sustainable oxidation of polysaccharides by laccase...
TRANSCRIPT
Sustainable Oxidation of Polysaccharides
by
Laccase CLEA-TEMPO
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Richard Aartsen CLEA Technologies
Oxidation of Polysaccharides
• Hypochlorite-TEMPO is currently used in the oxidation of:
– Starch
– Cellulose
– Hemicellulose
– Inulin
– Chitin
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Modified biopolymers with novel properties
Richard Aartsen CLEA Technologies
Example: Starch oxidation
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N
O .
TEMPO / Hypochlorite
O
O H
O H
H O H O
H O
H O
H O O H
O OH
H O H O
n O
O
O
O
O H
O H
H O H O
H O
H O
H O O H
O
H O H O
n O
O
O
COOH
Richard Aartsen CLEA Technologies
A new and green approach
• Getting rid of hypochlorite because:
– Hypochlorite is not green
– After oxidation with hypochlorite the subsequent neutralization step generates high amounts of salts leading to pollution and disposal problems
– Hypochlorite is essentially chlorine in water that can lead to organochlorine impurities that end up as contaminants in your final product
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Richard Aartsen CLEA Technologies
Laccase-TEMPO system
• Laccase-TEMPO system is the green alternative • Uses O2 and produces H2O as the only by-product • Waste-free method for polysaccharide oxidation
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RCH2OH O2
H2O
l a c c a s e
l a c c a s e o x
.
N
O
RCHO
N
O
+
Richard Aartsen CLEA Technologies
Laccase-TEMPO explanation
• Laccase – Multi-copper oxidase (EC 1.10.3.2) enzyme
– Widely abundant in plants, fungi & bacteria
– Re-Oxidizes the reduced TEMPO
• TEMPO – Stable N-oxy radical (2,2,6,6-tetramethylpiperidinyl-N-oxy)
– Oxidation mediator
– Oxoammonium cation is active oxidant
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Richard Aartsen CLEA Technologies
Not every laccase is the same
• CLEA Technologies has selected the best laccase for TEMPO re-oxidation
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Textile and (paper) pulp bleaching
=
Biobleaching
Food
(modification, preservation)
Organic Synthesis
(alcohol oxidations)
Pharma/ Healthcare
(toothpaste, mouth care)
Industrial Laccase Applications
Richard Aartsen CLEA Technologies
The downside of laccase
• Disadvantages of enzymes in general – Low operational stability & shelf life
– Cumbersome recovery & re-use
– Product contamination
– Allergic reactions to proteins
• Biocatalytic applications are non viable – Costs are too high
– Soluble enzyme not practical in operational use
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Richard Aartsen CLEA Technologies
The Challenge
• To make the green alternative as cost effective as hypochlorite
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Richard Aartsen CLEA Technologies
Immobilization is the solution
• Binding to a carrier (Method 1)
– e.g. ion exchange resins
• Entrapment
– e.g. in silica sol-gel
• Cross-Linking (Method 2)
– e.g. Cross-Linked Enzyme Aggregate (CLEA)
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Carrier-bound / entrapped enzymes have inherently low volumetric & catalyst productivities (90->99% non-catalytic mass) R.A. Sheldon, Adv. Synth. Catal., 349 (2007) 1289
Richard Aartsen CLEA Technologies
Method 1: carrier based
• Particle size – Usually 100-300 µm
– Very good filterability
– Controllable pressure drop in column operation
• Mechanical Stability – Sensitive to stirrers, particle degradation
– Leaching in aqueous solutions
• Hydrophobicity/-phylicity – Not tunable
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Richard Aartsen CLEA Technologies
Cross-Linked Enzyme Aggregate
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Richard Aartsen CLEA Technologies
Method 2: proprietary CLEA
• Particle size – Usually 5-50 µm
– Determined by inter alia ratio crosslinker:enzyme
– Good filterability
• Mechanical stability – Very robust particle, ideally suited for CSTR
– NO leaching in aqueous solutions
• Hydrophobicity/-phylicity – Tunable e.g. by choice of co-polymer
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Richard Aartsen CLEA Technologies
Method 2: CLEA customization
• Our customized immobilization technology leads to bespoke solutions enabling e.g.: – Increased stability – Optimized activity – Easy recovery and re-usability
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Richard Aartsen CLEA Technologies 5/23/2012 slide | 15
Example: Starch oxidation*
O O
HO
O
OH
OH
] n
O O
HO
O
OH
] n
COOH
N
O .
Laccase (CLEA)/ O2
carboxy starch starch
Enzyme Total of units used Number of cycles Conversion after 24 h
Laccase 2000 1 61%
Laccase-CLEA 1377 multiple 64%
* WO 2006/046865 CLEA Technologies B.V.
Richard Aartsen CLEA Technologies
Easy to adopt
• Laccase CLEA replaces hypochlorite
• Process conditions are comparable
– Ambient reaction conditions
• System remains highly selective and efficient
– Specific for 1°-OH groups
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O O
HO
O
OH
OH
] n
O O
HO
O
OH
] n
COOH
N
O .
Laccase CLEA / O2
carboxy starch starch
Richard Aartsen CLEA Technologies
Laccase CLEA-TEMPO system
• Can be optimized for the oxidation of various polysaccharides
• Laccase CLEA is a green alternative to hypochlorite for the re-oxidation of TEMPO
• Optimization of the CLEA yields a stronger catalyst that can be recovered and re-used for multiple cycles
• Recycling significantly reduces costs which was the challenge
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Richard Aartsen CLEA Technologies
Summary of benefits
• Cost effective
• Green chemistry approach
• Easy to adopt in a current process
• High selectivity & high product quality
• Biocatalyst recovery & re-use
• No waste
• No end product contamination
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Richard Aartsen CLEA Technologies
Contact us
• Business Development
• +31 (0)15 7600 300
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