Synthesis and characterization of Al pillared montmorillonite impregnated with cobalt

Abstract

Aluminum pillared clay (AP) was synthesized using ≤ 74 μm fraction of Na-exchanged clay from Wyoming, USA (Na-Wy). The process of pillaring was carried out according to a common procedure comprising the following steps: pillaring, rinsing, drying and calcination. The obtained pillared clay was impregnated with Co2+ using incipient wetness impregnation method. The obtained sample was calcined and denoted as CoAP. Powder X-ray diffraction (XRD) patterns of Na-Wy, AP and CoAP indicated the presence of montmorillonite, quartz and feldspar. The pillaring affected montmorillonite peak corresponding to the 001 reflection. The d001 value increased from 1.17 nm for Na-Wy to 1.82 nm for AP. The pillaring process also fixed the basal spacing and no swelling was registered. In the diffractogram of CoAP the 001 peak was not well defined and was shifted to higher 2theta values. Nitrogen adsorption–desorption isotherms were used to determine textural properties of the samples. Pillaring resulted in enhanced textural properties such as increased total pore volume and specific surface area in the mesoporous region, as well as increased micropore volume comparing with that of Na-Wy. On the other hand, for CoAP textural parameters’ values were lower than those of AP, which could be ascribed to successful cobalt impregnation.