Performance of geopolymer as adsorbent on desulphurization of heavy gas oil

Abstract

AbstractGeopolymer is a porous aluminosilicate material and chemically similar to zeolites. As a low‐cost construction material, its suitability for adsorptive desulphurization (ADS) was studied using a petroleum feedstock. Geopolymer was produced by alkali activation of metakaolin and characterized by BET, NH3–TPD, SEM, FTIR, XRD, and XPS. The XRD and SEM studies evidenced the amorphous nature of geopolymer and the existence of macro‐ and mesopores. The XPS and NH3–TPD studies revealed the presence of surface Na and Al, and strong acid sites, respectively, in the prepared geopolymer. These sites interact with sulphur compounds of heavy gas oil through π‐π and acid–base interactions. The geopolymer showed a high sulphur adsorption capacity of 38.4 mg/g. The effects of adsorption parameters such as operating temperature, amount of adsorbent, and time for absorption on the adsorption capacity were examined using the Box–Behnken design statistical model. All three operating parameters significantly influenced the sulphur adsorption capacity of geopolymer. The adsorption of sulphur compounds on the geopolymer followed pseudo‐first‐order kinetics and did not affect its structural stability. Finally, the thermodynamic study revealed that adsorption of sulphur compounds on the geopolymer was spontaneous and exothermic.