Ru catalyzed continuous gas-phase hydrogenation of toluene – selectivity enhancement by ionic liquid coating and methanol co-feeding

Commercially available Ru/Al2O3 catalysts were modified by thin film coating with ionic liquids (SCILL). While the uncoated Ru resulted in highly active, but non-selective catalysis, the SCILL systems were less active, but significantly more selective toward the intermediate methylcyclohexene. Reaction parameter studies included the variation of the metal loading, the type of ionic liquid, inorganic and organic additives in the ionic liquid film and the addition of methanol to the feed. The latter resulted in significant increase in methylcyclohexene selectivity, improving the yield by a factor of >70 from 0.1% (uncoated) to 7.5% (ionic liquid coated, methanol addition). The cooperative effect between ionic liquid coating and methanol addition is shown.