Arene Hydrogenation by Metal Nanoparticles in Ionic Liquids

Abstract

Ionic liquids (ILs) have been extensively explored in controlling the selectivity and stability of metal nanoparticles and/or classical heterogeneous catalysts for the hydrogenation of aromatics. ILs provide a protective layer to metal surface catalysts and a physical barrier controlling the access of substrates/intermediates/products on the nanoconfined catalysts, acting as an electronic and geometrical modifier of the catalytic active sites. As a result, this allows the stability and electronic/geometrical properties of the catalyst to be modulated. The IL layers also allow nano‐environments to be designed for encapsulation and to change the kinetic/thermodynamic of the process compared to those reactions performed in classical heterogeneous catalysis. We will focus on the physical, geometric and electronic effects imposed by the IL on metal nanoparticles and classical heterogeneous catalysts on activity and selectivity in the hydrogenation of arenes, in particular benzene.

High catalytic activity of Rh nanoparticles generated from cobaltocene and RhCl3 in aqueous solution

“…Transition-metal nanoparticles (TMNPs) have attracted much attention from homogeneous to heterogeneous catalysis, [1][2][3][4][5][6][7][8][9] and among them rhodium nanoparticles (RhNPs) have appeared especially reactive for key reactions for which Earth-abundant metals are not efficient or not sufficiently active catalysts. [10][11][12][13][14][15][16][17][18][19][20] Most RhNPs have so far been synthesized by NaBH4 reduction of RhCl3(H2O)n that also generates sodium borohydroxyhydride influencing catalysis in an undefined fashion. Here we report the synthesis of RhNPs generated by reduction of RhCl3 in water using the commercial reducing agent cobaltocene 21 in THF in stoichiometric amount.…”

Efficient carbon dioxide hydrogenation to formic acid with buffering ionic liquids

“…Even at high temperatures and pressures (120°C, 60 bar (P H2 = P CO2 )), TEM and DLS analysis showed no evidence of nanoparticles (see ESI for more details). Furthermore, the catalyst was not active in a reaction typically catalysed by Ru nanoparticles [27][28][29][30][31] , such as the hydrogenation of benzene at 120°C under 50 bar H 2 in the presence of BMMI.OAc even when high catalyst loadings are used, see SI for more details. c Data reproduced two times, error values within the error margin of the NMR determination, which were used as the standard deviation.…”

Catalysis with Colloidal Ruthenium Nanoparticles

“…101 It is not surprising that Ru NPs have found applications as catalysts for a large panel of reduction reactions, mainly C=C and C=O bonds, in a broad range of reaction conditions. Ru NPs used as catalysts in reduction reactions are synthesised by one of the methodologies described above using a large variety of stabilizing agents, such as polymers, [73][74][102][103][104][105][106][107][108][109][110][111] phosphines, [112][113][114][115][116] N-donor ligands, 50,[117][118] ILs, [83][84][119][120][121][122][123][124][125][126][127][128][129][130][131] NHC, 96,[132][133][134][135][136][137][138][139] alkynes, 140 chitin,…”