Selective Hydrogenation Of Chloronitrobenzene Over Modified Skeletal Nickel

The objective of this study was to investigate the effects of amines and chlorides on the catalytic properties of quenched skeletal nickel(QS-Ni) in the hydrogenation of 3-chloro-4-methylnitrobenzene(CMNB). The selectivity of 3-chloro-4-methylaniline(CMAN) can reach 100% by using the method of introducing amines into the catalytic system and modifying QS-Ni using SnCl4·5H2O or SnCl2tydj·2H2O. The two methods above are efficient in the hydrogenation of o-chloronitrobenzene(o-CNB), m-chloronitrobenzene (m-CNB) and p-chloronitrobenzene(p-CNB), in which the yield of o-chloroaniline (o-CAN), m-chloroaniline (m-CAN) and p-chloroaniline(p-CAN) were more than 99.0%.Adding amines into catalytic system:The effects of amines and reaction parameters on the hydrogenation of CMNB were studied. We also investigated the influence of aminoethanol on the kinetics of CMNB hydrogenation. The results showed that the addition of amines to catalytic system can drastically increase the rate of CMNB hydrogenation, while the dechlorination can be suppressed sufficiently. Under optimum conditions, the selectivity to CMAN was more than 99.9% even another 30min reaction was extended after the CMNB were completely consumed. The aminoethanol has no effect on the active energy Ea but increase the pre-exponential factor A significantly. As a result, the rate of CMNB hydrogenation was increased remarkably. The introduction of aminoethanol can also sufficiently suppressed the dechlorination of o-CAN, m-CAN and p-CAN, in which the selectivity was up to 99%.The method of modifying QS-Ni using chlorides:the effect of chlorides and reaction parameters on the hydrogenation of CMNB were investigated. The kinetics of CMNB hydrogenation over SnCl4·5H2O modified QS-Ni was also studied. The results exhibited that Under optimized conditions, the rate of CMNB hydrogenation increased while the selectivity for CMAN maintained 100% even another 25 min reaction was extended after the CMNB were exhausted. The investigation on the kinetics of CMNB hydrogenation showed that Ea and A were both increased over SnCl4·5H2O modified QS-Ni. However, the increase of A was much more significant than Ea, which resulted in enhancement of the CMNB hydrogenation rate. The selectivity of o-CAN(99.8%), m-CAN(99.9%) and p-CAN(99.9%) were also increased evidently over SnCl4·5H2O modified QS-Ni.