Human impact, especially in form of environmental pollution, is considered to be one of the major causes of global climate change. Several nations have come together to reduce carbon footprint and release of other toxic substances in the air.
However, this struggle did not begin recently. In fact, a number of steps have been taken to reduce environmental pollution to prevent negative impact on both climate change and human health.
Treating exhaust is one prominent application of catalysts.
Catalytic converters
Catalytic converters are simple devices which perform a very complex function. They prevent the toxic gases and other pollutants from being released into the air and contaminating it.
These are mostly used as emission control devices that catalyze a redox reaction. Redox reactions, the simultaneous reduction and oxidation of reactants, result in conversion of harmful materials into less harmful substances.
Other than exhaust systems, these catalytic converters are used in electrical generators and other systems.
How does the conversion occur?
In essence, these converters change three major harmful components of exhaust; hydrocarbons, carbon monoxide and nitrogen oxide into less harmful carbon dioxide, oxygen, nitrogen and water.
These converters utilize expensive transition metal catalysts to enhance the reaction rate. Catalysts such as platinum and palladium are the ones most often used.
Catalysts
Platinum works as a catalyst for both reduction and oxidation reactions. While platinum is preferred in most reactions, it may not be used in certain applications due to higher reactivity and considerably higher costs.
Palladium and rhodium are also metal catalysts that can be used in place of platinum. Palladium is an oxidation catalyst while rhodium is a reduction catalyst. Nickel, iron, manganese and cerium also have limited usage.
Process
The catalysts are deposited over a ceramic honeycomb as thin layers exposed to the reactants. This allows a greater surface area, enhancing reaction while using the minimum amount of catalysts.
A typical reaction looks like this:
Pt/Pd/Rh
2CO + 2NO 2CO2 + N2
Enhancing catalysis by transition metals
Although transition metals are efficient in enhancing the reaction rate, these are often also supplemented with phosphine ligands. This is particularly true for reactions where organic synthesis have to take place by the formation of C-C, C-N and C-O bonds.
A number of such ligands and several other catalysts are offered by Watson International, a fine chemical company. A list of these catalysts can be viewed and ordered here.
A few prominent ones include:
- 2-diphenylphosphinobenzaldehyde: http://watson-int.com/2-diphenylphosphinobenzaldehyde-cas-50777-76-9-3/
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