Conversion of bio-glycerol to propylene glycol over basic oxides (MgO, La2O3, MgO-La2O3, CaO, and BaO2) supported Cu–Zn bimetallic catalyst: A reaction kinetic study

Abstract

The effect of various basic oxide support (MgO, La2O3, CaO, BaO2) as a catalyst promoter on the performance of Cu–Zn bimetallic catalysts was investigated for selective conversion of glycerol to 1,2-propanediol (1,2-PDO) in an autoclave reactor. Various catalysts developed were characterized by different techniques and the physicochemical properties of the catalysts were correlated with the activity data and compared. Among the basic oxide-supported catalysts, Cu–Zn(4:1)/MgO demonstrated a very high glycerol conversion of 98.7% with a 92.2% yield of 1,2-PDO at 210 °C temperature and 4.5 MPa pressure. It was observed that after the incorporation of La2O3, glycerol conversion reached 100%, and 1,2-PDO yield marginally improved to 93.1%. It has been observed that the acidity/basicity, average crystallite size, H2-consumption, and the degree of reduction of the catalyst played an important role to improve the catalyst activity and 1,2-PDO yield. Further, a Langmuir–Hinshelwood–Hougen–Watson​ (LHHW) model was developed in presence of Cu–Zn(4:1)/MgO-La2O3 catalyst. The numerical solution of the model equation was computed with the help of the ode23 solver in MATLAB combined with a genetic algorithm (GA). Results demonstrated that the experimental concentrations of the reactant and products were very well correlated with the model predicted data. The calculated activation energy and frequency factor for the conversion of glycerol to 1,2-PDO were 69.6 kJ mol−1 and 4.2 × 107 mol gcat−1 h−1, respectively.