Kinetic Studies on the Regeneration of Modified Semi-Coke Supported (Fe, Zn, Ce) Desulfurization Sorbent

Abstract

In this manuscript, the effects of the regeneration temperature and oxygen 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. Sulfate formed through side reactions was inferred from TGA curves and it can be reduced by increasing the regeneration temperature. The reasonable regeneration conditions must avoid the sulfate formation. Regeneration kinetic studies were also performed at regeneration temperatures ranging from 500°C to 700°C. The results show that the regeneration rate can be improved by increasing the oxygen concentration and regeneration temperature. The reaction order of regeneration with respect to O2 can reasonably be assumed to be first-order. The kinetic model tests show that the shrinking core model can be used to correlate with the experimental data. The regeneration is controlled by the chemical reaction in the early stage of reaction (x＜80%) and by the diffusion through the product layer at the latter stage (x>85%). According to the model, the apparent activation energy of chemical reaction and the corresponding frequency factor are 16.66kJ/mol and 0.132m/s, respectively, and the diffusion activation energy and the corresponding frequency factor are 52.91kJ/mol and 6.63×10-5m2/s, respectively.