Alkanes from Crude Oil Flashcards
What is fractional distillation?
the process in which the different fractions in the crude oil mixture are separated using boiling points as a means of separating the fractions.
what is cracking?
longer chain hydrocarbons are passed through a heated catalyst, usually zeolite, causing the large molecules to break into smaller, more useful ones.
why is cracking important?
we have less use of longer chain hydrocarbons, so cracking allows us to make more useful fuels from less used hydrocarbons which do not burn as well.
what is zeolite?
a compound of aluminium, silicon and oxygen.
what is reforming?
converting straight chained hydrocarbons into branched chained or cyclic hydrocarbons by heating them with a catalyst, usually platinum
why do need reforming?
straight chained hydrocarbons don’t burn evenly in an engine, while branched or cyclic hydrocarbons burn far more evenly
which catalyst is used in reforming?
platinum
what two products are formed in reforming?
newly arranged hydrocarbon and hydrogen
most of our energy comes from
fossil fuels
most compounds in crude oil and natural gas are
alkanes
the three main processes used to convert crude oil into fuels are
fractional distillation
cracking
reforming
crude oil is
a complex mixture of compounds, mostly hydrocarbons
the typical number of fractions obtained from crude oil is
six
fractionation is done in a
distillation column
in fractional distillation, the crude oil is first
heated until most of it turns to vapour
the column has what is called a
temperature gradient
temperature gradient in the column means
it is cooler near the top and hotter at the bottom
the vapour in the distillation column passes through a series of
bubble caps
different fractions condense at different
heights in the column
what kind of molecules collect at the bottom of the distillation column?
longer chained molecules with higher boiling temperatures
near the top of the distillation column, …….and…………molecules collect
smaller and shorter chained molecules collect
some hydrocarbons in crude oil are
gases, so do not condense in the distillation column
some fractions may contain different
compounds, so may undergo further distillation
