Synthesis, characterization, and application of hydotalcites in hydrodesulfurization of FCC gasoline

Magnesium–aluminum, copper–aluminum, zinc–aluminum hydrotalcite(HT) compounds were synthesized using co-precipitation method. The effects of stirring rate, feeding rate of reactants, pH, calcination temperature on the properties of Mg–Al mixed oxides were investigated by using XRD, TG-DTA and BET techniques. The catalytic activity and selectivity of CoMo/γ-Al2O3, CoMo/γ-Al2O3+HT catalysts for hydrodesulfurization of FCC gasoline were examined in a high pressure microreactor. The results showed that the catalysts with mixed oxide obtained from hydrotalcite as support give lower levels of olefin hydrogenation than the catalyst with γ-Al2O3 as support, and lower octane number reduction and hydrodesulfurization yield, too. The hydrodesulfurization activity order was as follows: CoMo/γ-Al2O3>CoMo/γ-Al2O3+Mg–Al(HT)>CoMo/γ-Al2O3+Cu–Al(HT)>CoMo/γ-Al2O3+Zn–Al(HT), and the olefin hydrogenation activity and octane number reduction order were as follows: CoMo/γ-Al2O3+Zn–Al(HT)<CoMo/γ-Al2O3+Cu–Al(HT)<CoMo/γ-Al2O3+Mg–Al(HT)<CoMo/γ-Al2O3.