(138a) Synthesis of 2-Acetoxy Propanoic Acid Via Reactive Distillation – an Intermediate in Synthesis of Biobased Acrylic Acid From Lactic Acid

The selective formation of 2-acetoxypropanoic acid (2-APA) by reaction of lactic acid with acetic acid has been carried out in continuous reactive distillation.  The reaction takes place in a six-meter tall, 50 mm ID Pyrex column operated at atmospheric pressure and is catalyzed by Amberlyst-15 cation exchange resin supported in Katapak-SP11 structured packing in the middle four meters of the column.  Lactic acid solutions in water were used as feedstock in the experimental study which was reacted with glacial acetic acid in the reactive distillation column.  High conversions of lactic acid and its oligomers were achieved along with high selectivity to monomeric 2-APA. Experimental studies are complemented by process analysis using AspenPlus simulation software.  By implementing a kinetic model and phase equilibrium data generated in our laboratories, we are able to predict the observed pilot-scale column behavior and simulate commercial-scale facilities.

The formation of 2-APA represents the first step of a process to produce acrylic acid from lactic acid.  In the second step of the process, 2-APA is cracked under high temperature to form acrylic acid and liberate acetic acid that can be recycled.  

Acrylic acid, its esters, and acrylate polymers are critical chemical building blocks used in a wide gamut of applications including superabsorbents, hard plastics, paints, detergents, and adhesives. The global acrylic acid market is estimated at 3.5 million tons and $8 billion annually, with a growth of 4% per year.  Acrylic acid synthesized from biobased lactic acid is a drop-in replacement for the petroleum-based product; lactic acid is a mature biobased feed stock with a proven track record of high yield (>95%) from glucose and low cost.