Investigation of arsenic resistance of plate-type De-NOx catalyst
Selective catalytic reduction(SCR)is currently the most widely used flue gas denitrification technology,with the core method SCR denitrification catalyst.The presence of the As element in coal combustion fly ash can cause catalyst poisoning and a significant decrease in service life,affecting the stable and efficient operation of the SCR system.V-Mo/Ti catalysts with different mass fractions of MoO3(3％ and 7％ )were prepared,in order to improve the As resistance of V-Mo/Ti catalyst.The As poisoned catalysts were also prepared by wet impregnation method.The physiochemical properties of the fresh and As-poisoned catalysts were characterized by XRF,ICP,XRD,N2-physisorption,H2-TPR,XPS,NH3-TPD,and O2-TPD.The NOx conversion and N2O concentration of the different catalysts in the temperature range 230-410 ℃ were tested via a micro fixed-bed reactor.The results show that As has negative influences on the pore structure of the catalyst,and reduces the specific surface area,pore volume,reducibility,acidity,and the amount of Oa of the catalyst.As a result,the catalytic activity of the catalyst declines and the generation of by-product N2O promotes.With the increase of MoO3 content,the pore structure of catalyst is improved,the decrease in specific surface area and pore volume is reduced,the reduction performance and surface acid content are increased,and the denitrification activity of catalyst is increased.High mass fraction of MoO3(7％ )can reduce the poisoning effect of As on the V-Mo/Ti catalyst.The catalytic performance of V-Mo(7)/Ti-As catalyst is obviously higher than that of the V-Mo(3)/Ti-As catalyst.In the other word,the As resistance of V-Mo(7)/Ti catalyst is superior to that of the V-Mo(3)/Ti catalyst.
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