Glycerol hydrogenolysis using a Ni/Ce-Mg catalyst for improved ethanol and 1,2-propanediol selectivities

Glycerol, a byproduct from biodiesel production, is an inexpensive and renewable alternative feedstock for producing valuable chemicals. Hydrogenolysis of glycerol produces ethanol and 1,2-propanediol (1,2-PDO) with the help of appropriate catalysts. Commercially available non-specific Ni-based catalysts have been reported for use in producing ethanol along with 1,2-PDO. In this work, a new Ni catalyst on various support materials was developed for the selective production of ethanol and 1,2-PDO using glycerol hydrogenolysis. The Ni catalyst on CeO2 showed the highest potential for producing both ethanol and 1,2-PDO. The catalyst with 0.15-0.50g/g (15-50wt%) Ni on CeO2 improved glycerol conversion at reaction temperatures of 215-245 degrees C, however 1,2-PDO selectivity was unsatisfactory. An improvement in 1,2-PDO selectivity was attained when Al, Si, Zn, and/or Mg were added as promoters to the Ni catalyst on CeO2, while improvement in the selectivity for ethanol occurred only with the addition of Si or Mg. A variation in Mg content showed that 1,2-PDO selectivity was favoured at higher Mg content, while ethanol selectivity peaked at 10% Mg. Systematic investigations found that the catalyst with 0.25g/g (25wt%) Ni on a Ce:Mg (4:1mol:mol) support provided good selectivities for 1,2-PDO at 68.10% and ethanol at 9.0%, respectively.