Nanoscale catalyst converts syngas to ethanol

By Ryan C. Christiansen
Web exclusive posted August 15, 2008 at 10:40 a.m. CST

Researchers from the U.S. DOE's Ames Laboratory and Iowa State University are using nanoscale porous catalysts to ferment gasified waste into ethanol. The scientists hope to be able to use the technology to create ethanol from a wide range of biomass, including corn stover, grass, wood pulp, as well as animal and municipal waste.

Using an oxygen-controlled, high-temperature and high-pressure gasification process developed by the university's Center for Sustainable Environmental Technologies, researchers are converting carbon-based feedstocks into synthesis gas, which is made up primarily of carbon monoxide and hydrogen with smaller quantities of carbon dioxide and methane.

The scientists then use nanoscale metal alloy catalyst particles dispersed widely within the structure of meso-porous nano-spheres which can be described as tiny sponge-like balls with thousands of channels running through them to produce ethanol. The nano-spheres increase the amount of surface area for the catalyst, allowing the catalyst to activate more carbon monoxide molecules and increasing ethanol yields from the process. The metal alloy that the researchers are using remains confidential, said Victor Lin, Ames Lab chemist and ISU Chemical and Biological Science Program director.

Lin said the research has been ongoing for two years. Within the next six months the scientists plan to construct a pilot-scale reactor.

"The ideal scenario will be sometime at the end of this year, we will have results at the [pilot-scale] level," Lin said, "and then we can actually decide how we will transfer this technology to either industries or find some way to commercialize this technology."

The current project is being funded by the DOE's Offices of Basic Energy Sciences and Energy Efficiency and Renewable Energy. Lin said the laboratory is building upon investigations that were completed in the 1970s and 1980s. "The problem was that catalysis technology at that time didn't allow selectivity in the byproducts," he said. "They could produce ethanol, but you'd also get methane, aldehydes and a number of other undesirable products."

Lin said when the current researchers started looking at the technology, there was some kind of theoretical investigation and experimental data out there in the literature suggesting that you need for the catalyst to behave in a certain way. "My group is interested in designing a new kind of nano-porous material and this kind of material has a very huge surface area," he said. "If you can take advantage of this huge surface area, you can jam-pack a lot of these catalytic species into very small volume. Per-unit volume, you can achieve a lot of catalytic events." The next stage of the research will include identifying which biomass source can be used with the catalyst to produce the most ethanol per reaction, he said.

Lin said the laboratory at ISU is very focused on renewable energy solutions. "We're in Iowa, it's an agricultural state, and we're surrounded by these cornfields and soybean fields," he said. "This kind of bio-renewable energy has always been a focus here."