Sulfur oxide emissions from fuel-powered vehicles significantly contribute to the atmospheric pollution
[1−2]. Accordingly, controlling sulfur-containing compounds at the source has become a global priority
[3−4]. In China, the National V standard for gasoline and diesel stipulates a sulfur content limit below 10 µg/g. Currently, hydrodesulfurization (HDS) remains the dominant technology in petroleum refining
[5−8], primarily owing to its high efficiency in removing aliphatic sulfur compounds. However, HDS operates under severe conditions (high temperature and pressure), requires highly active catalysts, and exhibits limited effectiveness toward aromatic sulfur compounds due to steric hindrance
[9]. These drawbacks have motivated extensive research efforts to develop alternative and more efficient desulfurization technologies.
Oxidative desulfurization (ODS) has emerged as a promising complementary technology to HDS, by virtue of its mild reaction conditions, low energy consumption, and notably high efficiency in removing aromatic sulfur compounds that are resistant to HDS
[10−11]. In ODS systems, both the oxidant and the catalyst play decisive roles in determining overall performance. Hydrogen peroxide is commonly employed as an oxidant due to its low cost, environmental compatibility, and the formation of water as the sole byproduct. Despite these advantages, its use is associated with practical challenges, such as equipment corrosion and potential explosion hazards. In contrast, molecular oxygen has attracted considerable interest as an alternative oxidant because of its abundance, low cost, intrinsic safety, and environmental benignity, with water typically being the primary oxidation product
[12−13]. However, activating the inherently stable triplet ground state of molecular oxygen under mild conditions remains a significant challenge, highlighting the critical need for the development of highly active and efficient catalysts for oxygen-mediated oxidative desulfurization.
In recent years, transition metal oxides have been widely investigated as catalysts for ODS due to their tunable oxidation states, structural stability, and ease of recovery
[14]. However, single-component metal oxides often suffer from limited catalytic activity. To enhance their performances, two primary strategies have been adopted: increasing the specific surface area and introducing heterometal ions into the catalyst structure. Such doping approaches can effectively modulate the electronic structure and surface physicochemical properties of the catalyst, thereby enhancing their performances. For example, Liu et al.
[15] incorporated Fe into MoO
x and demonstrated that Fe ions precisely regulated the electronic structure of Mo sites, significantly raising the surface oxygen vacancy concentration. After optimizing the dopant content, the catalyst exhibited excellent activity, achieving full conversion of various sulfur compounds. Uematsu et al.
[16] doped Mo ions into MnO
2 and observed that the introduction of high-valence transition-metal cations, particularly Mo
6+, notably shortened the fiber length of MnO
2, leading to the formation of aggregates composed of ultrafine nanocrystals. This structural evolution increased the specific surface area and the number of exposed active sites, enabling efficient oxidation of various sulfides into the corresponding sulfoxides and sulfones. Similarly, An et al.
[17] reported that Mn doping effectively altered the electronic structure and surface atomic composition of NiMoO
4, resulting in an increased oxygen vacancy density and enhanced O
2 activation capability.
In the field of ODS, vanadium-based catalysts, such as 2D-2D V
2O
5/BNNS and V
2O
5, have shown promising desulfurization performance
[18−19]. Cobalt-based catalysts have also been extensively studied. For example, Murata et al.
[20] achieved 97% sulfur removal from diesel using cobalt acetate or cobalt chloride as catalysts, with aldehydes serving as sacrificial agents. Wei et al.
[21] synthesized a Co/KIT-6 catalyst, which reached a desulfurization rate of 98% in model oil with cyclohexanone peroxide employed as the oxidant. Similarly, Deng et al.
[22] prepared a Co/SBA-15 catalyst by loading cobalt oxide onto SBA-15 and achieved a notable sulfur removal efficiency of 99.5% at room temperature.
Considering that Co-V-O can be regarded as a composite metal oxide comprising of cobalt oxide and vanadium oxide, it is reasonable to expect that such materials to demonstrate favorable ODS activity. In this work, both Co-V-O and Mn-doped Co-V-O catalysts were synthesized via a reflux-calcination method. The crystalline structure, morphology, elemental valence states, and optical properties of the prepared catalysts were systematically characterized using XRD, SEM, XPS, FT-IR and UV-vis DRS. The results confirm the successful incorporation of Mn into the Co-V-O lattice. The ODS performance of the catalysts was evaluated using dibenzothiophene (DBT) in model oil as the substrate. The effects of Mn doping content, reaction temperature, catalyst dosage, oxygen flow rate, and different sulfur compounds on the desulfurization efficiency were investigated. Furthermore, the stability of the catalyst was examined, and a preliminary reaction mechanism for the ODS process was proposed.
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