Hydrogen sulfide removal from normal heptane using zinc oxide, silicon dioxide and zeolite 13X: adsorption capacity, kinetics, selectivity, breakthrough and regeneration.

This article focuses on the HS adsorption from normal heptane (nC) as synthetic natural gas liquids (NGL) using ZnO, SiO and zeolite 13X in static mode. Results of the isotherm and kinetics of the investigated adsorbents for HS adsorption under ambient condition showed that ZnO had the highest HS adsorption capacity between 260 and 700 mgHS.g in the initial concentration range of 2500 and 7500 ppmHS with an equilibrium time of less than 30 minutes. Additionally, the ZnO selectivity was greater than 3.16. In continued, HS removal from nC with ZnO was examined in dynamic mode. The HS breakthrough time for ZnO reduced from 210 to 25 minutes as weight hourly space velocity (WHSV) was increased from 5 to 20 h at 30 bar. Also, the breakthrough time at 30 bar was about 2.5 times greater than that at atmospheric pressure. Furthermore, HS/CO mixture (i.e., 1000 ppmHS + 1000 ppmCO) caused the HS breakthrough time to increase approximately by 1.11-fold. Alternatively, the ZnO regeneration conditions with hot stagnant air were optimized at different initial HS concentrations (1000 ~ 3000 ppmHS) using the Box-Behnken design. For instance, ZnO contaminated with 1000 ppmHS was regenerated with an efficiency of more than 98 % for 160 minutes at 285 °C.