低温燃烧法制备Mn-CeO_x催化剂及其NH_3-SCR脱硝性能

通过低温燃烧法(LCS)制备了不同金属硝酸盐与柠檬酸物质的量比的系列Mn-CeO_x(LCS)锰铈催化剂,将其与共沉淀法(CP)制备的Mn-CeO_x(CP)锰铈催化剂相对比,结合XRD、XPS、FESEM和H2-TPR等技术表征,对其NH_3-SCR脱硝催化性能进行了研究。结果表明,金属硝酸盐与柠檬酸的物质的量比是影响Mn-CeO_x(LCS)催化剂脱硝性能的重要因素。虽然两种催化剂中的锰氧化物组分均为无定型,但相较于Mn-CeO_x(CP),Mn-CeO_x(LCS)表面具有较高的锰含量与Oα/(Oα+Oβ)比,其脱硝催化性能也较高;同时,Mn-CeO_x(LCS)锰铈催化剂上有更多的多级孔,有利于气体在催化剂上的吸附和反应。硝酸盐与柠檬酸物质的量比为36∶22的Mn-CeO_x(LCS)锰铈催化剂在80-180℃下脱硝率可达75%-100%;即使通入SO2,180℃下的脱硝率仍可稳定于74%。

Low-temperature combustion synthesis of the Mn-CeOx catalyst and its performance in the selective catalytic reduction of NOx by NH3

A series of Mn-CeO_x(LCS) catalysts with different molar ratios of metal nitrates to citric acid were prepared by low-temperature combustion synthesis (LCS) method. Through a comparison with the Mn-CeO_x(CP) catalysts prepared by coprecipitation method (CP) as well as various characterization techniques such as XRD, XPS, FESEM, H₂-TPR and nitrogen physisorption, the catalytic performance of Mn-CeO_x(LCS) in the selective catalytic reduction (SCR) of NO_x by NH₃ was then investigated. The results show that the molar ratio of metal nitrate to citric acid is an important factor affecting the denitrification performance of the Mn-CeO_x(LCS) catalysts. In comparison with the Mn-CeO_x(CP) catalysts, the Mn-CeO_x(LCS) catalysts are provided with a higher manganese content and high O_α/(O_α+O_β) ratio on the surface as well as more hierarchical pores favorable for adsorption and reaction of reactants, which affords the Mn-CeO_x(LCS) catalysts much better denitrification performance. Over the Mn-CeO_x(LCS) catalyst with a molar ratio of metal nitrate to citric acid of 36:22, the denitrification rate at 80-180℃ reaches 75%-100%; even in the presence of SO₂, the denitrification rate over the Mn-CeO_x(LCS) catalyst at 180℃ keeps at the level of 74%.