Chemistry: pctane numbers and fuels

mercaptons

compounds added to hydrocarbon fuels to make tehir detection easier

catalytic cracking

converts long chain carbons to short chains

octane number

measure of a fuel to resist knocking

knocking

premature ignition

2 refrence chemicals

2,2,4 trimethylpentane
heptane

factors that influence octane numbers

chain length
degree of branching
cyclic or aromatic

improving octane numbers

catclytic cracking
isomerisation
dehydrocyclisation
additives

MTBE

methyl tetra butyl ether

additives

tetraethyl lead
benzene
oxygenates - MTBE, ethanol

other fuels

hydrogen
ethanol
biodiesel
natural gasses

steam reforming of natural gas

CH4 + H2O = CO + 3H2

elextrolysis of water

dilute H2SO4 as catalyst
hydrogen is produced at cathod
oxygen is produced at anode

advantages of hydrogen

lots of energy per kg
non-polluting
can be used in fuel cells (effectient producer of electricity)

disadvantages of hydrogen

explosive
very small molecules so explode easily
takes lots of pressure to store large amounts

biodiesel produced from

algae
Rapeseed oil
waste cookign oil