A Novel Process for Synthesis of Benzaldehyde in Near-critical Water

A novel process for synthesis of benzaldehyde in near-critical water (NCW) without using any catalyst was proposed. The experiments show that, without the help of catalyst, the cinnamaldehyde can be hydrolyzed to form benzaldehyde in the NCW. During the hydrolysis, the product yield first increases and then declines with the residence time of the reaction, and as the temperature increases, the reaction rate undergoes a dramatic increase, which results in shorter the reaction time for obtaining the maximum product yield. Over 57.0%(mole) yield of benzaldehyde could be reached under the optimized conditions of 280℃, 15 MPa and 6h residence time. The kinetics of non-catalyzed hydrolysis of cinnamaldehyde in water at 15 MPa and temperature from 249℃ to 320℃ was investigated and the activation energy evaluated from the Arrhenius equation is 59.8 kJ·mol-1. Without introducing any other reagents in the reaction, the proposed novel process for synthesis of benzaldehyde in NCW offers not only an environmentally friendly, but also well conserved natural properties for benzaldehyde.