负载Cr和Mo锰矿粉基催化剂的脱硝脱氨性能

Denitration and deamination performance of manganese ore powder-based catalysts with Cr and Mo loading

氨选择性催化还原(NH_(3)-SCR)技术在焚烧烟气NO_(x)减排控制中广泛应用。然而,目前广泛商业化使用的SCR催化剂价格昂贵且低温活性差。以价格低廉的天然锰矿粉(MOP)为载体,采用浸渍法制备了Cr和Mo负载改性MOP,在温度范围150~400℃,对比研究了MOP和负载改性MOP的脱硝和脱氨催化效率,并基于NH_(3)-TPD-MS、FE-SEM-EDS、XRD和XPS对所制备的催化剂进行表征。结果表明:MOP具有较高的催化脱硝脱氨活性;Cr负载可大幅提升MOP的氨转化率,且对脱硝效率没有明显影响;Cr主要以无定形Cr_(2)O_(3)形式物理附着于MOP表面,Cr与Mn之间没有明显的相互作用。同时,Mo负载对MOP的氨催化转化也有明显促进作用,2%Mo负载仅轻微减少了MOP在150~250℃时的脱硝效率。在5%Mo改性MOP表面,酸性位点数量和NH_(3)吸附能力显著提高,但Mo与K反应生成钾钼盐结晶,导致Mn^(4+)和O_(α)的相对含量降低。该研究结果可为低温低尘尾部布设SCR的同时脱硝脱氨提供参考。

NH_3-SCR technology is extensively used in control of NOx emission from incineration flue gas.However,in recent decades the widely adopted commercial SCR catalysts were expensive and their activity at lower temperature was decreased.In the experiment,the cheap natural manganese ore powder(MOP)was selected as the carrier,and by impregnation method the modified MOP with Cr and Mo was prepared,respectively.In the temperature range of 150~400℃,NO and NH_(3)conversion efficiency between MOP and modified MOP was compared,and based on NH_3-TPD-MS,FE-SEM-EDS,XRD and XPS analysis the prepared catalysts were characterized.The results demonstrated that MOP had high catalytic de-NOx and ammonia removal activity.Cr loading on MOP significantly enhanced NH_(3)conversion performance,and had no significant effects on the denitration efficiency.Cr was mainly physically adsorbed on the surface of MOP as amorphous Cr_2O_3.There was no evident interactions occurred between Cr and Mn.Meanwhile,Mo loading also remarkably promoted catalytic deamination activity of MOP,and the denitration efficiency over MOP doped with 2%Mo was only slightly declined at 150~250℃.On the surface of 5%Mo-modified MOP,acid sites and NH3 adsorption capacity was notably increased,but crystal K_5Mo_4O_(6)was formed due to the reaction between Mo and K,leading to the lowered relative content of Mn^(4+)and adsorbed oxygen(O_α).In summary,the experiment results provided the important references for simultaneous denitration and deamination of SCR located at the downstream under the conditions of low dust and temperature.