The role of titania pillar in copper-ion exchanged titania pillared clays for the selective catalytic reduction of NO by propylene

A series of copper-ion exchanged titania pillared clays (Cu-Ti-PILC) with different Ti/clay rates were used for the selective catalytic reduction (SCR) of NO by propylene to examine the role of titania pillar in these catalysts. Among the catalysts tested, the sample with Ti/clay = 10 provided the best performance with 55.4% yield on N-2. XRD coupled with N-2 adsorption confirmed that the interlay spacing and surface area of the studied catalysts increased with a rise in Ti/clay rate. The TPR study showed that the Cu2+ amount reached a maximum of 0.69 mu mol/g-cat at Ti/clay = 10. The NO + O-2-TPD study indicated that the decomposition amount of the adsorbed nitrate species increased remarkably after the introduction of titania into clay as support. Moreover, the largest decomposition amount was obtained for the sample with Ti/clay = 10. It is concluded that the titania pillar provides the Cu-Ti-PILC samples with the increased interlay spacing, surface area and Cu2+ amount formed in the adjacent layers. These features make NO adsorbed more easily by copper species to form the intermediate of nitrate species, which enhances the conversion of NO into N-2. (C) 2011 Elsevier B.V. All rights reserved.