反应详情

It is known that acetaldehyde is obtained with a yield of 26% in the dehydration of glycerol in supercritical water at 500° C. and 34.5 MPa and with a residence time of 90 s [Ant1985]. A free radical mechanism by dehydration of the glycerol to 3-hydroxy-propionaldehyde and homolytic cleavage of this intermediate to give acetaldehyde and formaldehyde is assumed for the stated conditions. An alternative mechanism via homolytic cleavage of acetol can be ruled out. The selectivity with respect to acetaldehyde is lower under near-critical water conditions at 360° C. and the same conditions. Addition of sodium hydrogen sulphate as acidic catalyst merely leads to an increase in the yield of acrolein, which presumably results from the acid-catalysed dehydration of 3-hydroxypropionaldehyde.

1. customwith a residence time of 90 s