SCR and SNCR
Catalyst regeneration vs replacement
Also known as catalyst regeneration, SCR catalyst replacement, catalyst recycling.
Catalyst regeneration is the off-site process of removing accumulated masking deposits and reversing partial poisoning from used SCR catalyst modules, restoring activity to 80–95% of fresh-catalyst performance. Major service providers (CORMETECH, MHPS / Mitsubishi Power, STEAG / SCR-Tech) operate dedicated facilities. Catalyst replacement is the alternative — install a fresh layer, discard or recycle the spent one.
Economic comparison
| Option | Cost vs new (typical) | Performance recovery | Downtime |
|---|---|---|---|
| Regeneration | 30–40% of new | 80–95% of fresh activity | Few weeks (round-trip + change-out) |
| Replacement (new) | 100% reference | 100% | Layer change-out only |
| Skip change-out | 0% | Continuing decay | None until permit excursion |
For a large coal-fired or WtE SCR with 100–300 m³ of catalyst, regeneration typically saves USD 0.5–2 million per layer cycle.
Where regeneration falls short
- Severely poisoned catalyst (heavy arsenic, alkali, phosphorus) cannot be fully restored
- Physical damage (broken modules, eroded channels) is not reversible
- Layers that have already been regenerated twice tend not to support a third cycle
Where active cleaning fits
Sonic horns and steam sootblowing defer the need for either regeneration or replacement by keeping masking under control during operation. A catalyst kept clean from the start lasts 30–50% longer before needing service.
Related terms
Related terms
- Selective Catalytic ReductionSCR is the dominant NOx-control technology on industrial combustion plant. Ammonia is injected upstream of a catalyst that converts NOx to nitrogen and water.
- Catalyst poisoningCatalyst poisoning is the chemical binding of trace species (arsenic, alkali metals, phosphorus, sulphur) to SCR active sites. Usually irreversible — the catalyst layer must be replaced.
- Catalyst maskingCatalyst masking is the deposition of a thin ash layer on the SCR catalyst face that blocks ammonia and NOx from reaching the active sites. Distinct from pluggage and poisoning.
- Catalyst layer and moduleAn SCR catalyst module is a steel-framed cassette holding multiple catalyst elements. Modules are stacked into layers; layers are stacked into the SCR reactor.