Designation Of Polyoxometalates And Catalytic Performance Study Of Glycerol Oxidation

With the rapid development of modern social science and technology,the environmental and energy crisis caused by it has become increasingly serious.How to balance environmental protection on the basis of better integration of resources has become an important issue.Biomass energy is a kind of green and sustainable energy source with a unique advantage of wide source,easy access and large reserves.Glycerol as one kind of biomass energy,widely exists in nature and the by-products of industrial production,therefore,adoption of a certain chemical method,convert glycerol into other products,can realize win-win situation of waste utilization and development of new resources.In this work,high conversion rate of glycerol oxidation reaction and high selectivity of product are realized by that REDOX activity of green catalyst,heteropoly acid and composite heteropoly acid catalyst.According to the above content,this paper designed the catalyst containing Lewis metal,oxidized catalyst and solid carrier catalyst,and applied to the transformation of glycerol.The specific research contents are as follow:1.In he second chapter we designed and synthesized Keggin hetero-phosphotungstic acid salts catalysts with Lewis center-K₅PW₁₁MO₃₉(M = Co²⁺,Fe²⁺,Mn²⁺,Cu²⁺,Ni²⁺,K₅PW₁₁ M,for short).We investigated the oxidation-reduction properties and catalytic properties in glycerol oxidation reaction.For a series of hetero-phosphotungstic acid salts with eleven W,which have been replaced by different metals,the catalytic activity is linked to their composition and oxidation-reduction properties.The activity sequence is: K₅PW₁₁ Cu > K₅PW₁₁ Ni > K₅PW₁₁ Co > K₅PW₁₁ Fe > K₅PW₁₁ Mn,the selectivity to lactic acid aequence is: K₅PW₁₁ Cu > K₅PW₁₁ Ni > K₅PW₁₁ Mn > K₅PW₁₁ Fe > K₅PW₁₁ Co.The optimal reaction condition of K₅PW₁₁ Cu is: 3.40 mmol/L catalyst,140 ℃,1.0 MPa O₂,reacted for 7 h,glycerol conversion rate reached 65.3%,the highest lactic acid selectivity was 27.3%.In addition,K₅PW₁₁ Cu also has good cyclic usability and still maintains a high catalytic activity after 6 cycles.In addition,the acidic ionic liquid-MIMPS was used to regulate the Br?nsted acidity of K₅PW₁₁ Cu,and the experimental results proved: hetero-phosphotungstic acid salts ionic liquid [MIMPS]n K5-n PW11 Cu showed a higher catalytic activity than K₅PW₁₁ Cu,which was derived from the presence of Br?nsted acidity in the molecule,which promoted the acidification of intermediate products.2.In the third chapter,the vanadium substituted hetero-phosphotungstic acid catalyst HPMo₁₁ V was synthesized and characterized by elemental analysis,IR,XRD,CV,XPS,etc.It was applied to the experiment of glycerol oxidation and the optimal reaction condition is: 3.38 mmol/L HPMo₁₁ V catalyst,0.8 MPa O₂,when reaction under the condition of 120 ℃ for 4 h,glycerol conversion rate reached 92.3%,selectivity of oxalic acid reached 83.7%.Its catalytic activity is mainly derived from the oxidation activity center of Mo and V and the strong acidity of Br?nsted.3.In the fourth chapter,HPMo₁₁V/HAP（HAP is hydroxyapatite）was designed and synthesized with a series of characterization.Its activity in glycerol oxidation,and the relativity between component and properties of catalyst were investigated.The glycerol conversion and the selectivity of oxalic acid were found to be in linear relation to HPMo₁₁ V in carrying capacity of the HAP.The optimal reaction condition is: 0.08 g HPMo₁₁V/HAP（41.9%）catalyst,the reaction time was 5 h,the reaction temperature at 120 ℃ and oxygen intake to 1.0 MPa O₂.Glycerol conversion rate reached 90.7% and selectivity of oxalic acid reached 85.1%.The cyclic experiments show that the heterogeneous catalyst has good repeatability and stability.