CO Oxidation Catalyst Selection: Precious Metal vs Base Metal
Part of the CO Oxidation: The Complete Guide — this article is one of the detailed pages in the guide.
Direct answer: CO oxidation catalyst selection balances operating temperature, gas composition and budget. Precious-metal catalysts (Pt, Pd) win at low temperature and high activity density; base-metal (hopcalite-type) systems cost less and tolerate some poisons differently, but generally need higher temperatures. The deciding factors are the light-off requirement, the presence of SO₂ and moisture, and whether the duty is continuous or intermittent.
Where CO oxidation is needed
CO oxidation catalysts serve industries where carbon monoxide is generated incompletely or must be destroyed:
- Sintering plants and pelletizing lines
- Waste incineration and medical waste treatment
- Industrial furnaces, kilns and dryers
- Catalytic combustion tail gas
- Underground and enclosed-space CO removal
- Emergency CO abatement systems
The two catalyst families
| Property | Precious metal (Pt / Pd) | Base metal (Mn-Cu, hopcalite type) |
|---|---|---|
| Light-off temperature | Lower, typically from ~150°C | Higher, commonly 200°C+ |
| Activity density | High | Moderate |
| SO₂ tolerance | Sensitive to poisoning | Also sensitive; support choice matters |
| Moisture effect | Manageable with formulation | Can deactivate; formulation matters |
| Cost | Higher | Lower |
| Thermal stability | Good | More limited at high temperature |
The four selection questions
What is the minimum operating temperature? If the gas can dip below ~180°C, a precious-metal system with a low light-off is usually required. If the stream is stably above 250°C, both families are candidates.
Is SO₂ present? Sulfur oxides poison precious metals. Where SO₂ is unavoidable, the catalyst must be sized with margin or a sulfur-tolerant formulation selected. Base-metal catalysts are not automatically better — the answer depends on the specific system.
Is moisture high? Water competes for active sites at low temperature. Combined low temperature + high humidity + SO₂ is the hardest duty class and demands conservative sizing.
Continuous or intermittent? Intermittent duty (emergency systems, batch vents) must light off quickly after cold start — favouring low light-off precious-metal catalysts and possibly electric pre-heating.
Forms and substrates
- Honeycomb — low pressure drop, the default for high-flow continuous duty.
- Granular / pellet — for packed beds where higher bed depth or repacking flexibility is wanted.
- Heating tube systems — catalyst paired with electric heating for intermittent or low-temperature streams that need temperature boosting.
Manufacturer perspective
The most common sizing mistake is selecting on CO concentration alone. We ask for the full stream — CO, O₂, moisture, SO₂, temperature range, flow and duty pattern — because a catalyst that lights off at 150°C in dry clean gas may never light off in the real stream.
Related articles
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