Effect of Olefins on Desulfurization Mechanism of Thiophene Adsorption on Active Site Species of Mesoporous Molecular Sieve Al-MCM41

The Al-MCM-41 and Molecular Sieve with different aluminum loadings were prepared by post grafting method. Characterization of Molecular Sieves by XRD, N2 Adsorption- Desorption NH3-TPD, Py-FTIR and other methods. Evaluation of Thiophene Adsorption Performance by Fixed Bed. By correlating the thiophene adsorption capacity of molecular sieves with the acid properties and texture properties of molecular sieves, examine the influence of olefin presence on Al-MCM-41 and Adsorption and Desulfurization Mechanism of Active Site Species. The results show that the introduction of aluminum species produces B-type acid center, as well as two types of L acid center, L1 and L2. The introduction of low content aluminum species is beneficial to the formation of Btype acid centers and L1-type acid centers, while the introduction of high content aluminum species is beneficial to the formation of L2-type acid centers. Among them, L2-type acid center has the best adsorption effect on Thiophene. Olefins and thiophenes undergo competitive adsorption and catalytic conversion reactions at B and acid centers, and catalytic conversion reactions dominate. The existence of L2 acid center promotes the catalytic conversion reaction on the B acid center, and the generated macromolecular sulfide replaces thiophene to be adsorbed on the molecular sieve acid active center, thus improving the saturated sulfur adsorption capacity of Al-MCM-41 molecular sieve.