Adsorption and Reaction of Sulfur Dioxide on Alumina and Sodium-Impregnated Alumina

Abstract

The adsorption and oxidation of SO2 on alumina and sodium-impregnated alumina has been examined using thermogravimetric analysis and diffuse reflectance infrared Fourier transform spectroscopy. Sulfur dioxide chemisorbs initially at basic sites to form an adsorbed sulfite, which is quantitatively converted to sulfate on oxidation. It has been observed that at low coverages, ∼2.6 μmol/m2, sodium acts as a promoter for the formation of an adsorbed sulfite and sulfate which have structures similar to those of aluminum sulfite and sulfate, respectively. At higher sodium loadings, a second type of adsorbed SO2 is formed, similar to sodium sulfite and sulfate. The species with the aluminum sulfate structure appears to be more easily decomposed than does the sodium sulfate species and accounts for the regenerable adsorption capacity. Formation of the sodium sulfate species appears to account for the loss of adsorption capacity as the number of adsorption/regeneration cycles increases. Oxidation of the sulfite form to the sulfate form can occur in the absence of added oxygen, but it is an activated process and begins to occur in measurable amounts at temperatures between 150 and 300 °C. Partitioning of adsorbed SO2 between aluminum and sodium forms is not a function of temperature and depends on only sodium loading.

Sulfur Management of NOx Adsorber Technology for Diesel Light-duty Vehicle and Truck Applications

“…We have been applying spectroscopic techniques to identify and quantify surface adsorbing/ desorbing species responsible for sulfation and desulfation processes. The surface characterization provides insights about the underlying chemistry of the adsorption/desorption processes and the degradation mechanism (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26). The temperature and temporal probes of surface adsorbing species permit us to derive thermodynamic and kinetic parameters required for model development (13)(14)(15)(16)(17)(18).…”

SO uptake and release properties of TiO2/Al2O3 and BaO/TiO2/Al2O3 mixed oxide systems as NO storage materials

“…3a, spectrum ii) the 1368, 1102 signals become more visible which correspond to the 3 and 1 modes of surface sulfates on Al 2 O 3 , [60], respectively. Furthermore, the shoulder located at 1170 cm −1 which can be associated with bulk Al 2 (SO 4 ) 3 [56] starts to be more discernible. In addition, a relatively minor contribution from sulfate species that are interacting with the surface -OH groups which reveal typical signals at 1290 and 1080 cm −1 cannot be excluded [58].…”

“…The formation of sulfates on alumina surface was considered in numerous former studies [56,57,60,68]. Typically, SO 2 binds to the acidic sites (i.e.…”

“…coordinately unsaturated aluminum cations, Al 3+ ) forming physisorbed SO 2 . The adsorption of SO 2 on the basic adsorption sites is followed by a cleavage of an Al O bond on the surface (primarily at OH sites or at exposed oxygen atoms, Table 1 Typical FTIR signals associated with common SOx species [7,[54][55][56][57][58][59][60][61][62][63][64][65][66][67].…”

Uptake and conversion of carbonyl sulfide in a lawn soil

“…3B). The surface HSO À 3 ð1242 cm À1 , Laniecki et al, 1987;Mitchell et al, 1996) and SO 2À 4 species (1363 cm À1 , Saur et al, 1986;Meunier and Ross, 2000;Goodman et al, 2001) were observed in addition to the surface HCO À 3 and HSCO À 2 species. It is also found that the peaks for surface HCO À 3 , HSO À 3 , HSCO2 À , and SO 2À 4 species increase in intensity with time in the soil.…”