Fossil Fuels (HL Option C.2) Flashcards
How were fossil fuels formed?
Reduction of biological compounds that contained carbon, hydrogen, nitrogen, sulfur and oxygen
What is petroleum?
A mix of hydrocarbons that can be split into different component parts called fractions by fractional distillery
What are the three main fossil fuels?
Coal, Gas, Crude Oil
How are the components of crude oil separated?
Fractional Distillation
Why does fractional distillation work?
Some chains of hydrocarbons are longer than others, longer chains have stronger Van der Waals forces which influences boiling point.
What is the process of fractional distillation?
- Crude oil is heated to make it less viscous
- Oil is fed into a fractionating column with varying temperatures at different heights, low temperature is at the top
- Short-chained hydrocarbons boil, and leave the top of the column
- Substances with higher boiling points condense at the bottom of the column
What are characteristics of the hydrocarbons which leave the top of the column in fractional distillation?
Small molecules, more volatile, more flamable
What are characteristics of the hydrocarbons which leave the bottom of the column in fractional distillation?
Large molecules, less volatile, less flamable
What are the benefits of using short chained hydrocarbons as energy?
better fuels, cleaner flame
Why must the process of cracking be used?
There are more long-chained hydrocarbons in crude oil so cracking is used to make more short-chained hydrocarbon
What is the process of cracking?
Long-chained alkaline hydrocarbons are heated over a catalyst to crack them into two shorter chain alkalines
What is made when cracking Naphtha?
Naphtha is cracked to make alkenes such as ethene and alkanes such as octanes used in petrol.
Why are zeolites employed over alumina and silica catalysts?
Zeolites are more selective in producing the higher octane C5-C10 range of hydrocarbons with more branched hydrocarbons
What system for octane number is used in Europe, South Africa and Australia?
Research Octane Number (RON)
What system for octane number is used for motor sports?
Motor Octane Number (MON)
What system for octane number is used in Canada and the US?
Pump Octane Number (PON) - Average between RON and MON
What is an octane rating?
Measure of a fuels ability to resist auto-igniting
Why are higher octane fuels better than lower octane fuels?
Higher octane fuels can be compressed more and therefore give better performance
What are the harms of using toluene as a octane booster?
It is an aromatic compound and hurts the environment
How does octane rating increase?
With branching, branching resists auto ignition; aromatic compounds
How does octane rating decrease?
length of carbon chain
What is catalytic reforming?
Process used to convert low-octane numbered alkanes into higher octane isomers
What is the process of catalytic reforming?
- Straight chain alkanes are isomerized by heating with a platinum catalyst
- Products are passed over zeolite
What does isomerizing straight chain alkanes over a catalyst do?
chains break apart and reform, increasing the proportion on branched alkanes
Why is a platinum catalyst with aluminum oxide or other metal catalyst used in catalytic reforming?
reforms and dehydrogenates an alkane into a aromatic compound
Catalytic reforming is the summative effect of ____
cracking, unifying and isomerizing
What is the order from top to bottom in a fractional column in fractional distillation?
- Refinery Gas
- Gasoline (Petrol)
- Naphtha
- Kerosene
- Diesel Oil
- Fuel Oil
- Residue
What makes oxidation happen?
Adding oxygen to a compound
What are ways that fuels are made cleaner?
remove sulfur, lower environmental impact, produce alternative or blended petrochemical fuels, develop renewable and alternative resources and technologies
How is sulfur removed from fossil fuels?
scrubbing, filters and engineered compounds for sulfur compounds
What are the advatages of removing sulfur from fossil fuels?
reduces sulfur dioxide emissions that could cause acid rain, sulfur extracted coulf also be used in sulfiric acid production
How are fuels developed to have a lower environmental impact?
remove lead, benzene, sulfur; use catalytic converters in cars
What are the advantages of producing fuels with a lesser environmental impact?
reduces emissions of nitrogen oxides, carbon dioxide, and sulfur dioxde, lead oxides and carcinogenic benzines
How are alternative or blended petrochemical fuels produced?
mix ethanol with petrol, develop engines that work on liquified natural gas (LNG) or methane
What are the benefits of alternative or blended petrochemical fuels?
Reduces carbon dioxide emissions, lowers carbon footprint, reduced emissions of carbon dioxde and nitrogen oxides
What are examples of renewable and alternative fuels and technologies?
bioethanol, biodiesel, electric cars, hybrid cars, fuel cells
What are the advantages of developing renewable and alternative resources and technologies?
reduce dependance on oil, move toward carbon neutral fuels which absorb carbon dioxide as they grow, more renewable and sustainable
What is coal gasification?
process of producing coal gas by reacting coal with oxygen and steam in a gasifier to create hydrocarbons
Why is coal gasification used?
Coal is a more abundant resource than crude oil and can be converted to other useful forms cheaper than converting crude oil; leaves a relatively clean and efficient fuel; gasification produces materials that can be used in roofing materials
Inside the gasifier, what is the oxygen reaching the coal limited to?
it is limited to the combustion that will not occur
What is carbon capture and storage?
capturing carbon from industrial processes, compressing it and transporting it to be injected in rock formations at selected safe sites
What conditions must be present for coal gasification to occur?
High pressure, high temperature, corrosive slag (molten rock)
What are the products of coal gasification?
carbon monoxide and hydrogen gas
What are the by-products of coal gasification?
H2S, carbon dioxide, slag, mercury, arsenic, cadmium and selenium
What is pyrolysis (in coal gasification)?
C + H2O -> CO + H2
What is reduction (in coal gasification)?
CO + 3H2 -> CH4 + H2O
What is the clean-up stage (in coal gasification)?
C + O2 -> CO2
Desired products are cleaned up and removed, note there will be excess carbon monoxide and this is burnt in this phase
What is coal liquefaction?
method which adjusts the carbon to hydrogen ratio in the presence of a catalyst
What is the process of coal liquefaction?
filtered and cleaned synthesis gas is added to water over a catalyst
What are the two types of coal liquefaction and what is the difference between each?
Indirect coal liquefaction, direct coal liquefaction;
What is the Fischer - Tropsch process and what is it used for?
nCO + (2n + 1)H2 - catalyst -> CnH(2n+2) + nH2O
It is used to adjust the carbon hydrogen ratio and to produce liquid fuels
Do you need coal in coal gasification or coal liquefaction? If so, why is that good?
no, you can use a short chained hydrocarbon if you want the reverse reaction to occur, maybe you want the hydrogen gas for a hydrogen fuel cell!
What is a carbon footprint?
measure of the net quantity of carbon dioxide produced in a process
