High-efficiency Metal Solid Acid Bifunctional Catalyst For Hydrogenolysis Of Glycerol To 1,3-propanediol

The burning of traditional non-renewable fossil fuels brings about such issues as environmental pollution and the greenhouse effect.The search for alternatives to non-renewable energy has become an urgent hot topic.Biodiesel,as a green renewable energy,refers to the fatty acid esters of short-chain monoalcohols with the advantages of environmental friendliness,lubricity,safety and reproducibility.The application of biodiesel can greatly reduce the consumption of traditional petrochemical energy mining and consumption,and has quickly become the bright spot of the petrochemical diesel alternative fuels,with a wide range of market application.Biodiesel is usually prepared by transesterification.It is based on the transesterification of short-chain alcohols under the condition of acid/base catalyst with animal or vegetable oils as raw materials to generate a large amount of by-product glycerol.The increasing use of biodiesel year by year has resulted in the excess of glycerol heavily.Therefore,the rational use of glycerol is in line with the requirements of green chemistry and sustainable development.Among the many downstream products of glycerol,1,3-propanediol is an important organic chemical raw material for the synthesis of a new type of polyester-polytrimethylene terephthalate(PTT),but the low selectivity to 1,3-propanediol has objectively limited its large-scale practical application.One of the methods to solve this problem is to design a highly efficient catalyst to promote the selectivity to 1,3-propanediol.At present,the common catalytic system is mainly divided into tungsten-doped metallic catalysts and rhenium-containing bimetallic catalyst.Preliminary studies have shown that: metal serves for the activation and dissociation of hydrogen,solid acid and polyol are closely related to dehydration.Therefore,this thesis plans to prepare efficient metal and solid acid composite catalyst to achieve high glycerol conversion and selectivity to 1,3-propanediol.The first part of this thesis mainly focused on the performances of Pt/W/Al catalysts for glycerol hydrogenolysis.The catalysts with different W content were prepared by traditional isostatic impregnation method.The correlation of W content to the catalytic performances of hydrogenolysis of glycerol to 1,3-propanediol was discussed detailly.The effect of metal dispersion,the preparation method of solid acid,the role of tungsten oxide and hydrogen overflow on the catalytic properties were studied.Under the optimal conditions,180 ?,5.0MPa hydrogen,a 42.95% yield of 1,3-propanediol was achieved.In the second part of this thesis,bimetallic Pt-Re/W/Al catalysts for glycerol hydrogenolysis was studied.In the first part,the selectivity to 1,3-propanediol was relatively low.As a promoter,on the one hand,the metal Re connected with Pt is participate to have a synergistic activation of hydrogen;on the other hand,it is favorable to the acid-catalyzed alcohol dehydration process.For bimetallic Pt-Re/W/Al catalysts,the reaction parameters was investigated,including reaction temperature,reaction pressure,the proportion of Pt-Re,the order of loading and so on,focusing on the key role of metal Re in bimetallic catalysis system.The reaction mechanism was explored to reveal the structure-activity relationship.