An Efficient, Selective Process for the Conversion of Glycerol to Propylene Glycol Using Fixed Bed Raney Copper Catalysts

Propylene glycol is formed in yields of up to 95% at 100% conversion using a Raney Cu catalyst in a fixed bed reactor. The reaction uses an 80% aqueous glycerol solution and a hydrogen pressure of 600 psi. The primary byproduct is ethylene glycol formed in 1–3% yield. In a reaction run continuously for 24 d using a sample of a commercial preparation of Raney Cu, the selectivity to propylene glycol at 100% glycerol conversion was 94.6% with a space–time yield (STY) of 0.49 g of 1,2-propylene glycol/mL Raney Cu/h. Ethylene glycol was formed in 2.5% yield, while methanol, ethanol, n -propanol 1,3-propylene glycol, and acetol were present in less than 1% yield.