This presentation discusses the alternative reaction paths for the synthesis of hydrocarbons from coal. It identifies and discusses two major reaction paths. Process flow diagrams were used to illustrate the mechanisms of reactions.

2.  There are two major reaction paths for
Hydrocarbon production from coal. These are:
 Gasification of Coal
 CTL Technology

3.  High temperature carbonisation is the oldest process for
producing liquids from coal. Coal is heated to around
950°C in a closed container – decomposition takes place,
and the volatile matter is driven off. This is typical of the
coke making process, and the hydrocarbon liquid (coal
tar) is predominantly a by-product.
 The process produces very low yields and upgrading
costs are relatively high – so the coal tar is not
traditionally used in the transportation fuel sector. Coal
tar is used worldwide for the manufacture of roofing,
waterproofing, and insulating compounds and as raw
materials for many dyes, drugs, and paints.

4.  This process can be divided into two steps
which are:
 Pyrolysis and Hydrocracking
 Gasification and Hydrocracking

6.  Coal volatiles include all gases, tar, and light gaseous
hydrocarbons. The pyrolysis reaction occurs under
all conditions of gasification. The tar undergoes
hydrocracking and gasification reactions producing
CH4, H2, and CO. The char undergoes
hydrogasification reactions producing CH4, H2, and
CO.
 The shift conversion reaction takes place under all
conditions of gasification. Sulfur, nitrogen, and
oxygen present in coal are converted to H2S, NH3,
and organic compounds containing sulfur, nitrogen,
and water respectively.

7.  The Fischer-Tropsch process uses hydrogen (H2) and carbon-monoxide (CO) to make different types
of hydrocarbons with various H2:CO ratios
 In a CTL facility the H2 and CO can be supplied from the coal gasifier.
 The original Fischer-Tropsch process is described by the following chemical equation:
 (2n+1)H2 + nCO → CnH(2n+2) + nH2O
 The initial FT reactants in the above reaction (i.e. CO & H2) can be produced by other
reactions such as the partial combustion of a hydrocarbon or by the gasification of coal
or biomass:
 C + H2O → H2 + CO
 FT reactants can also be produced from methane in the gas to liquids process:
 CH4 + ½O2 → 2H2 + CO
 There are two main processes involved. These are:
 Coal to SynGas &
 SynGas to FT Fuels