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Abstract <p>The study aims at comparing the properties of magnetically recoverable Ag/FeO<sub><i>x</i></sub> catalysts synthesized by different methods (impregnation, coprecipitation, and impregnation of a pre-reduced support) and at testing their activity in 4-nitrophenol reduction in an aqueous solution at room temperature. The most active catalysts in 4-nitrophenol reduction are the samples obtained by impregnation with Ag precursors (AgNO<sub>3</sub> and [Ag(NH<sub>3</sub>)<sub>2</sub>]NO<sub>3</sub>) of the γ-Fe<sub>2</sub>O<sub>3</sub> support (<i>k</i> = 2.19 min<sup>–1</sup>) and the iron oxide support pre-reduced in an H<sub>2</sub>/Ar flow at 250°C (<i>k</i> = 3.21 min<sup>–1</sup>). This is due to the in situ formation of dispersed and active Ag particles from the cationic silver precursor under the action of the reducing agent NaBH<sub>4</sub>. The nature of the Ag precursors (Ag<sup>+</sup> or <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11502_2025_3796_Article_IEq1.gif" Format="GIF" Height="22" Rendition="HTML" Resolution="72" Type="Linedraw" Width="77" /> </InlineMediaObject> <EquationSource Format="TEX">\({\text{Ag}}\left( {{\text{N}}{{{\text{H}}}_{{\text{3}}}}} \right)_{2}^{ + }\)</EquationSource> <!--InrgChem2560111Taratayko-m1--> </InlineEquation>) affects the activity of Ag particles. Catalysts in which the ammonia complex <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11502_2025_3796_Article_IEq1.gif" Format="GIF" Height="22" Rendition="HTML" Resolution="72" Type="Linedraw" Width="77" /> </InlineMediaObject> <EquationSource Format="TEX">\({\text{Ag}}\left( {{\text{N}}{{{\text{H}}}_{{\text{3}}}}} \right)_{2}^{ + }\)</EquationSource> <!--InrgChem2560111Taratayko-m2--> </InlineEquation> was the silver precursor exhibit lower activity compared to samples in which AgNO<sub>3</sub> was used. Differences in the thermodynamics and kinetics of the Ag<sup>+</sup> or <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11502_2025_3796_Article_IEq1.gif" Format="GIF" Height="22" Rendition="HTML" Resolution="72" Type="Linedraw" Width="77" /> </InlineMediaObject> <EquationSource Format="TEX">\({\text{Ag}}\left( {{\text{N}}{{{\text{H}}}_{{\text{3}}}}} \right)_{2}^{ + }\)</EquationSource> <!--InrgChem2560111Taratayko-m3--> </InlineEquation> reduction to Ag<sup>0</sup> determine the morphology and dispersion of the metallic silver particles, which affects the activity of the resulting catalysts. The presence of magnetic properties of the catalyst samples is shown by exposing them to an external magnetic field.</p>

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Influence of a Silver Precursor Introducing Method on the Properties of Magnetically Recoverable Ag/FeOx Catalysts in 4-Nitrophenol Reduction

  • 期刊论文

  • 发表日期：

    2025年9月1日

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  • A. V. Taratayko,
  • T. A. Kuznetsov,
  • M. V. Kozhina,
  • G. V. Mamontov

摘要

Abstract

The study aims at comparing the properties of magnetically recoverable Ag/FeOx catalysts synthesized by different methods (impregnation, coprecipitation, and impregnation of a pre-reduced support) and at testing their activity in 4-nitrophenol reduction in an aqueous solution at room temperature. The most active catalysts in 4-nitrophenol reduction are the samples obtained by impregnation with Ag precursors (AgNO3 and [Ag(NH3)2]NO3) of the γ-Fe2O3 support (k = 2.19 min–1) and the iron oxide support pre-reduced in an H2/Ar flow at 250°C (k = 3.21 min–1). This is due to the in situ formation of dispersed and active Ag particles from the cationic silver precursor under the action of the reducing agent NaBH4. The nature of the Ag precursors (Ag+ or \({\text{Ag}}\left( {{\text{N}}{{{\text{H}}}_{{\text{3}}}}} \right)_{2}^{ + }\) ) affects the activity of Ag particles. Catalysts in which the ammonia complex \({\text{Ag}}\left( {{\text{N}}{{{\text{H}}}_{{\text{3}}}}} \right)_{2}^{ + }\) was the silver precursor exhibit lower activity compared to samples in which AgNO3 was used. Differences in the thermodynamics and kinetics of the Ag+ or \({\text{Ag}}\left( {{\text{N}}{{{\text{H}}}_{{\text{3}}}}} \right)_{2}^{ + }\) reduction to Ag0 determine the morphology and dispersion of the metallic silver particles, which affects the activity of the resulting catalysts. The presence of magnetic properties of the catalyst samples is shown by exposing them to an external magnetic field.