Supported silver adsorbents for selective removal of sulfur species from hydrocarbon fuels

Dispersed silver oxides on supports such as TiO2, γ-Al2O3 and SiO2 were observed to be effective desulfurizing agents for refined fuels at ambient conditions. TiO2 was determined to be the most stable support for silver oxide. Ag (4 wt%)/TiO2 demonstrated a saturation sulfur capacity of 6.3 mgS/g for JP5 fuel containing 1172 ppmw sulfur. This high affinity for sulfur translated to one sulfur heterocycle associated with every two surface Ag atoms in the sorbent even in the presence of a 160-fold excess of other aromatics found in the fuel. A unique attribute of these sorbents was that they were thermally regenerable at 450 °C using air as a stripping medium over multiple cycles. Desulfurization characteristics also varied with fuel composition. Variation in desulfurization performance between JP5, JP8 and a light fraction JP5 were established and associated with the differences in sulfur composition of these fuels. The effects of surface area, porosity and crystal structure of the sorbent on sulfur capacity are also presented.