Mechanism Analysis and Kinetic Modelling of Cu NPs Catalysed Glycerol Conversion into Lactic Acid

Mechanism analysis and kinetic modeling of glycerol conversion into lactic acid in the alkaline media with and without heterogeneous catalyst Cu NPs are reported. The reaction pathways were determined in agreement with the experimental results and comprise several types of reactions, namely dehydrogenation, hydrogenolysis, dehydration and C-C cleavage. Experimental concentration-time profiles were obtained in a slurry batch reactor at different glycerol, NaOH and Cu NPs concentrations in a temperature range of 483-518 K. Power law, Langmuir-Hinshelwood (LH) and Eley-Rideal (ER) models were chosen to fit the experimental data. The proposed reaction pathways and obtained kinetic model adequately describe the experimental data. The reaction over Cu NPs catalyst in the presence of NaOH proceeds with a significantly lower activation barrier (E-a = 81.4 kJ.mol(-1)) compared with the only homogeneous catalytic conversion (E-a = 104.0 kJ.mol(-1)). The activation energy for glycerol hydrogenolysis into 1,2-propanediol on the catalyst surface without adding hydrogen is estimated of 102.0 kJ.mol(-1). The model parameters obtained in this study would be used to scale an industrial unit in a reactor modeling.