The performance of micro-meso-pore HY zeolite for supporting Mo toward oxidation of dibenzothiophene
2020
Dadashi, Mohaddese | Mazloom, Golshan | Akbari, Azam | Banisharif, Farhad
A uniformly distribution of 3 wt.% Mo (with tetrahedral coordination) on a commercial HY zeolite having both micro- and meso-pores, provided a new active catalyst which resulted 100% removal of DBT in this work. Respectively, H₂O₂ and acetonitrile were used as the oxidant and extraction solvent for oxidative desulfurization (ODS) at a mild condition. The structure of three-dimensional meso-pores, despite major micro-pores, was proved to be intriguing for the use of acidic HY zeolite as a support material in this process. The catalyst samples were characterized by different analyses of XRPD, XRF, FTIR, SEM, EDX, TEM, N₂ adsorption desorption, BET, BJH, UV-vis, and NH₃-TPD. High amounts of Mo were not in favor of the catalytic performance because of increasing non-framework polymolybdate formation, which led to decreasing meso-pore volume. Acid sites strength also decreased by increasing Mo content. The Mo active sites at a low loading of 3 wt.% reached the best performance for the complete removal of DBT (t = 90 min, T = 60 °C, catalyst/fuel = 8 g/L, O/S = 2, VSₒₗᵥₑₙₜ/VOᵢₗ = 1/2, DBT = 1000 ppm), mainly due to the presence of isolated Mo species in the framework of HY. The efficiency still reached to 90% after recycling the catalyst three times. The reusability of catalyst revealed the adsorption of the aqueous phase by this hydrophilic catalyst during the process being as a major deactivation factor. This was significantly diminished via a subsequent washing by acetonitrile.
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