Zirconia-Supported Pt, Pd, Rh, Ru, and Ni Catalysts in the Hydrotreatment of Fatty Amides and Amines

Active catalysts for simultaneous hydrodeoxygenation (HDO) and hydrodenitrogenation (HDN) enable the production of fuels from renewable feedstocks. In this work, zirconia-supported nickel, ruthenium, rhodium, palladium, and platinum catalysts were evaluated in the HDO and HDN of n-hexadecanamide (C16 amide). The HDN of 1-hexadecylamine (C16 amine) was studied separately to assess the HDN activity and the preference between C-C and C-N bond cleavage routes without the interference of HDO. The differences in the catalytic activity were mainly attributed to the metal identity. Pt/ZrO2 and Ru/ZrO2 exhibited the highest activity toward the conversion of both model compounds. The C16 amide was converted more efficiently than the C16 amine over the studied catalysts, and a high HDO activity did not translate to a high activity in HDN, which was particularly evident in the case of Rh/ZrO2. The active metal strongly influenced the preferred reaction routes, as observed from differences in the yields of C15 and C16 n-paraffins and C32 condensation products. Ni/ZrO2 and Pd/ZrO2 exhibited the lowest activity and paraffin selectivity in the hydrotreatment of both model compounds. Ru/ZrO2 and Rh/ZrO2 favored the formation of n-pentadecane from both the C16 amine and C16 amide, whereas Pt/ZrO2 produced n-hexadecane and high intermediate yields of the C32 condensation products.