In situ hydrogenation of phenol using sodium formate in an aqueous medium on unmodified palladium catalysts supported on KIT-5: Investigation of calcination temperature effect

Abstract

In this research, in situ hydrogenation of phenol to cyclohexanone and cyclohexanol mixture (KA oil) in aqueous medium using sodium formate as the hydrogen source is studied by using Pd catalysts supported on mesoporous KIT-5. The effect of calcination temprature of catalysts as well as reaction temperature, time, catalyst types, the amount of initial phenol and sodium formate, which are the most effective factors for phenol conversion, were investigated and the optimum values are reported. The Pd10%@KIT-5/350 catalyst (calcined at 350°C) exhibited as the most effective catalyst. Using this catalyst, the best results were gained at 40°C and a reaction time of 6 h, the optimal ratio of phenol: catalyst 0.1:0.05 with 0.5 g sodium formate. Under these conditions, 99% phenol conversion was obtained. Pd10%@KIT-5/350 as the most effective catalyst was successfully regenerated by centrifugation and filtration after reaction and reused in four consecutive cycles. The results showed that the calcination temperature in the preparation of Pd@KIT-5 catalysts has an important role in the hydrogenation reaction of phenol. The studies in this research showed that the higher the calcination temperature, the lower the percentage of phenol conversion, but the selectivity of the catalyst for the production of cyclohexanone increases.