Co改性α-MnO_(2)催化剂低温同时脱硝脱氯苯活性研究

Activity study of Co modifiedα-MnO_(2) catalyst for simultaneous removal of NO_(x) and C_(6)H_(5)Cl at low temperature

采用一步水热法制备α-MnO_(2)以及Co改性α-MnO_(2)催化剂(MnCo_(β)O_(x),β为Co与Mn的摩尔比),通过NH_(3)选择性催化还原(NH_(3)SCR)和氯苯(CB)催化氧化反应(CBCO)测试催化剂单独脱硝、单独脱氯苯以及同时脱硝脱氯苯的活性,并考察催化剂的稳定性。结果表明:β=1.0的MnCo_(1.0)O_(x)催化剂催化性能最佳,在150~250℃温度区间内的催化活性有明显提高,NO转化率和CB脱除效率分别增加了约19%和12%。同时通入NH_(3)、NO和CB时,MnCo_(1.0)O_(x)催化剂在200~300℃内NO转化率和CB脱除效率分别达到94%和82%以上,并且发现CB的存在能够抑制NO催化还原反应的进行,而NH_(3)和NO的存在能够提高CB催化脱除效率。250℃稳定性测试结果表明MnCo_(1.0)O_(x)催化剂在长达12 h的连续反应后仍然能够保持良好的活性,NO转化率和CB脱除效率分别接近100%和在80%以上。H_(2)程序升温还原(H_(2)-TPR)、比表面积测试(BET)、X线光电子能谱(XPS)等测试表明Co的掺入能够提高催化剂的氧化还原能力、增加活性位点数量和表面活性氧物种,这些都能够促进NO的转化和CB的催化脱除。

α-MnO_(2) and Co modifiedα-MnO_(2)(MnCo_(β)O_(x),βwas the molar ratio of Co and Mn)catalysts were prepared by one-step hydrothermal method.The activity of catalysts for separate catalytic removal of NO_(x),separate catalytic removal of chlorobenzene(CB)and simultaneous catalytic removal of NO_(x) and CB were tested by NH_(3)-selective catalytic reduction(NH_(3)-SCR)and CB catalytic oxidation reaction(CBCO),and the stability of the catalysts was also investigated.The MnCo_(1.0)O_(x) catalyst(β=1.0)displayed better catalytic performance,and the catalytic activity was significantly improved between 150 and 250℃,the NO conversion rate and CB removal efficiency increased by 19%and 12%,respectively.When NH_(3),NO and CB were injected at the same time,NO conversion and CB removal efficiency reached more than 94%and 82%respectively between 200 and 300℃.Besides,the presence of CB inhibited the NO conversion,while the presence of NH_(3) and NO improved the CB removal efficiency.The stability test at 250℃showed that the MnCo_(1.0)O_(x) catalyst could still maintain high activity after 12 h continuous reaction,with NO conversion rate and CB removal efficiency of 100%and 80%,respectively.The results of H_(2) temperature programmed reduction(H_(2)-TPR),specific surface area(BET)test and X-ray photoelectron spectroscopy(XPS)showed that the addition of Co improved the redox ability of the catalyst,increased the number of active sites and surface active oxygen species,which promoted the catalytic removal of NO and CB.