Direct amination of toluene to toluidine with hydroxylamine over CuO–V2O5/Al2O3 catalysts

Abstract

A series of CuO-V 2 O 5 /Al 2 O 3 catalysts were prepared and characterized by various techniques such as XRF, BET, XPS and XRD. These catalysts were used for liquid-phase amination of toluene to toluidines. It was found that adding copper species to V 2 O 5 /Al 2 O 3 catalyst showed a peculiar behavior, maintaining a high activity toward toluene amination. An optimum CuO content appeared at 1.6 wt% with a CuO/V 2 O 5 molar ratio of 0.25. More than 60% total yield of toluidines was obtained over 1.6%CuO-15%V 2 O 5 /Al 2 O 3 catalyst under optimized conditions. Catalyst characterizations revealed that the addition of copper improved the formation of V 5? species, thus enhancing the activity of the catalyst.

One step C–N bond formation from alkylbenzene and ammonia over Cu-modified TS-1 zeolite catalyst

“…The instantaneously generated ˙NH 3 + reacted with the aromatic ring to produce an amino intermediate, followed by producing toluidine, and then a fraction of toluidine was transformed to nitrobenzene by deep oxidation. The data shown in Table 8 indicate that the yield of toluidine was higher at a relatively lower pH value, which is in accordance with our previous work [26][27][28] in an acidic system. Meanwhile, the protonated amino cation attacked the C-H bonds of the side chain to form benzylamine, and then was oxidized further to cyanobenzene.…”

“…The instantaneously generated hydroxylamine and ˙NH 3 + were unstable in the alkaline system, resulting in the fact that the yield of toluidine was not as high as that when using hydroxylamine hydrochloride as the aminating reagent in an acidic system. [26][27][28] We also used methylcyclohexane as the substrate to promote the catalytic reaction in a control experiment, but no amination products were obtained, indicating that the activity of the amination process in the present reaction system was related to the benzene ring structure; a further deep study is needed here.…”

“…In previous work, the direct amination of toluene to toluidine has been realised with an acceptable yield using hydroxylamine hydrochloride. [26][27][28] The TS-1 zeolite is a kind of molecular sieve, which is crystalline, with an MFI topology structure and is widely used as a catalyst. [29][30][31][32] Since the discovery of the synthesis method of TS-1 zeolite in 1983 at Enichem, 33 the properties of the TS-1 zeolite continue to attract attention by researchers.…”

Controllable wettability of micro- and nano-dendritic structures formed on aluminum substrates

“…In the Al region, as shown in Fig. 3a, a peak with a binding energy of 74.3 eV is associated to Al 2p 3/2 emission, 40,41 and this means Al always exists on the surfaces whether annealed or not, and this also can be demonstrated by the XRD spectra shown in Fig. 2.…”

High-Performance Metal Oxide-Modified V/TiO2 Catalysts for Selective Oxidation of 2-Methylnaphthalene to 2-Naphthaldehyde: An Experimental and Theoretical Study

“…Figure b shows the XPS bands for Cu 2p 3/2 of V-Cu/TiO 2 samples. All of the V-Cu/TiO 2 catalysts exhibit a peak of Cu 2p 3/2 at about 935 eV and the satellite peaks caused by the electron shake-up process in the BE range of 938–946 eV, which represent the Cu 2+ in all catalysts, while the weak peak at low BE 932.7 eV can be ascribed to Cu +1 . , These results indicate the coexistence of Cu 2+ and Cu 1+ in the catalysts, and Cu 1+ species may originate from the strong synergistic effect between VO x and Cu: Cu 2+ + V 4+ ↔ Cu + + V 5+ . The synergy can also be reflected on the BE shifts of Cu 2p of synthesized V-Cu(1)/TiO 2 to a higher region compared with the pure CuO (934.2 eV).…”