Nb-containing mesoporous molecular sieves - a possible application in the catalytic processes

Nb-containing MCM-41 mesoporous molecular sieves were modified with ammonium and copper cations and characterised by ESR, FTIR and H-2-TPR techniques. The prepared materials were tested in the following catalytic reactions: NO decomposition, reduction of NO with NH3, hydrosulphurisation of methanol, and oxidation of thioethers with hydrogen peroxide. The oxidising character of the NbMCM-41 mesoporous molecular sieves was revealed, which induces their application as very active and selective catalysts in the oxidation of thioethers with H2O2 to sulphoxides. HNbMCM-41 samples, which exhibit Lewis acidity after dehydroxylation, are selective catalysts in the methanethiol synthesis in the reaction between methanol and hydrogen sulphide. Copper modified NbMCM-41 sieves indicate the higher reducibility of cupric cations than that observed when AlMCM-41 matrix for copper is used. The higher reducibility of cupric ions does not cause a higher activity in the catalytic NO decomposition. (C) 2000 Elsevier Science B.V. All rights reserved.