3. Hydrogen management

It is essentially the very low H/C atomic ratio that differentiates coal from other fossil fuels (table 10 ). Gasoline and conventional petroleum contain between 1.5 and 2 hydrogen atoms per carbon atom, while lignite contains only 0.85 and anthracite 0.4, with bituminous and sub-bituminous coals in between. This hydrogen is introduced throughout the process chain, first in the liquefaction unit, then in the hydrotreating unit, where the volume consumed depends almost directly on the gains in density and cetane required from the diesel cut via the aromatic hydrogenation and naphthenic hydrocracking reactions. This hydrogen consumption has a major impact on the efficiency of the liquefaction plant when it is produced from coal (the only possible solution in the absence of a natural gas source), due to the low hydrogen yield inherent...