Mesoporous nickel (or cobolt)-doped silica-pillared clay: Synthesis and characterization studies

The metals-doped silica-pillared clay (SPC) materials with ordered pore structure in the gallery were obtained by a surfactant-directed assembly of silica species in the interlayer space of natural montmorillonite (MMT). The novel method afforded SPC derivatives with basal spacings of 4.4-4.5 nm, BET specific surface areas of 382.4-472.6 m²/g, pore volumes of 0.64-0.71 cm³ g⁻¹ and uniform pores (3.6 nm) between the layers. The main nickel and cobalt species was tetrahedrally coordinated Ni²⁺ or Co²⁺ in the gallery silica framework. Our results indicate that surfactant plays a decisive role in pore formation, because in acts as a micelle-like template during the hydrolysis of TEOS. In particular, the formation of metal-ammonia complex and rapid adsorption by surfactant in galleries controls metal species outflow from interlayers and contributes to the formation of metal species containing firm silica-pillars.