Ionic Liquid Immobilized Nickel(0) Nanoparticles as Stable and Highly Efficient Catalysts for Selective Hydrogenation in the Aqueous Phase

Abstract

Nickel nanoparticles (NPs) well-dispersed in the aqueous phase were conveniently prepared by reducing nickel(II) salt with hydrazine in the presence of the functionalized ionic liquid 1-(3-aminopropyl)-2,3-dimethylimidazolium bromide. UV/Vis spectroscopy, elemental analysis, thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS) show the presence of a weak interaction of the functionalized ionic liquid with Ni(II) and Ni(0) complexes. The face-centered cubic structure of the Ni(0) NPs was confirmed by X-ray diffraction (XRD) characterization. Transmission electron microscopy (TEM) images reveal that smaller Ni(0) particles of approximately 6-7 nm average diameter assemble to give larger, blackberry-shaped particles with an average diameter of around 35 nm. The Ni NPs were employed as highly efficient catalysts for the selective hydrogenation of C=C double bonds in the aqueous phase under mild reaction conditions (40-90 degrees C at 1.0-3.0 MPa), and the Ni(0) nanocatalysts in the aqueous phase are stable enough to be reused at least seven times without significant loss of catalytic activity during subsequent reuse cycles.

Reduction Reactions in Green Solvents: Water, Supercritical Carbon Dioxide, and Ionic Liquids

“…strates. [96] Other metal nanoparticles of cobalt [97] and nickel [98] have also shown an efficient catalytic activity for the hydrogenation of alkenes. One of the advantages of using supported ionic liquid systems is that they requires much-reduced amounts of the ionic medium, which is environmentally and economically beneficial.…”

Catalytic hydrogenation of aromatic nitro compounds by functionalized ionic liquids-stabilized nickel nanoparticles in aqueous phase: The influence of anions

“…The water-soluble Ni NPs stabilized with amino group functionalized ILs and Blank-Ni catalyst were prepared by a chemical reduction method as shown in Figure 1 [39]. As shown in Figure 2, the XRD patterns of the isolated Ni displayed a complex, blackberry-like morphology and very good dispersity in aqueous phase.…”

“…Nickel acetate tetrahydrate (≥98.0%) and aqueous hydrazine (80 wt.%) were purchased from Sinopharm Chemical Reagent Co., Ltd. and used as received. The water-soluble Ni NPs stabilized with amino group functionalized ILs and Blank-Ni catalyst were prepared by a chemical reduction method as shown in Figure 1 [39].…”

“…Enlightened by the numerous advantages of nanocatalysts in aqueous phase, we attempted to develop a new hydrophilic, easily prepared amino-functionalized imidazolium IL, 1-(3-aminopropyl)-2,3-dimethylimidazolium acetate [AMMIM][AcO], as a ligand to stabilize nickel NPs. Based on our previous study [39], the catalytic performance of [AMMIM][Br]-stabilized nano-sized nickel(0) particles has been demonstrated to be superior than that of conventional Raney nickel for hydrogenation reactions in aqueous phase. We further examined the effect of ionic liquid anions on catalytic hydrogenation.…”

Enantioselective hydrogenation of α‐ketoesters catalyzed by cinchona alkaloid stabilized Rh nanoparticles in ionic liquid

“…Ionic liquids have been employed as useful media for the preparation of transition‐metal nanoparticles of various sizes and shapes . So far, ionic liquid‐stabilized metal nanoparticles have been used as catalysts mainly in the hydrogenation of alkenes or arenes . We previously reported the use of ionic liquid‐stabilized ruthenium nanoparticles to catalyze the tunable chemoselective hydrogenation of aromatic ketones and quinolines .…”