Three-Way Catalyst

Products

Catalytic Converters for Off-Road

Catalytic Mufflers for Off-Road

Catalytic Converters and Silencers for Stationary Engines (Below 700hp)

Catalytic Converters and Silencers for Stationary Engines (Above 700hp)

Catalytic Converters and Mufflers for On-Road

 

The three-way catalyst is used in rich-burn or stoichiometric engines for simultaneous conversion of oxides of nitrogen (NOx), carbon monoxide (CO), hydrocarbons (HC), formaldehyde (CH2O) and EPA classified Hazardous Air Pollutants (HAPs). The three-way catalyst is effective in a wide variety of engine applications and fuels, including natural gas, propane and gasoline. A closed loop air-fuel ratio controller is required for the three-way catalyst to work effectively.

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Typical Conversion Efficiencies
NOx CO HC CH2O HAPs
90-99% 90-99% 50-90% 80-95% 80-95%


Reactions

Oxidation reactions with O2:

CO + ½ O2 → CO2

HC + ½ O2 → CO2 + H2O

HC + ½ O2 → CO + H2O

H2 + ½ O2 → H2O
Oxidation/reduction reactions with NO:

CO + NO → ½ N2 + CO2

HC + NO → N2+ H2O + CO2

HC + NO → N2 + H2O + CO

H2 + NO → ½ N2 + H2O

H2 + 2 NO → N2O + H2O

5/2 H2 + NO → NH3 + H2O

2 NO + 2 NH3 + ½ O2 → 2N2 + 3 H2O
Water-gas shift reaction:

CO + H2O → CO2 + H2
Reforming reactions:

HC + H2O → CO2 + H2

HC + H2O → CO + H2