Abstract
Pyridine (Py) adsorption on ceria surfaces, prepared by thermal decomposition of diammonium hexanitratocerate at 400 °C, was studied by infrared spectroscopy and gravimetric techniques. At room temperature, Py was irreversibly adsorbed via coordination to Lewis sites of different acid strengths. High temperature calcination (at 800 °C) of ceria greatly reduced the Py adsorption capacity of the surface. Upon thermoevacuation at 100–400 °C, Py cracking occurred with formation of various surface species (among these caboxylates and nitrites) deriving from cleavage of the ring via attack of surface oxygen on adsorbed Py. Doping of ceria with Na
+, Al
3+ and Cr
3+ ions (at 1 atom dopant per Ce atom) largely modified the Py adsorption capacity and surface reactions, thus revealing disparate impacts on acid/base properties of the surface.