The organic side Flashcards
What is the limit of sulfur content found in Canadian gasoline?
40ppm
The majority of refined petroleum is used in?
Motor gasoline
What are the 3 rules for predicting octane number?
- Higher branching or amount of rings gives higher octane number
- Increasing multiple bonds increases octane number
- aromatics, alkenes, alkynes > cyclic and branched alkanes > straight chain alkanes
Combustion is a what type of reaction?
A radical reaction
What are the three main steps used to increase and refine petroleum?
- Hydrotreating
- Catalytic cracking or thermal cracking
- Catalytic reforming
What happens in ‘hydrotreating’? What catalyst does hydrotreating use?
In hydrotreating, the amount of sulfur and nitrogen gets reduced - however a reduction in octane number for some of the hydrocarbons cannot be prevented.
The catalyst used in hydrotreating is cobalt or nickel oxide over molybdenum catalyst.
What does catalytic cracking do? What is the catalyst used in catalytic cracking?
Catalytic cracking breaks down long hydrocarbon chains into smaller ones. Hydrocarbons also rearrange due to their differences in radical stabilities. Catalytic cracking uses a silica - alumina catalyst (SiO2 - Al2O23)
What is the difference between catalytic and thermal cracking?
Thermal cracking does not involve a catalyst, but gives a higher yield of C2, C3 & C4 olefins (and BTX) - these chemicals are needed in the chemical industry. ‘Beta - scissons’ occur in thermal cracking - and produces ethane.
What happens in catalytic reforming and what catalyst does catalytic reforming use?
Catalytic reforming increases the amount of double bonds in a hydrocarbon without changing the amount of carbons - this is done by 1,2 methyl and 1,2 H shifts. The catalyst used in catalytic reforming is platinum and/or rhenium (Re) on alumina.
What acts as the Lewis acid in catalytic reforming?
The alumina.
Where can we find methane?
97% of methane is in natural gas and 85% is in ‘typical’ natural gas
What are the 4 steps when refining methane?
- Dehydration
- Elimination of hydrogen sulfide and carbon dioxide
- Dissolution of the higher boiling point gas
- Fractional distillation which separates out the methane, ethane, propane, n - butane and isobutane
How is ethylene made?
By thermal cracking (thermal cracking requires no catalyst).
During the synthesis of ethylene, what is used to inhibit “coking” (coal forming) and to increase the amount of ethylene made?
Steam.
What is the main use of ethylene? Name two other polymers made from ethylene.
To make polyethylene - a plastic. Polyvinyl - chloride and styrene.
What is the main and minor way that propylene is made?
The main way propylene is made is by thermal cracking. The minor way pure propylene is made is by steam cracking - which is used in chemical manufacture.
What is propylene mainly used for? Name two other chemicals made from propylene.
To make polypropylene - a plastic used in films, containers, packaging, etc. Acrylonitrile and cumene.
C4 composition #1, 3 butadiene. What are the two steps in making 1,3 butadiene?
- Dehydrogenation
2. Extraction distillation
What is the catalyst used in the dehydrogenation step when making 1, 3 butadiene?
Fe2O3
How does 1, 3 butadiene get extracted in the ‘extraction distillation’ steps (3 steps)?
- The crude mixture is extracted with acetone since the pi bonds are more polar than the saturated hydrocarbons (gets rid of butane).
- A non volatile solvent that mixes well with 1, 3 butadiene is added to change the volatility of 1, 3 butadiene.
- 1, 3 butadiene is then extracted by conventional distillation.
What is the main use of 1,3 butadiene?
To make styrene - butadiene rubber.
What is the main use of isobutylene?
For alkylation or polymerization of gasoline.
Why are there 2 ways of forming isobutylene?
The first way just makes isobutylene and the second way makes isobutylene and gives off useful side products. < be able to draw out those two reactions>
What does BTX stand for?
Benzene, toluene and xylene.