Synthesis of hierarchical CoAPO-5 catalysts in different fluoride medium and optimization of its catalytic oxidative desulfurization process

BACKGROUND Fluoride ions can form corresponding complexes with transition metal elements (Co, Ti, V, Cr, Mn, Fe, Ni, Cu, etc.), so it is easier to synthesize heteroatomic molecular sieves in a fluorine-containing system than in a fluorine-free system. RESULTS In this paper, a hierarchical CoAPO-5 molecular sieve was synthesized in a fluorine system, and the effects of different fluorine resources on its synthesis were investigated. The CoAPO-5 samples were characterized by X-ray diffraction, scanning electron microscopy, N-2 adsorption-desorption and temperature-programmed desorption of NH3. CONCLUSION The results showed that, compared with other fluorine resources, the sample D-AFI-1 synthesized with HF possessed more acid sites, which appeared to be more attractive for oxidative desulfurization. The central composite design of response surface methodology was applied to design experimental schemes employing D-AFI-1 as catalyst. The volume ratio of oxidant/fuel, extractant/fuel and the mass ratio catalyst/fuel were screened out as the significant factors after the investigation of single factors. The quadratic model of the three significant factors and desulfurization rate was established. On the basis of optimizing the reaction conditions, oxidant/fuel volumetric ratio, catalyst/fuel mass ratio and extractant/fuel were 0.07 mL mL(-1), 0.01 g g-1 and 1.65 mL mL(-1), respectively, the desulfurization rate was 85.0%, which was consistent with the predicted value of the model (83.7%). (c) 2022 Society of Chemical Industry (SCI).