“Doing More with Less”: Ni(II)@ORMOSIL, a Novel Sol-Gel Pre-Catalyst for the Reduction of Nitrobenzene

Abstract

Reduction of nitrobenzene with NaBH4 using zero-valent iron nanoparticles (ZVI-NPs) and NiCl2∙6H2O incorporated in organically modified hybrid silica matrices as ZVI@ORMOSIL and Ni(II)@ORMOSIL catalysts is proposed as a remediation strategy. Ni(II)@ORMOSIL is prepared by ion-exchanging H+ of the ORMOSIL matrix with NiII. Ni(II)@ORMOSIL is a pre-catalyst that undergoes reduction by NaBH4 by an in-situ reaction and promotes nitrobenzene reduction by the unconsumed NaBH4, leading to sparing use of the catalyst. Ni(II)@ORMOSIL undergoes color change from green to black in this process, returning to a green hue after washing and drying. Nitrobenzene reductions were examined in aqueous acetonitrile solvent mixtures, and the reduction cascade produced the reaction end-products with catalytic implications. Plausible mechanisms of ZVI@ORMOSIL and Ni(II)@ORMOSIL catalyzed reductions of nitrobenzene are discussed. This work is the first to report M(II)@ORMOSIL pre-catalysts for in-situ reduction of nitrobenzene, and expands the scope of the ORMOSIL series of catalysts for the reduction of polluting compounds. This approach enables the development of catalysts that use very low concentrations of transition metal cations.

Photocatalytic Multielectron Reduction of Nitroarenes to Anilines by Utilizing an Electron-Storable Polyoxometalate-Based Metal–Organic Framework

“…Generally, aniline derivatives are obtained by the hydrogenation reaction reduction of nitroaromatic hydrocarbons via a multielectron process with precious metal catalysts Pt, Pd, etc. and reductants such as high-pressure H 2 , NaBH 4 , and HCOOH under harsh conditions. − The reduction of nitroarenes produces different products such as azo, azoxy, and anilines, and their selective formation often depends on the properties of catalysts and reaction conditions. , Therefore, it is of great significance to design precious metal-free photocatalysts for the highly selective reduction of nitrobenzene using light as the driving force . In this case, the combination of both photosensitizers and electron-storable components in a cooperative photocatalysis fashion is a powerful approach to generate catalysts for prospective practical applications .…”

Antibacterial Activity of Rose Bengal Entrapped in Organically Modified Silica Matrices

“…Visible spectra of free RB and RB6 matrix were measured by a method proposed by Trabelsi et al, 2020 [ 14 ], and Meistelman et al, 2021 [ 48 ]. Then, 0.2 g specimens were mixed with 4 drops of nujol oil using mortar and pestle.…”

Shape and Stability Matter: Enhanced Catalytic Reactions via Sol–gel-Entrapped Catalysts

“…Progress will continue to encompass many other ORMOSIL-entrapped metal catalysts based for example on low-cost, abundant metals such as Ni. Recently, for example, Albo and coworkers showed the excellent performance of ORMOSIL xerogels incorporating Ni(II) in mediating the reduction of nitrobenzene to aniline with small amounts of sodium borohydride [ 50 ].…”