EXTRACTION OF HIGHVALUE CHEMICALS FROM WHEAT STRAW BY SUPERCRITICAL CARBON DIOXIDE

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EXTRACTION OF HIGH-VALUE CHEMICALS FROM WHEAT
STRAW BY SUPERCRITICAL CARBON DIOXIDE

• FABIEN DESWARTE
• Supervisors Prof. James Clark, Dr. Jeff Hardy

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PLAN

• Background of the project
• High-value wheat straw wax products
• Solvent SCO2 extraction/fractionation
• Pilot and commercial trials
• Variation between varieties components
• Conclusions

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WHAT IS WHEAT STRAW ?

• Wheat worlds foremost crop plant
• UK 2 million hectares
• 17 million tonnes
• Straw stem from which the seed head has been
  removed.
• - 3 botanical components

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TRADITIONAL USESAVAILABILITY
WHEAT STRAW
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BENEFITS OF ALTERNATIVE USES
Inexpensive raw material - 24 / ton.
Stable price vs crude oil
Readily
available and renewable - 4M tons out of 10 are
going to waste every year in the UK
National security -
could help UK to substantially reduce dependence
on petroleum. Environmental
protection - could provide valuable net savings
in greenhouse gas emissions Rural
Economic growth will stimulate rural
development
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CHEMICAL COMPOSITION
LIGNIN
(15-20)
MINOR CONSTITUENTS
(5-10)
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WAXES DEFINITION
Alkanes
Fatty acids
Fatty alcohols
Sterols/ Steryl esters
Wax esters
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MINOR CONSTITUENTS
COSMETICS, COATINGS, ETC..
Polycosanols/ sterols
INSECT SEMIOCHEMICALS
CHOLESTEROL REDUCING AGENTS
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SOLVENT EXTRACTION
WAXES
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CHEMICAL COMPOSITION
Variety Consort
Sterols
Alkanes
Fatty acids
Wax esters
Fatty alcohols
C29
C12
C18/ C181
C31
C33
C182
C28
unknown
C16
C183
C14
C22
C24
C20
C26
C24
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ALKANES FROM WHEAT STRAW
C31
C29
C27
C33
C30
C25
C28
C26
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POLYCOSANOL FROM WHEAT STRAW
HEXANE/ETHER (85/15, v/v) FRACTION
POLYCOSANOL
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SUPERCRITICAL CO2
SUPERCRITICAL FLUID substance above both its
critical T(TC) and P (PC) CO2 Tc 31
C Pc 73 bars
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PILOT SCALE EXTRACTION
Sabre wheat variety 200g scale 22 factorial
design - Pressure - Temperature
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PILOT SCALE EXTRACTION
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QUALITY OF MODEL FIT
T55C/P200bar (coded value T0/P0)
y0.36-0.36?exp(-t/19)
R20.99537
y0.35-0.15T0.13P-0.07PT
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PILOT SCALE FRACTIONATION
C16
Sitosterol
Stigmasterol
Hentriacontane?
Cholestone?
Sterol derivatives
Cholesterol
C14
C29
C12
C18
C31
C15
C27
C31
C18
C29
C28
Stigmasterol
C16
Sitosterol
C24
Sterol derivatives
C27
C12
C14
C28
C30
C28
C26
C30
C26
C24
Sitosterol
C32
C24
C29
C31
C34
C22
C16
C12
C18
C20
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COMMERCIAL SCALE EXTRACTION
Product testing
770g of wax
75kg of chopped wheat straw
Patent pending GB patent 0502337.9, 4th Feb 2005
Green Chemistry, 8 (2006) 39-42
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COMMERCIAL SCALE EXTRACTION
Pilot scale
Commercial scale
variety
Sabre
Sabre
Harvest year
2003
2005
Wax content (DM)
0.90 0.06
0.81 0.01
-11
Extraction yield ( DM)
0.55
1.04
2
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WAX YIELD ? BETWEEN VARIETIES
Wax yield ( dry matter)

• Grown under field control conditions
• Hexane extracts

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TRANSPORT/STORAGE ISSUE
DENSITY BY A FACTOR 10
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NOVEL COLLECTION TECHNOLOGY
Reducing the cost of -
Collection - Transportation
- Storage is critical to
developing a sustainable and economically viable
process !
Researchers in the US and in the EU are
developing a single-pass multi-component
harvesting technology
www.eere.energy.gov (US department of
Energy) www.biomatnet.org (Biological materials
for non food products
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WHEAT STRAW COMPONENTS
Nodes
Leaves
Internodes
Nodes
Botanical components within wheat straw
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WAX YIELD ? WITHIN PLANT
Wax yield ( dry matter)
? Consort variety ? Hexane extracts
Straw ulization for bionergy, biomaterial ..
has been limited .. because of the waxy cuticle
that coats the straw. Thompson et al. have
demonstrated that the the waxy leaves and nodes
could be separated from the straw and left on the
field. Thompson D.N., et al., Idaho National
Engineering and Environmental Laboratory
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SURFACE OF COMPONENTS
leaf
internode
Nodes
node
Botanical components within wheat straw
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NOVEL COLLECTION TECHNOLOGIES
2 approaches
(1)
Ground straw
On-field straw grinding
Ground leaf node
(2)
On-field straw fractionation grinding
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CONCLUSIONS
Low environmental impact technology
Low value, natural and renewable resource
Development of crops harvesters
BIOREFINERY
Applications to other crops
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Les Moeres, FRANCE Summer 1949
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Wheat straw today A new beginning for an old
resource?
Source www.inl.gov (Idaho National Laboratory)