Preparation Of Porous Carbon Nanofibers And Study On NO Adsorption And Catalysis At Room Temperature

As the industrialization process continues to accelerate,the number of fuel-powered vehicles continue to increase in human life.The proportion of nitrogen oxides(NOx)in atmospheric pollutants is also increasing year by year,which will have a serious impact on air and human health.Therefore,it is very important to study and prepare new and efficient NOx removal materials.In this paper,we uses polyacrylonitrile(PAN)as raw material.Dissolve PAN in N,N-dimethylformamide(DMF)to form a uniform and stable polymer solution.The carbon nanofiber precursor is prepared by electrostatic spinning technology,and the carbon nanofiber is obtained by subsequent processing.Using PAN as a carrier,graphite oxide(GO)and iron acetylacetonate(AAI)were used as the second phase materials to prepare graphite composite porous carbon nanofibers.It can determine the optimal concentration and catalytic oxidation performance of low concentration NO of fiber at room temperature;and determine the best preparation conditions of composite carbon nanofibers.The experiment used scanning electron microscope(SEM),Raman spectrometer(RAMAN),physical adsorption instrument(BEL),transmission electron microscope(TEM),nitrogen oxide analyzer and other characterization methods to analyze the microscopic morphology of nanofibers.The experiment is based on the best preparation concentration,and study the effect of treatment temperature on the catalytic performance of NO.The experimental results of this paper were summarized as follows:1.When the amount of PAN added accounts for 15%of the mass fraction of the solution,porous carbon nanofibers are obtained after NH3 carbonization activation treatment.The ID/IG value is the smallest and the value is 0.94.Therefore,the nanofiber reaches the maximum graphitization degree.The N2 adsorption and desorption test showed that the adsorption capacity of N2 reached 153.53 cm3(STP)g-1.Nanofibers have a higher microporous structure,and contains some mesoporous structures.The corresponding specific surface area reaches a maximum of 354.8 m2·g-1.The catalytic oxidation efficiency of low concentration NO reaches 3.26%at room temperature.Therefore,the concentration of PAN is selected to be 15%,which is used in the following research.2.Graphene oxide(GO)was added to the polymer solution with polyacrylonitrile(PAN)as the precursor in this experiment.Electrostatic spinning technology will be used to prepare composite carbon nanofibers.Experiments show that different amounts of GO(Relative to PAN quality scores are 2,5,10,15 and 20 wt.%)were successfully incorporated into the PAN matrix.The N2 adsorption and desorption test showed that the adsorption amount of the composite carbon nanofibers prepared by adding 15%of GO reached a maximum of 278.27 cm3(STP)g-1.The fibers are mainly micropores and contain few mesoporous structures.At the same time,the specific surface area of the fiber also reaches the maximum value of 605.48 m2/g.Proper GO addition and NH3 activation treatment significantly increased the proportion of micropores in the composite carbon nanofibers.3.PAN as a carbon precursor and iron acetylacetonate(AAI)as a catalyst to prepare composite carbon nanofibers by electrostatic spinning.The experiments showed that different amounts of AAI(relative to PAN mass fractions of 2,5,10,15 and 20 wt.%)were successfully incorporated into the PAN matrix.The porous composite carbon nanofibers were obtained after activation treatment at 900℃ NH3 atmosphere for 10min.Fe particles are generated in situ on the fiber surface.During the activation process,NH3 etched the outer surface of the composite nanofiber.Due to its etching effect,some Fe particles inside the fiber are also exposed.The N2 adsorption and desorption test shows that when the amount of AAI added is 5%,the adsorption capacity of the composite carbon nanofibers reaches a maximum of 219.67 cm3(STP)g-1.The fibers are mainly micropores and contain some mesoporous structures.The corresponding specific surface area also reached the maximum value of 439.23 m2/g.Proper AAI addition and NH3 activation treatment significantly increased the proportion of micropores in the composite carbon nanofibers.Composite carbon nanofibers treated with different carbonization temperatures under the same conditions.Spherical Fe elements are evenly distributed on the surface or inside of the nanofibers.Graphite streaks are apparent on the fiber surface or edge.The arrangement of these stripes is relatively regular.A large number of uniformly arranged graphite stripes with a certain degree of orientation are formed around the Fe elemental substance.The formation of these structures is mainly attributed to the good catalytic graphitization of Fe elemental,and the effect of graphitization is obvious.4.Adopt 15%polyacrylonitrile(PAN)as a precursor polymer solution,and use the electrospinning method to prepare porous carbon nanofibers.And it was subjected to carbonization activation treatment at different temperatures(800,850,900,950℃).When the temperature reaches 950℃,the ID/IG value of the nanofibers is smallest and the value is 0.93.Therefore,the degree of graphitization of PCNF15-950 reaches the maximum.The N2 adsorption and desorption test showed that the fiber’s adsorption capacity of N2 reaches a maximum of 330.04 cm3(STP)g-1,The relative content of micropores also reached the highest,and the total volume of pores reached a maximum of 0.5076 cm3/g.The corresponding specific surface area reaches a maximum of 728.92 m2·g-1.The catalytic oxidation rate reaches a maximum of 3.4%of carbon nanofibers obtained by carbonization activation treatment at 950℃ at room temperature.