REACTIVITY OF FORMULATED METAL OXIDE SORBENTS WITH HOT HYDROGEN SULFIDE

Abstract

Three metal oxide sorbents, labeled TU-19, TU-24, and TU-25 were formulated with zinc oxide powder as an active sorbent ingredient, bentonite as a binding material, and titanium oxide as a supporting metal oxide. Equilibrium absorption of H2S into sorbents increases with concentrations of H2S. Reactivity of sorbents increases with increased reaction temperatures. Reaction rates of H2S with the sorbent increase with increased amounts of sorbents. A cylindrical rod model for a H2S-metal-oxide-sorbent reaction system was developed with experimental reaction data obtained from a constant-volume batch reactor to compute intraparticle diffusivity of H2S through sorbent matrix. An initial reaction rate equation was developed with initial experimental reaction data. Thermodynamic equilibrium constant for a heterogeneous H2S-sorbent reaction keeps H2S concentrations constant, in spite of increasing sorbent amounts in a constant-volume batch reactor. Partial pressures of hydrogen appear to affect significantly equilibrium absorption of H2S into the TU-19 sorbent at high equilibrium concentrations of H2S, while partial pressures of hydrogen appear not to affect significantly equilibrium absorption of H2S into the sorbent at low equilibrium concentrations of H2S. However, reactivity of the TU-25 sorbent with H2S in the presence of the initial 14.7-psia hydrogen is higher than that in the presence of the initial 24.7-psia hydrogen for the 1-min reaction duration.