Characterisation of ceria supported chromia catalysts

A series of ceria supported chromia catalysts of different loading were prepared and the effect of support in stabilising various chemical and molecular states of chromium with the calcination temperature were studied. XRD results showed that the chromia phase is randomly dispersed, disordered, and the crystallite size may be smaller than the detection limit. BET surface area and pore volume results suggested some plugging of pores on the support by chromia phase. EGA analysis suggested the existence of the surface heterogenity involving weakly and strongly chemisorbed CO2. EGA and NIR DRS studies revealed the bulk-like behaviour in the catalysts having chromia loading of more than 5 wt.%. EGA, FTIR and UV-VIS-DRS studies supported the formation of anchored surface chromium species. Moreover, the nature of molecular states of chromium and the coordinative environment under various thermal conditions were investigated using FTIR and UV-VIS-DRS techniques. (C) 2000 Elsevier Science B.V. All rights reserved.