Methods, processes and systems for using solid catalysts to simultaneously produce lactic acid and propylene glycol from glycerol are provide, as are methods, processes and systems of converting glycerol use heterogeneous catalytic agents. Different combinations of catalysts and reaction conditions provide tunable ranges for the yields of lactic acid and propylene glycol. The conversion methods, processes and systems are not reliant on external hydrogen. Applications to crude glycerol, including that co-produced during biodiesel production, are also described.