Hydrogenation chemistry Metal-free hydrogenation Hydrogen sources Substrates and catalysts Homogeneous catalysts Heterogeneous catalysts Transfer hydrogenation Electrolytic hydrogenation Thermodynamics and mechanism Inorganic substrates Industrial applications of hydrogenation chemistry Food industry Petrochemical industry Organic chemistry Hydrogenation of coal Equipment used for hydrogenation Batch hydrogenation under atmospheric conditions Batch hydrogenation at elevated temperature and/or pressure Flow hydrogenation Industrial reactors