Solvent effect in the liquid-phase hydrogenation of acetophenone over Ni/SiO2: A comprehensive study of the phenomenon

Solvent effects in heterogeneous selective hydrogenation of acetophenone: differences between Rh/C and Rh/Al2O3 catalysts and the superiority of water as a functional solvent

“…Marchi et al also reported less significant solvent effects on the selectivity with Ni/SiO2. 12,13 It should be noted that the highest PhE yield can be achieved in water for both the Rh catalysts using different support materials of C and Al2O3.…”

“…[7][8][9][10][11] The group of Marchi et al investigated the selective hydrogenation of AP with a Ni/SiO2 catalyst in 10 organic solvents including protic polar, aprotic polar, and aprotic apolar ones. 12,13 They found that the rate of AP hydrogenation was even larger in cyclohexane than in aprotic polar solvents; the latter solvents were suggested to have strong interactions with the catalyst, as indicated by adsorption enthalpies, blocking its active sites. It is also indicated that the extent of solvent effects depends on supported metals used, being Ni > Co > Cu (all on SiO2).…”

“…It is also indicated that the extent of solvent effects depends on supported metals used, being Ni > Co > Cu (all on SiO2). 12,13 In their work, the group of Marchi et al reviewed previous results on solvent effects in the heterogeneous AP hydrogenation. 12,13 Shirai et al reported the superiority of water for the hydrogenation of AP with a Pd/C catalyst, which showed a higher activity in water as compared to the reactions in methanol, ethanol, and heptane.…”

“…12,13 In their work, the group of Marchi et al reviewed previous results on solvent effects in the heterogeneous AP hydrogenation. 12,13 Shirai et al reported the superiority of water for the hydrogenation of AP with a Pd/C catalyst, which showed a higher activity in water as compared to the reactions in methanol, ethanol, and heptane. 14 Recently, Subramaniam et al reported solvent effects on hydrogenation of different oxygenates in 10 solvents including water over a Ru/C catalyst and also indicated the superiority of water.…”

“…The two Rh catalysts have been employed because the catalystliquid interface should be important, 12,13 and thus the solvent effects would be different depending on the surface properties of heterogeneous catalysts to be used. Attempts have been made to explain the solvent effects observed on the total conversion and the product selectivity by considering such solvatochromic solvent parameters 1 as hydrogen-bonddonation (HBD) capability (α), hydrogen-bond-acceptance (HBA) capability (β), and the polarity/polarizability index (π*).…”