Multi-Functional Sorbents for the Removal of Sulfur and Metallic Contaminants from High-Temperature Gases

A multi-functional sorbent is developed for the simultaneous removal of alkali vapor, toxic metal vapors, and sulfur oxides from combustion gases. The sorbent is tested in a bench-scale reactor at the 800-1000 °C temperature range, using simulated flue gas containing controlled amounts of sodium, potassium, lead, and sulfur vapor compounds. The kinetics of sorption for these contaminants, both individually and in combination, are measured. In general,the sorption process consists of adsorption followed by the diffusion of the metal in the product layer and finally reaction with the sorbent. The product layer is a porous alkali aluminosilicate in the case of alkali and a molten lead aluminosilicate in the case of lead. S0₂ reacts with the calcium sites distributed over the aluminosilicate matrix. The tailored sorbent is effective in simultaneous removal of the tested contaminants; it even shows synergistic removal in some cases.