In New York state, a research team led by William Jones at the University of Rochester has developed a series of reactions that results in the selective conversion of ethanol to butanol, without producing unwanted byproducts.
Jones was able to increase the amount of ethanol converted to butanol by almost 25 percent over currently used methods. Jones describes his process in a paper just published in the Journal of the American Chemical Society.
One method of converting the ethanol to butanol is the three-step Guerbet reaction, which involves temporarily giving up hydrogen atoms in an intermediate step, then adding them back in to create the final product. One problem with the Guerbet reaction is that an intermediate product—acetaldehyde—can react with both itself and the butanol product to create unwanted molecules.
Jones modified the Guerbet reaction by using iridium as the initial catalyst and nickel or copper hydroxide, instead of potassium hydroxide (KOH), in the second step. While the best current conditions for the Guerbet reaction convert ethanol to butanol with about 80% selectivity, Jones’ reaction produced butanol in more than 99 percent selectivity. No undesirable side products are produced.
Jones says the process currently terminates after one day because one or more of the substances—the iridium, nickel, and copper—has broken down.