catalytic pyrolysis of biomass/upgrading of...
TRANSCRIPT
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