Fast Pyrolysis of Residues to Produce Phenolic Chemicals

(Project: ORF-2)

Dongbing Li, Cedric Briens, Franco Berruti*

(Paper in press: http://dx.doi.org/10.1016/j.fuel.2013.12.042)

NSERC/FPInnovations IRC & ORF-RE Project AGM, ICFAR, Western University, London, ON. Jan 7, 2014

Introduction• Bio-oil from Fast Pyrolysis of bio-residues has great potential

for the production of fuels and aromatic chemicals• Fractional Condensation provides dry bio-oil with ~1% water• Autothermal pyrolysis process would be attractive: - No need for external heating. - Simplified reactor design. - Better bio-oil quality?

Research Objectives:• Develop a self-sustainable fast pyrolysis process with partial

(air) oxidation, for both birch bark and Kraft lignin• Maximize bio-oil yield and quality

Autothermal Fast Pyrolysis with Fractional Condensation

Experimental Setup/Conditions

Carrier N2

PLC

Pinch valve

Solenoid valve

Pulse gas (N2)

Compensating line

Biomass

Pre-heater

biomass slug

N2

Air

T T

C

Condenser 1(dry bio-oil)

Ice bath

T

C

Hot air exit

T

C-ESP(dry bio-oil)

Preheate

r

Cottondemister

To vent

Cold air in

T

N2

T

Air

Electrode

Hot box

Vapors from the pyrolysis reactor

Sand bed

Carrier gas: N2+AirVapor residence time: 1.7 sReactor temperature: 500, 550 °CBiomass feeding rate: 600 g/h(Mechanical mixer needed for processing Kraft lignin only)

80 °C70 °C

Mechanical Stirrer

Cooling jacket with ice water

110 °C

55 °C

15 °C

Biomass Feeder Pyrolytic Reactor Fractional Condensation Train

Condenser 3(water fraction)

• Biomass: Birch Bark/Kraft lignin, 5% moisture content• Heat input to the pyrolytic reactor, before (at steady state) and after

biomass feeding, was calculated based on the signals from the current sensors attached to the power supply for the ceramic heaters.

Achieving Energy-Neutrality

• Autothermal pyrolysis operation was achieved with an oxygen feed of 0.08 g per g of biomass at the reaction temperatures of 500 and 550 °C

• The corresponding O2 molar fraction in the carrier gas was 2.8%• Lignin: 0.065 g/g biomass O2 at energy-neutrality

BIRCH BARK

Effect of Partial (Air) Oxidation on Gas, Char and Dry Bio-oil Yields

°C °C

(b) Dry bio-oil Yield

Oxygen feed (g/g biomass)

0.00 0.02 0.04 0.06 0.08 0.10 0.12

Bio-char yield (%

)

0

5

10

15

20500550

°C °C

(a) Bio-char Yield

Oxygen feed (g/g biomass)

0.00 0.02 0.04 0.06 0.08 0.10 0.12

Dry bio-oil yield (%

)

20

25

30

35

40

45

500550

22 %relative

loss31 %relative

loss

biomass ash contentEnergy-neutral (550 )°C

Energy-neutral (500 )°C

• Char and bio-oil were partially combusted to give higher gas yield• 22% or 31% of dry bio-oil was lost at autothermal pyrolysis conditions

for the reaction temperature of 500 and 550 °C• Lignin: 23% (500 °C) or 21% (550 °C) dry bio-oil loss

BIRCH BARK

Effect of Partial Oxidation on Bio-oil Quality: Yield of Phenolic Chemicals

Comparing autothermal pyrolysis with regular, oxygen-free fast pyrolysis, the production of 7 most abundant chemical species (GC-MS/FID):• More phenolics were produced under autothermal pyrolysis conditions• Phenolics are less susceptible to partial oxidation

BIRCH BARK

Effect of Partial Oxidation on Bio-oil Quality: HHV and Molecular Weight/Distribution

• Dry bio-oil HHV was slightly decreased from autothermal pyrolysis• GPC results showed better bio-oil quality as average MW and its

dispersity were both reduced deeper pyrolysis, less heavy sugars and pyrolytic lignin in the resulting bio-oil

(a) HHV °C °C

(b) Molecular weight/distribution

Oxygen feed (g/g biomass)

0.00 0.02 0.04 0.06 0.08 0.10 0.12

Dry bio-oil H

HV

(MJ/kg)

24

26

28

30

32

34

36

Oxygen feed (g/g biomass)

0.00 0.02 0.04 0.06 0.08 0.10 0.12W

eight-average molecular w

eight (g/m

ol)

100

200

300

400

500

Dispersity (-)

1.2

1.4

1.6

1.8

2.0

2.2

2.4

500 , molecular weight550 , molecular weight500 , dispersity550 , dispersity

°C °C °C °C

500 550

Ethanol

BIRCH BARK

Conclusions• Autothermal pyrolysis operation of bio-residues, both birch

bark sawdust and Kraft lignin (results not shown in this presentation), is possible with introduction of oxygen (air) into the pyrolysis reactor.

• For birch bark: under autothermal conditions, 22 % of the dry bio-oil chemicals and 25 % of total bio-oil energy are lost at the preferred reaction temperature of 500 °C.

• Partial oxidation provides better bio-oil quality:- enriched phenolics concentration- reduced amount of heavy sugars and pyrolytic lignin

Future work: - Efforts on the analyses of the composition of the phenolic fractions: GC-MS-FID, ORBITRAP LC-MS- Possible applications for the phenolic fractions

Acknowledgements

• NSERC/FPInnovations Industrial Research Chair (IRC) Program in Forest Biorefinery

• Ontario Research Fund (ORF) from Ministry of Economic Development and Innovation