This invention consists of a novel composition of matter as well as a process for the efficient conversion of glycerol to lactic acid.
Lactic acid is important for several commodities, such as biodegradable fibers, polylactic acid esters (e.g. biodegradable plastics), and acrylic acid. Nearly 95 percent of worldwide lactic acid production is by fermentation of sugars and sugar alcohols. This fermentation route produces low concentrations of lactic acid (<10 wt%), requires complex multistep separation, and is very slow (4-6 days!).
Hydrothermal conversion of glycerol to lactic acid has been investigated as an alternative to the fermentation route. The advantage of this route is that glycerol from the global biodiesel production process, which contains water and alkali, can be used directly with no need for a separation step. However, the process operates at high temperatures (573 K) near the critical temperature for water. This temperature causes decomposition of key reaction intermediates as well as the lactic acid product. Moreover, the alkaline medium at this high temperature causes severe corrosion to the reactors. As an added concern, either oxygen or hydrogen must be added depending on the system.
An ideal process would operate at lower temperatures, have high selectivity for lactic acid, use cheap and renewable starting materials, and not require an oxidative or reductive environment
To learn more about the technology a published white paper (pdf) is available for download.
The invention is applicable to the materials industry since lactic acid is a sought after component of biodegradable materials.
The invention consists of a new supported metal catalyst and a process for converting glycerol to lactic acid. The invention produces high yields of lactic acid at significantly lower temperatures within 4 - 6 hours, has high selectivity for lactic acid, and does not require an oxidant or reductant.
The metal catalyst has excellent stability under the reaction conditions for prolonged use.
The invention is highly selective for lactic acid and uses a starting material that is readily available.
The catalytic process is extremely efficient and does not require the use of harsh oxidants or reductants. Also, the explosive danger is minimized.
Efficient route to acrylic acid via catalytic dehydration of lactic acid