Fe/Ti-PILC用于C_3H_6选择性催化还原NO的研究

采用二氧化钛对蒙脱土进行柱撑改性后,以离子交换法制备了铁负载二氧化钛柱撑蒙脱土催化剂Fe/Ti-PILC,考察了其在富氧条件下催化C_3H_6选择性还原NO(C_3H_6-SCR)的性能。并借助N_2等温吸附-脱附、XRD、UV-vis、H_2-TPR、Py-FTIR等表征方法研究了催化剂的结构与性能之间的关系。结果表明,所制备的19Fe/Ti-PILC催化剂在400℃时即可实现到NO的完全脱除,N2选择性能够达到90%以上。且具有较好的抗水蒸气和抗SO_2的能力。N_2吸附-脱附和XRD结果显示,蒙脱土的结构被撑开,交联柱撑有效,形成了较大的比表面积和孔体积。UV-vis结果表明,催化剂的脱硝活性与铁氧低聚物种FexOy的含量有关,Py-FTIR结果表明,催化剂表面同时存在Lewis酸和Brnsted酸,Fe~(3+)负载到柱撑黏土中能够显著增加Lewis酸的含量,Lewis酸是影响催化剂脱硝活性的影响因素之一。H_2-TPR表征表明,催化剂在400℃左右有较强的还原能力,催化剂的还原能力主要体现为Fe~(3+)→Fe~(2+)的还原。

Experimental study on selective catalytic reduction of NO by C3H6 over Fe/Ti-PILC catalysts

Ti-pillared interlayer clay (PILC)-based catalysts ion exchanged with Fe were prepared and used for selective catalytic reduction of NO_x using propylene as the reducing agent under oxygen-rich conditions. The relationship between structure and properties of the catalysts was studied using N₂-adsorption/desorption, XRD, UV-vis, H₂-TPR, and Py-FTIR. The results show that the prepared 19Fe/Ti-PILC catalyst can achieve complete removal of NO at 400 ℃, and N₂ selectivity can reach over 90% and has better resistance to water vapor and SO₂. N₂-isothermal adsorption/desorption and XRD results show that structure of montmorillonite is opened, cross-linked pillars are effective, and a large specific surface area and pore volume are formed. UV-vis results show that the denitrification activity of the catalyst is related to content of oligomeric Fe_xO_y. Py-FTIR results show that both Lewis acid and Brønsted acid are presented on the catalyst surface. Fe³⁺ loading into the pillared clay can significantly increase the Lewis acid content. Lewis acid is one of the influencing factors on the denitrification activity of the catalyst. H₂-TPR indicates that the catalyst has a strong reduction ability at about 400 ℃, and the reduction ability of the catalyst is mainly represented by the reduction of Fe³⁺→Fe²⁺.