(49f) Kinetic Modeling of Tandem Hydrogenolysis/Reforming of Glycerol to 1,2-Propanediol with In Situ Formed Hydrogen In a Batch Slurry Reactor

Glycerol is viewed as an important feedstock due to its availability in large quantities, as a byproduct during biodiesel production and possible production from sugar derived polyols. The efficient conversion of glycerol into higher value added chemicals, such as 1,2-propanediol, ethylene glycol and lactic acid is necessary to achieve the economic viability of such processes. When using a supported bimetallic Pt-Ru catalyst, this reaction system offers the possibility of generating hydrogen in situ instead of providing it from an external costly source, greatly improving the economics of the process. Furthermore, since the reaction can run at milder conditions compared to traditional hydrogenolysis with externally added hydrogen at high pressures, it improves the inherent safety of the process. This tandem approach has been recently demonstrated in our group (Roy et al., Catalysis Today 156 (2010) 31–37) for glycerol to 1,2-propanediol using admixture of supported Ru and Pt catalysts. In this presentation, a detailed kinetic model of this reforming/hydrogenolysis reaction using supported bimetallic Pt-Ru catalyst will be addressed. We build on our previous efforts (Torres et al., I&EC Research, 49 (2010) 10826–10835) by including several additional reaction pathways discerned by performing experiments with selected intermediate products such as 1,2-propanediol, ethylene glycol, methanol, syngas, among others. The experiments were carried out in a batch slurry reactor, using a 2%Pt-2%Ru/C catalyst, in which both gas and liquid phase product distribution was measured. The effects of different glycerol concentrations, pressure, and catalyst loading over a temperature range of 453-493 K were studied. A detailed analysis of mechanistic Langmuir Hinshelwood type kinetic models following a rigorous model discrimination procedure will be presented along with statistical analysis of the model parameters. This study is useful in understanding the mechanism of the reactions involved in hydrogenolysis of polyols in general, as well as the modeling and scale up of slurry and fixed bed reactors.