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Chemoselective hydrogenation of 3‐nitrostyrene over supported gold catalysts: Effect of loadings of gold
Author(s) -
Tan Yuan,
Li Xing Chi,
Liu Xiao Yan
Publication year - 2021
Publication title -
journal of the chinese chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.329
H-Index - 45
eISSN - 2192-6549
pISSN - 0009-4536
DOI - 10.1002/jccs.202000512
Subject(s) - chemistry , nanoclusters , xanes , selectivity , catalysis , colloidal gold , fourier transform infrared spectroscopy , chemoselectivity , absorption (acoustics) , nanoparticle , spectroscopy , chemical engineering , nanotechnology , organic chemistry , materials science , composite material , physics , quantum mechanics , engineering
The chemoselective hydrogenation from 3‐nitrostyrene to 3‐vinylaniline is quite challenging due to coexistence of the C=C bond and the –NO 2 group in the same molecule. Previously, we found that the selectivity to the 3‐vinylaniline is very high in wide temperature and time windows when taking the ZnAl‐hydrotalcite supported Au 25 nanoclusters as the precatalyst. Here, we investigated the loading effect of gold on the catalytic performance for the chemoselectivity of this reaction. The loadings of gold ranged from 0.5 to 10 wt%. The results showed that the reaction rate decreased greatly with the increasing loading of gold, and selectivity dropped obviously after the loading of gold attaining 10 wt%. The UV–Vis (ultraviolet visible absorption spectroscopy), XRD (X‐ray diffraction), and HAADF‐STEM (high angle annular dark field‐scanning transmission electronic microscope) results suggested that the gold nanoparticles aggregated with the increasing loading of gold. The X‐ray absorption near edge structure (XANES) and in situ CO‐DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy) results indicated that the valent state of gold tended to be slightly positively charged when the loading of gold increased. The origin of the high selectivity to the 3‐vinylaniline was discussed subsequently based on the above results.