Efficient and labor-saving Ru/C catalysts for the transformation of levulinic acid into γ-valerolactone under mild reaction conditions

Abstract

Ru/C catalysts for the transformation of levulinic acid into gamma-valerolactone have been prepared using carbon materials with different textural and chemical properties, and morphology. In the mild reaction conditions used (70 °C, 15 bar H₂, 1 h), all the reduced catalysts are active and selective, with similar behavior independently of the support's properties. Surprisingly, the un-reduced (as prepared) catalysts show also catalytic activity, which varies (from moderate to high) with the carbon support type, indicating that an in situ (under reaction) reduction process takes place. The catalysts prepared with the supports of lower surface chemistry are almost as active as their reduced counterparts, whereas those prepared with rich surface chemistry supports are noticeably less active, but become activated in consecutive runs. The size of the developed Ru particles depends on the reduction conditions (i.e., reduction treatment at 250 °C or reaction conditions) and is highly influenced by the support's surface chemistry, which determines the metal–support interaction.