Montmorillonite intercalated with SiO2, SiO2-Al2O3 or SiO2-TiO2 pillars by surfactant-directed method as catalytic supports for DeNOx process

Abstract

The intercalation of natural montmorillonite with SiO2, SiO2-Al2O3 or SiO2-TiO2 pillars by the surfactant-directed method resulted in the formation of high surface area porous materials; these were tested as catalytic supports for the process of selective catalytic reduction of NO (DeNOx). The incorporation of titanium or aluminium into the structure of the silica pillars significantly increased the surface acidity of the clay samples. Iron and copper were deposited onto the surface of the pillared clays mainly in the form of monomeric isolated cations and oligomeric metal oxide species. The contribution of the latter species was higher in the clay intercalated with SiO2-TiO2 pillars than in the samples modified with SiO2 and SiO2-Al2O3 pillars. The pillared clay-based catalysts were active in the DeNOx process but, in this group, the best results were obtained for the clay intercalated with SiO2-TiO2 pillars and doped with iron and copper. The catalytic performance of the samples is discussed in respect of their surface acidity and active forms of transition metal species deposited.

Synthesis, Characterization, Uses and Applications of Porous Clays Heterostructures: A Review

“…The use of other alkoxides to incorporate other heteroatoms such as alumina, zirconia, or titania, alone or mixed with silica causes modifications of the physicochemical properties of the PCHs as will be seen in next sections. Nonetheless, the different rate of polymerization in the alkoxides leads to irregular distribution in the formation of the pillared gallery structure.…”

“…Thus, the PCHs have been synthesized from vermiculite, saponite and montmorillonite with SiO 2 ,, SiO 2 −TiO 2 ,, or SiO 2 −Al 2 O 3 in the walls and they have been used as support using Fe and Cu in the selective catalytic reduction of NO x by ammonia for the elimination of nitrogen oxides emitted by stationary sources, obtaining interesting results for the Cu catalyst supported on PCH‐SiO 2 −TiO 2 . PCHs have also been used as catalytic support (Figure ) in the preferential oxidation of CO to CO 2 using CuO‐CeO 2 as active phase.…”

Synthesis of new porous clay heterostructures: The influence of co-surfactant type

“…These changes were assigned to the PCH formation [41,42]. The results suggested that the amine type used as co-surfactant influenced the textural parameters.…”

Modified Layered Silicas as Catalysts for Conversion of Nitrogen Pollutants in Flue Gases—A Review

“…Cationic layered clay minerals have been intensively studied as precursors for the synthesis of catalysts for several decades [3,4,[11][12][13][14][15]. The interest from scientists and engineers is related to the great variety of clay minerals with different layered structures and containing various intralayer and interlayer chemical elements.…”