Study On Synthetic Technolohy Of Antioxidant 44PD

Using p-phenylenediamine and methyl-ethyl ketone as raw materials,the antioxidant N,N'-di-sec-butyl p-phenylenediamine?antioxidant 44PD?was synthesized using self-made Pt/C catalyst,and its reaction conditions were optimized.First from the catalytic hydrogenation of industry commonly used catalyst carrier activated carbon from four kinds of activated carbon.Boehm titration,N2 adsorption-desorption,laser particle size analysis and electron scanning electron microscopy?SEM?were used to characterize the samples,and combining with the characteristics of reaction chose the larger specific surface area,pore size larger for the preparation of activated carbon catalyst carrier.The results of oxidation,hydrothermal and high-temperature pretreatment of the activated carbon carrier showed that the oxidation of nitric acid and hydrogen peroxide could effectively increase the content of various oxygen-containing groups on the carrier surface.Water heat treatment can increase the content of phenolic hydroxyl group,but reduce the content of carboxyl group and inner lipid group,which has little effect on the total amount of oxygen-containing groups.High temperature treatment will decompose the oxygen-containing groups and reduce the content of oxygen-containing groups.Catalysts were prepared by different methods and characterized by transmission electron microscopy?TEM?,Inductively Coupled Plasma-Atomic Emission Spectrometer?ICP?and N₂ adsorption-desorption characterization analysis.The influences of metal load,pretreatment and reduction methods on the performance of catalysts were studied and the results show that the higher the metal load,load rate is lower,and the greater the metal particle size;After reduction by liquid phase method,metal particles have larger particle size and slightly aggregate,while metal ions have smaller particle size and uniform distribution after reduction by gas phase method.The prepared catalyst was applied to the catalytic synthesis of antioxidant 44PD,and the performance of the catalyst was evaluated according to the conversion rate,selectivity and reaction time.The results showed that after 5%nitric acid pretreatment,the carrying capacity of Pt metal was 3%,and the catalyst Cat4 for gas phase hydrogen reduction had good catalytic performance in the catalytic synthesis reaction of antioxidant 44PD.The optimal reaction conditions were optimized by using the selected catalyst Cat4antioxidant 44PD.The catalyst life was studied under the optimal reaction conditions.After 20 repeated experiments,the catalyst Cat4 was deactivated.In the first 18experiments,the conversion rate of p-phenylenediamine remained more than 99.5%,and the selectivity of antioxidant 44PD remained above 98%.After the reaction,the butanone was recovered from the reaction solution,and the catalyst life experiment was carried out with the recovered butanone.The results showed that the recovery of butanone had no effect on the catalyst life and reaction.TEM,N₂ adsorption-desorption,ICP,CO chemical adsorption and other characterization analysis of the deactivated catalyst showed that after deactivation,the specific surface area of the catalyst and the surface area of the Pt metal decreased significantly,and the decrease rate was the same,which was determined to be the catalyst deactivation caused by the blockage of the catalyst channel.In the catalyst regeneration experiment,5%acetic acid,1%sulfuric acid,butanone and N-methyl pyrrolidone were selected as solvents to wash the catalyst,and the regenerated catalyst was characterized by nitrogen adsorption-desorption and CO chemisorption.The catalyst washed with N-methyl pyrrolidone has good regeneration effect.The regenerated catalyst was applied to the reaction of antioxidant 44PD,and the deactivation occurred after the experiment was repeated for 17 times.