Controllable Synthesis of Spherical Al-SBA-16 Mesoporous Materials with Different Crystal Sizes and Its High Isomerization Performance for Hydrodesulfurization of Dibenzothiophene and 4,6-Dimethyldibenzothiophene

Comprehensive Composition, Structure, and Size Characterization for Thiophene Compounds in Petroleum Using Ultrahigh-Resolution Mass Spectrometry and Trapped Ion Mobility Spectrometry

Thiophene compounds are the main concern of petroleum desulfurization, and their chemical composition and molecular configuration have critical impacts on thermodynamic and kinetic processes. In this work, atmospheric pressure chemical ionization (APCI) was employed for effective ionization of thiophene compounds in petroleum with complex matrix, in which carbon disulfide was used for generating predominant [M]^+• ions without the need of derivatization as for electrospray ionization. APCI coupled with ultrahigh-resolution mass spectrometry (UHRMS) was successfully applied to the composition characterization of thiophene compounds in both a low boiling petroleum fraction and a whole crude oil. APCI coupled with trapped ion mobility spectrometry (TIMS) was developed to determine the shape and size of thiophene compounds, providing configuration information that affects the steric hindrance and diffusion behavior of reactants in the desulfurization reaction, which has not been previously reported. Moreover, the comprehensive experimental structural data, expressed as the collision cross section (CCS) of the ions as surrogates of molecules, provided clues to the factors affecting the desulfurization reactivity of thiophene compounds. Further exploration showed that not only qualitative analysis of thiophene compounds can be achieved from the correlation between m/z and CCS, but also molecular size was found to be correlated with CCS that can be used as structural analysis. Overall, the molecular composition and dimension analysis together can provide substantial information for the desulfurization activity of thiophene compounds, facilitating the desulfurization process studies and catalyst design.

The Influence of Pore Structure and Acidity on the Hydrodesulfurization of Dibenzothiophene over NiMo-Supported Catalysts

A series of mesoporous materials of SBA-16 were in situ incorporated into ZSM-5 crystallites via a two-step self-assemble method, and hydrodesulfurization (HDS) catalysts were prepared on the corresponding ZSM-5/SBA-16 (ZS) composites. The characterization results indicated that ZSM-5 nanoseeds were fabricated into the silica framework of the ZS composites, and the three-dimensional Im3m cubic structure of SBA-16 was retained simultaneously. In addition, the ZS series materials possessed open pores and large surfaces, which would facilitate the diffusion of reactants in the mesoporous channels. Moreover, the introduction of ZSM-5 seeds into composites could enhance the acidities of supports. As a result, the NiMo/ZS series catalysts exhibited high activities for DBT HDS processes. The NiMo/ZS-160 catalyst exhibited the highest catalytic efficiency (96.5%), which was apparently attributed to the synergistic contributions of the physicochemical properties of ZS supports and the dispersion states of active metals. Correspondingly, DBT HDS reactions over the NiMo/ZS series catalysts mainly proceeded via a hydrogenation desulfurization route that benefitted from the enhanced acidities especially the total Brønsted acid.

Mechanical exfoliation of boron carbide: A metal-free catalyst for aerobic oxidative desulfurization in fuel

Metal-free catalysts have been proved to be a low-cost and environmentally friendly species in aerobic oxidative desulfurization (ODS). In this work, exfoliated metal-free boron carbide with few-layered structure, small size, and abundant defects, was first employed in an aerobic ODS system for ultra-deep desulfurization. The exfoliation process was realized by employing a planetary ball mill strategy. Detailed characterizations showed that the ball milling process not only induces thinner layers and small sizes but also introduces numerous defects into the boron carbide catalysts, which is vital in metal-free catalysis. Furthermore, the exfoliated boron carbide catalyst was applied in aerobic ODS system, and 99.5 % of sulfur removal was obtained. Moreover, the catalyst can be recycled 17 times without a significant decrease in catalytic activity. In particular, it was found that ∼90 % of the sulfur compounds in real diesel oil could be removed by the current aerobic ODS system.