No technology unlocks Coal-Coke.
I loaded into the editor, unlocked all technologies, and set a chemical plant to Coal-Coke. The recipe is disabled due to "Recipe not researched".
I checked with the only mods being Coal-Coke and SpaceAge/ElevatedRails/Quality so it's not a conflict.
The description also says coke should be a byproduct of coal liquifaction but it's not. Coal Liquifaction isn't listed as an alternate recipe in the factoriopedia, or listed as a product under the coal liquifaction recipe.
