Sustainable, highly selective, and metal-free thermal depolymerization of poly-(3-hydroxybutyrate) to crotonic acid in recoverable ionic liquids

Abstract

Valorization of renewable and biodegradable biopolymers to value added chemicals and green fuels is currently considered as an important research topic aiming at reducing the dependency on fossil derived feedstocks...

Ionic-Liquid-Mediated Deconstruction of Polymers for Advanced Recycling and Upcycling

“…45 For example, the base-catalyzed deconstruction of poly ( 3a). 106 A similar trend is revealed in the alcoholysis of polycarbonate (PC) in which highly basic [HDBU]-based ILs produce near quantitative yields of bisphenol A (BPA), whereas neutral or acidic ILs yield less BPA (0−90 mol %). 107 The optimized IL-mediated PC deconstruction provides significant advantages in yield and reaction conditions over PC pyrolysis.…”

“…139 The same effect transpires at higher water loadings (25−50 wt %) in the deconstruction of PHB but is less influential at lower water loadings (2.5 wt %). 106 In short, the chemical design of ILs can be exploited to enhance catalytic deconstruction through control of IL acidity/ basicity, sterics, hydrogen bonding, and reactive sites. These characteristics can be tuned through changes to experimental parameters, namely, temperature, polymer concentration, and impurities.…”

Crotonic Acid Production by Pyrolysis and Vapor Fractionation of Mixed Microbial Culture-Based Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

“…22 Ionic-liquidbased media was also examined as a green solvent and catalyst to obtain CA from PHB. 21 About 97% yield of CA was obtained by applying an ionic liquid, namely [EMIM][AcO], as a solvent and catalyst at 140 °C and 90 min. Based on these PHB-pyrolysis results, showing promising potential to obtain CA in scales beyond analytical, we decided to study PHBV pyrolysis from MMC-based PHBV to obtain a mixture of CA and 2-PA, originating from HB and HV repeating units, respectively.…”

“…The yield of CA produced through pyrolysis of PHB/PHB-enriched biomass at 310 °C is reported to be about 63%, which is 30% higher than the yield obtained by the conventional petroleum-based route. ,, Moreover, the biobased CA yield can be increased to about 80% using a catalyst or pretreatment technique . Solvent-based pyrolysis of the commercial PHB can increase the CA yield even further. , Thermal decomposition of the PHB in cyclohexane solvent at 210 °C and 5 h, followed by solvent separation by distillation, resulted in 89% CA yield with a purity of 91% . Ionic-liquid-based media was also examined as a green solvent and catalyst to obtain CA from PHB .…”

“…Solvent-based pyrolysis of the commercial PHB can increase the CA yield even further. , Thermal decomposition of the PHB in cyclohexane solvent at 210 °C and 5 h, followed by solvent separation by distillation, resulted in 89% CA yield with a purity of 91% . Ionic-liquid-based media was also examined as a green solvent and catalyst to obtain CA from PHB . About 97% yield of CA was obtained by applying an ionic liquid, namely [EMIM]­[AcO], as a solvent and catalyst at 140 °C and 90 min.…”