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 C-O 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.