Selective Catalytic Reduction – How NOx Reduction Make the World Go Green

With the turn of the century, there has been an increase in concern over the health of the planet. Scientist and the government work hard to try and make changes to the environment. There was a realization that without the world, there was no life and therefore, it was imperative to save the world. With nations continuing to industrialize, it has become increasingly difficult to curb the greenhouse gases and dangerous toxins that are destructive to the world.

One of those toxins is called NOx. NO is nitric oxide and NO2 is nitrogen dioxide. Both of these are components of NOx in different concentrations. Typically, people have no idea that there is NOx around because not only is it colorless, it also has no odor. Because of this, it can unwittingly be released into the environment.

There are a plethora of places that have nitrogen oxide emissions. Almost half of all these emissions come directly from automobiles. At the turn of the century, a lot of people were driving around in large, gas guzzling SUVs that did nothing more than produce an increase in these emissions.  Ironically, the economic downturn has shaped the society into a more green-friendly nation.  However, anything that uses some sort of a hydrocarbon for its gas will produce some form of NOx. Typically, most are found to be NO.

Often times, people question why this matters. They don’t appreciate the environmental concerns connected to NOx. The most important concern is the effect NOx has on the human respiratory system. NO combines with ammonia which leads to the formation of nitric acid which is an incredibly strong acid that can do a serious amount of damage to the body. Small particles get into the lungs and puncture holes in them which can lead to a potentially fatal result.

There are things that are being done to try and prevent this NOx from becoming too much of an issue. In some areas, one of the big tools being used is selective catalytic reduction. What this does in non-technical terms is create elemental nitrogen and water. Neither of these is harmful on the environment. In more technical terms, urea is used in the engine and then broken down into ammonia. The products of this reaction, after it has gone through a catalyst are those elemental nitrogen and water.

The SCR Catalyst has been shown to do a significant amount of work on the NOx reduction. However, there are other routes, as well, that can be used to try and reduce the NOx concentrations in the environment. One of these is the use of engine management which, as the name suggests, is the control of the amount of emissions in an engine. There are fewer emissions released, but then the engine runs less effectively which results in the build-up of soot.

One final method is a NOx trap which catches the NOx and then catalytically converts that stored NOx, through acts of reduction, into basic N2 and CO2. Nitrogen in its elemental form is not damaging to the environment. While CO2 can be damaging to the environment, it is not nearly as damaging as the NOx gases that are released by the automobiles. CO2 is the lesser of two evils.

What these three techniques have in common is that they all are trying to reduce the NOx levels. However, SCR catalyst is the one that has been shown to have the most effect on the reduction of NOx concentration levels. There is no concern of a lower effectiveness of the automobile and there is no need for a “lesser of two evils” approach because most of the NOx is converted into water and elemental nitrogen. The only downfall is that there needs to be some way of getting the urea into the system. If that occurs, this is definitely an effective tool.

Each technique has its ups and downs. Some work better than others (SCR), but even that has its negatives. It is important to determine what the cost to productiveness ratio is that automobile companies are willing to spend. What is too much? What is clear, though, is that the environment is not getting any stronger and if people are truly concerned about it, they need to take the necessary steps to prevent against further degradation, if that means spending a little more money, that might be the necessary course of action.