Fabrication And Performance Investigation Of Polyphenylene Sulfide Composite Filter Materials With Denitration Function

Recently,bag filter has been widely applied in controlling flue gas emissions from stationary sources because it can accommodate to adverse working conditions,such as strong acid,high concentration dust and high temperature.Polyphenylene sulfide(PPS)filter was the main material of bag filter with excellent thermal stability,good properties of flame retardant and chemical resistance.If we can fabricate the bag filter with denitration function via immobilizing denitration catalyst on the surface of filter materials,it will be able to greatly reduce the complexity of tail gas purge system and space requirements.However,the existing commercial catalysts need to operate at the high temperatures(300?400?),which may damage PPS filter material because its operating temperature is always lower than 190?.Thus,this paper focuses on the investigation and development of the highly active low-temperature catalysts and its combination technology with PPS filter material.Manganese oxides(MnOx)exhibited outstanding low-temperature SCR activity,and can also be loaded on different catalyst carriers to not only achieve a higher catalytic activity due to the better dispersion of active components,but also show better catalytic stability.Carbon nano fibers(CNFs)have potentially broad application in the fields of catalytic support material because of their high length-to-diameter ratio,strong mechanical strength and superb thermal stability.Therefore,in this paper,the pristine CNFs were first used to immobilize manganese oxides by liquid-phase co-precipitation method.The characterization results showed that the nano-flake MnO2 catalysts were uniformly distributed on the CNFs.Among all of the samples,the 8%Nf-MnO2/CNFs catalyst exhibited the superior SCR activity and its NO conversions could reach 98%at 180?.Based on the above experiments,the 8%Nf-Mn02/CNFs catalyst was directly dispersed on the PPS filter material by solidification method,coating method and liquid-phase dispersion method.The characterization results displayed that the composite filter material obtained by the solidification method achieved high NO conversion and strong bond strength,whereas the air permeability was bad because of the overmuch catalyst loading amount of 8%Nf-MnO2/CNFs catalyst.The composite filter material prepared by the coating method exhibited highest NO conversion,and meanwhile behaved good bonding strength and air permeability.The composite filter material fabricated by the liquid-phase dispersion presented fine air permeability,but low NO conversion and bad bond strength.Flake-like MnO2 catalysts were coated on the PPS material by a redox method,and the results showed that all the composite filter materials presented excellent SCR activity and its activity could reach 100%NO conversions at 180?.The optimum preparation conditions were determined as follows:mass ratio of KMnO4 to PPS was 0.5 and reaction time 5h.The FESEM displayed that the flake-like MnO2 catalysts were uniformly distributed on the surface of PPS filter material.Finally,the above-mentioned composite filter material was then covered by a layer of polypyrrole composites via the interfacial polymerization technique.And the results showed that the bond strength,air permeability,and catalytic stability of this as-fabricated filter material were better than that of flake-like Nf-MnO2/PPS composites,but the NO conversion decreased slightly.