The hydrogen presumably reacts with free radicals generated by the coal decomposition
to stabilize them and prevent further cracking, which would lead to gas formation.
Free radical coupling, which leads to coke formation, is also prevented.
The naphthalene produced is rehydrogenated to tetralin.
The same technique can be used on heavy crude oils and on residues from crude oil distillation.
The cheap petroleum of the late 1980s argued against commercialization of this process.
There are thus three routes from coal to petroleum-like fuels.
The Fischer–Tropsch and Mobil processes are more attractive than the Bergius process.
Whether or not coal ever becomes a raw material for petroleum-like fuels on a world scale depends on the severity of the petroleum shortage, the available of the huge capital investment required, and the feasibility of various other possible sources of energy such as nuclear fission, nuclear fusion or renewables.