Kinetic study of glycerol oxidation network over Pt–Bi/C catalyst

Identifying new uses for glycerol, a waste of biodiesel production from transesterification of vegetable oils, is of great current interest. Towards this end, catalytic oxidation of glycerol to produce the high-value chemical dihydroxyacetone (DHA) is a promising approach. The challenge, however, is the relatively complex reaction network. The kinetics of the complete glycerol oxidation network over Pt–Bi/C catalyst was investigated systematically in this study. Based on a detailed reaction mechanism including adsorption/desorption and reaction steps on the catalyst surface, a kinetic model was developed. To overcome the difficulty in finding the global optimum in the model, the full complex network was decomposed into five progressively larger sub-networks with different intermediates as initial reactants. The corresponding reactions starting with these initial reactants were conducted and the collected data were used to fit the kinetic model for each sub-network. The experimental and calculated results were in good agreement and the kinetic parameters for each step were obtained. These results can be used to design and develop new appropriate catalysts with high stability, activity and selectivity for DHA. In fact, this approach is a powerful tool for the microkinetic study of other complex reaction networks as well. Based on the concentration of each component and rate expression of each reaction step, a simplified network was identified and studied. The parameters thus obtained can be used to develop reactor models which could be used to determine the optimum operating reaction conditions for maximizing the yield of desired product DHA. The effective conversion of glycerol to high value chemical will increase the profitability of biodiesel production, a promising renewable energy source.

The kinetics of glycerol oxidation network over Pt–Bi/C catalyst was investigated systematically by performing studies for five progressively enlarging sub-networks. The obtained insights provide suggestions for the development of superior catalysts and the obtained kinetic parameters will be used to develop a continuous-flow reactor model for process design and optimization of DHA yield.Figure optionsDownload as PowerPoint slideHighlights
► Glycerol oxidation network involves 10 steps and 9 species.
► Kinetic study was performed individually for 5 progressively enlarging subnetworks.
► All kinetic parameters associated with the 10 steps were determined.
► Tartronic acid has strong adsorption on Pt active sites.
► A 4-step simplified network represents the complex reaction network well.