Al–Fe and Al–Ti Pillared Saponite Clay Catalysts: Preparation and Characterization

Abstract

Saponite clay, a trioctahedral smectite clay was modified with Aluminum–Iron and Aluminum–Titanium solutions to form Al–Fe and Al–Ti pillared interlayer catalysts (PILC’s). The PILC’s were characterized using FTIR, XRD, N2 adsorption–desorption isotherms, SEM, WD-XRF, and TGA/DTG techniques. The OH stretching region in IR spectra of saponite reflected the trioctahedral character with mainly Mg(OH)2 units. XRD analysis showed the increase in basal spacing of Al–Fe PILC (18.37 A) and Al–Ti PILC (16.99 A) as compared to saponite clay (11.77 A). The nitrogen adsorption indicated an increase in specific surface area and micropore volume of Al–Fe PILC (94.44 m2/g) and Al–Ti PILC (73.78 m2/g) as compared to smectite clay (33.96 m2/g). SEM and WD-XRF analysis results indicated successful pillaring with oxides of Al–Fe and Al–Ti between the layers of the saponite clay. Thermal stability of the saponite clay and PILC’s in nitrogen atmosphere was analyzed up to 900 °C. Al–Fe PILC and Al–Ti PILC were found to be thermally stable in the temperature range 200–600 °C with weight loss 6.7% and 3.5%, respectively, whereas for natural saponite clay it was 10.1%. The study revealed the increase in basal spacing, specific surface area and higher thermal stability of Al–Fe PILC and Al–Ti PILC over saponite clay.