Study On The Catalytic Performance Of Methyl Tetrahydrophthalic Anhydride Hydrogenation Over Pd/C Catalyst

Due to the saturability molecular structure and relatively nonpolarized,methyl hexahydrophthalic anhydride has the advantage of strong heat-resistance,faster cure,shorter gelation time which is superior to methyl tetrahydrophthalic anhydride.With those properties,methyl hexahydrophthalic anhydride has become the indispensable raw materials applied in epoxy resin coating and pharmaceutical industry.In the industrial production,two-step process was usually used to synthetic methyl hexahydrophthalic anhydride.In the first step,the,conversion of methyl hexahydrophthalic anhydride is 80%under nickel catalysts.In the second step,the conversion rise to 98%.However,this method has some drawbacks:craft complicacy and high producing cost.In this thesis,one-step production is employed.I studied the preparation of assembled Pd catalyst.The main research contents in this thesis include three components.First,I studied the impact on the catalytic activity by changing the catalyst preparing condition including the decomposition pressure,the stirring speed,the preparing temperature and precursor concentration.The results show that the optimal reaction condition as follows:preparing temperature 293.15K,decomposition pressure 4.0 MPa,stirring speed 250 r/min,precursor concentration 1mg/ml,Pd/C catalysts exhibited high activity.Second,Influences of pre-activated carbon and acidic oxide as carrier were investigated.It turned out that Pd/C catalysts activity was improved with the addition of Fe and activated carbon calcined at 1173 K.Acidic oxide-supported Pd as catalyst for methyl tetrahydrophthalic anhydride hydrogenation.The following activity order was found as 1%Pd/γ-Al2O3>1%Pd/SiO2>1%Pd/TiO2.The effects of activated carbon support treatd with nitric acid of different concentration on behaviors of Pd/C catalysts were investigated and the reaction activity of the catalysts are as follows:1 mol/L>3 mol/L≈5 mol/L.Third,the sulfur resistance of catalysts was tested.The results show that the catalysts modified by Co exhibited best anti-poisoning ability of sulfur.However,the addition of Cr and Zn did not improve the performance of catalysts.Additionally,TEM,XRD and XPS were employed to investigate the surface structure,the surface electronic state and the spread of Pd nanoparticles distribution.XRD results showed that precious metal nano-particles existed with amorphous structure and Al2O3 exists withγ-Al2O3 amorphous structure.XPS results showed that Pd exists with zero valence,Pd and metallic oxide support interact with each other.In conclusion,it is clear that assembled Pd catalyst exhibits high activity on methyl tetrahydrophthalic anhydride hydrogenation reaction.The one-step production has wide application prospects with the advantage in quality,stability and cleanness.