Glycerol Hydrogenation Over Pt-based Catalyst Modified With Metal Promoter

At present,advances in the biodiesel industry have resulted in the production of large amounts of glycerol as a byproduct.How efficient and reasonable use of this part of the glycerol,will help the whole biological industry to achieve high benefit,low energy consumption,low pollution of benign development.Propylene glycol(1,2-propanediol,1,3-propanediol)is a key intermediate for the production of?-caprolactam,which widely used in organic synthesis,pharmaceutical,medicine and other fields.Among them,the most important purpose of 1,3-propanediol is used for synthesis of polytrimethylene terephthalate(PTT),which is an important raw material.Choosing glycerol as raw materials and using efficient catalysts to produce 1,3-propanediol receive much concern of the researchers.In the paper,hydrogenolysis of glycerol to produce 1,3-propanediol in the one-pot implements the high selectivity,high conversion rate l,3-propanediol production.Noble metal Pt/WO./AC and catalysts which were modified by promoter were prepared and applied in glycerol hydrogenation.In the paper,we used GC to detect the amount of main products and by-products.We choose 1,4-butanediol and N-butyl alcohol as internal standard.The conditions of chromatographic analysis for hydrogenation of glycerol were determined.The PtAVOx/AC catalysts were prepared by an impregnation method,which applied them to the glycerol selective hydrogenation process.Different platinum catalyst?different active carbons and different Pt loading on glycerol hydrogenation.We found wooden activated carbon loaded with Pt loading of 2%showed better catalytic performance.Over those catalysts the conversion of raw material glycerol 54.2%,and the target product of 1,3-propanediol selectivity at 37.6%.Then we optimized the process conditions using 2%Pt/WOx/AC catalyst,finally we found the optimal conditions:reation pressure at 3.5MPa,reaction temperature at 200 ?,reaction time at 6h and the amount of catalyst at 0.1g.To improve the yield of 1,3-propanediol,we tried to add some promoters such as La?Al?Fe to modified Pt/WOx/AC.Modified with additives of some promoters Pt/WOx/AC catalysts.This paper examined the impact of different promoters,different promoter loading and reduction temperature,on glycerol hydrogenation.And through the following characterization:XRD,TEM,XPS and H2-TPR found that between promoters and active component have the good synergy.Then we found that promoters made lower reduction temperature of the active component,which contributed to the reduction of active components,and a certain extent may increase the specific surface area of the active component of metal platinum.Among them,1%Fe-2%Pt/WOx/AC catalytic glycerin hydrogenation,which gained 1,3-propanediol selectivity increased from 37.6%to 40.1%.1%La-2%Pt/WOx/AC catalytic glycerin hydrogenation,which the conversion of glycerol was 54.2%increased to 60.2%,and 1,3-propanediol selectivity increased from 37.6% to 41.7% too.