Oxidative denitrogenation of liquid fuel over W2N@carbon catalyst derived from a phosphotungstinic acid encapsulated metal–azolate framework

• Published in: Applied catalysis. B, Environmental Vol. 285; p. 119842
• Main Authors: Bhadra, Biswa Nath, Baek, Yong Su, Kim, Sunghwan, Choi, Cheol Ho, Jhung, Sung Hwa
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.05.2021; Elsevier BV
• Subjects: Ammonia; Carbazole; Carbazoles; Carbon; Catalysts; Denitrogenation; Electron density; Electron paramagnetic resonance; Electron spin; Electron spin resonance; Electrons; Intermediates; Irradiation; Liquid fuels; Nitrogen compounds; Organo-nitrogen compounds; Oxidation; Pyrolysis; Recyclability; Spin resonance; Tungsten; Tungsten nitride; Ultrasound; Organo-nitrogen compounds; Oxidation; Tungsten nitride; Ultrasound; Denitrogenation
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2020.119842

[Display omitted] •Highly effective W2N@carbon catalyst was firstly prepared from new PTA(x)@MAF-6 s.•W2N@carbon had huge activity in oxidative denitrogenation (TOF ≥ 80 times of old catalysts).•Various organo-nitrogen compounds (with different characters) can be removed in one step.•Both non-radical (W-peroxo species) and radical (•O2–) were active species in the oxidation.•The removal efficiency depends on electron density on the N-atom of the ONCs. Tungsten nitride-incorporated carbon (W2N(x)@C) was firstly prepared via pyrolysis of a newly developed phosphotungstic acid-loaded metal-azolate framework-6, PTA(x)@MAF-6 s. The obtained (without ammonia feeding) W2N(x)@C materials, were utilized as catalysts for oxidative denitrogenation (ODN) of fuels. The W2N(x)@C materials, especially W2N(15)@C, under ultrasound (US) irradiation was found to be a very efficient catalyst for oxidative removal of various organo-nitrogen compounds (ONCs). Importantly, the W2N(15)@C showed around 80–147 times turnover frequency those of reported catalysts for stubborn carbazole oxidation. Electron density on the N-atom of the ONCs has a dominant role in the oxidation. The oxidation mechanism was suggested mainly based on the calculated electron density of the reactants and analysis of major intermediates/products. Moreover, the US-assisted ODN was progressed by both non-radical and radical paths, as supported by the electron spin resonance and radical scavenger experiments. The recyclability of the catalyst in the US irradiative ODN was also confirmed.