Effects of Metal and Method Used for Synthesis of Supported Catalysts on Catalytic Performance in Olefin Production from Fatty Acids

A number of metal sulfide catalysts were synthesized by hydrogen treatment of nickel, cobalt, copper, and iron sulfates supported on gamma-Al2O3 (with a metal content of 5% and 10%). The resultant materials catalyze the decarbonylation of stearic acid to the corresponding higher olefins in the presence of hydrogen. The yield of target products decreases in the following order: Ni, Co > Cu > Fe. In the nickel and cobalt catalysts, X-ray diffraction (XRD) analysis identified interplanar distances (d-spacings) attributable to Ni3S2 and Co9S8. Such sulfides are likely responsible for their performance in decarbonylation. Hydrogen pretreatment time was found to be a factor that affects the activity of nickel and cobalt catalysts. XPS examination showed a decline in the sulfide sulfur to metal atomic ratio with an extension of hydrogen treatment time. The optimal time was found to range from 1 to 3 h.