lignites: Overall technical approach

to petrochemical

upgrading

T= 300 - 400 0C

p = 10 - 25 MPa

Slurry

preparation

Water

Pulverized lignite

Catalyst

Hydrothermal

liquefaction

Atmosphere:

inert: N2

reactive: H2, CO

CO

Tail

gas

Solvent

extraction

Extraction of

water-solubles Spent

water chemical

products

Water recycle

Residues

(char, mineral matter)

Liquid

hydrocarbons

5

Lignite samples for HTL tests: Origin

„TURÓW”

lignite deposit

6

Open Pit Mine „TURÓW”

Source: PGE S.A.

7

Lignite characteristics: Proximate and ultimate analysis

No. Parameter Value

As received

1 Total moisture Wtr, % 47.1

2 Ash Atr , % 5.17

3 Volatiles Vr, % 27.71

4 Total sulphur Str, % 0.20

5 Calorific value Qir, kJ/kg 13 074

Analytical

6 Total moisture, % 0.52

7 Ash Aa, % 9.71

8 Volatiles Va, % 52.02

9 Heat of combustion Qsa, kJ/kg 25 734

10 Calorific value Qia, kJ/kg 24 545

11 Total sulfur Sa, % 0.38

12 Carbon Cta, % 61.65

13 Hydrogen Hta, % 5.39

14 Nitrogen Na, % 0.57

15 Oxygen Oda, % 21.94

8

HTL tests: Process parameters and laboratory test stand

Optimized process parameters:

Reaction time: 15, 30 min

Temperature: 300 – 400 0C

Pressure: 7 – 30 MPa

Constant process parameters:

Lignite fraction: 100 – 250 µm

Lignite/water ratio: 1:10 wt.%

Heating rate: 10 0C/min

Atmosphere: inert (N2) Batch-mode high-pressure autoclave (Autoclave Engineers Inc.)

9

HTL experiments: Products fractionation procedure

HTL products

Gas

benzene/toluene solubles

Solid and liquid

benzene/toluene

benzene/toluene insolubles

hexane THF

hexane

solubles (oils)

hexane

insolubles

(asphaltenes)

THF solubles

(preasphaltenes)

THF insolubles

(residues)

0

5

10

15

20

25

300 320 340 360 380 400

Yie

ld, w

t.%

Temperature, 0C

15 min

30 min

10

HTL process optimization: Reaction time

Supercritical parameters

>(t=374⁰C, p=221 bar)

Subcritical parameters

<(t=374⁰C, p=221 bar)

Liquid fraction yields (heavy oil)

0

10

20

30

40

50

60

70

80

300 320 340 360 380 400

Yie

ld, w

t.%

Temperature, 0C

Char

Heavy oil

Gas

11

Results: Product yields

Reaction time: 15 min

Supercritical parameters

>(t=374⁰C, p=221 bar)

Subcritical parameters

<(t=374⁰C, p=221 bar)

24.5

40.8

47.5 47.0 47.7

52.3

0

10

20

30

40

50

60

300 320 340 360 380 400

Tota

l co

nve

rsio

n,

wt.

%

Temperature, 0C

12

Results: Conversion rate

Supercritical parameters

>(t=374⁰C, p=221 bar) Subcritical parameters

<(t=374⁰C, p=221 bar)

13

Heavy oil characterization: Elemental analysis and calorific value

0.00

0.40

0.80

1.20

1.60

2.00

0.00 0.20 0.40 0.60 0.80

H/C

mo

lar

rati

o

O/C molar ratio

400 0C380 0C

300 0C

360 0C320 0C

340 0C

HTL at 320-3600C

Biomass

Anthracite

Hard coal

Lignite

Peat

Crude oil

Temperature

[⁰C] C [%] H [%] O [%] N [%] S [%]

CV

[MJ/kg]

300 72.3 10.21 16.97 0.28 0.28 31.03

320 76.2 10.45 12.79 0.30 0.40 33.54

340 74.4 9.41 15.69 0.30 0.22 33.19

360 76.1 11.13 11.94 0.36 0.48 32.56

380 74.0 6.91 18.33 0.41 0.32 31.87

400 79.5 8.16 11.43 0.50 0.45 34.64

7.9

17.2

8.1 7.8

12.2

4.1

16.6 16.1 15.4 14.6

8.210.0

75.5

66.7

76.5 77.779.6

85.9

0

10

20

30

40

50

60

70

80

90

300 320 340 360 380 400

Yie

ld, w

t.%

Temperature, 0C

Preasphaltenes (PA) Asphaltenes (A) Light oil (LO)

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Heavy oil characterization: Solvent analysis

Preasfhaltenes (PA)

Asphaltenes (A)

Light Oil (LO)

Decrese in molecular weight

Increse in product value

Heavy oil:

• 340 0C,

• p= 14.5 MPa

• time=15 min

15

Heavy oil characterization: GC-MS analysis

5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95

5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95

5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95

5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95

5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95

5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95

More that 500 chemical compounds identified in heavy oil 300 0C

320 0C

340 0C

360 0C

380 0C

400 0C

RT (min) Peak % area at given temperature

Compound Formula 300 ⁰C 320⁰C 340⁰C 360⁰C 380⁰C 400⁰C

40.791 9.89 3.81 6.80 2.94 8.06 3.36 Heneicosane C21H44

34.678 9.09 3.44 6.08 2.47 7.64 3.07 Eicosane C20H42

46.488 10.41 3.88 0.82 2.90 8.83 3.70 Tricosane C23H48

57.448 10.41 2.54 4.72 2.31 6.31 3.11 Heptacosane C27H56

68.486 7.34 2.98 5.85 2.39 8.13 2.05 Hentriacontane C31H64

50.793 9.65 3.09 - 2.34 7.57 3.39 Pentacosane C25H52

30.756 5.47 2.25 3.86 1.70 5.09 2.24 Octadecane C18H38

87.209 2.93 4.28 3.54 1.87 3.14 1.63 Nonatriacontane C39H80

29.164 - 4.41 1.64 5.18 1.41 3.70 2-Hexadecene, 3,7,11,15-tetramethyl-,

[R-[R*,R*-(E)]]- C20H40

35.361 1.13 4.06 1.26 3.93 0.72 2.67

4,14-Dimethyl-11-

isopropyltricyclo[7.5.0.0(10,14)]tetradec-

4-en-8-one

C19H30O

58.578 - - 4.15 1.75 5.37 - Squalene C30H50

68.921 2.63 - - - 6.95 1.62 β-Amyrin C30H50O

24.173 0.36 1.92 1.60 1.50 1.48 4.08 Naphthalene, 2,3,6-trimethyl- C13H14

38.199 1.00 2.45 1.13 2.24 0.75 2.48 Benzo[b]furan, 3-(4-methoxyphenyl)-2,6-

dimethyl- C17H16O2

29.439 - 3.37 1.01 2.56 0.46 1.61 1-Dodecanol, 3,7,11-trimethyl- C15H32O

46.909 - 0.73 7.07 1.09 - - α-Guaiene C15H24

76.572 - 2.67 2.07 2.30 - 0.76

2-[4-methyl-6-(2,6,6-trimethylcyclohex-1-

enyl)hexa-1,3,5-trienyl]cyclohex-1-en-1-

carboxaldehyde

C23H32O

50.426 - 2.13 3.51 1.52 - - Betulin C30H50O2

21.48 0.42 2.16 1.14 - 0.96 1.41 Naphthalene, 1,2,3,4-tetrahydro-5-

methyl-1-(1-methylethyl)- C14H20

24.702 1.03 0.73 1.06 - 1.95 1.17 Hexadecane C16H34

16

Product classification: chemical composition of HTL oil

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57

Crude oil

Petrol

Diesel

Jet fuel JP-4

Naphta

Jet fuel Jet A

Heating oil

Heavy oil

Lubricant oils

Waxes

Asphalt and pitch

Number of C atoms in a molecule

51.8%

32.9% 11.8%

3.4%

17

Composition of HTL gas product

0

10

20

30

40

50

60

70

80

90

100

CO2 C2H6 H2 CH4 CO H2S

%, v

ol.

300

320

340

360

380

400

0

1

2

3

4

5

6

7

8

9

10

C2H6 H2 CH4 CO H2S

%

300

320

340

360

380

400

Temperature,

⁰C

Calorific

value,

MJ/m3

300 2.1

320 1.9

340 2.3

360 3.5

380 4.5

400 5.5

18

Conclusions

The highest heavy oil yields from hydrothermal processing of low-grade lignite were obtained under

subcritical water conditions in the temperature range 320 - 360 ⁰C.

Under supercritical water conditions, the oil yields significantly decreased due to thermal decomposition

of liquid products leading to the increased yields of the HTL gaseous by-product.

Results showed that the HTL gas yields increases with rising temperature when production of the solid by-

product (char) decreased with the liquefaction temperature. The total lignite conversion rate increased with

reaction temperature and the highest conversion rate – 52.3% was obtained at 400 ⁰C.

The GC-MS studies of the final liquid product showed that the major products are n-alkenes and

oxygenated products, mainly phenolic derivatives, aldehydes, alcohols and ketones with a total number of

carbon atoms in the range C4-C31

The relatively high oxygen contents in the HTL oils (12-18 wt%) suggest the necessity of further

hydroprocessing (to remove heteroatoms), if production of liquid fuels is a primary application of the oils.

Thank you for your kind attention!

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Dr Krzysztof Kapusta Główny Instytut Górnictwa Podleska 72, 43-190 Mikołów, Poland kkapusta@gig.eu +48 32 324 65 35

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