蜂窝状Mnx/PG-CC催化剂中低温CH_4-SCR脱硝性能

Low temperature CH_4-SCR honeycomb Mnx/PG-CC catalysts for catalytic reduction of NO

采用悬浮浆液法将凹凸棒石(PG)涂覆于堇菁石(CC)表面,制备PG-CC载体.将PG-CC载体以过饱和浸渍法经Mn(NO_3)_2前驱体溶液处理后依次干燥、煅烧制得Mnx/PG-CC整体式催化剂,应用于柴油车尾气净化处理.考察了制备参数(锰负载量、煅烧温度)和工况条件(氧气含量,CH_4/NO)对Mnx/PG-CC催化剂在CH_4-SCR反应中脱硝活性的影响.采用BET、FE-SEM、XRD、XPS和NO吸脱附等表征手段对催化剂的结构和形貌进行表征.结果表明,在锰负载量为11%、煅烧温度为300℃下所制得的催化剂具有较佳的CH_4-SCR脱硝活性,O_2含量为5%、CH_4/NO为1,反应温度为300℃时反应条件最优.锰氧化物活性组分在催化剂表面的高度分散和均匀分布有利于催化剂的CH_4-SCR脱硝活性提高,且有助于NO吸附在载体表面并形成硝酸盐中间体参与催化反应.

Cordierite honeycomb ceramic（ CC） was immersed in Palygorskite（ PG）-water mixed slurry to prepare a Palygorskite（ PG） coated CC as catalysts＇ carrier（ PG-CC）. PG-CC carrier was then treated into a manganese nitrate solution as precursor followed by drying and incineration to obtain Mnx / PG-CC catalysts for diesel exhaust treatment. The effects of the preparation parameters（ manganese oxide content,calcination temperature） and operation conditions（ oxygen content,CH4/ NO） on the performance of the monolith catalysts for CH4-SCR were also investigated. Catalysts were characterized by BET,XRD,FE-SEM and Adsorption and TPD profiles of NO. It was observed that the catalyst calcined at 300 ℃ with 11 wt% of manganese（ Mn11 / PG-CC（ 300 ℃）） showed the best CH4-SCR activity when tested at 300 ℃ with a CH4/ NO ratio at 1 and 5 vol% O2 presented.manganese oxide active specie was observed to be highly dispersed on the catalyst＇ s surface,which is benificial for the CH4-SCR activity of the catalyst mainly due to the enhancement of NO adsorption and formation of surface nitrate as active mediate for SCR.