Thermodynamic evaluation and experimental validation of candidate sulfur acceptors for reactive adsorption desulfurization adsorbent

Abstract

Abstract Reactive adsorption desulfurization (RADS) has been played an important role in producing clean fuel due to its deep desulfurization ability and low octane number loss. In order to optimize the adsorbent, it is essential to know what element in which chemical state can be used to be the component. In this work, Gibbs reaction energy minimization method was used to screen the candidate sulfur acceptor from 18 elements considering the variation of their chemical state, the effect of temperature and hydrogen. Interestingly, except for MgO, ZrO2, TiO2, Al2O3 and SiO2, the other thirteen metal oxides discussed in this work are thermodynamically feasible for sulfur acceptor. But considering the facile reaction with H2O and CO2, Na2O, K2O, CaO, SrO and BaO are not suitable candidates. CuO, SnO2 and PbO are not competent either because of their facile reducibility but can be used as dopants to decrease octane number loss. MoO3, Co2O3, MnO2, WO3 and Fe2O3 may be the optimal candidates due to all of their low valence oxides show negative Gibbs reaction energies. Consequently, whether a candidate can be a sulfur acceptor mainly depends on its existence state at reaction condition. The validation tests showed that Ni/MoO3, Ni/Co3O4, Ni/MnO2, Ni/WO3, Ni/Fe2O3 had excellent RADS performance. While Ni/CaO and Ni/SnO2 had poor RADS performance due to the formation of CaCO3 and Sn, which are thermodynamically unfavorable. It is proved that thermodynamic evaluation is a simple but effective method to screen the candidates or optimize the preparation and reaction parameters.