From Catalyst Aging to Operational Vulnerability: A Benchmark-Validated Framework for Industrial SO2 Converters

Catalyst activity loss reduces both the performance and operating flexibility of industrial sulfur dioxide converters, yet its consequences are rarely assessed beyond conversion decline. This work develops an activity-loss vulnerability framework for a four-bed double- contact SO2 converter model evaluated against an industrial fresh-catalyst benchmark and applies it to four prescribed activity scenarios (a = 1.0, 0.8, 0.6, 0.4). At the reference inlet-temperature policy, reducing activity from a = 1.0 to a = 0.4 lowered conversion from 99.758% to 96.812%, increased outlet SO2 slip from 230 to 2960 ppmv, and raised the hotspot from 613.7 to 660.3 °C, exceeding the adopted illustrative limit of 650 °C. Sensitivity, vulnerability, hotspot-risk, and feasible-region maps show that prescribed activity loss progressively shrinks the permissible operating envelope and creates a coupled productivity–emissions–thermal-safety tradeoff. A non-uniform activity profile at the same mean activity as uniform a = 0.6 produced a hotspot 9.3 °C higher, demonstrating that average activity alone is insufficient for thermal-risk assessment. Finally, a scenario-relative Operating Efficiency Reduction Index (OERI) integrates conversion loss, SO2-slip increase, and thermal-margin loss into an illustrative scenario-screening score. The results show that catalyst activity loss should be assessed as a coupled performance, emissions, and operational-vulnerability problem rather than conversion decline alone.