Preparation Of Highly Efficient Metal Catalysts And Their Application In Glycerol Hydrogenolysis

In recent years,the excess of glycerol that caused by the development of biodiesel drives people to develop the new ways of transforming glycerol into the high value-added chemicals.Hydrogenolysis of glycerol is one of the most attractive ways.A series of alcohol compounds can be obtained from hydrogenolysis of glycerol,such as propylene glycol(1,2-propanediol and 1,3-propanediol),ethylene glycol and n-propanol.These alcohol compounds have important application in the pharmaceuticals,industrial solvents and the polyester fiber synthesis.Therefore,the development of glycerol to prepare high value-added chemicals can bring enormous economic benefits.Firstly,the article explored the conversion of glycerol to ethylene glycol catalyzed by ruthenium catalyst.A series of lanthanum modified 2Ru/x%La-ZrO2 catalysts(x% represents the mass fraction of lanthanum in the catalyst)were prepared by deposition-precipitation method and used in the reaction of the glycerol hydrogenolysis.It was found that a small amount of lanthanum modification can significantly improve the catalytic activity and the bonding cleavage ability.Among these modified catalysts,the 2Ru/1.0%La-ZrO2 catalyst had the highest glycerol conversion.Besides,this part of article studied the effect of reaction conditions on hydrogenolysis of glycerol and found that decreasing the reaction time and temperature,increasing the substrate concentration were benefit for the improvement of ethylene glycol.On this basis,after optimization of the reaction conditions,55% selectivity of ethylene glycol can be obtained over the 2Ru/x%La-ZrO2 catalyst.After the characterization,the significant improvement of catalytic activity for the catalysts with small content lanthanum modification was attributed to the increase of acid and alkali sites and the formation of Ru?-particles.At last,the other elements who have the similar properties with lanthanum were used to modified the 2Ru/ZrO2 catalyst.It was found these elements had similar promotion effects with lanthanum,and this promotion was related to the electronegativity of the elements: the smaller the electronegativity,the higher the conversion rate of the catalyst.It was proved that the improvement of the catalyst's activity was indeed related to the formation of Ru?-particles.Secondly,the different ratio Zr-Al mixed oxide were synthesized and used as the support to load the platinum by impregnation method.These catalysts were used in the glycerol hydrogenolysis reaction to study the effect of supports for the hydrogenalysis of glycerol to n-propanol.The results showed that the glycerol conversion was improved when increasing the amount of aluminum in the catalyst.Besides,the selectivity of propanol(n-propanol + i-propanol)was enhanced when raising the ratio of zirconium to aluminum more than 5:5.What's more,the catalyst 2.5%Pt/Zr7Al3 had a highest n-propanol selectivity.After the characterization of the catalyst,it was found that the change of the above-mentioned catalytic results was attributed to the change of acid strength and total acid number in the catalyst's surface.In addition,through the investigation of the reaction conditions,it was found that increasing the reaction temperature and hydrogen content could promote the conversion of glycerol.After optimization of the reaction conditions,93.7% glycerol conversion and 85.4% n-propanol selectivity were obtained over the 2.5%Pt/Zr7Al3 catalyst.