Selective conversion of aromatic alcohols in almond-scented aldehydes on inexpensive ZnO/MnCO3 catalysts.

DIEZ, V. K.; SAD, M.E.; ZELIN, J.; LUGGREN, P.J.; DUARTE, H.A.; DI COSIMO, J.I.

Buenos Aires

Congreso; 11th World Congress of Chemical Engineering; 2023

Asociacion Argentina de Ingenieros Químicos

Oxidation of alcohols to the corresponding carbonyl compound is a key reaction in organic synthesis for the synthesis of fine chemicals and intermediates. Aldehydes have been widely used as intermediates of synthesis of pharmaceuticals, vitamins, fragrances and agrochemicals. Especially, the oxidation of benzyl alcohol (BA) to the most valuable chemical benzaldehyde (B) has received increasing attention due to the large number of applications of this product. In this work, the synthesis of B from BA was studied at 373 K using Zn and Mn-based catalysts and O2 as oxidant. An inexpensive commercial MnCO3 sample was impregnated with aqueous solutions containing different concentration of Zn2+ to obtain a series of xZnMn solids with x = 1.0, 2.0, 4.3, 8.7, 15.4 and 22.6 wt.% Zn. Changes in structural phases and surface species of xZnMn solids were analyzed by XRD, XPS and through temperature-programmed decomposition experiments in flowing N2 (TPN2). XRD and TPN2 characterization showed that solids investigated consist of different crystalline phases containing Mn and/or Zn species. In these phases Mn oxidation state changes from 2+ toward higher values (3+ and 4+) as Zn content increases entailing the subsequent transformation of MnCO3 to ZnMn2O4 spinel and MnOx oxides. XPS analysis confirmed the transformation Mn2+ species into more oxidized Mn species as Zn loading increased.