Within the framework of FRACTION`s WP4, partners FUNDITEC, VTT and KINGSPAN continue working on the development of organosolv lignin valorization methods, through its depolymerization using novel catalysts or by using it as monomer in the synthesis of polymeric resins.
Lignin models such as 4-(benzyloxy-)-3-methoxybenzyaldehyde (b-4-O model); 1,2-diaryl-1,3-propanediols (b-1 model) and phenyl coumarin (b-5 model) are currently being used in the catalytic oxidation approach to test the MOF, POM and POMO@MOF catalysts, synthesized by FUNDITEC.
For the lignin depolymerization based on solvolysis with ethanol and hydrogenolysis with either ethanol or hydrogen gas, two catalyst families (unsupported molybdenum carbides and phosphides) were synthesised and tested by VTT.
Up to 90 wt% of lignin was recovered as ethanol soluble oil with up to 20 wt% of monophenolic products.
A significant reduction in lignin molecular weight upon depolymerisation (from 2500 Da to less than 1000 Da) was achoieved as resuksts of the work devloped by VTT.
Organosolv lignin has been used by FUNDITEC as monomer in the synthesis of polyurethane resins (PUR), in combination with three type of polyols: polycaprolactone diol PCL, castor oil (CO) and Boltorn H2004 (BTL). The fossil-based polyol was replaced by lignin at 10, 20, 30, 40 and 50% wt. content.
The PURs produced by FUNDITEC exhibit good film forming ability even with high lignin content (up to 50% in case of PCL-PURs). The materials present good thermal properties (Td between 360°C and 400°C), very good wettability properties (contact angle up to 98,3º) and good mechanical properties where lignin rigidity increases the tensile strength.
The developed resins are currently being applied on various substrates (wood, glass and metal) to test their performance as adhesives and coatings.
With an aim to replace (part of) the fossil sourced phenol monomer in the synthesis of phenol-formaldehyde (PF) resins by a biobased alternative (lignin polyphenol) and reduce the CO2 footprint of the final products, KINGSPAN has been working on the use of organosolv lignin. KINGSPAN has achieved promising simulation of the entire process on lab scale from a mix of phenol, formaldehyde and organosolv lignin to an LPF-foam meeting the key properties for the final application as thermal insulation. Further work on improving the resin synthesis and modifying the composition foam recipe on lab scale is required before scaling up to pilot or industrial environment.
Read about Task 4.4. – Implementation of lignin as alternative to phenol in PF-resins for the manufacture of thermal insulation foams here.