CuO/g-Al2O3和CuO-CeO2-Na2O/g-Al2O3催化吸附剂的脱硝性能

利用改进的溶胶凝胶法制备纳米孔径的CuO/γ-Al2O3和CuO-CeO2-Na2O/γ-Al2O3催化吸附剂颗粒，在固定床上测试其催化脱硝活性。两类催化吸附剂250～400℃范围内脱硝效率稳定在70％以上。在350℃时效率稳定在最高值。利用程序升温方法研究了两类催化剂对NH3和NO的氧化性能，发现NH3在高于400℃下急剧氧化，是脱硝效率下降的主要原因。CuO/γ-Al2O3催化剂能将NO氧化生成NO2，NO2生成有利于脱硝反应的进行。NO在催化剂上的吸附对脱硝过程有重要作用。改进的CuO-CeO2-Na2O/γ-Al2O3催化剂能使NH3在高温400℃下不被氧化，也促进了NO在催化剂表面的吸附，从而提高催化剂了脱硝效率。催化剂反应的机理为NO吸附在催化剂表面，氧化生成吸附态的NO2，其再与吸附催化剂上的NH3反应。

Selective Catalytic Reduction of NO over CuO/g-Al2O3 and CuO-CeO2-Na2O/g-Al2O3 Catalysts

CuO/g-Al2O3 and CuO-CeO2-Na2O/g-Al2O3 granular sorbents were synthesized by the modified sol-gel method. Selective catalytic reduction (SCR) of NO over the two kinds of sorbents was carried out in a fixed bed reactor. The optimum temperature ranges of the two catalysts are 250~ 400 ℃. The maximum efficiency is stably reached at 350 ℃. Preliminary tests were carried out to study the behavior of NO and NH3 over fresh sorbents in the presence of oxygen. The NO oxidation experiments reveal that NO is oxidized to NO2 over the sorbents. The NH3 oxidation experiments show that NO and N2O are gradually produced with temperature increasing. The oxidation degree of NH3 is lower over the CuO-CeO2-Na2O/g-Al2O3 sorbent than that of the CuO/g- Al2O3 sorbent at 400 ℃, and the adsorption amount of NO over the CuO-CeO2-Na2O/g-Al2O3 sorbent is larger. So the denitration efficiency of the CuO-CeO2-Na2O/g-Al2O3 sorbent is improved. The NH3 and NO desorption experiments show that NH3 and NO could be absorbed on the granular catalysts and the NO2 intermediate species could play an important role in the reaction mechanism.