Process Design and Economic Analysis of Renewable Isoprene from Biomass via Mesaconic Acid

Combined fermentation and thermocatalytic conversion of biomass to isoprene comprises a hybrid process to provide the key monomer in the manufacturing of renewable synthetic rubber. In this work, design and economic evaluation of a chemical process considers the three-step process chemistry: (a) fermentation of glucose to either mesaconic or itaconic acid, (b) catalytic hydrodeoxygenation of mesaconic or itaconic acid to 3-methyl-tetrahydrofuran, and (c) catalytic dehydra-decyclization of 3-methyl-tetrahydrofuran to isoprene. Detailed reaction and separation systems were designed to maximize catalytic yield to isoprene and recover it with high purity. An economic sensitivity analysis identified hydrodeoxygenation and dehydra-decyclization catalytic selectivity as the critical opportunities for improving process economics. The process based on existing catalytic performance achieves a minimum sale price of isoprene (defined as the price which results in a project net present value of zero) of $4.07 kg(-1) ($1.85 lb(m)(-1)) at a scale of 100,000 t yr(-1) of mesaconic acid purchased at $1.00 kg(-1). Six process enhancements based on improved future catalytic technology are considered, with several scenarios achieving a minimum sale price of isoprene below $2.50 kg(-1) ($1.13 lb(m)(-1)).