What are the methods for catalyst regeneration?

Methods depend on deactivation mechanism: Coke removal - controlled oxidation (burn coke with dilute O2 at elevated temperature), steam stripping, or hydrogen treating. Poison removal - washing or chemical treatment (remove sulfur by oxidation and washing). Redispersion - controlled oxidation-reduction cycles restore metal dispersion. Chlorination may restore acidity in zeolites. In-situ vs ex-situ regeneration depends on process constraints. FCC uses continuous regeneration in separate vessel; fixed beds use periodic regeneration cycles or swing reactors.