Study on the Toluene Oxidation to Benzaldehyde in Subcritical Water

The toluene was oxidized to benzaldehyde in subcritical water by using hydrogen peroxide and without any catalysts. The chemical technology of toluene oxidization to benzaldehyde in subcritical water was studied and the effect of reaction parameters (reaction temperature, reaction time, molar ratio of hydrogen peroxide to toluene) on yield of benzaldehyde in subcritical water was also investigated. The experiment results show that the optimum operation parameters for toluene oxidization to benzaldehyde in subcritical water are: reaction time 60 min, reaction temperature 350°C, molar ratio of hydrogen peroxide to toluene 3.5. Under the optimum condition, the yield of benzaldehyde could reach 17.4%. The experiment results also show that if the molar ratio of hydrogen peroxide to toluene is controlled in a reasonable range, the by-products could be reduced obviously. When the molar ratio of hydrogen peroxide to toluene is less than 2.2 , the amount of phenol and p-cresol produced in reaction may be negligible. This technology adopting water as reaction solvent and without using any catalyst is an environmental friendly technology.