Preparation Of Ni Nanofiber Materials And Its Application In Purification Of Motor Exhaust Gas

The particulate matter and NOx emitted by automobile exhaust is one of the main culprits of serious air pollution and respiratory diseases at present.And the traditional three-way catalytic converter and particulate filter are faced with the problems of high cost and easy carbon deposition.Therefore,it is urgent to develop a new filter which can filter the particulate and purify NOx in the flue gas.In recent years,nanofibers have excellent performance in particle filtration applications,and nanofibers have the advantages of high specific surface area and controllable porosity,which show great potential in gas adsorption and even gas catalysis.Electrospinning is a simple and efficient method for the preparation of nanofibers,which can continuously prepare micron/nanometer organic fibers by applying high voltage to polymer solution drops.In addition,inorganic nanofibers can also be prepared by adding inorganic salts to polymer precursor,and then calcined by heat treatment under a certain situation,which can meet the needs of most fibers.The nanofibers prepared by this method have the advantages of small diameter,high specific surface area and controllable porosity.The nanofibers with this special structure have great application advantages in the application of catalysis and accumulation mode and even Aitken nuclear mode fine particle filtration.In order to achieve a better purification effect of the fiber on NOx in the exhaust gas,the transition metal Ni with catalytic effect was used to prepare nanofibers,and its particle filtration performance and NOx purification ability were studied.In addition,in order to improve the adaptability of common fiber in the complex environment of tail gas emission end,the surface layer of PVP organic fiber which is easy to melt and hydrolyze is treated by magnetron sputtering Ni,and its environmental adaptability and fine particle filtration ability are studied.The inorganic metal Ni nanofiber film was prepared by electrospinning and heat treatment.The Ni nanofiber film was observed and analyzed in detail by various characterization methods.It was found that the fiber with an average diameter of 300 nm was well formed,with a certain toughness and a specific surface area of 201.336 m²g^-1,and the pore diameter was mainly distributed at 3⁸ nm.In addition,the adjacent fibers are connected by melting,instead of the simple lapping state between ordinary fibers.In the test of fine particle filtration,when the standard wind speed is 5.3 cm/s,the filtration efficiency of Ni nanofiber at the most easily tunneled particle size@300 nm reaches 99.86%,and excellent filtration efficiency has been achieved in other tests at different wind speeds;In the NO purification experiment,the continuous adsorption performance of Ni nanofiber for NO gas at low temperature has been tested.Under the test condition of 300?,NO gas reacts with Ni fiber on the surface of the fiber and NO was reduced to N₂.The reaction mechanism of NO gas on the surface of Ni fiber is studied and analyzed by means of TG-MS analysis and variable temperature XPS detection.Ni/PVP composite nanofiber films were prepared by electrospinning and magnetron sputtering.Ni coating was successfully sputtered on the surface of organic PVP nanofiber.The surface morphology of the films was observed by SEM and TEM,and the relationship between the coating thickening and sputtering time was studied.The prepared composite fibers were soaked in deionized water and heat treated at 100?³00?.The results showed that the morphology of the composite fibers remained good and the internal pores were not damaged.In the filtration test,Ni/PVP composite nanofibers also achieved excellent performance with the lowest filtration efficiency of 99.76%.