Effect of precipitating agents on activity of co-precipitated Cu–MgO catalysts towards selective furfural hydrogenation and cyclohexanol dehydrogenation reactions

Abstract

The major industrial application and study of hydrogenation of furfural-to-furfural alcohol and dehydrogenation of cyclohexanol to cyclohexanone, over different precipitating agents namely K2CO3, Na2CO3, KOH, NH3 and (COOH)2.2H2O was carried out in vapour phase reactor. Efforts were made to study the effect of these different precipitating agents on Cu–MgO catalyst and its activity towards the hydrogenation and dehydrogenation reactions due to its industrial applications. The prepared co-precipitated Cu–MgO catalysts were characterized by using various modern analytical and spectroscopic techniques which include FE-SEM, BET, XRD, XPS, TPR and DTA. The characterization data revealed that different precipitating agents strongly influenced the physiochemical properties of the developed heterogeneous catalysts. Additionally, FE-SEM images revealed that employing different precipitating agents resulted in various morphologies for the final catalysts. The hydrogenation and dehydrogenation reactions over the Cu–MgO catalyst revealed that the catalyst prepared by K2CO3 as precipitating agent exhibited high catalytic activity. Meanwhile, The presence of more Cuo/Cu+ species on this catalyst with smaller Cu crystallite size as evidenced by XPS and XRD results seems to be accountable for its high activity towards the formation of furfural alcohol and cyclohexanone compared to the other catalysts with different precipitating agents. Additionally, the time on stream (T.O.S) studies performed and it revealed that the catalyst was fairly stable for 300 min showing consistency in its activity towards both reactions. The yield obtained for furfural alcohol and cyclohexanone was 97% and 64%, respectively.