Process flowsheet development for bio-ethyl acetate production from sugar mill feedstocks: A techno-economic approach

Ethyl acetate (EA) is an important platform chemical used as an organic solvent, providing a sustainable alternative to fossil fuel-based aromatic compounds. Ten production scenarios were modelled in Aspen Plus ® for a biorefinery annexed to a sugarcane mill, utilising either A-molasses (1G-only) or A-molasses and lignocelluloses (1G2G). The analysis assessed mass and energy balances for equipment sizing, costing, and greenhouse gas emissions (GHG). The discounted cash flow method was applied to evaluate profitability and determine the minimum selling price (MSP) necessary for a 20 % internal rate of return (IRR). In the 1G-only scenarios, the production of EA through catalytic dehydrogenation of ethanol (CDH) combined with solvent extraction followed by distillation (ED) (1 G CDH-ED) resulted in a reduction of specific energy by ca. 11 % (7.60 kWh/kg_EA) compared to pressure swing distillation (PSD) which required 8.40 kWh/kg_EA. This led to a competitive MSP of $1477/t compared to the $1600/t fossil-based price, achieving an 80 % GHG emission reduction (ER) with a revised MSP of $1330/t with a green premium (10 %). However, the 1G2G counterpart resulted in a higher MSP of $2000/t, which remained uncompetitive ($1800/t) despite similar GHG reductions. The 1 G CDH-PSD scenario resulted in an MSP of $1550/t, about 5 % higher than 1 G CDH-ED at $1477/t. The Fischer esterification (FE)-EA pathway using one-step acetic acid (AA) production from 2 G feedstock achieved an MSP of $1995/t and over 80 % GHG reductions but reducing MSP to $1795/t when considering green premium remained uncompetitive. While 2 G feedstock improves sustainability, economic challenges persist at scale. • The 1 G CDH-based scenarios' MSPs were market-competitive. • The 1G-only EA production by CDH using ED was energy efficient compared to a similar PSD process. • In a 1G2G scenario, the one-step AA production from 2 G reduced GHG emissions to 100 % carbon neutrality. • GHG emissions of greater than 80 % were achieved across several scenarios.