Study On Preparation,Characterization And Application Of Ni/MgO Catalysts

Hydrochloride condensate is an important intermediate for the synthesis of hydrochloride berberine,The optimum process for preparing the hydrochloride condensate is accomplished by hydrogenation of Schiff base,Industrial Schiff base hydrogenation is usually used Raney nickel as a catalyst,but the application of Raney nickel has many shortcomings.This paper aims to prepare a new catalyst in place of Raney nickel in this context.Supported nickel catalyst with different loading was prepared by impregnation method and combustion method,x%Ni/MgO?x=5,10,15,20,25??wt?,the catalysts were characterized by BET,XRD,SEM,H₂-TPR,CO₂-TPD,TG-DTA and FT-IR.The hydrogenation of Schiff base condensation hydrochloride as the probe reaction of Schiff base hydrogenation in high pressure reactor,Ni catalyst instead of Raney nickel catalyst,which can solve the catalytic activity of Ni is difficult to control,spontaneous combustion,air preparation process is complicated and difficult to long time preservation and other issues.In this paper,the effects of different magnesium oxide loads on the structure and acidity of Ni catalyst were studied.Magnesium oxide has a basic surface and a high specific surface area,the catalyst is a good carrier.The high activity,high selectivity,low temperature and long service life of the Ni catalysts are high.The results show that the combustion method is superior to the impregnation method in the preparation process,but also the catalyst has a significant effect on the hydrogenation of Schiff base.The catalyst was prepared by combustion method,when the loading of nickel was 15%,the yield of Schiff base was the best.Therefore,the catalyst is 15%Ni/MgO,the catalyst reduction temperature of 550?,the reaction raw material methyl ortho vanillin and 3,4-methylenedioxy-phenethylamin ratio was 1.041:1,the reaction temperature is 110?when the yield rate reached the highest conversion,Schiff base yield reached 90.4%,conversion rate reached 98.7%,the selectivity reaches 91.6%,indicating that15%Ni/MgO can be Schiff hydrogenation catalyst to replace the original.It has important theoretical significance and practical value to develop it as a new type of catalyst.