Catalytic Hydrogenation of p-Chloronitrobenzene to p-Chloroaniline Mediated by γ-Mo2N

Zainab N Jaf; Mohammednoor Altarawneh; Hussein A Miran; Mansour H Almatarneh; Zhong-Tao Jiang; Bogdan Z Dlugogorski

doi:10.1021/acsomega.8b01936

Catalytic Hydrogenation of p-Chloronitrobenzene to p-Chloroaniline Mediated by γ-Mo₂N

ACS Omega. 2018 Oct 30;3(10):14380-14391. doi: 10.1021/acsomega.8b01936. eCollection 2018 Oct 31.

Authors

Zainab N Jaf^{1

2}, Mohammednoor Altarawneh^{1

3}, Hussein A Miran^{1

2}, Mansour H Almatarneh^{4

5}, Zhong-Tao Jiang¹, Bogdan Z Dlugogorski¹

Affiliations

¹ School of Engineering and Information Technology, Murdoch University, 90 South Street, Murdoch, Western Australia 6150, Australia.
² Department of Physics, College of Education for Pure Sciences (Ibn Al-Haitham), University of Baghdad, Baghdad 10071, Iraq.
³ Department of Chemical Engineering, Al-Hussein Bin Talal University, Ma'an 71111, Jordan.
⁴ Department of Chemistry, The University of Jordan, Amman 11942, Jordan.
⁵ Department of Chemistry, Memorial University, St. John's, Newfoundland and Labrador A1B 3X7, Canada.

Abstract

Promoting the production of industrially important aromatic chloroamines over transition-metal nitrides catalysts has emerged as a prominent theme in catalysis. This contribution provides an insight into the reduction mechanism of p-chloronitrobenzene (p-CNB) to p-chloroaniline (p-CAN) over the γ-Mo₂N(111) surface by means of density functional theory calculations. The adsorption energies of various molecularly adsorbed modes of p-CNB were computed. Our findings display that, p-CNB prefers to be adsorbed over two distinct adsorption sites, namely, Mo-hollow face-centered cubic (fcc) and N-hollow hexagonal close-packed (hcp) sites with adsorption energies of -32.1 and -38.5 kcal/mol, respectively. We establish that the activation of nitro group proceeds through direct pathway along with formation of several reaction intermediates. Most of these intermediaries reside in a significant well-depth in reference to the entrance channel. Central to the constructed mechanism is H-transfer steps from fcc and hcp hollow sites to the NO/-NH groups through modest reaction barriers. Our computed rate constant for the conversion of p-CNB correlates very well with the experimental finding (0.018 versus 0.033 s^-1 at ∼500 K). Plotted species profiles via a simplified kinetics model confirms the experimentally reported high selectivity toward the formation of p-CAN at relatively low temperatures. It is hoped that thermokinetics parameters and mechanistic pathways provided herein will afford a molecular level understanding for γ-Mo₂N-mediated conversion of halogenated nitrobenzenes into their corresponding nitroanilines; a process that entails significant industrial applications.