Research Of Efficient Platinum Supported Catalyst Applied To Low-temperature H₂-SCR

Nitrogen oxides(NOx)is one of the main pollutants in the atmosphere.The large amount of NOx emitted by coal and motor vehicles causes environmental problems such as photochemical smog and acid rain.To achieve further emission reduction of NOx,more efficient and feasible denitrification treatment technology is needed.In particular,the treatment of oxygen-enriched flue gas emitted by lean-burn engines.The selective catalytic reduction(H2-SCR)technology,which uses clean,non-polluting H2 as a reducing agent,can efficiently convert NO to N2 by the high catalytic activity of the noble metal catalyst at low temperature.Based on H2-SCR technology,noble metal platinum-based catalysts were prepared from different support materials and applied to H2-SCR reaction through gas diffusion reactor.The NO conversion,H2 conversion and N2 selectivity of the catalysts were investigated at low temperature(<100?).Combined with physical and chemical characterization techniques such as XRD,EDS,SEM and specific surface area analysis,the intrinsic relationship between the structural properties of the support materials and the denitrification activity of the catalysts was investigated.Also,the denitrification activity of the catalysts was optimized to reduce the amount of noble metal Pt used in the catalysts,and the effect of H2 and O2 concentration on the denitrification performance of the catalysts was explored.Firstly,the supported metal platinum catalyst was prepared by hydrothermal method using zeolites(ZSM-5,Mordenite,Beta)as the supports.The activity sequence of the three catalysts under the same metal platinum loading was:Pt/Beta>Pt/ZSM-5>Pt/Mordenite,and 0.15 wt%Pt/Bta catalyst achieves 90%NO conversion at 90? under oxygen-rich(4%O2)conditions,while H2 conversion and N2 selectivity are above 60%.At the same time,the Pt/Beta catalyst was selected to increase the dispersion of platinum on the surface of the catalyst through the addition of the structure-directing agent(SDA)polyvinylpyrrolidone(PVP),and increased the sulfur resistance of the catalyst through the addition of the metal additive Cc.Secondly,the Zr-centered metal organic framework material(MOF)UiO-66-NH2 was used as the template.The carbon-coated octahedral ZrO2 supported metal platinum catalyst with core-shell structure was prepared by one-step pyrolysis.The 0.1 wt%Pt/Zr02@C catalyst exhibited excellent H2-SCR denitrification activity,achieving more than 95%NO conversion at 90? under oxygen-rich(4%O2)conditions,and more than 60%H2 conversion and N2 selectivity.Finally,the supported metal platinum catalyst was prepared by hydrothermal method using transition metal(Mn,Co,Ni,Cu)oxides as the support materials.The results show that the platinum-based catalyst with transition metal oxides as the support materials at low temperature shows poor H2-SCR denitrification activity.Combined with the physical and chemical characterization of the support materials and the catalysts,the influence of the specific surface area,morphology,structure of the support materials and the valence state,particle distribution state of the active metal platinum on the H2-SCR denitrification activity of the catalysts were investigated.