Adsorptive removal of organic sulfur compounds from jet fuel over K-exchanged NiY zeolites prepared by impregnation and ion exchange

NiY zeolites with different Ni loadings were synthesized by incipient wetness impregnation and liquid-phase ion-exchange methods using NH ₄Y and KY zeolites. These Ni-containing Y zeolites were tested as adsorbents for removing organic sulfur compounds from a model jet fuel containing 510 ppmw sulfur and a real JP-8 jet fuel containing 380 ppmw sulfur under ambient conditions either without reduction or after reduction around 600°C. At the adsorption temperature of 80 °C, NiY zeolite containing 30 wt % Ni synthesized by incipient wetness impregnation of NH ₄Y zeolite was able to clean only about 10 mL of a model jet fuel per gram of the adsorbent to produce a desulfurized fuel containing below 1 ppmw sulfur. Under the same experimental conditions, a K-containing NiY zeolite cleaned about 30 mL of the fuel per gram of the adsorbent. A better sulfur adsorption performance was observed when the NiY zeolite was synthesized by ion exchange and reduced before sulfur adsorption. The reducibility and surface properties of some of the selected NiY zeolites were investigated by temperature-programmed reduction (TPR) and in-situ X-ray photoelectron spectroscopy (XPS). TPR studies indicated that the reducibility of NiY zeolite was improved when K was present as a cocation. The in situ XPS studies of unreduced and reduced samples revealed that the presence of K as a cocation in the zeolite matrix helps Ni dispersion at the surface. The promoting effect of K on the sulfur adsorption performance of NiY zeolites was therefore attributed to improved reducibility and surface dispersion of Ni when K was present as a cocation.