catalytic pyrolysis of biomass/upgrading of...

Catalytic pyrolysis of biomass/upgrading of bio-oil

PyrolysisPyrolysis

GasesVapours

Pyrolysis

Biomass

CO, CO2,H2, HC

Char

Bio oil

Upgradingover

ZeolitesCondensationPyrolysis

CarbonizationLow temperatureLong residence time

Fast pyrolysisModerate temperatureShort residence time

GasificationHigh temperatureLong residence time

Fast pyrolysis

Moderate temperature400-500°C

High heating rateShort residence time

1-2sRapid cooling

Fluidized bed reactor

[http://media3.washingtonpost.com/wp-srv/photo/gallery/090418/GAL-09Apr18-1902/media/PHO-09Apr18-158607.jpg]

Fast pyrolysisFast pyrolysis

Gas

Char

Char

Water

Bio-Oil

Gas

Bio- oil

Biomass

PineCelluloseGalactoglucomannanSugar beet pulp

[http://commons.wikimedia.org/wiki/File:SugarBeet.jpg][http://www.innventia.com/templates/STFIPage____6935.aspx][http://www.lifepinlaricio.org/pin-fi.htm]

Scaling -up

Fluid Bed ReactorsGood temperature controlEasy scaling30 years of experience since first experiments at University of Waterloo in 1980sSmall particle sizes neededHeat transfer to bed at large scale has to be proven

Industrial installations

CFD

Good temperature control in reactorLarger particle sizes possible,CFBs suitable for very large vthroughputs,

Well understood technology,Hydrodynamics more complex,Char is more attrited due to higher

velocities; separation is by cyclone,Heat transfer to bed at large scale has to be

proven.

Bio-oil

Poor volatility, high viscosity, coking, corrosiveness, and cold flow problemsIn diesel engines: difficult ignition (due to low heating value and high water content), corrosiveness (acids), and coking (thermally unstable components). Bio-oil upgrading (catalytic) is needed

hydrodeoxygenationzeolite upgrading via cracking

Problems with bio-oilProblems with bio-oil

Bio-oil

Complex mixture of organic molecules and waterAldehydes, acids, alcohols, ketones, phenols, polyaromatic hydrocarbons etc.

More than 200 different compoundsThe chemical composition of the bio-oil is dependent on the raw material

Bio-oil

Carbohydrates, cellulose and hemicellulose

Furans, cyclopentanonesOpen chain acids, aldehydes, ketones and alcohols

LigninAlkyl, methoxy, carbonyl and hydroxy substituted phenols

OHO

O

5-(hydroxymethyl)furan-2-carbaldehyde

CH3 O

3-methylcyclopent-2-en-1-one

CH3

OOH

1-hydroxypropan-2-one

O

OH

CH3

acetic acid

OHO

hydroxyacetaldehyde

CH3O

O

OH4-hydroxy-3-methoxybenzaldehyde

Catalytic pyrolysis experiments

Thermogravimetric analysis(TGA)Two fluidized bed reactors

Zeolites as bed material providing heat and upgradingproductsSeparation of pyrolysis and catalytic upgrading

Heat

Fluidization gas

Preheating

1

2

Ten-3-Gas

VapourCondensation

GasAnalyser

Dual-fluidizedbed reactor

BiomassFeeder

Fluidization gasNitrogen 1.3L/min

Biomass andgas feeding

Nitrogen2L/min

Reactor set-up

Acidic zeolite catalystsCrystalline aluminosilicate minerals3-D microporous framework structureTetrahedrons of silicon (Si4+) and/or aluminium (Al3+) surrounded by four oxygen (O2-) anionsNeutral framework (silicon and oxygen)Negativelly charged framework (aluminium, silicon and oxygen)Framework balanced by a metal cation (Lewis acid) or a hydroxyl proton (Brønsted acid)

Ferrierite

Al-

O+

Si

H

Determination of acidityPyridine is adsorbed to the zeolite sample

FTIR is used to determine the acid sites

Brønsted 1545 cm-1

(hydron H+ donor)Lewis 1450 cm-1

(electron acceptor)

Quantitative amount of acid sitescalculated with the constants of Emeis

[Emeis C.A., Journal of Catalysis 1993]

Brønsted Lewis

TGA

Polymers (LDPE)C-C bonds breaks at high temperaturesBrønsted acidity decreases the temperature needed for crackingEnergy saved

BiomassDifferent zeolites testedNo difference in non-catalytic and catalytic thermograms

[J. Agullo et al., Kinetics and Catalysis 2007][A. Aho et al., Catalysis in Industry 2008]

zeolites thermal

Fluidized bed reactor

Zeolites as heat carrierand catalysts in same reactorStudy the influence of acidity and structure of the zeolitesPine wood450°C

Influence of structure and acidityZeolite structures

ZSM-5, 3-D 10 ring 5.2 x 5.7Å and 5.3 x 5.6Å Intersection cavity: 9Å

Beta, 3-D 12 ring 6.6 x 6.7Å and 5.6 x 5.6Å

Mordenite, 2-D 12 ring 7.0 x 6.5Å and short 8-ring channels 3Å

Y, 3-D 12 ring 7.4 x 7.4Å and 11.8Åsupercages

Beta zeolites with different silica-alumina ratios (acidity)

Y

ZSM-5

Mordenite

ResultsPyrolysis over zeolites compared to non-catalyticpyrolysis

Decreased the bio-oil yieldIncreased the water yieldChanged the chemical compositionof the bio-oilAcidity influenced the formation of PAHsCoke was formed on the zeolites

Possible to partly de-oxygenate the bio-oil over zeolite catalysts

0

2

4

6

8

10

12

Aldehydes Acids Alcohols Ketones Phenols PAHs

yiel

d w

t-%

H-Beta-25 H-Y-12 H-ZSM-5-23 H-MOR-20 Quartz

[A. Aho et al., Fuel 2008][A. Aho et al., IChemE, part B, Process Safety and Environmental Protection 2007]

Dual-fluidized bed reactor

Smaller amount of zeolites neededEasier to separate char and spent zeolitesSeparation of pyrolysis and catalysis reactorsImproved condensation

Gas analysis

Zeolites as bed material providing heat and upgradingproductsSeparation of pyrolysis and catalytic upgrading

Heat

Fluidization gas

Catalytic pyrolysisCatalytic pyrolysis

gas heater

pyrolysisreactor biomass

feeding

catalyticup-grading

inlet forfluidizationgas

gases to coolers

thermocouples in-pyrolysis reactor-up-grading reactor

Thermal pyrolysis and catalytic upgradingThermal pyrolysis and catalytic upgrading

Dual-fluidized bed reactor

Effect of binder (bentonite)Beta and ZSM-5

Iron modification (ion-exchange)Beta, ferrierite and Y

Reaction conditionsPyrolysis reactor 400°CCatalytic upgrading reactor 450°CPine

Zeolite characterizationIron content analysed by ICP-OESinductively coupled plasma - optical emission spectrometry

Fe-H-FER-20 0.1 wt-%Fe-H-Beta-25 3.4 wt-%Fe-H-Y-12 5.4 wt-%

The oxidation state and coordination of iron were investigated by ESRElectron spin resonance spectroscopy

Structure and phase purity analysed by XRD

0 10 20 30 40 50 60

2θ

Cou

nts

H-Y-12

Fe-H-Y-12 fresh

Fe-H-Y-12 reg

Based on ESR the iron on Beta wasmostly tetrahedral Fe3+

Iron modification and regeneration of the iron modified Y does not change thestructure nor the phase purity

Zeolite regenerationCoke was formed on the zeolites

Regeneration by burning away the coke

2h, 450°C in air atmosphere

Specific surface area

0

100

200

300

400

500

600

700

H-Beta-25 Fe-H-Beta-25

[m2 /g

]

Iron modification increases the specificsurface areaThe spent zeolites has a fairly low areaPossible to regain the surface area through regeneration

Zeolite characterization

H-Beta-25

H-Beta-25

H-Beta-25

H-Beta-25

H-Beta-25

H-Beta-25

Fe-H-Beta-25

Fe-H-Beta-25

Fe-H-Beta-25

Fe-H-Beta-25

Fe-H-Beta-25

Fe-H-Beta-250

20

40

60

80

100

120

140

160

weak medium strong weak medium strong

Brønsted acid sites (μmol/g) Lewis acid sites (μmol/g)

Iron modification changes the distribution of acid sites

Most of the acid sites can be regained throughregeneration of the spent sample

0

20

40

60

80

100

120

140

160

weak medium strong weak medium strong

Brønsted acid sites (μmol/g) Lewis acid sites (μmol/g)

μmol

/g

Mass balance

char

oil

watercokegas

0

10

20

30

40

50

60

70

80

90

100

non-catalytic H-Fer-20 Fe-H-Fer-20 H-Y-12 Fe-H-Y-12 H-Beta-25 Fe-H-Beta-25

yield [%]

CO/CO2

0.00

0.25

0.50

0.75

1.00

non-catalytic H-Fer-20 Fe-H-Fer-20 H-Y-12 Fe-H-Y-12 H-Beta-25 Fe-H-Beta-25

Water yield

0

2

4

6

8

10

12

non-catalytic H-Fer-20 Fe-H-Fer-20 H-Y-12 Fe-H-Y-12 H-Beta-25 Fe-H-Beta-25

yield [%]

Chemical compositionLevoglucosan transformed into

Glycolaldehyde, formaldehyde, acetaldehyde, acetic acid and furfural

Concentration of methoxy substituted phenols decreasedConcentration of methyl substituted phenols increased

CH3

OOH

2-methoxyphenol

CH3

O

CH3

OH

2-methoxy-4-methylphenol CH3OH

2-methylphenol

CH3

OH3-methylphenol

CH3

OH4-methylphenol

OOH

CH3CH3

2-methoxy-6-methylphenol

OOH

CH2

CH3

4-ethenyl-2-methoxyphenol

Conclusions: Bio-oil

Many challenges including:Scale-upCost reductionBetter oil qualityNorms and standards for bio-oil

Conclusions: catalytic

TGA not suitable for investigating catalyticpyrolysis of woody biomassPossible to use zeolites as heat carriersand catalysts simultaneouslyEasier screening of catalysts by separating the pyrolysis and catalyticupgrading reactors

Conclusions

Catalytic upgrading resulted in a less oxygenated bio-oilMore CO and water formedMethoxy phenols transformed into methylphenolsPossible to regain acidity and surface area through regeneration of the spent zeolite