Selective hydrogenation of bromonitrobenzenes over Pt/γ-Fe2O3

The Pt/γ-Fe2O3 nanocomposite catalyst exhibited high catalytic activities and superior selectivities to ortho-bromoaniline (o-BAN), meta-bromoaniline (m-BAN) and para-bromoaniline (p-BAN) in the hydrogenation of ortho-bromonitrobenzene (o-BNB), meta-bromonitrobenzene (m-BNB) and para-bromonitrobenzene (p-BNB), respectively. The hydrodebromination of bromoanilines (BANs) over the Pt/γ-Fe2O3 nanocomposite catalyst was fully suppressed even at complete conversion of the substrates for the first time. Elevating hydrogen pressure from 0.1 to 2.0 MPa could not only increase the hydrogenation rates of o-BNB, m-BNB and p-BNB by 8.8, 11.8 and 10.0 times, respectively, but also further improve the selectivities to o-BAN, m-BAN and p-BAN to a level higher than 99.9%. A new hydrodebromination pathway in the hydrogenation of bromonitrobenzenes (BNBs), i.e. through the hydrodebromination of the condensation intermediates was revealed.

Graphical abstractThe Pt/γ-Fe2O3 nanocomposite catalyst exhibited very excellent catalytic properties for selective hydrogenation of o-bromonitrobenzene, m-bromonitrobenzene and p-bromonitrobenzene to the corresponding bromoanilines.Figure optionsDownload full-size imageDownload as PowerPoint slide