Catalytic cracking uses a temperature of approximately 550°C and a catalyst known as a zeolite which contains aluminium oxide and silicon oxide. Steam cracking uses a higher temperature of over 800°C and no catalyst.
What are two conditions for cracking?
Thermal cracking uses harsh conditions like high temperature and high pressure . It breaks the alkanes into a high percentage of alkenes and comparatively few alkanes. Thermal cracking is done at about 1,000 degrees Celcius and 70 atm pressure.
What are the conditions for thermal cracking?
In thermal cracking, high temperatures (typically in the range of 450 °C to 750 °C) and pressures (up to about 70 atmospheres) are used to break the large hydrocarbons into smaller ones. Thermal cracking gives mixtures of products containing high proportions of hydrocarbons with double bonds – alkenes.
How does cracking occur?
Cracking, in petroleum refining, the process by which heavy hydrocarbon molecules are broken up into lighter molecules by means of heat and usually pressure and sometimes catalysts . Cracking is the most important process for the commercial production of gasoline and diesel fuel.
What temperature is thermal cracking?
Thermal cracking (pyrolysis) involves the degradation of polymeric materials by heating in the absence of oxygen and is usually conducted between 350°C and 900°C (650°F and 1650°F) .
Why is broken porcelain used in cracking?
As the porcelain chips are heated the vapour from the paraffin is ‘cracked’, or broken down into smaller hydrocarbons . ... Cracking them into smaller hydrocarbons makes them easier to use.
What is the difference between thermal cracking and catalytic cracking?
The main difference between thermal cracking and catalytic cracking is that thermal cracking uses heat energy for the breakdown of compounds whereas catalytic cracking involves a catalyst to obtain products.
Why is cracking in air absent?
Answer: In the absence of air, steam and raw material are mixed and heated to temperatures around 800oC inside a furnace. ... Carbon dioxide and hydrogen sulfide are unwanted byproducts of thermal cracking. These gases must be removed before they escape into the atmosphere by reaction with sodium hydroxide solution.
Why is catalytic cracking better than thermal cracking?
Catalytic cracking produces less cracked residuum and more of the useful gas oils (which can be used as hydrocracker feedstocks) than thermal cracking. ... Catalytic cracking produces less residuum and more of the useful gas oil constituents than thermal cracking.
Is thermal cracking the same as steam cracking?
Thermal cracking is currently used to “upgrade” very heavy fractions or to produce light fractions or distillates, burner fuel and/or petroleum coke. Two extremes of the thermal cracking in terms of the product range are represented by the high-temperature process called “steam cracking” or pyrolysis (ca.
Can alkenes be cracked?
Cracking is a reaction in which larger saturated hydrocarbon molecules are broken down into smaller, more useful hydrocarbon molecules, some of which are unsaturated: the products of cracking include alkanes and alkenes , members of a different homologous series.
What causes the house to crack?
In the vast majority of cases, cracks in houses are caused when the soil underneath the house starts to dry and contract , causing the footing of the house to shift unevenly, which leads the walls to move and crack.
How big is a hairline crack?
Size of cracks
0 – Hairline cracks: Less than 0.1 mm in width . No repair action required. 1 – Fine cracks: Up to 1 mm in width. Generally restricted to internal wall finishes.
What are the advantages of thermal cracking?
There are many benefits of thermal cracking such as: It can be carried out on all longer carbon chains. Has a very high yield of short chain alkenes (mainly ethene)
What are the products of cracking?
The products of cracking include alkanes and alkenes , members of a different homologous series . An alkene is a hydrocarbon that contains a carbon-carbon double bond.
Why do you use mineral wool in cracking?
You are going to crack (thermally decompose) the longer-chain alkanes in liquid paraffin to produce shorter-chain alkanes and alkenes. You will need to work with a partner. A Put some mineral wool in the sealed end of a boiling tube. ... This provides a larger hot surface for the decomposition to take place on.
