Synergistic effect of CoOx and Ni-Co alloy in Ni-Co/SAPO-11 catalysts for the deoxygenation of stearic acids

It is important to improve the chemical stability and calorific value of bio-diesel by removing oxygen containing components (e.g., fatty acids). A novel Ni-Co/SAPO-11 catalyst, possessing Ni-Co alloy and CoOx active sites, is designed and evaluated in the deoxygenation of stearic acids. Compared to monometallic Ni, Ni-Co active sites exhibit excellent hydrogenation activity of carbonyl carbon to form aldehydes. CoOx has a strong adsorption and activation ability of carboxyl groups of stearic acids, decreases the energy barriers to remove hydroxyl group from carboxyl, and breaks CO bond on the carbanyl group. Under the synergistic effect of Ni-Co alloy and CoOx active sites, Ni/Co-S has a high selectivity (i.e., 90.0%) for C16 and C18 paraffins. Besides, isoparaffins are obtained due to the isomerization activity of SAPO-11. The current research proposes the role of CoOx and Ni-Co alloy to control the deoxygenation path of stearic acids and provides insights for the development of high efficient deoxygenation catalysts for fatty acids.