Abstract:

CuLaHY zeolite absorbents with different Cu loadings were prepared by the equal volume impregnation method under an air atmosphere. They were characterized by X-ray diffraction (XRD), BET surface area measurement, and X-ray photoelectron spectroscopy (XPS). The crystalline structure and distribution of Cu2+ and La3+ cations in the cages of the Y zeolite were determined by powder XRD. The performance of adsorption desulfurization for CuLaHY zeolite adsorbents was investigated using a model diesel containing dibenzothiophene (DBT). Results showed that a large amount of Cu from the precursor CuCl2 exchanged with the LaHY zeolite and entered the cages of the Y zeolite while a very small amount of Cu from the precursor CuCl2 was highly scattered in the cages of the Y zeolite in the formof CuCl. The La3+ cations and a portion of the Cu2+ cations entered the cages of the Y zeolite and situated at the SI' sites in the beta cages while another portion of the Cu2+ cations situated firmly at the SII and SIII sites in the supercages of the Y zeolites. They were coordinated to skeleton-oxygen atoms and water molecules. Cu2+ cations in the supercages can adsorb DBT molecules from the model diesel and thus become centers of adsorption desulfurization. However, naphthalene molecules will result in competitive adsorption with DBT molecules.

Key words: CuLaHY, Zeolite absorbent, Characterization, Crystalline structure, Adsorption desulfurization