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Speed Chemical Reactions

January 21, 2013

CATALYST

Due to the participation of catalyst the change in the rate of a chemical reaction is called as catalysis. A catalyst is not consumed by the reaction itself unlike the other reagents which are taking part in that chemical reaction. In multiple chemical transformations, a catalyst can take place. A positive catalyst is the one which speed up the reaction, while on other hand one which speed down the reaction is negative catalyst or inhibitors. Those substances are known as promoters that speed up the activity of a catalyst; on other hand a deactivater decreases the activity of catalyst.

Speed Chemical Reactions: Typical Mechanism

Catalytic cycle

Intermidate that subsequently give the final reaction product is formed by reaction of the catalyst with one or more reactants, catalyst is regenerated in this process. Typically reaction scheme is given in which  C represents the catalyst, X and Y are reactants, and Z is the product of the reaction of X and Y:

X + C → XC (1)

Y + XC → XYC (2)

XYC → CZ (3)

CZ → C + Z (4)

Although in first reaction catalyst is used but it is regenerated in 4th reaction,so overall reaction is as follows:

X + Y → Z

As there is regeneration of catalyst in the reaction, often to increase the rate of the reaction only small amounts are needed.

Significance of Catalysis for Speed Chemical Reactions

It is estimated that about  90% of all commercially produced chemical products in the process of their manifacture use catalysis. In 2005, about $900 billion in products produced worldwide, was generated by catalytic processes.

Energy processing

For alkylation Petroleum refining , makes intensive use of catalysis,  naphtha reforming and steam reforming (conversion of hydrocarbons into synthesis gas),catalytic cracking (breaking long-chain hydrocarbons into smaller pieces).Catalysis treat even exhaust from the fossil fuel burning:  some of the more harmful byproducts of automobile exhaust.are broken down by the catalytic converters which are  typically composed of rhodium and platinum.

2 CO + 2 NO → 2 CO2 + N2

Fischer-Tropsch synthesis of hydrocarbons from synthesis gas is s, an old but still important process  with regard to synthetic fuel, which is processed by the  water-gas shift reactions, iron acting as catalyst.

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