Ru-MOF enwrapped by montmorillonite for catalyzing benzene hydrogenation

• Metal–organic frameworks of ruthenium were for the first time grown on montmorillonite.
• The Ru-MOF is able to enlarge surface area of the composite materials.
• Coordinatively unsaturated sites (CUS) are produced after H2-annealing.
• The CUS are readily preserved by clay layers and can sustain harsh reactions.
• The hybrid was highly active in catalyzing reactions of benzene hydrogenation.

In this work, the metal–organic frameworks of ruthenium [Ru2II,III(BTC)2XxY1.5 − x] (BTC = 1,3,5-benzenetri-carboxylate, X, Y = Cl− or OH−, termed as Ru-MOFs) that are grown on montmorillonite (Mt) in a solvothermal reaction, and a type of composite materials (Ru-MOF_Mt) with open channels have been fabricated. Due to the high pore volume, the Ru-MOF particles are found to greatly enlarge the surface area of the hybrid material. To activate the metal centers in the Ru-MOF, the hybrids are annealed in a flow of H2 at mid-level temperatures (~ 300 °C). With this H2-annealing treatment the frameworks are found to be partly decomposed, and the coordinatively unsaturated sites (CUS) are produced. The annealed Ru-MOF_Mt is highly efficient in catalyzing reactions of benzene hydrogenation. The turn-over frequency (TOF) of benzene to hexane reaches 3478 h− 1. This catalyst is able to be reused at least five times without any de-activation demonstrating that the CUS are readily protected by the Mt layers.

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