The kinetics of the reaction of hydrogen chloride with fresh and spent Ca-based desulfurization sorbents

Abstract

The absorption of hydrogen chloride by spent desulfurization sorbents containing calcium carbonate, calcium oxide and calcium hydroxide was investigated. The experiments were carried out in a fixed-bed reactor in two temperature ranges: 423–523 K for slaked lime and 673–873 K for limestone and quicklime. The spent Ca-based sorbents can still react with hydrogen chloride, and after calcining and slaking they even show the same reactivity as pure Ca(OH) 2. A model combining both fixed-bed reactor and shrinking-core model was derived. The activation energy of the surface reaction between hydrogen chloride and limestone was determined to be 84 kJ mol −1 at 673–873 K. The pore diffusion activation energy was 11 kJ mol −1 for limestone at 673–873 K, 29 kJ mol −1 for CaO at 673–873 K and 12 kJ mol −1 for slaked lime at 423–523 K.