Deep desulfurization of gasoline by selective adsorption over solid adsorbents and impact of analytical methods on ppm-level sulfur quantification for fuel cell applications

The objectives of this work were to comparatively study the performance of a Ni-based adsorbent and a Cu(I)Y-zeolite for the desulfurization of a commercial gasoline by fixed-bed adsorption experiments at room temperature and 200°C, and to clarify the impacts of analytical methods on the ppm-level sulfur quantification in desulfurized liquid fuels for fuel cell applications. A series of standard fuel samples containing known amounts of sulfur compounds in n-decane was prepared and was analyzed by using gas chromatograph coupled with a flame photometric detector (GC-FPD), pulsed flame photometric detector (GC-PFPD) and a total sulfur analyzer. The results show that the GC-FPD and GC-PFPD are not suitable for quantitative estimation of total sulfur concentration in complex hydrocarbon fuels at low ppm-level without considering both the nonlinear response and the quenching effect. The adsorptive desulfurization of a commercial gasoline over the Cu(I)Y-zeolite and a Ni-based adsorbent was conducted and compared using a fixed-bed adsorption system. The Cu(I)Y-zeolite prepared in the present study showed a breakthrough capacity of 0.22 mg S/g of adsorbent (mg/g) at room temperature for removing sulfur in a commercial gasoline to less than 1 ppmw. Under the same experimental conditions, the Ni-based adsorbent exhibited a breakthrough capacity of 0.37 mg/g. The breakthrough capacity of the Ni-based adsorbent was increased by 38% at 200°C. Moreover, the breakthrough capacity of the Ni-based adsorbent corresponding to the outlet sulfur level of 10 ppmw was 7.3 mg/g, which was over an order of magnitude higher than that of Cu(I)Y-zeolite.