Reaction Of NO With Metal Oxides And Urea Supported On Activated Carbons At Low Temperature

Nitrogen oxides （NO_x） is the formation of acid rain, one of the major airpollutants, as China is increasingly stringent the standards NO_xemissions, flue gasdenitrification turned in to an important issues of air pollution control. SelectiveCatalytic Reduction （SCR） is the most widely used technology in the areas of flue gasdenitrification, catalyst is the core technology of the SCR. The inevitable trend of fluegas denitrification technology is to develop a good catalyst for low temperatureSCR.In recent years, carbon materials as the carrier of the NO_xcatalyst with its goodactivity at low temperature become a research focus. Activated carbon fiber （ACF） isa high activity, high surface area carbon adsorption material, compared with thetraditional carriers, with high surface area, uniform pore size distribution, theadvantages of fast adsorption capacity. Activated carbon fibers are rich in oxygen andnitrogen functional groups. Oxygen-containing functional groups can increase theadsorption active sites, enhanced oxidation catalytic activity, and to improve ACFhydrophilic; surface functional groups can provide basic adsorption sites, and thusenhance the adsorption affinity of NO_x, When the surface existing the nitrogenfunctional groups, NO_xcan be reduced at low temperature. Therefore, ACF is not onlyan excellent adsorbent, but also has good catalytic activity.Denitrification at Low temperature using Activated Carbon Fiber is Advancedand extensive adaptability,low-temperature SCR technology is the key step ofdenitrification processing, In this paper, catalytic reduction of NO with ACF atlow-temperature was investigated．The catalysts were prepared by activated carbonfiber（ACF） loaded different contents of NiO,CeO₂and NiO-CeO₂, Urea was loaded onthe prepared catalysts as reductent. The experiments of selective catalytic reductions（SCR） of NO were carried out from30to120℃. The experiments of SEM, BET andXRD of the samples were also carried out selectively to study the catalysts properties,respectively.The experimental results showed that the loaded mass fraction of NiOcould greatly affect the catalytic activity of the catalysts.10%NiO catalyst activityand activity stability were both higher than that of the others, and it could yield about50%removal efficiency of NO at90℃. With the loaded mass increasing, the catalyticactivity was obviously decreased.10%CeO₂catalyst activity and activity stabilitywere Also reflects the same advantages, And furthermore, the catalyst of5%NiO-5%CeO₂/ACF had the best catalytic activities on SCR NO and stability among the prepared NiO-CeO₂/ACF catalysts, and its NO removal efficiency was over55%at110℃. When the loaded mass increased, the similar phenomenon was observed,which was due to the decreasing of specific surface area of the catalysts. The metaloxides, loaded on ACF, were the catalytic centers in this study. Moreover,5%CeO₂-5%NiO/ACF had the highest catalytic activity than10%CeO₂/ACF and10%NiO/ACF. Therefore, there should be synergistic effect between CeO₂and NiO.Finally, the catalytic mechanism of SCR on NO at low temperature was discussed.