Temperature-tuned selectivity to alkanes or alcohol from ethyl palmitate deoxygenation over zirconia-supported cobalt catalyst

Abstract

Highly active Co/ZrO2 catalysts were synthesized for the conversion of ethyl palmitate to alcohol or diesel-like alkanes, with high yield and tunable selectivity, controlled by reaction temperature. The formation of hexadecanol was favored at lower temperatures, while higher temperatures promoted the formation of alkanes. Over 15Co/ZrO2, the highest yield of alkanes (~82%) was achieved at 240 °C, 8 h, while the highest yield of 1-hexadecanol (85.7%) was obtained at 200 °C, 24 h. The dominant pathway for the formation of alkanes proceeded via hydrogenation to aldehyde, followed by decarbonylation to Cn-1 alkane, accompanied by small fraction of total hydrodeoxygenation to Cn alkane and cracking to shorter-chain alkanes. The decrease in reaction temperature blocked the decarbonylation and hydrodeoxygenation routes, generating hexadecanol from hexadecanal with high yield and selectivity by prolonging the reaction time. The deoxygenation of ethyl palmitate was synergistically catalyzed by the Co site and oxygen deficient ZrO2 site.