Function of catalytic converter

 

A catalytic converter is a device used in the exhaust system of vehicles to reduce harmful emissions. It converts toxic gases from engine combustion into less harmful substances before they exit the exhaust pipe.

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🔧 Working Principle of Catalytic Converter

🔥 Step-by-Step Process:

1. Exhaust Gas Enters
   The exhaust gases (from engine combustion) enter the catalytic converter. These gases typically include:

   • Carbon Monoxide (CO)
   • Hydrocarbons (HC)
   • Nitrogen Oxides (NOx)

2. Catalyst Reaction Chamber
   Inside the catalytic converter, there’s a ceramic or metal honeycomb structure coated with catalyst metals like Platinum (Pt), Palladium (Pd), and Rhodium (Rh).

3. Redox Reactions
   The catalyst facilitates chemical reactions without being consumed:

   • ✅ Oxidation Reaction:

     • CO → CO₂ (Carbon monoxide to carbon dioxide)
     • HC → CO₂ + H₂O (Hydrocarbons to carbon dioxide and water)

   • ✅ Reduction Reaction:

     • NOx → N₂ + O₂ (Nitrogen oxides to nitrogen and oxygen)

4. Cleaner Exhaust Out
   The result is a much cleaner exhaust, mainly consisting of:

   • Nitrogen (N₂)
   • Carbon dioxide (CO₂)
   • Water vapor (H₂O)

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📘 Diagram (Text Representation):

 [Engine Exhaust] 
     ↓
 [Catalytic Converter]
 ┌────────────────────┐
 │  Platinum, Palladium│
 │   and Rhodium Coated│
 │     Honeycomb       │
 └────────────────────┘
     ↓
[Clean Gases Out]
(N₂, CO₂, H₂O)

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⚙️ Types of Catalytic Converters:

1. Two-Way Catalytic Converter (used in older petrol engines)
2. Three-Way Catalytic Converter (modern vehicles; removes NOx also)

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🛑 Important Notes:

• Requires high temperature (~400–800°C) to operate efficiently.
• Unleaded fuel only – lead damages the catalyst.
• Faulty oxygen sensors or rich fuel mixtures can reduce its efficiency.