Ask A Scientist Chemistry Archive

name         Tim A. M.
status       educator
age          50s

Question -   How is coal turned into gasoline?
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Tim,

There are several approaches to the process to which you refer and all are far too 
complex to be contemplated by the average energy-conscious person. In one, the 
coal is simply heated in the absence of air until it breaks down into a complex 
mixture of hydrocarbons and coke. The hydrocarbon fraction (a tarry mess) can be 
fractionated into components of different volatility. Some of the hydrocarbons 
represented by one fraction correspond to molecular sizes similar to those found 
in gasoline. Of course, although coal is carbon rich, it is hydrogen poor and very 
different from petroleum. Thus, a coal gasification plant is perforce, very 
different from an oil refinery. Indeed, the U.S. has much coal. Alas, we have 
little in the way of coal-to-gasoline conversion infrastructure. Why? Because 
(short-run) it is cheaper to depend on petroleum. Is that wise? Only time will 
tell.

Regards,
ProfHoff 877
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Back in 1949, the Bureau of the Mines in Louisville, Missouri  put together a 
demonstration plant to produce gasoline from coal.  Raw coal was first crushed 
to about 3/4 inch size and then pulverized in a ball-mill  to less than 60 mesh, 
then dried to 1 or 2 percent moisture content.  This is mixed with a small 
quantity of catalyst, such as iron oxide or tin oxalate, and with a heavy oil into 
a paste containing about 47 percent solids.  Steam-driven pumps at 10,000 psi force 
this paste into a radiant-type heater in which the high pressure tubing is protected 
by a superheated jacket.  The plant was designed to work at 700 atmospheres or over 
10,000 lb. pressure, in two major steps.  This liquifies the coal and produces 
gasoline and its by-products.  The output of the plant was from 300 barrels of 
gasoline  per day depending on the coal used and the catalyst used.  Taken from 
ENCARTA 2004 by Microsoft.

I hope that this helps.

Sincerely,

Bob Trach
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