Commercial catalysts screening for the direct amination of cyclohexanol

Abstract

Two groups of commercially available Ni- and Pd-based catalysts were used for the direct amination of cyclohexanol (CHOL) with NH3 as aminating agent and in the presence of H2, aiming the selective production of cyclohexylamine (CHA) and aniline. The fresh catalysts were characterized in terms of metal loading, support composition (prevailing SiO2 and Al2O3) and metallic dispersion. Ni-based catalysts revealed to be highly active while Pd-based were more selective towards aniline, however requiring higher temperatures and catalyst loading to reach significant CHOL conversions (from 17 up to 67 %). The activity of the catalysts is intrinsically related to their metallic dispersion regardless the metal loading. The Ni-based catalyst with 46wt. % of Ni is the most promising once it presents higher turnover frequency (TOF) values, as 10 fold high, particularly related to the ratio of desired to undesired by-products. Moreover, operating conditions considerably affect catalysts’ performance.