Supported silver nanoparticles as catalysts for liquid-phase betulin oxidation

Anna Grigoreva, Ekaterina Kolobova, Ekaterina Pakrieva, Päivi Mäki-Arvela, Sónia A.C. Carabineiro, Alina Gorbunova, Nina Bogdanchikova, Dmitry Yu Murzin, Alexey Pestryakov

Research output: Contribution to journalArticlepeer-review

Abstract

Herein, it has been shown that betulin can be transformed into its biologically active oxo-derivatives (betulone, betulinic and betulonic aldehydes) by liquid-phase oxidation over supported silver catalysts under mild conditions. In order to identify the main factors determining the catalytic behavior of nanosilver catalysts in betulin oxidation, silver was deposited on various alumina supports (γ-alumina and boehmite) using deposition–precipitation with NaOH and incipient wetness impregnation methods, followed by treatment in H2 or O2. Silver catalysts and the corresponding supports were characterized by X-ray diffraction, nitrogen physisorption, inductively coupled plasma optical emission spectroscopy, photoelectron spectroscopy and transmission electron microscopy. It was found that the support nature, preparation and treatment methods predetermine not only the average Ag nanoparticles size and their distribution, but also the selectivity of betulin oxidation, and thereby, the catalytic behavior of Ag catalysts. In fact, the support nature had the most considerable effect. Betulin conversion, depending on the support, increased in the following order: Ag/boehmite < Ag/boehmite (calcined) < Ag/γ-alumina. However, in the same order, the share of side reactions catalyzed by strong Lewis acid centers of the support also increased. Poisoning of the latter by NaOH during catalysts preparation can reduce side reactions. Additionally, it was revealed that the betulin oxidation catalyzed by nanosilver catalysts is a structure-sensitive reaction.

Original languageEnglish
Article number469
Pages (from-to)1-24
Number of pages24
JournalNanomaterials
Volume11
Issue number2
DOIs
Publication statusPublished - Feb 2021

Keywords

  • Acid-base properties of support
  • Alumina polymorphic modification
  • Betulin oxidation
  • Silver catalyst
  • Structure sensitivity

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Materials Science(all)

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