Session: General Catalysis:

The bioethanol industry has seen a decline in profitability owing to overproduction of ethanol and suppressed demand for transportation fuel. Production of higher priced derivatives like acetaldehyde from ethanol can provide a viable solution to this problem. Commercial silver catalyzed acetaldehyde production from ethanol suffers from drawbacks like low selectivity, very high operating temperature and low single pass conversions. Enzymatic ethanol conversion to acetaldehyde, catalyzed by NAD dependent alcohol dehydrogenase from Saccharomyces cerevisiae (ScADH) offers high selectivity and high catalytic activity at room temperature. For an economical process, the expensive NAD cofactor, which is reduced during the reaction, must be regenerated. In a single enzyme cascade process inexpensive butyraldehyde may be reduced to butanol while NADH is oxidized to NAD+.The catalytic activity of ScADH has been characterized at pH ranging from pH 7.0 to pH 9.0 and at concentrations up to 1M ethanol, a concentration expected for cellulosic ethanol biorefineries.The high relative volatility of acetaldehyde (b.p.= 21 °C) versus ethanol (b.p.= 78 °C) is expected to facilitate separations and will be discussed in the context of current technoeconomic modeling.

Victor K Sharma

Graduate Research Assistant, The University of Kansas

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