Thermodynamic analysis of glycerol conversion to olefins

Thermodynamic equilibrium analysis of glycerol steam reforming to light olefins has been investigated based on the total Gibbs free energy minimization method. Equilibrium product compositions for glycerol steam reforming were determined according to the following range: temperature, 573-1273 K; GWR (glycerol/water ratio), 1:12 - 2:1 and pressure, 1-12 bars. Analysis of the feasible reactions revealed hydrogen as the main product followed by carbon monoxide, methane and ethane. The equilibrium analysis indicated light olefins formation was not spontaneous. The amount of ethylene produced was very small, but improved at higher pressure and temperature between 873-1023K. Coking was also dependent on GWR and temperature. From Gibbs analysis, light olefin formation at equilibrium is thermodynamically not feasible, but experimental work involving catalyst proved that ethylene selectivity could be improved in a heterogeneous reaction.