Within the concept of the replacement of fossil with biobased resources, bacterial polyhydroxybutyrate (PHB) can be obtained from volatile fatt y acids (VFAs) from agro-food waste streams and used as an intermediate toward attractive chemicals. Here we address a crucial step in this process, the conversion of PHB to methyl crotonate (MC), which can be converted via cross- metathesis w ith ethylene to methyl acrylate and propylene, two important monomers for the plastics industry. The conversion of PHB to MC proceeds via a thermolysis of PHB to crotonic acid (CA), followed by an esterification to MC. At pressures below 18 bar, the thermolysis of PHB to CA is the rate-determining step, where above 18 bar, the esterification of CA to MC becomes rate lim- iting. At 2008C and 18 bar, a full conversion and 60% selectiv ity to MC is obtained. This conversion circumvents processing and application issues of PHB as a polymer and allows PHB to be used as an intermediate to produce biobased chemicals.
- gas-chromatographic analysis
- poly(-(d)-beta-hydroxybutyric acid)
- abiotic hydrolysis