Cellulosic Propylene Glycol Production

By: Katie Schaefer, C&T magazine

Posted: September 29, 2010, from the October 2010 issue of Cosmetics & Toiletries.

Scientists continue to source different forms of biomass—i.e., plant material and animal waste—to produce renewable energy and alternative fuels. For example, biomass from corn is currently converted to glucose, then converted to fuel. Researchers would like to employ cellulose in this process since it is found in most plants but to do so becomes more challenging according to Walter Trahanovsky, PhD, a professor at Iowa State University’s department of chemistry, who may have discovered just how to do it. Trahanovsky developed a method to convert cellulose to glucose using pressure and high temperatures, but he was surprised to find the method also produced ethylene glycol and propylene glycol—two high value chemicals, one a major component in skin care products.

Cellulosic Ethanol Production

The two polymers of the monosaccharide glucose are cellulose, and while it is somewhat easier to convert starch to glucose, as is the case with corn, it is more difficult to do so with cellulose. Trahanovsky noted that glucose is already being produced from cellulose but via processes using enzymes or acids, which pose challenges.

“In making cellulosic ethanol, the procedures that use enzymes or acids to produce glucose from cellulose are expensive, or they do not produce the purity of glucose needed,” said Trahanovsky. “If someone is going to use glucose for the production of ethanol, there cannot be impurities because they will inhibit the enzyme reaction.”

As a first step toward converting cellulose to glucose, Trahanovsky’s team investigated cellulose from a number of plant sources. “We’ve used wood chips but the yields are not as good because about 30% lignin is present,” explained Trahanovsky. He added that his team tried using paper before deciding to purchase pure cellulose samples and optimize the production of cellulose from plant materials at a later time.

Trahanovsky and his team combined the cellulose sample with alcohols, which form a supercritical fluid when heated and applied with pressure. This combination was then heated to about 300°C with 150 atmospheres of pressure, and although Trahanovsky could not disclose which specific alcohols were used, he noted that nearly all the alcohol was accounted for at the end.

Separation Anxiety