Study of silica-immobilized sulfur model compounds as calibrants for the AP-TPR study of oxidized coal samples

Desulfurization of coal prior to combustion has developed the need for an a ccurate technique to determine which sulfur groups are present before and a fter chemical treatment. Atmospheric pressure-temperature programmed reduct ion (AP-TPR) is a technique that can determine the sulfur distribution by u sing model compounds as calibrants. This study deals with a series of model compounds for oxidized sulfur functionalities. It is proven by AP-TPR and AP-TPR-MS that the sulfur groups of these model compounds are decomposed an d that decomposition products (SO/SO2) are only partially reduced. Diaryl s ulfoxides and sulfones are found to be more stable than their aryl alkyl-su bstituted counterparts, and sulfones are more stable than the structurally related sulfoxides. Sulfates are generally found to be the most stable oxid ized forms of sulfur.