title: Hydrogen-donor solvent
text: # Hydrogen-donor solvent
  
  A hydrogen-donor solvent is hydrocarbon that transfers hydrogen to hydrogen-poor substrates, such as coal. The hydrogen-poor substrates could be a solute or suspension. The classic hydrogen-donor solvent (or just donor solvent) is tetrahydronaphthalene, which converts to naphthalene by transfer of two equivalents of $H_2$ to the substrate. The enthalpy of hydrogenation of naphthalene is relatively low, which allows the tetrahydronaphthalene to be regenerated in the presence of high pressure $H_2.$ Catalysts are often used, such as molybdenum disulfide. Related hydrogen donor solvents or solvent components are dihydrophenanthrene and tetrahydroquinoline.
  
  