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26/06/2019 A new process scheme for 100% chemical recycling of - - PowerPoint PPT Presentation
26/06/2019 A new process scheme for 100% chemical recycling of - - PowerPoint PPT Presentation
26/06/2019 A new process scheme for 100% chemical recycling of polyurethanes Lukasz Pazdur, Christophe Vande Velde, Pieter Billen Polyurethanes problems and challenges Facts: - One of the most relevant polymer - 6 th most used
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Polyurethanes – problems and challenges
Facts:
- One of the most relevant
polymer
- 6th most used plastic
- The world production 18
milion tons per year Problems:
- High resistance to
biodegadation
- Environmental issue with
landfjlling
- Physical recycling applied
- nly to thermoplastic PURs
Challenges:
- Chemical recycling
- Thermal recycling (pyrolysis)
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Success story of polyurethanes (PURs)
- Condensation polymers
- Synthesized from polyols and isocyanates
- Wide diversity of polyols and isocyanates numerous
difgerent polymers tunable properties
- Classifjcation of PURs:
Foams
Flexible (mattresses)
Rigid (buildings isolation)
CASEs (Coatings, Adhesives, Sealants, Elastomers)
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Recycling of PUR
- Mechanical recycling
Only 1% of total amount of produced PURs
Not applicable for PURs foams
- Thermal recycling
High temperature required (at least 250 °C)
Inert atmosphere required
Complex mixture
Not yet industrially applied
- Chemical recycling
Recovery of polyols only
Lack of circular process
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Chemical recycling
- Hydrolysis
- Glycolysis
- Aminolysis
- Phosphorolysis
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First attempt for chemical recycling
Challenges:
- Complete recovery (both polyols and
isocyanates)
- Circular approach
Problems:
- High number of products (and side-products)
- Diffjculties with separation
- Diffjculties with analysis
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First attempt for chemical recycling
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New process scheme
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Model synthesis and chemical recycling
- Control synthesis (full track of functional
group formation)
- Easier analysis
- Screening of side products formation
- Infmuence of molecular size on hydrolysis /
glycolysis
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Model synthesis
Selected isocyanates: Selected alcohols:
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Model synthesis:
- Synthesis of simple urethane (carbamate) bond:
- Synthesis of dicarbamates
By means of diol
By means of diisocyanates
- Synthesis of polyurethanes
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Reactivity of isocyanates - infmuence of catalyst
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20 40 60 80 100 120 140 160 180 200 20 40 60 80 100 120
Infmuence of catalyst
Tin 2- hexanoate Sulfuric acid Without catalyst
Time [min] Conversion [%]
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Cleavage of urethane bond
- Alcoholysis
- Hydrolysis (base- and acid catalyzed)
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Results
Cleavage Model molecule Condition Results Alcoholysis (with MeOH) Tin 2-ethyl hexanoate No alcoholysis NaOH 90 % of MPhC 10 % of Aniline NaOH + H2O 5 % of MPhC 95 % of Aniline Hydrolysis Acidic (H2SO4) No hydrolysis Alkali (NaOH) 98 % of Aniline Alkali (NaOH) 99 % of Aniline * Alkali (NaOH) 94 % of Aniline
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* MW = 2500 – 3000 D
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Conclusions
- Alkali cleavage more effjcient than acidic
cleavage
- The more sterically hindered molecule, the
more diffjcult cleavage
Higher temperature required
Longer time
Presence of co-solvent
- Pre-study regarding the thermal
decomposition
Small amount of isocyanates obtained
Up to now only on lab scale, lack of industrialization
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Further actions
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A comprehensive “toolbox” will be generated, to be used for:
- The recycling of polyurethanes
- Analysis of the difgerent
products
- Screening of possible side-
products
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Bibliography
- Molero C, Ramos MJ, et al (2010). WIT T
ransaction on Ecology and the Environment 140:69-78
- A European Strategy for Plastics in a Circular Economy (2018).
COM/2018/028 fjnal
- Behrendt G, Naber BW (2009). J Univ Chem T
echnol Metallurgy 44(1):3-23
- Simon D, Borreguero AM et al (2015) The Handbook of Environmental
- Chemistry. Vol. 32, Springer, 229-260
- Wu CH, Chang CY et al (2003). Polym Degrad Stabil 80(1):103-111
- Nikje MMA, Mohammadi FHA (2009). Polimery/Polymers 54(7-8):541-
545
- Herlinger H (2007) Structure and reactivity of isocyanate. Stuttgart
- Dai Z, Hatano B, et al (2002). Polym Degrad Stabil 76(2): 179-184
- Shi Y, Zhan X at el (2009). Chem React Eng T
echnol 25:88
- Bauer G (1996) Recycling of polyurethanes. Munchen: Hanser
Publications, 518-537
- Molero C, de Lucas A, et al (2009). J Mater Cycles waste Manage
11(2):130-132
- Simon D, Garcia MT (2013). Polym Degrad Stabil 98(1):144-149
- Modesti M (1996) Recycling of Polyurethane Polymers. Vol. 13,
T economic Publishing CO., USA.
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