Study of calcium-based sorbents for high-temperature H{sub 2}S removal. 2: Kinetics of H{sub 2}S sorption by calcined limestone

Journal Article · Sat Jul 01 04:00:00 EDT 1995 · Industrial and Engineering Chemistry Research

DOI:https://doi.org/10.1021/ie00046a015· OSTI ID:178393

Fenouil, L A; Lynn, S ^[1]

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1. Lawrence Berkeley Lab., CA (United States)

Samples of calcined limestone particles having a diameter of about 1 mm were exposed to simulated coal gases containing between 500 and 18,000 ppm H{sub 2}S for temperatures ranging from 560 to 1,100 C in a differential tube reactor. The formation of CaS was followed quantitatively as well as qualitatively to elucidate the reaction mechanism. Contrary to the limited conversion of CaCO{sub 3} to CaS, it was found that the limestone particles could be completely converted to CaS by 1% H{sub 2}S in about 1 h if the particles are precalcined or if the rate of calcination is higher than the rate of sulfidation. The reaction then takes place between CaO and H{sub 2}S and follows a shrinking-core mechanism. The reaction kinetics is controlled by the diffusion of H{sub 2}S through the pores of the CaS product layer formed around the lime particle (effective diffusivity between 2.8 {times} 10{sup {minus}6}and 5.1 {times} 10{sup {minus}6} m{sup 2}/s). The kinetics of the sorption of H{sub 2}S by CaO is relatively insensitive to the reaction temperature, and the reaction rate does not decrease significantly when the CaO is severely sintered for several hours at 1,050 C prior to sulfidation.

• Sponsoring Organization: USDOE
• OSTI ID: 178393
• Journal Information: Industrial and Engineering Chemistry Research, Journal Name: Industrial and Engineering Chemistry Research Journal Issue: 7 Vol. 34; ISSN IECRED; ISSN 0888-5885
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
CALCINATION
CALCIUM CARBONATES
CALCIUM OXIDES
CALCIUM SULFIDES
CHEMICAL REACTION KINETICS
CHEMISORPTION
COAL GASIFICATION
DESULFURIZATION
FUEL GAS
HYDROGEN SULFIDES
LIMESTONE
PARTICLE SIZE
SULFIDATION