Abstract
Novel Ni/ZnO–HZSM-5 adsorbents were synthesized by incipient wetness impregnation. The Ni/ZnO–HZSM-5 adsorbent can achieve deep desulfurization and olefin aromatization at the same time. Thiophene sulfur was removed from 495 to less than 10 ppm via reactive adsorption desulfurization (RADS). Olefins were also converted into aromatics. HZSM-5 did not only support adsorbents but also cooperated with active Ni sites to catalyze olefins into aromatic hydrocarbons. Aromatization of 1-pentene, 2-pentene, 2-methyl-2-butene, and 1-hexene on adsorbents was investigated. The adsorbents were characterized by the Brunauer–Emmett–Teller, X-ray diffraction, temperature-programmed reduction, and temperature-programmed desorption of ammonia and thermogravimetric analysis. The experimental results showed that strong acids on the adsorbent disappeared after HZSM-5 loaded active metal sites, and almost no coke was generated on adsorbents in RADS.
Highlights
Deep desulfurization of fossil fuels and upgrading the quality of gasoline will be an inevitable tendency for stringent environmental legislations in various countries
If olefins can be efficiently converted to other high-octane and stable components such as aromatics or isoparaffins, the quality of gasoline will significantly improve, and the octane number of gasoline will be maintained at the same time
The results suggest that the positions of carbon–carbon double bonds and branched chains in the olefins would significantly affect their reactivity, but olefin aromatization reactivity showed no positive correlation with conversion reactivity
Summary
Deep desulfurization of fossil fuels and upgrading the quality of gasoline will be an inevitable tendency for stringent environmental legislations in various countries. The mechanism of adsorption has been put forward by Song [8] and Velu et al [9], who considered that organic sulfide compounds were adsorbed on active metal Ni sites via direct sulfur–adsorbent (S–M) interaction, forming organometallic complexes, rather than by π-complexation. Wang et al [10] confirmed that thiophene was adsorbed via direct S–M interaction through the study of adsorption heat, whereas olefins were adsorbed through π-complexation. S–M interactions are much stronger than π-complexation, they still exhibit fierce competitive adsorption due to the larger quantity of olefins than sulfides in FCC gasoline. As a result, this competitive adsorption would decrease the selectivity of desulfurization on the adsorbents, and olefins would saturate in the H 2 atmosphere.
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