Integrated syngas biorefinery for manufacturing ethylene, acetic acid and vinyl acetate

The paper presents the design of an innovative process for manufacturing sustainable biochemicals, as acetic acid, ethylene and vinyl acetate monomer (VAM), in an integrated syngas biorefinery using renewable feedstock as biomethane and captured CO₂. The work is supported by full design and simulation of six plants imbedded in a large process: syngas1H₂/CO 2:1 by catalytic partial oxidation of methane, syngas2 H₂/CO 1:1 by dry methane reforming, methanol, acetic acid by carbonylation, ethylene and vinyl acetate. A key contribution is the development of a novel acetic-acid-to-ethylene process starting from syngas. This consists of catalytic hydrogenation of acetic acid (exothermic) followed by catalytic ethanol dehydration (endothermic). The thermal integration of reactors leads to low energy process and superior sustainability measures versus petrochemical and methanol-to-olefin processes. The comprehensive simulation of the integrated biorefinery allows getting consistent mass and energy balances, performing energy analysis and capital cost estimation, and finally delivering reliable sustainability measures. Based on syngas the carbon-yield, mass-yield, carbon footprint (kg CO₂/kg product) and energetic requirement (MJ/kg) are 78.6 %, 34.7 %, 1.6 % and 11.2 % for ethylene, and 80.8 %, 46.8 %, 1.5 % and 11.9 % for VAM. At high biomethane price the ethylene may be costly but manufacturing the higher value VAM is fully profitable.