Ce-Sn-W-O_x催化剂的配伍优化及脱硝影响因素

Compatibility optimization and de-NO_x influencing factors of Ce-Sn-W-O_x catalyst

采用共混热解法制备系列Ce-Sn-W-Ox复合氧化物,用于NH3选择性催化还原NO。通过正交实验优化CeSn-W-Ox配方,采用环境扫描电镜(ESEM)、X-射线衍射仪(XRD)等表征分析催化剂的微观形貌和固相结构,确立Ce-Sn-WOx最佳配比及结构形貌。结果表明,以粒度为5~8 mm的堇青石瓷片担载分散Ce-Sn-W-Ox,进行NH3-SCR脱除NO,当Ce/Sn/W元素摩尔比为1∶0.8∶0.6时,Ce Sn0.8W0.6Ox/堇青石NH3-SCR脱除NO效果最好。当空速为7 200 h-1,催化剂在252~426℃内脱除NO效率均大于94%。重点考察了反应空速(GHSV)、水蒸气(H2O)、SO2等对Ce Sn0.8W0.6Ox/堇青石NH3-SCR脱除NO活性的影响。研究表明,空速低于10 000 h-1时,催化剂脱硝活性受空速影响小;单独通入5%H2O对催化剂脱硝活性基本没有影响;单独通入429 mg/m3SO2导致催化剂活性略有降低;同时通入429 mg/m3SO2和5%H2O,催化剂脱硝活性下降至85.33%,除去SO2和H2O后,催化剂活性又能明显回升。

Series of Ce-Sn-W-Oxcomplex oxides were prepared by blending thermal decomposition and tested for selective catalytic reduction( SCR) of NO with NH3. Ce-Sn-W-Oxcompatibility were designed and optimized by orthogonal experiments,and characterized by scanning electron microscope( ESEM),transmission electron microscope( TEM) and X-ray diffraction( XRD) to establish the optimal compatibility and its structural morphology.Experimental results showed that the Ce-Sn-W-Oxwith the Ce / Sn / W molar ratio of 1∶ 0. 8∶ 0. 6,supported on cordierite ceramics with particle sizes of 5 ~ 8 mm,exhibited the best catalytic activity for NH3-SCR of NO. The Ce Sn0. 8W0. 6Ox/ CC was able to obtain more than 94% NO conversions in the active temperature range of 252 ~426℃ under the gas hourly space velocity( GHSV) of 7 200 h-1. Moreover,effects of GHSV,water vapor( H2O)and SO2 on catalytic activity for NH3-SCR of NO over Ce Sn0. 8W0. 6Ox/ CC were studied. Results showed that the GHSV had little influence on catalytic activity when the GHSV was less than 10 000 h-1,furthermore,the catalytic activity almost not changed in presence of 5% H2 O,and the catalytic activity slightly decreased in presence of 429 mg / m3SO2. The catalytic activity decreased to 85. 33% in presence of 5% H2 O and 429 mg / m3SO2,while the catalytic activity was able to obviously recover after moving away the SO2 and H2O.