Peak Energy by James G. Speight & James G. Speight

Author:James G. Speight & James G. Speight
Format: epub
ISBN: 9781119301400
Publisher: John Wiley & Sons, Inc.
Published: 2016-05-06T04:00:00+00:00

The initial reactants in the above reaction (i.e., CO and H2) can be produced by other reactions such as the partial combustion of a hydrocarbon:

Or by the gasification of coal or biomass:

The energy needed for this endothermic reaction of coal or biomass and steam is usually provided by (exothermic) combustion with air or oxygen. This leads to the following reaction:

The mixture of carbon monoxide and hydrogen is called synthesis gas (syngas). The resulting hydrocarbon products are refined to produce the desired synthetic fuel.

The carbon dioxide and carbon monoxide is generated by partial oxidation of coal and wood-based fuels. The utility of the process is primarily in its role in producing fluid hydrocarbons from a solid feedstock, such as coal or solid carbon-containing wastes of various types. Non-oxidative pyrolysis of the solid material produces syngas, which can be used directly as a fuel without being taken through Fischer-Tropsch transformations. If a liquid fuel, lubricant, or wax is required, the Fischer-Tropsch process can be applied successfully in the manufacture.

The liquid fuels produced in this way have several potential advantages, not the least of which is the absence of the odiferous, particle-producing aromatics. The liquid fuels formed by the Fischer-Tropsch process burn much cleaner and are environmentally more acceptable.

With respect to coal, there are several processes for the conversion of coal to gas. One in particular, the Karrick process, is a low-temperature carbonization process in which coal is heated at 360 to 749 °C (680 to 1380 °F) in the absence of air to produce oil and gas. For example, Karrick processing of 1 ton (2,000 lbs) of coal yields up to 1 barrel of coal tar (12 percent by weight, rich in lower molecular weight hydrocarbons suitable for processing into fuels), 3000 cubic feet of fuel gas (a mixture of hydrogen, carbon monoxide, methane, and other volatile hydrocarbons), and 1,500 pounds of solid smokeless char or semi-coke. Smokeless char can be used for utility boilers and cooking coal in steel smelters, yields more heat than raw coal and can be converted to water gas which, in turn, can be converted to hydrocarbon fuel by the Fischer-Tropsch process.

In the process, methanol is first made from methane (natural gas) in a series of three reactions:

Steam reforming: CH4 + H2O → CO + 3H2 ΔrH = +206 kJ/mol

Water shift reaction: CO + H2O → CO2 + H2 ΔrH = +206 kJ/mol

Methanol synthesis: 2H2 + CO → CH3OH ΔrH = –92 kJ/mol

Overall: CO2 + CO + 5 H2 → 2CH3OH + H2O + heat

The methanol is then converted to gasoline by (1) a dehydration step to produce dimethyl ether:

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