Liquefaction of wood and its applications for the production of bio-based materials

Prof. Dr. M. Hakkı Alma Res. Assist. Tufan Salan

KAHRAMANMARAS SUTCU IMAM UNIVERSITY, FACUTY OF FORESTRY, KAHRAMANMARAS, TURKEY

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The 3rd FOREBIOM Workshop: Potentials of Biochar to mitigate climate change

June 5th-6th, 2014 Eskisehir, Turkey

Introduction Today, lignocellulosic biomass can be converted by to a broad range of value-added: Fine chemicals Biofuels Green polymeric materials via Biorefinery Concept.

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Biorefinery Conversion Methods

PHYSICAL UPGRADING METHODS (drying, pulverisation, briquetting, and pelletizing)

CHEMICAL AND BIOCHEMICAL METHODS (hydrolysis followed by fermentation or chemical conversion)

THERMOCHEMICAL METHODS (torrefaction, pyrolysis, gasification, liquefaction, and combustion)

OTHER METHODS (e.g., production of composites or fractionation followed by chemical conversion - cellulose derivatives)

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Product Groups from Thermal Conversion of Cellulosic Biomass

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Biorefinery Concept For The Liquefaction of Biomass

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Biomass

Thermochemical Platform

Direct Liquefaction

Pyrolysis

*Bio-oil

Solvolysis Liquefaction

Bio-polyols

*Biomaterials

High-pressure Liquefaction

*Bio-crude

Indirect Liquefaction

(Gasification)

Syn-gas

Catalytic or Biochemical

Processes

Fuels and Fine

Chemicals

Sugar Platform

Hydrolysis

Catalytic Routes (Aqueous Phase

Processing)

*Liquid Hydrocarbon Fuels

Biochemical Routes

*Bioethanol

Feedstock

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Forest Residues Agricultural Residues

Wood Bark

Bamboo

Bagasse

Solvolysis Liquefaction Biomass is firstly converted bio-polyols by

thermochemically due to solvolytic liquefaction, and then bio-polyols are used to produce useful green materials.

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Solvents

• Glycerol • Ethylene

Glycol • Polyethylene

Glycol (PEG) • Phenol • Dioxane • Ethanol • Acetone

Catalysts

• Sulfuric Acid • Hydrochloric

Acid • Oxalic Acid • Phosphoric

Acid • NaOH • MgSO4

Heat

• 80-150 ˚C (With Catalysts)

• 240-270 ˚C (Without Catalysts)

Time-Pressure

• 60-150 min. • Atmospheric

pressure or high pressure

Composition of Wood

8 …which has plenty hydroxyl groups. Hydroxyl groups make it possible to convert liquefied biomass into biopolymers.

Solvolysis Liquefaction

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Microwave Assisted Conventional Glass Flask Pressure-proof Autoclave

Applications of Liquefied Wood

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PU Foams Phenolic Resins Adhesives

Carbon Fibers Polyesters Moldings Bakalite

Biomass PEG-Glycerol

H2SO4

Liquefied Product (Liquefied Biomass,

Residue)

Unliquefied Residue Soluble Fraction

Pressure Reduced Destilation

Liquefied Biomass

Dilution with Methanol

Neutralized by NaOH

150 ˚C 60-120 min

Liquefaction Process

Filtrasyon

Methanol

Concentrated Liquified

Final Product

PU Foam Manifacturing-Stage1

Stirred at a speed of 8.000-14.000 rpm

Polyethylene Glycol Amine Catalyst Silicon Based Surfactant Blowing Agent (Water or

Boric Acid) Polymeric Diphenylmethane

Diisocyanate

Liquefied Product

PU Foam Manifacturing-Stage 2

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• Liquefied Biomass

HMTA

•130 ˚C • Stirring

Spinning Solution

•Melt Spinning

Cured by HCHO and

HCl

•Activation by

Carbonization

Carbon Fibers

Corbon Fiber Production

Phenelation of Wood and Its Resinifation Liquefaction of wood in the presence of phenol and its

application to thermosetting materials is a promising technique.

Wood liquefaction using phenol and an acid catalyst has long been studied as a novel technique to utilize biomass as an alternative to petroleum based products.

Carbohydrate and lignin content converted to small fragments or monomolecular compounds via hydrolysis, degradation, and decomposition reactions and after this they react with phenol to form derivatives.

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Wood meal+ Phenol+Acid

Phenolation

Phenolated wood

Filtration

Methanol (MeOH)

Phenelation of Wood-Stage 1

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Phenelation of Wood-Stage 2

Insoluble part in MeOH

Oven-drying

Dried methanol-insoluble part

Soluble part in MeOH

Neutralization with MgO

Evaporation of MeOH at 50 ˚C

Distillation of free Phenol at 180 ˚C

under vacum

Phenolated wood

GPC Flow Tester

Free Phenol

The liquefied wood resin is particularly inferior to the conventional novolak-resin in thermal flow properties such as, flow temperature and apparent melt-viscosity.

Condensation reaction of liquefied wood and formaldehyde is an efficient way to use the unreacted free phenol left behind after the liquefaction process.

Thus, mechanical properties and thermal flow properties would be much improved than that of the parent liquefied wood.

Phenol-liquefied products can easily react with formaldehyde; to form novalac or resol type phenol- formaldehyde resins.

Formaldehyde-based adhesives have important features such as low-cost, good adhesive force and insect prevention.

These adhesives are used mostly to produce wood composites.

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Novolac-type Resins Synthesized in the Presence of Acid Catalysts

Sulfiric, Hydrochloric, Phosphoric, Oxalic acids.. Sulfuric acid seemed to be the most effective catalyst on the

phenolation of unmodified wood at moderate temperatures. Liquefied wood products using a strong acid catalyst can

achieve higher combined phenol and lower wood residue content than that using a weak acid catalyst.

Phenolysis of wood components in the presence of an acidic catalyst resulted in dozens or even hundreds of different reactions that compete with each other.

Due to the cleavage of lignin in the presence of phenol, a variety of phenolic compounds such as guaiacol, coniferyl alcohol, vanilin, etc. formed.

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Scheme for degradation mechanisms of guaiacylglycerol--guaiacyl ether (GG) and reaction of guaiacol with phenol and formaldehyde.

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Also in the presence of phenol and an inorganic acid, cellulose and hemicellulose undergo transglycosylation to form hydroxymethyl furfural compound in high yield.

The furfural thus formed has been found to condense with phenol and formaldehyde through methylene bridges.

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Reactions Between Phenol and HMF

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Sulfuric acid has been used as a catalyst in the liquefaction of wood with phenol, and the liquefied products could become matrix resin for making molding materials with satisfactory mechanical properties.

The use of hydrochloric acid (HCl) as a catalyst is advantageous because it can be removed by evaporation after liquefaction, as well as being economic and fasting reaction.

In the preparation of phenolated wood, a large amount of free phenol must be removed after the liquefaction to obtain the final product, especially, when a weak acid is used as a catalyst such as oxalic acid.

Liquefaction ratio of wood in the presence of weaker acids was always lower than that of sulfuric acid under similar conditions.

Necessary for longer reaction times is a negative feature for commercial applications for week acids.

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Phenolic Resins Synthesized in the Presence of Alkaline Catalysts

Alkalis and metallic salts were efficient catalysts giving low biomass residue content, however, they were not effective catalysts to achieve a high amount of combined phenol. At an elevated temperature of 250 °C NaOH

was found to be the most effective base catalyst in the liquefaction of biomass in phenol.

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Preparation of Moldings Materials and Their Properties

After being mixed with a curing agent and other conventional molding agents, the resultant phenolated wood composites can be molded at a temperature of 170-200 ˚C for about 5 min under high pressure.

Various physico-mechanical properties (e.g., some mechanical properties, hardness, dynamic elastic properties, and water resistance), thermal properties and biodegradability of the acid-catalyzed phenolated and resinified with formalin wood-based moldings were examined.

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Phenolated wood + Free Phenol +

Residue

Resinified phenolated wood

+ Residue

Filtration

MeOH Insoluble part

Oven-drying

Dried methanol-

insoluble part

MeOH Soluble part

Evaporation of MeOH at 50 ˚C

Distillation of free Phenol at 180 ˚C,

1h Free

Phenol Resinified Phenolated

wood

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Phenolated Biomass Resin

Formaldehyde NaOH PF

Adhesives

PF Glue

Powder Hexamethylenetetramine (HMTA) (as curing agent)

Zinc Stearate (as lubricating agent) Calcium Hydroxide (as accelerating

agent). Wood Powder

Hot Pressing (190 ˚C, 39 MPa,

5 min)

Molding Material

Tests: Mechanical

and Physical

Molding Production

The mechanical properties of the molding composites using novolac type liquefied wood resin were much higher than that of the the phenolated wood based ones and also a little better than that of the commercial conventional novolac resin based ones.

There is a big necessity to develop degradable polymeric products (i.e., biodegradable, photodegradable, chemidegradable, envirodegradable ones) has been increasing from an ecological standpoint, thus demanding that waste biomass is incorporated into biodegradable materials.

Thus, some studies has been made to evaluate the biodegradabilities of these materials systematically

Results showed that phenolated wood-based molding materials had much more weight loss per cent when compared with commercial novolak resin-based ones.

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Novolak resins can be extensively used as molding materials in electrical, automotive, radio and television, and appliance parts just the same as commercial novolak resin-type moldings.

To know the thermal properties of the thermosetting moulding material in the usage areas mentioned above is very important.

Themogravimetric weight losses and glass transition points (Tg) of the cured phenolated bark decreased with increasing catalyst concentration.

The thermogravimetric weight loss of the cured phenolated barks was found to be comparable to those of cured commercial novolak resin and phenolated wood.

Furthermore, the Tgs of the phenolated bark samples were found to increase with increasing catalyst concentration and to be obviously lower than those of commercial novolak resin. 29

High-Pressure Liquefaction • High-pressure liquefaction of biomass

is called direct liquefaction or hydrothermal liquefaction.

• In this process, basically liquid (bio-crude) is obtained by thermo-chemical conversion at low temperature and high pressure in the presence of catalyst in with or without reducing gas from biomass.

• Catalyst: Sodium carbonate and potassium carbonate

• Reducing Gas :Hydrogen or Carbon Monoxide

• 280-370 ˚C and between 10 -25 MPa. • Feedstock drying process not required. • Bio-crude obtained after liquefaction

has similar properties like bio-oil.

Conclusions The utilization of wood wastes, which are the most

abundant natural source, and renewable and cheap materials, becomes an important issue for many researchers nowadays.

There are several approaches in the utilization of the wastes: production of energy, oil, chemicals, plastics, and composite materials.

The last or the production of composite materials which consist of chemical modification or liquefaction of the wood wastes appears to be one of the ideal approaches in the utilization of the wastes, in terms of environment, economy, and availability of raw material.

A significant majority of the main transportation fuels and, new type adhesives, foams and molded wood products could be obtained from liquefied biomass particularly biomass wastes in the near future.

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Thank You

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