School of Engineering Mohammad. Taherzadeh @ hb. se Mohammad. Taherzadeh @ hb. se Tel : +46-70-7171032 Tel : +46-70-7171032 www. hb. se / ih / resourcerecovery

School of School of EngineeringEngineering

[email protected]@hb.se.se Tel: +46-70-7171032Tel: +46-70-7171032www.hb.se/ih/www.hb.se/ih/resourcerecoveryresourcerecovery

Pretreatment of different materials: An international perspective

Mohammad J. TaherzadehSchool of Engineering

University of Borås



A variety of lignocelluloses are attractive in different reagions!



Complex plants cell walls



A challenge by lignin and hemicellulose!

Lignin

Hemicellulose

Cellulose chains



Challenge of crystallinity!



Alternative patterns of aggregation

A. The fibrils were twisted individually and then the assembly also twisted.

B. The individual fibrils were twisted of 90°over 300 nm and then packed as closely as possible

C. The fibrils were collectively subjected to twist.

Helical form of a 6 by 6 nm nanofibrils is compared with that of nine 2 by 2 helical nanofibrils packed as close as possible, with the same period.



Alternative patterns of aggregation

Would not be mechanically stable

Cellulose is deposited alone

The most efficient load-bearing structure



Changes during Isolation

• Two stages in isolation will influence the final pattern of aggregation:

1.Elevation of temperature2.Effect of drying



Cellulose is hydrated in its native state at the level of elementary nanofibril

Effects of elevated temperature

Temperature elevation changes the state of aggregation of native

cellulose.



Drying results in distortion of nanofibrils by:Removing too much of the water needed to lubricate the motion of the nanofibrils relative to each other.

Drying?



Linear parallel segments, which are artifacts of isolation processes are easily mistaken for naturally accuring crystalline domains.

Changes during Isolation



Pretreatment in order to:

Release cellulose from the structure:Remove or hydrolyze hemicellulosesRemove lignin

Reduce cellulose crystallinity Provide enough accessible surface area to

absorb the enzymes Adsorption/desorption rates of the enzymes Remove inhibitory compounds following the

substrate



Pretreatment methods (various efficiency on different factors)

Physical methods Chemical & Physicochemicals

Biological

milling:- Ball milling- Two-roll milling- Hammer milling- Colloid milling- Vibro energy millingirradiation:- Gamma-ray irradiation- Electron-beam irradiation- Microwave irradiationOthers:- Hydrothermal- High pressure steaming- Expansion- Extrusion- Pyrolysis

Explosion:- Steam, Ammonia, CO2, SO2 , AcidsAlkali:- NaOH, NH3, (NH4)2SO3Acid:- Sulfuric, Hydrochloric & Phosphoric acidsGas:- ClO2, NO2, SO2 Oxidizing agents:- Hydrogen peroxide- Wet oxidation- OzoneSolvent extraction of lignin:- Ethanol-water extraction- Benzene-water extraction- Ethylene glycol extraction- Butanol-water extraction- Swelling agentsOrganosolvs/ Ionic liquids

Fungi and actinomycetes(lignin peroxidase, manganese peroxidase, laccase…)



Cellulose solvents effective for crystallinity



Possible non-aqueuous cellulose solvents



Low-temperature Ionic Liquids (80-130 C)

1-Ethyl-3-methylimidazolium acetate [EMIM]OAc

1-Ethyl-3-methylimidazolium chloride [EMIM]Cl

1-Allyl-3-methylimidazolium chloride [AMIM]Cl

1-Butyl-3-methylimidazolium chloride [BMIM]Cl

1-Butyl-3-methylimidazolium bromide [BMIM]Br

1-Butyl-3-methylimidazolium acetate [BMIM]OAc

1-Butyl-3-methylimidazolium tetrafluoroborate [BMIM]BF4

1-Butyl-3-methylimidazolium hexafluorophophate [BMIM]PF6

1-Butyl-3-methylimidazolium methylsulfate [BMIM]MeSO4

1-Octyl-3-methylimidazolium chloride [OMIM]Cl

Imidazole salts



Milling: Usually part of the process!

Milling: Ball milling Two-roll milling Hammer milling Colloid milling Vibro energy milling

Functions: Size reduction Degree of crystallinity

High energy costs!



Irradiations

Irradiation:– Gamma-ray irradiation– Electron-beam irradiation– Microwave irradiation

Usually good results Expensive! Ultrasound might have a good

a chance for commercialization (already in the market)



Hydrothermal process

Cooking in liquid hot water generally at 150-210 °C Water under high pressure can:

– Penetrate into the biomass, – Hydrate cellulose, – Remove hemicellulose (a major function),– Remove part of lignin (but not so effective),

Autohydrolysis occur due to releasing some carboxylic acids such as acetic acid,

Advantages:– No addition of chemicals,– No neutralization afterward,– No corrosion-resistant materials for reactor,– Could be combined with e.g. a delignification process

Industrial application such as by Danish Inbicon



High-pressure steaming (+explosion)

Cooking with steam generally at 150-220 °C & 0.5-20 min If followed by explosive releasing of the pressure = Steam

explosion Steam explosion is one of the most popular pretreatments Explosion has important function pH reduces due to autohydrolysis

Industrtial applications by e.g.– Cambi (Norway)– Chemtex (Italy)– Greenfield (Canada)



Dilute-acid processes!

Similar methods in pulp industries Similar temperature/Pressure as steam explosion! Improvement by addition of:

– Dilute-acid (0.1-1% acids: H2SO4, HCl, etc.)– Carboxylic acids (e.g. acetic acid)– 1-4% SO2– CO2

Functions:– Open up the polymers– Hydrolysis of hemicellulose

Potential commercialization by e.g :– POET (USA)– SEKAB (Sweden)– ABENGOA (USA)



Alkaline cooking! Treatment with alkaline solutions:

– NaOH,

– Ca(OH)2 (lime) or

– Ammonia (AFEX)

Popular in pulp industries (kraft process) To remove lignin effectively (+ sometimes a part

of the hemicellulose) To reduce crystallinity of cellulose Generally at about 90-130 C for a few minutes to

hours High pH (e.g. 11-12) or alkali concentrations 1-

20% High amount of NH3 is needed (e.g. 1:1 kg/kg

NH3/biomass) Can also be used with explosion



Oxygen treatments (wet oxidation)!

Wet oxidation = treatment with water and air or O2 at 140-200 C for e.g. 30 min.

It is exothermic process (because of oxidations) It is a combination of solubilization and

degradation reactions Hydrolytic reactions organic acids The hemicelluloses are extensively cleaved to

monomeric sugars; The lignins undergo both cleavage and oxidation; Cellulose is partly degraded.



Organosolves/Ionic liquids!

Lignocelluloses are mixed with organic liquid (and water?) and heated to dissolve:– Ligning– And/or cellulose

Temperatures of 80-200 °C can be used:– Depends on the solvent used!

Simple solvents such as ethanol or acetone can be used!

Low Temperature Ionic Liquids are hot research topic today!



Our latest results for high crystalline cellulose!

N-Methylmorpholine-N-oxide (NMO or NMMO) No toxicity Solvent of cellulose Industrial solvent 80-130 C



Conclusion Lignocelluloses are diffent:

Type, Age, Crystallinity Dryness, Type of the cell wall ….

Pretreatments have different effectivities on various lignocelluloses,

Great developments in pretreatments, but still long way to go…



Thank you!

Question?

Documents

School of Engineering Mohammad. Taherzadeh @ hb. se Mohammad. Taherzadeh @ hb. se Tel : +46-70-7171032 Tel : +46-70-7171032 www. hb. se / ih / resourcerecovery