Exclusive Production of Chloroaniline from Chloronitrobenzene over Au/TiO 2 and Au/Al 2 O 3

The gas‐phase continuous hydrogenation of p ‐chloronitrobenzene ( p ‐CNB) over 1  mol % Au/TiO 2 and Au/Al 2 O 3 was compared for the first time. Both catalysts exhibit 100 % selectivity in terms of ‐NO 2 group reduction, resulting in the sole formation of p ‐chloroaniline ( p ‐CAN). Au/TiO 2 exhibited a narrower particle size (1–10 nm) distribution than Au/Al 2 O 3 (1–20 nm) and a smaller surface‐area‐weighted mean Au size (6 nm versus 9 nm). Au/TiO 2 delivered a higher specific hydrogenation rate (by a factor of up to four), a response that is discussed in terms of Au particle size and a possible contribution of the support to p‐CNB activation. A CNB isomer reactivity sequence was established, that is, o > p > m , which is attributed to resonance stabilisation effects. The results presented establish a basis for the development of a sustainable alternative route for the production of haloamines.