Fabrication of nanoconfined spaces of KIT-6 with small-sized SnO₂ for enhanced oxidative desulfurization of fuel: Kinetics and thermodynamics

SnO₂ functionalized catalysts have great potential in oxidative desulfurization (ODS) of fuels. However, a facile strategy is required to enhance its catalytic performance. In this contribution, solid phase grinding (SPG) strategy is proposed to functionalize as-synthesized KIT-6 (AK-6) with SnO₂ NPs. The SnCl₂·2H₂O was directly incorporated into the confined spaces between silica walls and template of AK-6 and the subsequent calcination not only remove template (P123) but also convert SnCl₂·2H₂O to SnO₂, which saves much time and energy. Confined spaces and silanols of AK-6 regulated the size and dispersion of SnO₂ NPs up to loading of 10 wt% SnO₂ (Sn10AK-6). In contrast, larger SnO₂ NPs were observed in Sn10CK-6 derived from calcined KIT-6 (CK-6). The activity of Sn10AK-6 is also higher than Sn10CK-6 and converts 96.5 % DBT to sulfones at 303 K in 40 min with 0.1 g of catalyst using O/S = 4 M ratio of NaOCl. The DBT conversion over Sn10AK-6/NaOCl followed pseudo first order kinetics. Moreover, the calculated activation energy of 46.08 kJ/mol and thermodynamic parameters like ΔH = 49.70 kJ/mol, ΔS = −437 J/mol K and ΔG = 180.30 kJ/mol evinced that the ODS over Sn10AK-6 is endergonic, non-spontaneous and practicable under ambient conditions.