氧化还原沉淀法制备Mn-Ce-Co-O_x/PPS滤料及其低温SCR活性

Preparation of the Mn-Ce-Co-O_x/PPS filter material by a redox method and its activity in the low-temperature selective catalytic reduction of NO_x

先用十二烷基硫酸钠(SDS)对聚苯硫醚(PPS)滤料进行表面改性,随后通过氧化还原沉淀法制得不同质量比的MnCe-Co-O_x/PPS复合滤料。考察了复合滤料在低温选择性催化还原(SCR)反应过程中的催化活性,并通过XRD、FESEM、TEM和XPS等表征手段对复合滤料的结构及性能进行表征分析。结果表明,Mn-Ce-Co-O_x/PPS复合滤料在120-160℃时的脱硝效率达到86%-100%,明显优于超声法制备的Mn-Ce-Co-O_x/PPS-UM复合滤料的低温SCR活性,且1.2Mn-Ce-Co-O_x/PPS复合滤料的活性最优。1.2Mn-Ce-Co-O_x/PPS复合滤料中MnO_2、Ce_2O_3、CeO_2、CoO、Co_3O_4以蜂窝状形式均匀分散在PPS纤维表面,且呈弱结晶性结构;其较高的Ce^(3+)/(Ce^(3+)+Ce^(4+))比值和Co元素浓度是该1.2Mn-Ce-Co-O_x/PPS复合滤料具有优异低温SCR活性的主要原因。此外,与Mn-Ce-Co-O_x/PPS-UM复合滤料相比,1.2Mn-Ce-Co-O_x/PPS复合滤料也具有良好的抗H_2O和抗SO_2性能。

A series of Mn-Ce-Co-O^/PPS composite filter materials with different mass ratios were obtained by modifying the pristine polyphenylene sulfide （PPS） filter material with sodium dodecyl sulfate （SDS） and then treated by a redox precipitation method. The Mn-Ce-Co-Ox/PPS composite filter materials were characterized by XRD,FESEM,TEM and XPS; their catalytic performance in the low-temperature selective catalytic reduction （SCR） of NOx was then investigated. The results show that the Mn-Ce-Co-Ox/PPS composite filter materials obtained by the redox method presents higher low-temperature SCR activity than the Mn-Ce-Co-Ox/PPS-UM composite filter material fabricated via the ultrasonic method; over the former material,the NOX conversion reaches 86% -100% at 120-160 益.Among them,the 1.2Mn-Ce-Co-Ox/PPS composite filter material displays the highest SCR activity,which is probably ascribed to the high Ce^3＋/ （Ce^3＋＋Ce^4＋） ratio and high concentration of Co; moreover,honeycomb-like MnO2,Ce2O3,CeO2,CoO and Co3O4 are uniformly distributed on the PPS filter material in the weak crystalline structure. In comparison with Mn-Ce-Co-OyPPS-UM,the 1 .2Mn-Ce-Co- Ox/PPS composite filter material also exhibits higher resistance to H2O and SO2.