Bifunctional catalyst enables economically viable production of bio-based acrylates

The prospects for a bio-based route to acrylates (diagram) received a significant boost recently, when startup company Låkril Technologies Corp. (Chicago, Ill.; www.lakril.com) licensed technology from the laboratory of Paul Dauenhauer at the University of Minnesota (Minneapolis, Minn.; twin-cities.umn.edu).

Dauenhauer has invented a catalyst said to be the first in the world capable of generating yields greater than 90% in the dehydration reaction of lactate to acrylate. Previous efforts to catalyze the reaction typically achieve yields of only 50–60% — too low to make the transformation an economically viable alternative to the petroleum-based route to acrylic acid (which is accomplished by the oxidation of propylene).

Låkril has obtained funding to scale up production of the catalyst and further develop the technology for commercial use. The company plans to start commercial production in late 2024.

The catalyst under development is an acidic solid zeolite (aluminosilicate) that has been functionalized with an engineered amine. The rationale for adding functionalization came out of previous mechanistic studies of the dehydration reaction. When lactate comes into contact with zeolite, dehydration or decarbonylation can occur, explains Chris Nicholas, co-founder and president of Låkril. The amine functionalization on the zeolite suppresses side reactions, including the primary one — decarbonylation, he says. The nature of the functionalized catalyst is proprietary, but is proposed to work wherein a base out-competes the weaker oxygenated functional groups on lactate, resulting in a higher coverage of base than lactate on Brønsted acid sites generated during reaction.

A technoeconomic analysis of the lactate dehydration process suggests that by suppressing side reactions and generating higher yields of acylate, the reaction moves into cost parity with the petroleum-based route, while reducing carbon intensity by at least 35%, Nicholas says.

Acrylates are industrially important for a range of products, including superabsorbent polymers in diapers, and as precursors for esters used in fibers, paints, adhesives and other products. With this new catalyst development, making more environmentally benign bio-based acrylates — by fermenting corn sugars into lactic acid, then dehydrating the lactic acid to acrylate — becomes economically attractive.