Complementary phenomenological and spectroscopic studies of propane sensing with tin dioxide based sensors

Sensing of propane with SnO2-based thick film gas sensors was studied by using a combination of experimental techniques. In order to assign reaction pathways, direct IR surface spectroscopic measurements (DRIFT) were performed. For a better understanding of the full picture, the spectroscopic information was completed with catalytic conversion and electrical measurements. We observed that during propane interaction with SnO2 the surface ionic species play a crucial role. The results indicate that: the C3H8 dehydrogenation is initiated by hydrogen abstraction over a surface acid-base lattice pair site (Sn4+O2−) while its further transformation is caused by reaction with adsorbed oxygen ions and with surface hydroxyl groups. In parallel with the rupture of the CH and/or CC bond, the ionic carboxylate species are formed and through further oxidative dehydrogenation, forms CO2− and CO32− surface species. The carbonates and carboxylates are finally desorbed as CO2(g).