Hydrogenation of nitriles to primary amines on metal-supported catalysts: Highly selective conversion of butyronitrile to n-butylamine

The selective liquid-phase hydrogenation of butyronitrile to n-butylamine was studied in a batch reactor on Co(9.8%)/SiO2, Ni(10.5%)/SiO2, Cu(9.2%)/SiO2, Pt(0.27%)/SiO2, Pd(0.33%)/SiO2, and Ru(1.8%)/SiO2 catalysts. At 373 K and 13 bar (H2), the initial butyronitrile conversion rate (rBN0, mmol/h g) followed the order Ni > Co > Pt > Ru > Cu > Pd. Cu/SiO2 and Pd/SiO2 did not form n-butylamine and rapidly deactivated during the progress of the reaction. Pt/SiO2 produced mainly dibutylamine and only minor amounts of n-butylamine and tributylamine. In contrast, Ru/SiO2 formed preponderantly n-butylamine but also produced significant amounts of dibutylamine and butylidene–butylamine, an intermediate in the formation pathway of the secondary amine. The highest yield to n-butylamine was obtained on Ni/SiO2 (84%). Co/SiO2 was initially highly selective to n-butylamine but with the progress of the reaction the butylamine concentration in the reaction mixture diminished because it partially reacted with the solvent (ethanol) to form N-ethylbutylamine. In an attempt to reduce the formation of byproducts, Ni/SiO2 and Co/SiO2 catalysts were tested at lower temperatures and higher H2 pressures. Butyronitrile was selectively converted to n-butylamine on Co/SiO2 at 343 K and 25 bar, yielding 97% of n-butylamine, similarly to the highest yields reported on Raney Co catalysts.

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► Co/SiO2 and Ni/SiO2 selectively hydrogenate butyronitrile to n-butylamine.
► Ni/SiO2 is the most active catalyst for converting butyronitrile to n-butylamine.
► Co/SiO2 is the most selective catalyst for converting butyronitrile to n-butylamine.
► Co/SiO2 yields 97% of n-butylamine from butyronitrile hydrogenation.