Trash to treasure: Converting red mud into efficient catalysts for the hydrogenation of p-nitrobenzene compounds

Iron-Based Catalysts with Oxygen Vacancies Obtained by Facile Pyrolysis for Selective Hydrogenation of Nitrobenzene

“…The peaks with binding energies of 284.3, 284.8, 285.2, 286.5, and 289.6 eV could be attributed to the presence of carbon–iron bonds (C–Fe), carbon–carbon bonds (C–C), carbon–nitrogen bonds (C–N), carbon–oxygen bonds (C–O), and the carbonyl carbon (CO), respectively. , In the high-resolution XPS pattern of the O 1s (Figure b), it could be fitted into three peaks centered at 530.45, 532.09, and 533.38 eV, corresponding to three kinds of the O species. Based on the microcrystalline binding energy of magnetite, the peaks at 530.45 might be assigned to lattice oxygen (O latt ) related to metal oxide. , The peaks centered at 532.09 and 533.38 eV were ascribed to the oxygen species adsorbed on the surface (O ads ) and the surface-absorbed molecular H 2 O (O surf ), respectively. − As illustrated in the high-resolution XPS spectrum of Fe 2p (Figure c), it had two broad peaks at 711.6 and 724.3 eV, corresponding to the Fe 2p 3/2 and Fe 2p 1/2 spin orbitals, respectively. Six peaks could be deconvoluted.…”

“…Based on the microcrystalline binding energy of magnetite, the peaks at 530.45 might be assigned to lattice oxygen (O latt ) related to metal oxide. 29,46 The peaks centered at 532.09 and 533.38 eV were ascribed to the oxygen species adsorbed on the surface (O ads ) and the surface-absorbed molecular H 2 O (O surf ), respectively. 47−49 As illustrated in the high-resolution XPS spectrum of Fe 2p (Figure 3c), it had two broad peaks at 711.6 and 724.3 eV, corresponding to the Fe 2p 3/2 and Fe 2p 1/2 spin orbitals, respectively.…”

“…The binding energy for all plots was calibrated based on a standard binding energy of 284.8 eV for C 1s. The survey spectrum of catalyst Fe@C-2 (Figure 3d 29,32 In the highresolution XPS pattern of the O 1s (Figure 3b), it could be fitted into three peaks centered at 530.45, 532.09, and 533.38 eV, corresponding to three kinds of the O species. Based on the microcrystalline binding energy of magnetite, the peaks at 530.45 might be assigned to lattice oxygen (O latt ) related to metal oxide.…”

“…The strategies of catalyst preparation have been continuously optimized, and the exploration of iron-based catalysts suitable for the field of catalytic hydrogenation has never stopped. − Beller and co-workers innovatively used iron­(II) acetate and 1,10-phenanthroline to prepare nanoscale iron oxide-based catalysts for the selective hydrogenation reaction of nitrobenzene . Zhang and co-workers reported the strategy of obtaining catalyst Fe–N–C through copyrolysis using cellulose and iron chloride as raw materials .…”