Kinetics of high pressure and temperature sulfidation of CaO sorbents: Influence of sorbent structural properties

Experiments are performed to study kinetics of interaction of H{sub 2}S with CaO sorbent using four different CaO powders (particle diameter < 15 {micro}m) under high pressure (10 atm) and high temperature (700--900 C) conditions in a differential bed flow-through reactor. Particles of CaO are reacted with simulated coal gas containing up to 3,000 Pa of H{sub 2}S. The influence of reaction temperature, H{sub 2}S partial pressure and sorbent surface area on the extent of sulfur capture and sorbent conversion are investigated. The interaction of CaO and H{sub 2}S is analyzed using grain theory to show that at later stages of the reaction, diffusion through product layer is the controlling step. The order of sulfidation reaction with respect to H{sub 2}S partial pressure is found to be approximately 1.0 and the apparent activation energy is determined to be 16.5 kcal/mol. A strong positive effect of the sorbent initial surface area and pore volume on the sulfidation conversion is observed.