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Alkane vapours travel over red-hot metal in the absence of oxygen, resulting in the breakdown of the compound into simpler hydrocarbons.
There is no catalyst used in this process, which takes place at extremely high temperatures and pressures.
Because of the low temperatures and pressures involved in this reaction, the presence of a catalyst such as platinum or palladium is essential to complete it.
It is commonly accepted that the big hydrocarbons are obtained during the fractional distillation of crude oil (petroleum).
Cracking is the process through which hydrocarbon molecules randomly break apart into smaller hydrocarbon molecules.
Double bonds between carbon and carbon are found in several of the chemicals produced by cracking.
Pyrolysis
It is the thermal degradation of materials at high temperatures in an inert atmosphere that is referred to as pyrolysis (or devolatilization).
It is characterised by a shift in chemical composition. pyrolysis is derived from the Greek components pyro, which means fire, heat, fever, and lysis, which means separating.
When it comes to the treatment of organic materials, pyrolysis is the most widely utilised method.
It is one of the processes that take place during the charring of wood.
In general, pyrolysis of organic compounds results in the formation of volatile chemicals and the formation of char, a carbon-rich solid residue.
Carbonization is the term used to describe extreme pyrolysis that results in a primarily carbon-based residue.
Pyrolysis is regarded as the first step in the processes of gasification and combustion, respectively.
For example, the method is widely used in the chemical industry to manufacture ethylene, numerous types of carbon, and other compounds from petroleum, coal, and even wood, as well as to produce coke from coal, among other things.
It is also employed in the conversion of natural gas (mainly methane) into non-polluting hydrogen gas and non-polluting solid carbon char, which has just recently become commercially viable on an industrial level.
Aspirational applications of pyrolysis would turn biomass into syngas and biochar, waste plastics back into useful oil, and garbage into substances that could be disposed of securely in landfills.
The Following are the Factors that Influence the Development of Products during Cracking:
- Chemical nature of Alkanes
- Temperature and pressure are important factors to consider.
- The presence or absence of a catalyst is a condition.
Pyrolysis of Alkanes is a chemical reaction that occurs when alkanes are heated
When compared to combustion, the rate of pyrolysis increases with the increase in the molecular weight and branching of an alkane, whereas the rate of combustion decreases.
The fission of C-C bonds results in the formation of alkanes and alkenes, whereas the fission of C-H bonds results in the formation of alkenes and hydrogen.
C-H bond fission happens as a result of the catalytic action of Cr2O3, V2O3, and MoO3, while C-C bond fission occurs as a result of the presence of SiO2, Al2O3, and ZnO in the presence of the catalysts Cr2O3, V2O3, and MoO3.
The cracking of alkanes is caused by the action of free radicals.
It is critical in the petroleum industry’s development and growth.
Cracking is the process by which higher-molecular alkanes are converted into lower-molecular alkanes (petrol C6 to C11).
For example, heating dodecane (a component of kerosene oil) to 973 degrees Celsius under the catalytic action of platinum, palladium, or nickel results in the formation of a mixture of heptane and pentane as pyrolysis products.
Cracking
As described by the International Chemical Industry Organisation, cracking is defined as a process in which complex organic compounds, such as long chain hydrocarbons or kerogens, are broken down into smaller molecules, such as light hydrocarbons.
The breakdown of carbon-carbon bonds is the cause of this phenomenon. Several parameters, such as the presence of catalyst and temperature, have a significant impact on the pace of catalyst formation.
The cracking of hydrocarbons is depicted in the diagram below.
This technique is utilised in the manufacturing of gasoline, diesel, and other fuels in the petroleum refining industry.
In chemistry, it is the process of breaking down a big alkane into smaller alkenes and alkanes that are more easily digestible.
Additionally, breaking down a complex long chain of hydrocarbons into smaller ones is part of the cracking process for oil and natural gas.
Cracking can be classified into several categories
Fluid catalytic cracking (FCC) is a process that is mostly employed in petroleum refineries.
A high molecular weight, high boiling hydrocarbon is converted into olefinic, gases, gasoline, and other products by this method.
Hydro cracking is a catalytic cracking method in which hydro cracking is used to break C–C bonds in order to produce a product.
Diesel, jet fuel, and LPG are among the products that can be made using this technique.
Hydrocarbons are broken down into smaller unsaturated hydrocarbons through the process of steam cracking, which is a petrochemical process.
Thermal cracking is a process that involves the conversion of large non-volatile hydrocarbons into gasoline through the use of heat.
Conclusion
When compared to combustion, the rate of pyrolysis increases with the increase in molecular weight and branching in an alkane, whereas combustion does not.
Alkenes and alkanes are created through the fission of C-C bonds, whereas hydrogen and alkene are produced during the fission of C-H bonds.
The C-H bond fission happens as a result of the catalytic action of V2O2, Cr2O3, and MoO3, while the C-C bond fission occurs as a result of the presence of Al2O3, ZnO, and SiO2 in the reaction.
The cracking of alkanes occurs as a result of a mechanism known as the free radical mechanism.
It is critical in the petroleum industry’s operations.
Cracking is the process by which the higher molecules of an alkane are changed into the lower molecules (i.e., from petrol C6 to C11).
For example, when Dodecane (a component of kerosene oil) is heated to 973 degrees Celsius under the catalytic action of palladium, nickel, or platinum, it transforms into a combination of pentane and heptane as Pyrolysis products.
