Magnetically Separable and Sustainable Nanostructured Catalysts for Heterogeneous Reduction of Nitroaromatics

Abstract

This review is focused on the strategies and designs of magnetic nanostructured catalysts showing the enhanced and sustainable catalytic performances for the heterogeneous reduction of nitoaromatics. Magnetic catalysts have the benefits of easy recovery and reuse after the completion of the reactions and green chemical processes. Magnetic separation, among the various procedures for removing catalysts, not only obviates the requirement of catalyst filtration or centrifugation after the completion of reactions, but also provides a practical technique for recycling the magnetized nanostructured catalysts. Consequently, discussions will address the methodologies and exemplars for the reusable magnetic composite catalysts. Because the synthesis of ideal magnetic nanostructured catalysts is of primary importance in the development of high-quality sustainable processes, the designs, preparation methods and recyclability of various recoverable magnetic nanostructured catalysts are emphasized. The representative methods and strategies for the synthesis of durable and reusable magnetic nanostructured catalysts are highlighted. The advantages, disadvantages, recyclability and the efficiency of the introduced heterogeneous systems have been explored in the reduction of nitrobenzene derivatives.

Process Intensification of Alkynol Semihydrogenation in a Tube Reactor Coated with a Pd/ZnO Catalyst

“…However, the TON of 9 × 10 4 was obtained in Figure 8, and the values above 10 5 were observed in the capillary reactor wall-coated with Pd-Bi catalysts [28]. The high TON demonstrated in the current study show an excellent catalyst reusability without the need for intermediate catalyst separation in contrast to alternative catalyst regeneration methods, such as centrifuging or magnetic separation [71,72]. The catalysts after the long-term study were removed and characterised.…”

Aqueous-Phase Catalytic Chemical Reduction of p-Nitrophenol Employing Soluble Gold Nanoparticles with Different Shapes

“…The catalytic reduction of PNP in the presence of NaBH4-in which the reduction of the nitro functional group of the molecule is observed-is, in fact, a reaction model usually adopted for the evaluation of potential catalysts. Moreover, the reduction of nitro compounds is a fundamental transformation that occurs in many chemical inputs and intermediates at both laboratory and industrial levels [27]. This catalytic reaction normally occurs with an excess of the hydride source NaBH4, since a considerable part of the activated hydride on the surface of the catalyst is lost as gaseous molecular hydrogen [20,28].…”

The Isomerization of Limonene over the Ti-SBA-15 Catalyst—The Influence of Reaction Time, Temperature, and Catalyst Content

“…Mesoporous silica catalysts can be obtained in soft-templating processes, in which self-assembly of organic molecules (surfactants and block copolymers) is used to create pores of controlled sizes. This procedure forms an inorganic network around the templates via a sol-gel process [26][27][28][29][30].…”