Regeneration Characteristics and Kinetics of Modified Semi-coke Supported (Fe, Zn, Ce) Desulfurization Sorbents

The effects of the regeneration temperature and sulfur dioxide concentration on the regeneration behavior of modified semi-coke supported (Fe, Zn, Ce) sorbent were investigated using a fixed bed reactor and a thermogravimetric analyzer in the present work. Regeneration kinetic studies were also performed at regeneration temperatures of 650–750 °C. The results show that the optimum regeneration temperature and SO 2 concentration are 700 °C and 12 vol %, respectively. The reaction order of regeneration with respect to SO 2 is first-order. The equivalent grain model can be effectively used to correlate with the experimental data. In the early stage of reaction ( x < 35%), the regeneration is controlled by the chemical reaction, while it is controlled by the diffusion through the product layer in the latter stage ( x > 85%). According to the model, the apparent activation energy and the corresponding frequency factor of the chemical reaction are 12.45 kJ/mol and 0.255 m/s, vs 27.08 kJ/mol and 1.05 × 10 –4 m 2 /s for the diffusion reaction. The chemical reaction, ZnS + FeS + CeS 2 + 6SO 2 → ZnFe 2 O 4 + CEO 2 + S x, for regeneration over our sorbent are obtained according to the XPS and XRD results.