Glacial acetic acid production from biomass: separation/distillation techno economic comparison

Current commercial production of glacial acetic acid is exclusively by petrochemical routes with a current market price of $550-850/ton. Acetic acid is an intermediate for the production of plastics, textiles, dyes, paints and acetate deicers. Production of acetic acid from biomass might be a sustainable and economically feasible alternative to petroleum derived routes. However, when producing pure acid from biomass, conventional liquid liquid extraction (LLE) using ethyl acetate for acetic acid purification is a major expense, and requires considerable energy.

The purpose of this study is to evaluate and compare technical and economic feasibility of glacial acetic acid production using ethyl acetate and a tertiary amine (Alamine) in kerosene as organic solvents for LLE purification. To meet large energy requirement for the processes, different energy sources including combustion of natural gas, and lignin supplemented with natural gas were investigated. Aspen Plus software was used to simulate a biorefinery processing 250,000 tons/yr poplar, producing 136,600 tons/yr of glacial acetic acid. Capital and operating expenses for each configuration and profitability using discounted cash flow analysis to establish minimum selling prices (MSP) were used to assess economic viability.

Techno economics estimated the CAPEX ranged from $180.7 to $241 MM. On average the CAPEX was 21% lower when natural gas was used a source of energy for both LLE solvents. When Alamine was used as organic solvent, 50% less energy was required for acetic acid purification. The acetic acid MSPs of $649 and $563 were estimated for ethyl acetate and Alamine LLE respectively.