Catalysis Today, Vol.183, No.1, 65-71, 2012
Improved performance of magnetically recoverable Ce-promoted Ni/Al2O3 catalysts for aqueous-phase hydrogenolysis of sorbitol to glycols
The addition of cerium into Ni/Al2O3 catalysts afforded a remarkable promoting effect on catalytic performance of aqueous-phase hydrogenolysis of sorbitol to produce glycols (e. g., 1,2-propylene glycol and ethylene glycol). This effect was observed whether the catalysts were prepared through deposition-precipitation (DP) or co-precipitation (CP) methods. However, the Ce-Ni/Al2O3-DP catalyst went through rapid deactivation during the consecutive recycles. The Ce-Ni/Al2O3-CP catalyst was recovered easily by magnetic separation and reused over ten times. At a temperature of 513 K and pressure of 7.0 MPa, the Ce-Ni/Al2O3-CP catalyst maintained sorbitol conversion at above 90% and selectivity to glycols at 55-60% for 12 h. Characteristic studies indicate that the addition of cerium to the Ni/Al2O3 catalysts slightly lowered the reduction temperature of nickel oxide but considerably enhanced the H-2-chemisorption amount. Furthermore, the co-precipitation method was conducive for preparing the catalyst with high thermal stability, which was shown by 20% Ni/Al2O3-CP being more stable in structure than 20% Ni/Al2O3-DP under higher temperatures. The catalyst deactivation was due to the agglomeration of Ni nanoparticles during hydrogenolysis process in aqueous-phase. (C) 2011 Elsevier B. V. All rights reserved.