垃圾+奈米科技+氣化技術=乙醇

A method of making potentially cheap ethanol fuel out of garbage and other waste materials by deploying a combination of modern and old technologies is under development by government and university researchers.

The process involves the use of nanotechnology and gasification to convert carbon-based materials into a product called synthesis gas, or syngas, which in turn can be made into ethanol.

Developing new ways of producing biofuels such as ethanol is urgent business as the country and world scout for alternatives to fossil fuels. For now, ethanol is made chiefly by fermenting corn, diverting the valuable commodity from serving as food for people and livestock.

"The great thing about using syngas to produce ethanol is that it expands the kinds of materials that can be converted into fuels," said Victor Lin, director of the Chemical and Biological Science Program at the U.S. Department of Energy's Ames Laboratory."

Ames scientists, working with colleagues at Iowa State University, are employing gasification to make syngas. To make the gas, they subject carbon-based feedstocks to high temperature and pressure in an oxygen-controlled atmosphere.

Syngas is composed mainly of carbon monoxide and hydrogen, along with a smaller amount of carbon dioxide and methane, according to the lab.

Gasification is not a new technology but has been around since the 1800s, when it was used to extract gas from coal to produce fuel for lighting and cooking.

The attempt to turn syngas into ethanol also is not new. Scientists have been researching the process for 90 years, according to a study published in January in "Energy & Fuels," a journal of the American Chemical Society. "There was some interest in converting syngas into ethanol during the first oil crisis back in the ?0s," Lin said, but there was a problem. "They could produce ethanol, but you'd also get methane, aldehydes and a number of other undesirable products."

The fault lay with the catalysts, materials that promote and speed chemical reactions without themselves being changed.

Lin and his colleagues hit upon using as catalysts invisibly small nanoparticles of a metal alloy.

The nanoscale is almost inconceivably small. A nanometer - one billionth of a meter - is about the size of 10 hydrogen or five silicon atoms, and the width of a human hair is about 80,000 nanometers.

Ames Laboratory describes the catalyst nanoscale particles as having thousands of channels running through them, which increases the amount of catalytic surface area 100-fold over ordinary-sized catalysts.
While nanotechnology offers a solution to the catalyst problem, gasification is another technology that is required to produce ethanol from garbage.

Private industry is chasing the syngas-to-ethanol goal, as well, and employing gasification to do it.

The company Coskata Inc., in partnership with General Motors, is building a $25 million demonstration plant near Pittsburgh, Pennsylvania, where it plans to make ethanol from woody biomass, and farm and industrial wastes. The company's goal is to produce ethanol from non-food-based sources for less than $1 a gallon.

CSET director Robert Brown says, "Gasification to ethanol has received increasing attention as an attractive approach to reaching the federal Renewable Fuel Standard of 36 gallons of biofuel."