Techno-economic Analysis of a Chemical Process to Manufacture Methyl-Îμ -caprolactone from Cresols

Methyl-e-caprolactone is a monomer used in the manufacture of elastomeric biodegradable polymers with enhanced properties. We present here the conceptual process design for the production of methyl-e-caprolactone from para-cresol, a biorenewable feedstock obtained from lignin. The two-reaction process consists of cresol hydrogenation to methyl-cyclohexanone followed by Baeyer-Villiger oxidation to methyl-e-caprolactone. Details for designing an optimized process include unit operation design of two reactors, one decanter, one flash tank, and five distillation columns. Distillation and integrated heat transfer were determined via process simulation, with the objective of optimizing the process for net present value. For cresol obtained at $1.00 kg^-1, the minimum selling price of methyl-e-caprolactone (defined as the product selling price that results in a zero net present value of the entire 30 year project) was $3.521, $2.798, and $2.557 kg^-1 ($1.600, $1.272, and $1.162 lb_m ^-1) at three process scales of 10, 30, and 60 kton yr^-1 of para-cresol feed. A sensitivity analysis of the major process variables identified catalyst selectivity to methyl-e-caprolactone in the Baeyer-Villiger oxidation reaction as the key parameter for improving process economic potential.