Chemical News

Tuesday, August 5, 2008

Biomass to Alcohols in Vapor phase

Nonfermentation routes to Ethanol and higher alcohols are under development. Using corn- or sugarcane-based Ethanol as an additive for gasoline or as the major constituent in automotive fuel consumes a major food crop. This issue is especially serious as food prices around the world rise sharply.

To circumvent the “food versus fuel” debate, researchers are racing to develop organisms capable of fermenting the cellulose in biomass. This approach is problematic because it is difficult to develop organisms that can attack cellulose, and it is even more difficult to carry out this fermentation at fast enough rates to make the overall process economical.

An alternative is to gasify the biomass to synthesis gas (a CO–H2 mixture) and convert the syngas to higher (C2+) alcohols. C. Iordache-Canza and K. Smith disclose catalyst formulations that convert syngas to mixtures of MeOH, higher alcohols, and hydrocarbons. Some of these catalysts can produce substantially more C2+ alcohols than MeOH.

In one example, a Pd0.002 Mo0.7 CeZrK0.29 catalyst dry-impregnated on to a silica support was loaded into a tubular reactor. Syngas was passed over the catalyst at 275 °C, 68 atm, and a gaseous hourly space velocity of 5,925 h-1. The selectivity to products was MeOH, 23%; C2+ alcohols, 75%; and hydrocarbons, 2%.

This method can be used with any source of syngas—including natural gas, naphtha, or coal—in addition to biomass.

Source: Syntec Biofuel & USPTO - 7384987