Ni–In Intermetallic Nanocrystals as Efficient Catalysts toward Unsaturated Aldehydes Hydrogenation

Abstract

The chemoselective hydrogenation of unsaturated carbonyl compounds is one of the most important and challenging chemical processes in the fine chemical synthesis field, where intermetallic compounds (IMCs) have attracted extensive interest as efficient catalysts. In this work, we demonstrate the preparation of several Ni–In IMCs (Ni3In, Ni2In, NiIn, and Ni2In3) with a tunable particle size via the utilization of layered double hydroxides (LDHs) precursors that exhibit largely enhanced catalytic activity and selectivity toward the hydrogenation of α,β-unsaturated aldehydes. H2-TPR and semi-in situ XRD measurements reveal a coreduction process in the topotactic transformation of NiIn-LDHs materials to Ni–In IMCs. The catalytic behavior toward various unsaturated carbonyl compounds (e.g., furfural, 1-phenyltanol, crotonaldehyde, and 2-hexenal) can be improved by the modulation of the Ni/In ratio and the particle size of these Ni–In IMCs. For instance, a yield of 99% for the hydrogenation of furfural to furfuryl alcohol was obtained over supported Ni2In catalyst (particle size 5.1 nm, 110 °C, 3 MP, 2 h). The XAFS characterization and DFT calculation further reveal the electron transfer and active-site isolation in Ni–In IMCs, accounting for the largely enhanced hydrogenation selectivity. The control over the activity and selectivity of Ni–In IMCs catalysts makes them promising candidates for the chemoselective hydrogenation of unsaturated carbonyl compounds.

Recent advances on the utilization of layered double hydroxides (LDHs) and related heterogeneous catalysts in a lignocellulosic-feedstock biorefinery scheme

“…Besides the bimetallic Ni-Cu LDHs-derived catalysts described before, few other reports have focused on the combination of one of these two transition metals (nickel or copper) with other different types of species, such as indium 114 and platinum. 115 Ni-In intermetallic compounds (IMCs) were prepared via the reduction of different types of LDH precursors described as Ni x In y -LDHs, Ni x Mg y In z -LDHs, Ni 3 AlIn-LDHs and Ni 2 AlIn-LDHs, and utilized as catalysts for the chemoselective hydrogenation of unsaturated carbonyl compounds, including the reaction of furfural to furfuryl alcohol.…”

“…115 Ni-In intermetallic compounds (IMCs) were prepared via the reduction of different types of LDH precursors described as Ni x In y -LDHs, Ni x Mg y In z -LDHs, Ni 3 AlIn-LDHs and Ni 2 AlIn-LDHs, and utilized as catalysts for the chemoselective hydrogenation of unsaturated carbonyl compounds, including the reaction of furfural to furfuryl alcohol. 114 The idea behind the design of these types of catalysts was to improve the preferential hydrogenation of the CvO group in the α,β-unsaturated aldehydes by combining (on the atomic scale) a highly active but low selective hydrogenation catalyst (nickel) with an inactive but more electropositive species (indium) via the formation of a Ni-In intermetallic compound. XAFS characterization and DFT calculation revealed the electron transfer and active-site isolation of the Ni-In IMCs accounting for the largely enhanced hydrogenation selectivity.…”

A Ship-in-a-Bottle Strategy To Synthesize Encapsulated Intermetallic Nanoparticle Catalysts: Exemplified for Furfural Hydrogenation

“…13 A layered double hydroxide (LDH) approach to obtain monodisperse nanoscale Ni−In intermetallic compounds for the enhanced chemoselective hydrogenation of α,β-unsaturated aldehydes has been reported. 14 Without the incorporation of Al or Mg in the Ni−In LDHs, however, severe aggregation was observed in the intermetallics during their synthesis.…”

Concerted Bimetallic Nanocluster Synthesis and Encapsulation via Induced Zeolite Framework Demetallation for Shape and Substrate Selective Heterogeneous Catalysis

“…[9] The addition of as econdary metallic element induces changes in the electronic density of states (ligand effect), [10] and/or decreases the number of multiple-fold adsorption sites by partially blocking the surface (ensemble effect). Bimetallic catalysts have shown superior performances in the chemoselective reduction of alkynes to alkenes, [12] conversion of a,b-unsaturated aldehydes to allylic alcohols, [13] and selective oxidation of CO to CO 2 in the presence of excess hydrogen. Bimetallic catalysts have shown superior performances in the chemoselective reduction of alkynes to alkenes, [12] conversion of a,b-unsaturated aldehydes to allylic alcohols, [13] and selective oxidation of CO to CO 2 in the presence of excess hydrogen.…”