Recyclable Rh-PVP nanoparticles catalyzed hydrogenation of benzoic acid derivatives and quinolines under solvent-free conditions

A Ru/RuO2 heterostructure boosting electrochemistry-assisted selective benzoic acid hydrogenation

Electrocatalytic hydrogenation of benzoic acid (BA) to cyclohexanecarboxylic acid (CCA) at ambient temperature and pressure has been recognized as a promising alternative to thermal hydrogenation since water is required as the hydrogen source. So far, only a few Pt-based electrocatalysts have been developed in acidic electrolyte. To overcome the limitations of reactant solubility and catalyst corrosion, herein, carbon fiber-supported Ru electrocatalysts with abundant Ru/RuO2 heterojunctions were fabricated via cyclic electrodeposition between -0.8 and 1.1 V vs. Ag/AgCl. In an alkaline environment, a Ru/RuO2 catalyst achieves an excellent ECH reactivity in terms of high BA conversion (100%) and selectivity towards CCA (100%) within 180 min at a current density of 200/3 mA cm-2, showing exceptional reusability and long-term stability. 1-Cyclohexenecarboxylic acid (CEA) was identified as the reaction intermediate, whose the selectivity is governed by the applied potential. Kinetic studies demonstrate that ECH of BA over Ru/RuO2 follows a Langmuir-Hinshelwood (L-H) mechanism. In situ Raman spectroscopy and theoretical calculations reveal that the Ru/RuO2 interface enhances the adsorption strength of CEA, thereby facilitating the production of fully hydrogenated CCA. This work provides a deep understanding of the ECH pathway of BA in alkaline media, and gives a new methodology to fabricate heterostructure electrocatalysts.

Colloidal ruthenium catalysts for selective quinaldine hydrogenation: Ligand and solvent effects

Colloidal Ru nanoparticles (NP) display interesting catalytic properties for the hydrogenation of (hetero)arenes as they proceed efficiently in mild reaction conditions. In this work, a series of Ru based materials was used in order to selectively hydrogenate quinaldine and assess the impact of the stabilizing agent on their catalytic performances. Ru nanoparticles stabilized with polyvinylpyrrolidone (PVP) and 1-adamantanecarboxylic acid (AdCOOH) allowed to obtain 5,6,7,8-tetrahydroquinaldine with a remarkable selectivity in mild reaction conditions by choosing the suitable solvent. The presence of a carboxylate ligand on the surface of the Ru NP led to an increase in the activity when compared to Ru/PVP catalyst. The stabilizing agent had also an impact on the selectivity, as carboxylate ligand modified catalysts promoted the selectivity towards 1,2,3,4-tetrahydroquinaldine, with bulky carboxylate displaying the highest ones.

Visible light driven selective NADH regeneration using a system of water-soluble zinc porphyrin and homogeneous polymer-dispersed rhodium nanoparticles

We discovered the catalytic activity of Rh nanoparticles dispersed by polyvinylpyrrolidone for regioselective NAD+ reduction to 1,4-NADH. Only 1,4-NADH was produced as the reduction product of NAD+ with visible-light irradiation.

Microcalorimetric adsorption and infrared spectroscopic studies of supported Pd, Ru and Pd–Ru catalysts for the hydrogenation of aromatic rings with carboxyl groups

Pd–Ru/SiO₂ showed special surface chemical properties that were totally different from those of Pd/SiO₂ and Ru/SiO₂ and exhibited high activity and selectivity for the hydrogenation of benzoic acid to cyclohexanecarboxylic acid.

Chemoselective hydrogenation of heteroarenes and arenes by Pd-Ru-PVP under mild conditions

Monometallic (Pd, Ru or Rh) and bimetallic (Pd_0.5–Ru_0.5) alloy NPs catalysts were examined for the hydrogenation of quinoline. Pd–Ru alloy catalyst showed superior catalytic activity to the traditional Rh catalyst. The characterization of Pd_0.5–Ru_0.5 catalysts, HAADF-EDX mapping and XPS analysis suggested that the alloy state of PdRu catalysts remained unchanged in the recovered catalyst. Furthermore, the catalyst was highly selective for the hydrogenation of different arenes.

Recyclable Pd_0.5Ru_0.5–PVP catalyst showed higher activity than monometallic Pd or Ru catalyst for the hydrogenation of quinoline. Furthermore, Pd_0.5Ru_0.5–PVP was able to hydrogenate different arenes.

Chemoselective reduction of quinoline over Rh–C60 nanocatalysts

Highly selective hydrogenation of quinoline by electron-deficient Rh species containing fullerene.