Characterization of Al, Cr-pillared clays and CO oxidation

Bentonite from Turkey was used in pillared clay synthesis by use of single and mixed oxide pillars of aluminium and chromium. X-ray photoelectron spectroscopy (XPS) confirmed that chromium was in two different oxidation forms, while energy dispersive spectroscopy (EDS) indicated the dispersion of chromium on the surface of the pillars and the clay mineral layers. The basal spacing of montmorillonite, and as a result, the specific surface area values were increased by pillaring. The microsurface area and micropore volume values occupied a considerable part of the total values. Nitrogen adsorption/desorption studies and scanning electron microscopy (SEM) images confirmed that the micropore and mesopore size distributions were not affected by synthesis conditions. Fourier transform infrared spectroscopy (FTIR) showed the presence of Brّnsted and Lewis acid sites. The maximum conversion of carbon monoxide was observed with the use of a pillaring solution having a Cr/Al ratio of 0.33.