PNNL develops one-step cellulose-to-HMF conversion

Posted June 10, 2009, at 5:20 p.m. CST

Scientists with the U.S. DOE's Pacific Northwest National Laboratory have discovered a way to convert cellulose to 5-hydroxymethylfurfural (HMF) in one step using ionic liquid and chloride catalysts under low temperatures.

HMF is an important component of biofuels, plastics and other materials. The team has researched the process for about three years and discovered that copper and chromium chlorides dissolved in the ionic solvent (1-ethyl-3-methylimidazolium chloride) at temperatures of 80 to 120 degrees Celsius (176 to 248 degrees Fahrenheit) breaks down the cellulose much faster and without many of the unwanted byproducts usually associated with the conversion. PNNL's process is 10 times faster than using acid and does not require mineral acid known to degrade the HMF, according to PNNL.

The team recovered more than 90 percent of the HMF formed, which was 96 percent pure, and discovered that it could consistently achieve a high yield, as the method converted about 57 percent of the sugar content in the cellulose feedstock. In addition, the ionic liquid and chlorides can be reused without losing effectiveness.

"I think it's an exciting development," said PNNL scientist David King, who presented the team's findings at the North American Meeting of the Catalysis Society Wednesday in San Francisco. "It all snowballs. That's the process. It raises the bar and attention spans of people. They want to learn more about it."

The team still has some research to do, but hopes to license its discovery. "We know what works so far, but we don't completely know how," King said, adding that studying the fundamentals of the chemistry involved is crucial. The team has been working with purified cellulose thus far. "That's another thing to investigate," he said. "One would have to look to less pure cellulose."

King and his team hope to eventually commercialize their method, which he says could impact the biofuels industry.