Production Of Liquid Alkanes From Fatty Acids And Esters Over Heterogeneous Cobalt Catalysts

The growing environmental and energy concerns caused by rapid development of economics and industry and consumption of fossil reserves have encouraged researchers to utilize renewable biomass instead of traditional fossil for the production of fuels and chemicals.The cobalt catalyzed biomass conversion is particularly attractive in recent years.However,the fabrication of highly dispersive Co nanoparticles at high metal loading with selective facet exposure is still questionable,which is important to achieve enhanced activity and specific selectivity.In this work,a series of nitrogen-doped carbon-supported cobalt catalysts were established for the conversion of biomass-based fatty acids and esters.The?10%?Co-N-C-550 catalyst with an average particle size of6.27 nm is most active,leading to a 97.8%yield of alkanes.Nitrogen-doping facilitates a highly uniform dispersion of Co nanoparticles even at a high Co loading of 10 wt%.Compared to most previously reported Co catalysts,the Co/N-C catalyst prefers an unconventional decarbonylation/decarboxylation?DCOx?dominant reaction pathway that consumes less H₂ over hydrodeoxygenation?HDO?due to the only exposure of the?111?facet of?-Co⁰ at a pyrolysis temperature of 550 ^oC used for synthesis.The ratio of heptadecane/octadecane?C17/C18?was as high as 9.3 at 30 wt%Co loading.The co-exist of Co and N-C leads to strong Lewis acidity and basicity,facilitating the interaction between catalyst and carboxylic acids substrate,and some important acid-catalyzed step-reactions such as oxygen removal during hydrogenation of carboxylic acid to aldehyde or deoxygenation of alcohol to alkane.The versatility of Co-N-C catalyst is successfully demonstrated through the conversion of various fatty acids and esters,and plant oil.The stability is confirmed by recycling tests.