Porous flake-like Al-rich MgAl2O4 endowed with Mg vacancies for efficient oxidative desulfurization

Abstract

Selective oxidation of H2S is a satisfactory alternative to traditional Claus process for H2S removal. A facile template-free strategy was developed to controllably synthesize MgAl2O4 with different Mg/Al molar ratios for this application. It is deduced that the rich-Al spinel structure can accommodate a large number of Mg vacancies (VMg''), and adjacent unsaturated coordination lattice oxygen could be converted into oxygen vacancies (VO∙∙). Moreover, porous flake-like structure was successfully fabricated. The distinctive structure endows the catalyst with satisfactory mass transmission channels and high approachability. As a result, the optimal sample with the highest content of VMg'' exhibits favorable desulfurization performance, ca. 100 % H2S conversion and 100 % S yield at 180 °C, which is better than most of reported metal-oxide desulfurizers. The chemically adsorbed oxygen and VMg'' play decisive roles in this process. Furthermore, the property of catalytic sites and plausible reactivity route for the H2S-selective oxidation over MgAl2O4 are presented, which supply a feasible motive impetus for the design of efficient sulfur removal catalysts.