ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Oxidative desulfurization of dibenzothiophene over highly dispersed Mo-doped graphitic carbon nitride

Diogo A. F. Gonçalves, Maurício V. B. Pinheiro, Klaus Krambrock, Rodrigo. R. Resende, Breno R. L. Galvão, and Eudes Lorençon

Departamento de Química, Centro Federal de Educação Tecnológica de Minas Gerais, Belo Horizonte, Brazil

E-mail: eudesquimica@hotmail.com

Received: 24 December 2021  Accepted: 27 January 2022

Abstract:

Mo-doped graphitic carbon nitride (Mo/g-C₃N₄) was successfully prepared by thermal condensation of a Mo/melamine precursor in a semi-closed alumina crucible at 550 °C without atmosphere. Thermogravimetric analysis (TGA) was used to evaluate the polymerization route of the precursor, and theoretical and experimental investigations revealed that the Mo species were likely dispersed and anchored to the pyridinic groups of g-C₃N₄. As a result, the obtained Mo/g-C₃N₄ displayed exceptional catalytic activity in the oxidative desulfurization of dibenzothiophene (DBT) with H₂O₂. The effects of catalyst dosage, O/S ratio, and temperature on the catalytic properties of Mo/g-C₃N₄ were investigated. The kinetic studies revealed a pseudo-first-order kinetic process for DBT oxidation with an apparent activation energy of 43.6 kJ mol⁻¹. Experimental and theoretical evaluation of the Mo/g-C₃N₄ stability suggests that catalytically active Mo species are progressively leached from the g-C₃N₄ structure. The decrease in the Mo–N bond order after forming reactive peroxo-Mo(VI) groups was associated with catalyst deactivation.

Keywords: Graphitic carbon nitride (g-C3N4); Oxidative desulfurization; Dibenzothiophene

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-022-02113-3

Chemical Papers 76 (6) 3401–3412 (2022)