Catalytic pyrolysis of fatty acids and oils into liquid biofuels and chemicals over supported Ni catalysts on biomass-derived carbon

Abstract

Herein, biomass-derived activated carbon (bio-AC) was synthesized using rice husk as a biotemplate and natural carbon source. After immobilization of Ni, the supported Ni/bio-AC showed excellent catalytic activity in the pyrolysis of fatty acids to paraffin-based biodiesel in H 2 -free and solvent-free conditions, corresponding to the conversion of 99.6% and a total alkane yield of 95.1%, including 88.9% heptadecane. Based on comprehensive characterizations, the calculated turnover frequency of Ni/bio-AC was 3.9 times that of conventional Ni/AC. Significantly enhanced olefin selectivity was further obtained by N-doping of Ni/bio-AC, which was attributed to the inhibition of -COO* dissociation by the Ni-N sites. The possible catalytic reaction pathways from stearic acid to heptadecane via aliphatic alcohol as a reaction intermediate were investigated. Besides, efficient conversions of saturated and unsaturated plant oils were also achieved over Ni/bio-NAC catalysts in Py-GC/MS through pulsed catalytic pyrolysis manner, showing a promising prospect for sustainable biofuels and chemical production. • Rice husk was used as template and carbon source for the synthesis of bio-AC. • H 2 -free deoxygenation of fatty acids to biofuels was performed over Ni/bio-AC. • The superior performance of Ni/bio-AC was attributed to the synergistic effects. • N-doped Ni/bio-AC can improve olefin selectivity by inhibiting alkane production. • Real plant oils can be converted to chemicals through pulsed catalytic pyrolysis.