Deoxygenations of palm oil-derived methyl esters over mono- and bimetallic NiCo catalysts

In this work, series of SAPO-11-supported monometallic Ni, Co and bimetallic NiCo catalysts were prepared and tested for their activities toward the deoxygenation of palm oil-derived fatty acid methyl esters (FAMEs). Effects of metal introduction methods, i.e., co-impregnation (NiCo/SAPO-11) and sequential-impregnation (Ni/Co/ SAPO-11 and Co/Ni/SAPO-11) for bimetallic catalysts on their catalytic performance were also investigated. It was confirmed by X-ray diffraction and transmission electron microscopy with elemental mapping that bimetallic Ni-Co alloy phase was formed. X-ray photoelectron spectroscopy results revealed that different metal loading steps caused different Ni:Co ratios on catalyst surfaces. Those values corresponded to the sequence of metal loading from which the outer shell possessed higher concentration than the co-impregnated NiCo/SAPO-11 with a comparable Ni and Co atomic concentration. H-2 temperature programmed reduction investigation showed that the incorporation of Co species could improve the reducibility of bimetallic catalysts. Among all synthesized catalysts, the deoxygenation of palm-oil derived FAMEs over Co/Ni/SAPO-11 catalyst, with Co surface enrichment, exhibited the highest yield of diesel range fuel (i.e., similar to 89% at 330 degrees C). It was revealed that Co active sites play an important role to promote the deoxygenation due to the strong Co-O interaction. The synergy through Ni-Co alloying would be an efficient approach to enhance the deoxygenation of palm-oil derived FAMEs to diesel-like hydrocarbon fuels.

Automated summary

A series of SAPO-11-supported monometallic Ni, Co and bimetallic NiCo catalysts were prepared and tested for deoxygenation of palm oil-derived FAMEs. It was found that the Co/Ni/SAPO-11 catalyst, with Co surface enrichment, exhibited the highest yield of diesel range fuel. The study showed that the synergy through Ni-Co alloying is an efficient approach to enhance the deoxygenation of palm oil-derived FAMEs to diesel-like hydrocarbon fuels.