Adsorption and desorption of sulfur dioxide on novel adsorbents for flue gas desulfurization. Final report, September 1, 1993--August 31, 1994

Abstract

Dry regenerative sorption processes have recently attracted increasing attention in flue gas desulfurization (FGD) because of their several advantages over the conventional wet-scrubbing processes. Dry sorbents are usually made by coating a transition or alkaline earth metal precursor on the surface of a porous support. Major disadvantages of these sorbents prepared by the conventional methods include relatively poor attrition resistance and low SO{sub 2} sorption capacity. The physical and especially chemical attrition (associated with the sulphation-oxidation-reduction cycles in the process) deteriorates the performance of the sorbents. The low SO{sub 2} sorption capacity is primarily due to the small surface area of the support. Materials with a high surface area are not used as the supports for FGD sorbents because these materials usually are not thermally stable at high temperatures. In the past year, the research supported by Ohio Coal Development Office was focused on synthesis and properties of sol-gel derived alumina and zeolite sorbents with improved properties for FGD. The sol-gel derived alumina has large surface area, mesopore size and excellent mechanical strength. Some alumina-free zeolites not only posses the basic properties required as a sorbent for FGD (hydrophobicity, thermal and chemical stability, mechanical strength) but also have extremely large surface area and selective surface chemistry. The major objectives of this research program were to synthesize the sol-gel derived sorbents and to explore the use of the zeolites either directly as adsorbents or as sorbent support for FGD. The research was aimed at developing novel FGD sorbents possessing better sorption equilibrium and kinetic properties and improved physical and chemical attrition resistance.