Deep Desulfurization of Gasoline by Selective Adsorption over Nickel-Based Adsorbent for Fuel Cell Applications

Adsorptive desulfurization of model gasoline fuels and a real gasoline over a nickel-based adsorbent Ni-Al was conducted in a flowing adsorption system at a temperature range of 25-200 (degree)C under ambient pressure without using H2 gas in order to evaluate the desulfurization performance of the adsorbent for producing ultra-low-sulfur gasoline for fuel cell applications. Adsorptive capacity and selectivity of the Ni-Al adsorbent for various sulfur compounds and the effects of coexisting olefin in gasoline as well as adsorptive conditions on the adsorptive performance were examined. It was found that the nickel-based adsorbent shows high capacity and selectivity for the adsorptive desulfurization of gasoline. Olefins in gasoline have a strong inhibiting effect on the desulfurization performance of the nickel-based adsorbent at room temperature. Increasing the temperature to 200 (degree)C can significantly improve the desulfurization performance of the nickelbased adsorbent for real gasoline. The adsorption mechanism and selectivity are discussed on the basis of the experimental results and computational analysis. The adsorption of sulfur compounds on the nickel surface involves C-S bond cleavage, as evidenced by the formation of ethylbenzene from benzothiophene in the absence of H2 gas in the flow adsorption system.