Solvent-Controlled Reactivity of Au/CeO2 Towards Hydrogenation of p-Chloronitrobenzene
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The solvent effect on catalyst activity and selectivity for the hydrogenation of para-Chloronitrobenzene (p-CNB) over Au/CeO2 catalyst was investigated. Reaction over Au/CeO2 generated p-chloroaniline as the sole product, whereas the p-CNB hydrogenation rate extremely hinged on solvent via modification of apparent activation energy (Ea) and pre-exponential factor (A). The apparent activation energy and the pre-exponential factor in different solvents followed the order: ethanol > i-butanol > s-butanol > t-butanol > t-pentanol, which linearly correlated with the hydrogen bond donation ability of solvents. Moreover, the constable plot was firstly found in the solvent effect on supported gold catalyst. From the ATR-FTIR analysis, N–O bond in p-CNB was strongly affected by the solvents via hydrogen bond compared with the benzene ring and C–Cl bond, thereby weaken the adsorption of the p-CNB on Au catalyst, inducing the increment of activity of p-CNB hydrogenation. These findings could provide a criterion to compare the performance of various catalysts in different solvents and a guideline to designate an appropriate solvent.
KeywordsSolvent effect Hydrogenation reaction Para-chloronitrobenzene Au catalyst Constable plot
We acknowledge the financial support from the Fundamental Research Funds for the Central Universities (xjj2016113), the China Postdoctoral Science Foundation (2017M613143), the Natural Science Foundation of Shaanxi Province of China (2017JQ2016) and the National Natural Science Foundation of China (U1662117).