Preparation Of Pd/Al₂O₃ Catalyst And The Study On Hydrogenation Of 2,5-DHF

Tetrahydrofuran?THF?is an important organic synthetic material,which can be directly used in synthetic fiber,synthetic resin and synthetic rubber,and also used in the pharmaceutical industry such as synthesis of carbetapentane,flavonoids,etc.At the same time,THF,called "Universal solvent",is also an excellent performance solvent,which is often used in surface coatings,anti-corrosion materials and so on.In view of its wide range of applications,the demand of THF will grow in the future,it will become more and more high standards for the quality of THF.The presence of 2,3-or 2,5-dihydrofuran byproducts can affect the chromaticity of tetrahydrofuran.The existence of by-products would affect downstream products,led to the high chromaticity values and low quality in finished product.In order to improve the purity and chromaticity of THF,removing the byproducts is particularly important.Compared to the method of removing the dihydrofuran by distilling,it is more economic and feasible by using hydrogenation catalyst to convert 2,3-or 2,5-DHF into THF.Currently,the reports about the above hydrogenation methods is scarcely studied,we know that the main catalysts used are Ni-based catalyst and precious metal catalyst.For achieving the hydrogenation of 2,3-or 2,5-DHF,we used Pd/Al₂O₃ as the catalyst in this article,starting from the precursor of PdCl2 and studied catalytic performance of the Pd/Al₂O₃ on the hydrogenation and finally examining effect of reaction condition on the hydrogenation reaction.The main contents and conclusions are as follows:1.PdCl2 was prepared by oxidation process which used HC1 and MxOy.We explored the conditions of the process,the results showed that the best proportion of raw material is that sponge palladium:HCl:MxOy=1:2?6:1?3,and the reaction temperature need to control under 100?,only in these conditions can sponge palladium achieve dissolve.In the evaporation process,we can flexibly control the temperature.Finally,the PdCl2 product was dried at 120?after grinding.As we all know,this process is environment-friendly and simple to operate,the conditions is also mild.When analyzing the content of Pd in product,we used the chemical analysis and instrumental analysis.The result showed that PdCl2 prepared by this way has high purity,which can satisfy the market's requirements,so it can be used as the raw material for preparing Pd/Al₂O₃.2.The catalyst Pd/Al₂O₃ was prepared by incipient wetness impregnation.We studied the performance of hydrogenation about converting 2,3-or 2,5-DHF into THF.We used Pd/Al₂O₃ to catalytic hydrogenation of 2,5-DHF,the 20 mL 2,5-DHF was added into the autoclave,the same time added 0.2 g 0.5%Pd/Al₂O₃,with the pressure of 3MPa and the temperature of 120?,the conversion rate of 2,5-DHF can be reached 99%.