Biobased acrylic acid production in a sugarcane biorefinery: A techno-economic assessment using lactic acid, 3-hydroxypropionic acid and glycerol as intermediates
Mensah S. Brobbey, Jeanne Louw, Johann F. Görgens
Abstract
Acrylic acid (AA) is a versatile platform chemical of immense global demand. Today, the biorefinery is among the most promising initiatives of sustainably producing this commodity from bio-derived precursors. This study evaluated the economic and environmental performance of three production pathways to biobased acrylic acid using sugarcane A-molasses as feedstock. The 3 intermediates were lactic acid (LA), 3-hydroxypropionic acid (3-HP) and glycerol. Production scenarios were simulated in Aspen Plus ® software and resultant mass and energy flows provided inputs for subsequent estimation of the minimum selling price (MSP) and greenhouse gas (GHG) emissions. The MSP in US$/kgAA and the net GHG in kgCO2/kgAA were the key metrics against which the performance of the developed scenarios were compared. Accordingly, the scenario using LA as intermediate emerged superior with an MSP that was 11 % higher than the actual market price for fossil-based AA. The same had an estimated net GHG emissions of 4.4 kgCO2/kgAA. 3-HP was the second best performing intermediate with an MSP of 2425 US t-1 and green premium of 30 %. The 3-HP pathway, however, had a fairly low yield at fermentation of about 0.51 g LA/g glucose compared to the 1 g LA/gram glucose recorded by the LA pathway. Ultimately, glycerol proved to be an unattractive intermediate owing to a dismal product yield (0.50 g GLY/g glucose) as well as the cost and complexity of glycol recovery from the fermentation soup.