Catalytic Properties of Single-Phase Intermetallic Compounds

Effect of Precursor and Temperature Annealing on the Catalytic Activity of Intermetallic Ni3Sn2 Alloy

The effect of nickel precursors and the temperature annealing to obtain intermetallic Ni3Sn2 alloy catalysts on its activity and selectivity in the selective hydrogenation of biomass-derived furfural (FFald) were investigated. Two types of nickel precursors (c.a., i) nickel metal (Ni°) derived from Raney®nickel and ii) nickel ion (Ni2+) derived from nickel chloride) were employed as the starting materials via hydrothermal at 423 K for 24 h followed by reduction with H2 at the elevated temperature of 573-873 K for 1.5 h. The physico-chemical properties of the intermetallic Ni3Sn2 were characterized by XRD, N2-, and H2-adsorption, ICP-AES, and NH3-TPD. The intermetallic Ni3Sn2 alloy catalysts, both bulk and supported, demonstrated high activity and selectivity towards hydrogenation of FFald. The activity and selectivity of g-Al2O3 and AA-supported Ni3Sn2 alloy catalysts in the hydrogenation of FFald to furfuryl alcohol (FFalc) were maintained even after annealing at up to 873 K, but that of bulk Ni3Sn2 drastically dropped. Ni-Sn alloy catalysts which were obtained from Raney®Ni precursor showed more stable than that of nickel salts during hydrogenation of furfural to furfuryl alcohol. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 

Well-structured bimetallic surface capable of molecular recognition for chemoselective nitroarene hydrogenation

Unprecedented molecular recognition ability governed by a simple bimetallic surface was demonstrated.

Unprecedented molecular recognition ability governed by a simple bimetallic surface is reported. A series of Rh-based ordered alloys supported on silica gel (Rh_xM_y/SiO₂, where M is Bi, Fe, Ga, Ge, In, Ni, Pb, Sb, Sn, or Zn) were tested in the hydrogenation of nitrostyrene to form aminostyrene. RhIn/SiO₂ showed remarkably high catalytic activity and good selectivity under 1 atm H₂ at room temperature. Moreover, various other nitroarenes containing carbonyl, cyano, or halo moieties were selectively hydrogenated into the corresponding amino derivatives using RhIn/SiO₂. Kinetic study and density functional theory (DFT) calculations revealed that the high selectivity originates from RhIn/SiO₂ adsorbing nitro groups much more favorably than vinyl groups. In addition, the DFT calculations indicated that the RhIn ordered alloy presents concave Rh rows and convex In rows on its surface, which are able to capture the nitro group with end-on geometry while effectively minimizing vinyl-π adsorption. Thus, the specific and highly ordered surface structure of RhIn enables the chemoselective molecular recognition of nitro groups over vinyl groups through geometric and chemical effects.

Highly efficient aerobic oxidation of various amines using Pd3Pb intermetallic compounds as catalysts

Various amines including primary, secondary, benzylic, aliphatic and cyclic ones are converted into imines with high yields using the Pd₃Pb/Al₂O₃ catalyst.