Hydrogenation of methyl benzoate to benzaldehyde over manganese oxide catalysts prepared from Mg/Mn/Al hydrotalcite-like compounds

Abstract

Mn–Al and Mg–Mn–Al hydrotalcite-like compounds (HTlcs) were synthesized by a coprecipitation method. The activity of the calcined HTlcs for hydrogenation of methyl benzoate to benzaldehyde was tested. The effects of Mn/Al and Mg/Mn ratio, preparation and reaction conditions, and potassium promoter on the catalytic performance of the catalysts were investigated. The prepared catalysts give better performance than conventional 10% Mn/ γ-Al 2O 3 catalyst. The conversion of methyl benzoate and selectivity to benzaldehyde on 3% K/Mg 0.2Mn 1.8Al 1 catalyst at 390 °C are 90.0 and 88.0%, respectively. XRD, TPR and CO 2-TPD studies show that the redox and basic properties of the catalysts play important roles in the reaction. A suitable degree of reduction and a small number of basic sites on the catalyst lead to a high activity and selectivity to benzaldehyde.