Study On Graphene-Supported Noble Metal Hydrodearomatization Catalyst

Excessive aromatics content in diesel fuel will reduce the life of the engine and pollute the environment,so hydrodearomatization of diesel oil is of great significance.Graphene has the characteristics of acid and alkali resistance and high-temperature resistance.Therefore,as a supporter of noble metal catalysts,it has important research value and application prospects in hydrodearmoatization reaction.In this work,GO?graphite oxide?was prepared by Hummers method at first,then graphene oxide dispersed in the ethylene glycol solution was obtained after drying and ultrasonic stripping of GO.Finally,Pt/rGO?reduced graphene oxide?catalyst was synthesized by reduction of graphene oxide with chloroplatinic acid,and the catalyst was applied to the reaction of naphthalene hydrogenation to prepare decalin.The effects of drying temperature,ultrasonic time of GO and Pt loading on the catalytic performance were investigated.The structure and properties of GO under different preparation conditions and corresponding Pt/rGO were analyzed were characterized by XRD,FT-IR,SEM,AFM,H₂-TPR,and XPS,and the relationship between structure and catalytic performance was investigated.The main findings and conclusions are as follows:?1?Compared with the GO-LT obtained by freeze-drying,the GO-60obtained by drying at 60 ^oC is simple in operation and energy-saving and time-saving.The interplanar spacing of GO-60 is slightly narrower than that of GO-LT,but GO-60 retains most of the oxygen-containing functional groups and has a high expansion degree,whose number of graphite layers is between 2 and 4layers.However,the expansion degree of GO-100 obtained by drying at 100^oC is weakened.Pt/rGO-60 prepared with GO-60 as a precursor,the carrier rGO has a weak stack,and the supported Pt active sites have high dispersibility and reducibility,thus Pt/rGO-60 exhibits better catalytic performance than Pt/rGO-LT and Pt/rGO-100,its naphthalene conversion and decalin selectivity were 98%and 96%,respectively.In order to study the advantages of graphene as a hydrodearomatization catalyst carrier,Pt/rGO-60 was compared with Pt/OMC.The rich oxygen-containing functional groups of graphene oxide promoted the dispersion of Pt during the preparation of Pt/rGO-60,and rGO has unique?-?overlap adsorption on the aromatic reactants,so Pt/rGO-60 shows better catalytic performance.?2?The prolongation of ultrasonic time of GO can weaken the graphitization degree of the carrier rGO,increase the reduction degree of the carrier rGO,and the more thorough exfoliation of graphene oxide and the hydroxyl groups produced at the edge of the torn graphene oxide are beneficial to the dispersion of Pt active sites.Due to good Pt dispersibility,lower degree of graphitization of rGO and higher degree of reduction,Pt/rGO-3h exhibits better catalytic activity and selectivity than Pt/rGO-1h and Pt/rGO-2h,its naphthalene conversion and decalin selectivity were 98%and 96%,respectively.?3?With the increase of Pt loading,the number of Pt active sites on the catalyst increased.Since naphthalene and tetrahydronaphthalene have competitive adsorption at the Pt active sites,sufficient Pt active sites can attenuate this competitive adsorption relationship,which is beneficial to increase the activity and selectivity of the catalyst.The catalytic activity and selectivity of 2%Pt/rGO are 98%and 96%,which are similar to that of3%Pt/rGO but higher than that of 1%Pt/rGO.From the economic point of view,a suitable Pt loading is considered to be 2%.