Facile manufacture of silver(I) complex/multilayer graphene composite for dynamic adsorption desulfurization

Abstract

The cyclic triangular complex – silver (I) 4-nitro-3,5-bis(trifluoromethyl)pyrazolate (Ag₃pz₃) with super π-acidity shows great potential in adsorptive desulfurization (ADS) as a novel adsorbent, however, it fails to work well in the continue flow adsorption study. In order to improve its dynamic adsorption performance, a composite has been prepared by mixing Ag₃pz₃ and multilayer graphene (MG) in methanol. Based on the results of characterization by FT-IR, XPS, SEM, and so on, the optimal mass ratio of Ag₃pz₃:MG in the synthesis is 0.14, so composite obtained under this condition is labeled as Ag₃pz₃/MG-0.14, in which the molecules of Ag₃pz₃ are uniformly distributed on the surface of MG via Ag∙∙∙C interactions and π-π stacking. The composite exhibits higher specific surface area than that of Ag₃pz₃. Importantly, the column test proves the practicality of the composite – Ag₃pz₃/MG-0.14 in continuous flow desulfurization with the enhanced dynamic capacity (4.0 mg S/g), in comparison with 1.9 mg S/g for graphene (C₀ = 200 mg S/L for dibenzothiophene in iso-octane, m_adsorbent = 0.5 g, T = 298 K, v = 0.1 mL∙min^-1). This work confirms the importance and advantage of the integration of functional coordination compound and suitable supporting materials for designing new type of high-performance ADS adsorbents.