Lean N0x Trap (LNT)

 Lean N0x Trap (LNT)

This is a kind of catalytic which control vehicles emissions system of the engine exhaust gases whether its petrol and diesel engines. This is a device Especially, to reducing  Nitrogen oxide (N0x) emission emitting from exhaust gases.

It all about making clean air environmental technology.The removal of N0x from lean exhaust great challenge to the automobile industry. 

 vehicles exhaust emission, for the N0x emissions control solution like Selective Catalyst Reduction (SCR) and Lean N0x Trap (LNT) both technologies, was developed by the automaker companies. Vehicles emit pollutants gases very much problem for the environment and human health. SCR or LNT catalysts it's both technologies for reducing nitrogen oxides (N0x) emissions on diesel engines. 

The main purpose of the Lean N0x Trap (LNT) catalysts is to reduce nitrogen oxide (N0x) from the engine exhaust gas.LNT catalyst very much similar to the three-way catalytic converter but it works differently. LNT catalysts system consisting three-segment, first one input side is the oxidation reaction process is done. This catalyst coated with precious metal platinum (Pt). Second segment absorber and stored N0x during lean mixture operation and when the engine turns the rich mixture operation. The conversion process occurs on the LNT catalysts, N0x gases trapped or captured and stored. A rich mixture ratio of the absorbed barium nitrate is released from the trap as barium oxide, in the presence of a reduction catalyst. Under the rich mixture conditions, the nitrogen oxide is reduced to N2 over the reduction catalysts. The Nitrogen oxide (N0x) is converted into nitrogen N2. 

LNT catalyst technology is only considered for a smaller car up to 1000 CC or 0.1-litre engines. The LNT catalyst that much cheaper than a urea solution selective catalyst reduction (SCR) technology system. According to Bharat Stage vehicle emission norms, BS-VI norms regulate toxic gases mainly nitrogen oxide (N0x) emits from vehicles. That why all automakers major changes their engine exhaust system, most of the vehicles adopted SCR catalysts technology on the commercial as well as light passengers cars in diesel engines. The LNT system one of the alternative options for micro or smaller cars. The main drawback is not able completely to neutralise emissions of Nitrogen oxide (N0x).LNT technology is considered as the after-treatment solution to reduce N0x emission from lean-burn or diesel engines.

N0x emissions control solution during a chemical reaction:

These are reactions taking place on Lean N0x Trap (LNT) catalysts, first during lean mixture operation. N0x converts nitrogen, the nitrogen dioxide react with Barium carbonate to form barium, nitrate and carbon dioxide, then it will react with carbon monoxide (CO) and hydrocarbon (HC) to produce, carbon monoxide free nitrogen and barium nitrate just like the initial stage.

LNT Conversion process during engine operation:

Lean mixture operations condition 

• N0x becomes N02 
• N02 react with BaCo3 to form BaN03 and CO2 

Rich mixture operation condition 

• BaN03  react with C0 and HC become C02, N2 and BaCo3.