Oxidation of Cyclopentene with Manganese Oxides Octahedral Molecular Sieves with Layer and Tunnel Structures

Abstract Manganese oxides type octahedral molecular sieves OL‐1, OMS‐1, and OMS‐2 were synthesized, impregnated with sodium tungstate, and evaluated as catalysts for the selective epoxidation of cyclopentene (CPE) to cyclopentene oxide (CPO) in the sodium bicarbonate/hydrogen peroxide (BAP) system. OL‐1 was the best catalyst with a conversion of 78.6 % and a selectivity to CPO of 31.4 %. Impregnation with sodium tungstate affected the structure and activity of OL‐1 and OMS‐1. Mn 2+ is required for the epoxidation of CPE. FTIR spectra provides evidence that tungstate ions react, during impregnation, with Mg 2+ and/or Mn 2+ present in OMS‐1 and OL‐1 producing an amorphous compound that is not active in the epoxidation reaction. The crystalline and chemical structure of OMS‐2 was not affected by tungstate impregnation, since most of the manganese occurs as Mn 3+ and Mn 4+ , which in presence of hydrogen peroxide, tend to form radicals, active in the total oxidation of organic compounds.