Catalytic Hydrogenation Of Glycerol To Propanediols

Biodiesel is produced from renewable sources and considered as an attractive alternative fuel,which provides glycerol as a major byproduct.In the biodiesel industry,the valuable by-products which produced from glycerol can play its vital role in the economic sustainability.By the catalytic hydrogenolysis of glycerol,the efficient products which we obtained are 1,2-propanediol(1,2-PDO)and 1,3-Propanediol(1,3-PDO).Though these products can also be produced by other methods,but this one is more efficient.(1,2-PDO)and(1,3-PDO)have many applications in chemical industry such as polyester resins,laundry detergents,polytrimethylene terephthalate and in the pharmaceuticals industry.In this research,catalysts were prepared with Pt,Ru and Ir as an active component and Al2O3,SiO2 as support via vacuum incipient wetness impregnation method.Moreover,then,K,W,Sn,Re were added as promoters with the purpose to improve the catalyst performance.The hydrogenolysis reaction of glycerol was carried out on a continuous fixed bed reactor.Pt-K/Al2O3 was found to give the highest selectivity to 1,2-PDO and 1,3-PDO compared to other catalysts.The impact of the Pt and K were evaluated in the process of hydrogenolysis glycerol.The results suggest that 0.4Pt-20K/Al2O3 gives good catalytic activity and selectivity to 1,2-PDO and 1,3-PDO.The effects of reaction conditions on 0.4Pt-20K/Al2O3 were tested in the temperature range of 150-225 ?,hydrogen pressure range of 10-20 bar,WHSV of 0.25-1.0 h-1,the H2/glycerol range of 30-100 molar ratios.The results showed that the highest selectivity to 1,2-PDO is 89.3%with 70%glycerol conversion,1.13%selectivity to 1,3-PDO under the condition of T = 180 ?,P = 20 bar,H2/glycerol = 30(molar ratio),WHSV = 0.5 h-1.The 0.4Pt-20K/Al2O3 was characterized using powder X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),N2-physical adsorption and temperature programmed Reduction(TPR).XRD results showed that K cluster was fully dispersed on Al2O3 support which helps to enhance the catalyst activity and selectivity.