A Study On The Adsorption Catalyst And Its Process For The Denitrification In Combination With Demercuration Of Coal-burning Flue Gas

Pollutions brought by nitrogen oxides and mercury can do harm to human beings and surroundings persistently. As it’s not economically feasible to get rid of nitrogen oxides and mercury separately over each other, the removal of nitrogen oxides in combination with that of mercury can not only be economic, but also make the process easier and more efficient. Herein, our objective is combine the removal of heavy metal Hg with NOx by preparing new, available adsorption catalyst in mild reaction conditions. The cooperative effect of the reactants and the mechanisms of adsorption as well as catalysis of the catalyst are also studied in this paper.The result shows that the removal rates of nitrogen oxides and mercury over four supports follow the order:γ-Al2O3>13X molecular sieve>5A molecular sieve>SiO2. Via the modification of the carriers by the transition metaloxides and rare earth metal oxides, adsorption catalysts were prepared. The catalysts modified by MnO2represent a wider temperature range of good catalytic activity, while the ones modified by CeO2have good activity only under low temperature. Fe2O3/13molecular sieve, MnO2/γ-Al2O3and CuO/5A molecular sieve were selected for research by comparing their denitrification and demercuration performance. In consideration of the effects of different gas components on denitrification and demercuration, we found that as the gas hourly space velocity (GHSV) increases, denitrification and demercuration decreases; as the concentration of O2increases, denitrification and demercuration almost keep unchanged; in oxygen conditions, the increase of NO concentration will promote the transformation of mercury; the increase of NH3concentration can inhibit the conversion of mercury conversely.The theoretical maximal adsorption capacities, adsorption equilibrium constants and adsorption rate equations at different reaction temperatures can be figured out by using two classical mathematical models, structuring kinetic equations and fitting the experimental data. The results are:at100℃,qmax=883ug/g, k=1.435×102m3/g; at175℃, qmax=1149ug/g, k=2.241×102m3/g; at200℃, qmax=948ug/g, k=2.73×103m2/g. The adsorption rate equation can be expressed as follows:q=qe[1exp(0.0399t0.6264)].