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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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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
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.
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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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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