Abstract: This disclosure describes systems, methods, and devices related to for estimating the end-of-life of a furnace catalyst bed. A method may include extracting first measurements of a furnace catalyst bed; determining time-period averages of the extracted first measurements of the furnace catalyst bed over multiple time periods; determining a catalyst activity indicative of an efficiency of a selective reduction catalyst in reducing NOx concentrations for the furnace catalyst bed at a first time; generating a first linear regression of the catalyst activity based on averages of the multiple time periods; and generating a health score of the furnace catalyst bed at a second time based on the first linear regression, the health score indicative of an estimated end-of-life of the furnace catalyst bed.