A Fe-promoted Ni–P amorphous alloy catalyst (Ni–Fe–P) for liquid phase hydrogenation of m- and p-chloronitrobenzene

The Fe-doped Ni–P amorphous alloy catalyst was prepared by the chemical reduction of the aqueous solution containing NiCl2 and FeCl3 with NaH2PO2 at 343 K and characterized by EDS, XRD, SAED, TEM, XPS and DTA. It was used as a catalyst for the liquid phase hydrogenation of m-chloronitrobenzene (CNB) and p-chloronitrobenzene (CNB) to corresponding chloroaniline (CAN) in alcohol at 383 K under 1.0 MPa of hydrogen. At a suitable Fe content (XFe), the Ni–Fe–P amorphous alloy catalyst exhibited much higher activity and selectivity than the Ni–P, Fe–P, and Raney Ni catalysts in the hydrogenation reaction. With the increase of XFe, the activity first increased and then decreased. The optimum XFe was 0.25, at which the conversions of CNB could reach 99.9% and the yields of m- and p-CAN could reach 97.3% and 98.1%, respectively. The promoting effect of the Fe-dopant could be attributed to both a dispersing effect that resulted in the higher stability and the electron donation of the metallic Fe to the metallic Ni that was favorable for the hydrogenation. The structure of amorphous alloy and the alloying P were also favorable for the hydrogenation. Very high contents of the Fe-dopant (XFe > 0.25) resulted in the decrease of the hydrogenation activity because Ni active sites were mostly covered by the inactive Fe.

At a suitable content of the Fe-dopant (XFe), the Ni–Fe–P amorphous alloy catalyst displayed excellent catalytic properties for the liquid phase hydrogenation of chloronitrobenzene (CNB) to corresponding chloroaniline (CAN). Based on EDS, XRD, SAED, SEM, TEM, XPS, DTA and catalytic properties dates, the optimum XFe was proved to be 0.25. The conversions of m- and p-CNB were both over 99.9% while the yields of m- and p-CAN were 97.3% and 98.1%, respectively. Dependence of the hydrogenation activity of the Ni–Fe–P amorphous catalyst on the Fe/(Ni + Fe) molar ratio (XFe). Reaction conditions: 0.5 g catalyst, 5.0 g m-CNB, 100 ml EtOH, PH2=1.0 MPaPH2=1.0 MPa, T = 383 K, stirring rate = 1000 rpm. Figure optionsDownload high-quality image (100 K)Download as PowerPoint slide