整体构件型La_(0.8)Sr_(0.2)MnO_3催化剂的制备和催化燃烧特性

为了解不同整体构件钙钛矿催化剂的VOCs催化燃烧特性,以不锈钢316L丝网和堇青石蜂窝陶瓷为基材,通过电泳沉积和浸涂技术在基材表面均匀涂覆γ-Al_2O_3粘合层,再在涂层表面负载钙钛矿型2.0%(wt)的La_(0.8)Sr_(0.2)MnO_3活性组分.SEM表征发现100 nm左右的La_(0.8)Sr_(0.2)MnO_3颗粒可以均匀、牢固地分散在不锈钢丝网和蜂窝陶瓷表面,经过550℃焙烧后无龟裂现象.超声振荡30 min后,活性组分损失率均小于5.0%(wt).甲苯催化燃烧测试表明,金属丝网型、蜂窝陶瓷型和颗粒型La_(0.8)Sr_(0.2)MnO_3催化剂表现出相似的催化性能,但金属丝网具有更好的传质效果和热响应速率,更适合处理高空速、温度和浓度波动较大的有机废气.

The Preparation of Monolithic La_(0.8)Sr_(0.2)MnO_3 Catalysts and its Performance for VOCs Catalytic Combustion

The 316L wire-mesh honeycomb and the ceramic honeycomb (cordierite) coated separately with a thick layer of γ-Al_2O_3, were prepared by electrophoretic deposition and wash-coating, respectively. The subsequent depositions of 2.0%(wt) La_(0.8)Sr_(0.2)MnO_3 on the coated monoliths were performed by impregnation method. The SEM images show that the La_(0.8)Sr_(0.2)MnO_3 particles with size of 100 nm are dispersed on the surfaces of wire-mesh honeycomb and ceramic honeycomb;they combine strongly with the structured support and lose only 5.0%(wt) after vibration for 30 min. The monolithic catalysts have no cracks happened after being treated at 550℃ for 5 h. The catalytic activities of the La_(0.8)Sr_(0.2)MnO_3 powder and monolithic catalysts exposed in toluene combustion both in fixed bed and in monolithic reactor were measured. The results show that the La_(0.8)Sr_(0.2)MnO_3 powder, wire-mesh honeycomb and ceramic honeycomb catalysts show almost the similar catalytic performance. The wire-mesh honeycomb catalyst exhibits better mass transfer characteristic and higher thermal response rate, and it is more adaptable to be used for treating VOCs with large blast volume and big temperature fluctuation.