Revisiting Classic Acetic Acid Synthesis: Optimal Hydrogen Consumption and Carbon Dioxide Utilization

Abstract Acetic acid is a bulk chemical with many applications in the manufacture of several important products. The carbon footprint of its classic synthesis process (methanol carbonylation) is around 1.3921 - 1.8746 kg CO2-eq/kg, which adds up as the commodity is used in further syntheses. Hence, a reduction in the acetic acid synthesis Global Warming Potential (GWP) would impact in many end products GWP. We propose an acetic acid synthesis superstructure, including different syngas synthesis processes, gas separation technologies and methanol synthesis, which is aimed at reducing both the cost and GWP of the process. Results show that, integrating the methanol synthesis process provides the best results in both objectives. When minimizing the cost (classic synthesis) is best to use an Auto-thermal Reforming (ATR) and CO absorption configuration (0.388 $/kg, 1.832 kgCO2-eq/kg). Adding a fuel cell and a Reverse Water Gas Shift (RWGS) reactor overall reduces both cost and emission (0.280 $/kg, 1.590 kgCO2-eq/kg) of the synthesis and changes the configuration to Partial Oxidation (POX) and cryogenic distillation. Minimum emission (0.102 kgCO2-eq/kg) can also be achieved with the fuel cell plus RWGS combo, POX and Pressure Swing Adsorption (PSA), although the cost is almost tripled (0.978 $/kg).