An XRD, FTIR and TPD investigation of NO2 surface adsorption sites of delta, gamma Al2O3 and barium supported delta, gamma Al2O3

In this paper an XRD, FTIR and TPD investigation of NO2 surface adsorption sites of delta, gamma Al2O3 and barium supported delta,gamma Al2O3 is reported. Aim of this study is to bring additional light on the surface structures involved in NOx adsorption. Two samples of barium supported aluminas have been prepared and aged at 800 degreesC. These samples were characterised in comparison with the relative alumina support. The XRD characterisation of these samples shows the presence of barium carbonate and barium aluminate supported on alumina. The comparison of the FTIR spectra, before and after NO2 adsorption, has revealed the formation, upon NO2 contact, of a complex variety of nitrate and nitrite groups. The thermal desorption of nitrate and nitrite species has been simultaneously studied by means of FTIR spectroscopy and by TPD technique.