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Advanced microwave absorption (MA) materials have attracted widespread attention to meet the challenges of electromagnetic (EM) pollution. Herein, MgFe2O4/MgO/C fibers were successfully prepared via electrospinning technology and carbonization, and their surfaces were coated by MoS2 via hydrothermal method. The EM wave absorption performance of composites was enhanced due to the introduction of MoS2. The results showed that the EM wave absorption performance of MgFe2O4/MgO/C could not meet the requirements due to low dielectric loss and poor impedance matching. The performance of the composites was improved after coating of MoS2, which showed the strong wave absorption capability and the broad absorption bandwidth. The optimal reflection loss (RL) is −56.94 dB at 9.5 GHz and the effective absorption bandwidth is 3.9 GHz (8.08–11.98 GHz) with a thickness of 2.7 mm. The excellent MA performance can be mainly attributed to excellent synergistic effect between MgFe2O4/MgO/C and MoS2. Furthermore, MoS2 also contributes to dielectric loss and ideal impedance matching. MgFe2O4/MgO/C@MoS2 composites may be utilized for lightweight and high-efficient MA materials.

Sub-nanosized PtAu particles within three-dimensional carbon materials were obtained via a mercaptosilane-assisted preparation method. This strategy can effectively control the size of PtAu particles while avoiding the use of an additional carbon precursor. The as-synthesized three-dimensional carbon (3D carbon) material possesses excellent properties compared to other carbon materials. PtAu particles on three-dimensional carbon (PtAu/3D carbon) exhibited superior activities for methanol oxidation and hydrogen evolution reactions compared to Pt/3D carbon and a commercial Pt/Carbon (Pt/C) catalyst. Specifically, the methanol peak current density on PtAu/3D carbon was almost 2.3 times higher than that of Pt/3D carbon and 1.9 times higher than that of commercial Pt/C. The Tafel slopes of PtAu/3D carbon, Pt/3D carbon, and the commercial Pt/C were approximately 112, 124, and 106 mV dec−1, respectively, demonstrating that electrochemical desorption is the rate-limiting step in the hydrogen evolution reaction of the as-synthesized catalysts.

Serial VPO catalysts with different compositions of crystalline phases were prepared at various activation temperatures. The characterization results revealed that the proportion of V5+ species, th...

This research was supported by the following projects: National Natural Science Foundation of China (nos. 21878330, 21676298, and 21808079), CNPC Key Research Project (2016 × 10−0707), King Abdullah University of Science and Technology (KAUST), Office of Sponsored Research (OSR) under award number OSR-2019-CPF-4103.2, and the Key Research and Development Program of Shandong Province (2019GSF109115).

Serial VPO catalysts with different crystal structures were prepared by adjusting ratios of air and N2 in calcination process. The results showed that, as the air and N2 ratios were lower than 1:1, the ordered VOHPO4•0.5H2O phase was mainly formed in precursors during calcination process. However, as the ratio of air and N2 reached 3:1, the amorphous VOPO4 phases would be formed over the surface of precursor during calcination process, which would prevent the formation of ordered V5+ species over the surface of VPO catalyst after activation. The evaluation results of n-butane oxidation showed that, as the ratio of air and N2 was 1:3, the corresponding VPO-1A catalyst presented the highest conversion of n-butane and yield of MA product (57.6 m% at 412 °C). Finally, a kinetic and thermodynamic model was established and calculated to investigate the characteristics of n-butane oxidation reactions for various VPO catalysts.

A series of Y zeolites with different pore properties was prepared as a support for hydrocracking catalysts for the production of BTEX (benzene, toluene, ethyl-benzene, and xylene) from tetralin. Some important characterizations, including N2 adsorption–desorption, NH3-TPD, Py-IR, and HRTEM, were applied to obtain the properties of different catalysts. Meanwhile, the tetralin hydrocracking performances of those catalysts were investigated on a high-pressure fixed-bed microreactor. The results showed that Si/Al ratio is the core property of zeolites and that the increase in the Vmicro/Vmeso of zeolites could facilitate the formation of BTEX products by hydrocracking tetralin. The method of hydrocracking tetralin was proposed. It was also found that the hydrogenation–cracking path was controlled by aromatic saturation thermodynamics, and strong acidity aided the backward shift of equilibrium temperature.

Light cycle oil (LCO) with high content of poly-aromatics was difficult to upgrade and convert, which had hindered upgrading fuel quality to meet with the standard of automotive diesel for the purpose of sustainable development. The hydrocracking behaviors of typical aromatics in LCO of naphthalene and tetralin were investigated over NiMo and CoMo catalysts. Several characterization methods including N2-adsoprtion and desorption, ammonia temperature-programmed desorption (NH3-TPD), Pyridine infrared spectroscopy (Py-IR), CO infrared spectroscopy (CO-IR), Raman and X-ray photoelectron spectroscopy (XPS) were applied to determine the properties of different catalysts. The results showed that CoMo catalyst with high concentration of S-edges could hydrosaturate more naphthalene to tetralin but exhibit lower yield of high-value light aromatics (carbon numbers less than 10) than NiMo catalyst. NiMo catalyst with high concentration of Mo-edges also presented a higher selectivity of converting naphthalene into cyclanes than CoMo catalyst. Subsequently, the naphthalene and LCO hydrocracking performances were also investigated over different catalysts systems. The activity evaluation and kinetic analysis results showed that the naphthalene hydrocracking conversion and the yield of light aromatics for CoMo-AY/NiMo-AY grading catalysts were higher than NiMo-AY/CoMo-AY grading catalysts at same condition. A stepwise reaction principle was proposed to explain the high efficiency of CoMo-AY/NiMo-AY grading catalysts. Finally, the LCO hydrocracking evaluation results confirmed that CoMo-AY/NiMo-AY catalysts grading system with low carbon deposition and high stability could remain high percentage of active phases, which was more efficient to convert LCO to high-octane gasoline.

Serial difunctional catalysts supported on γ-Al2O3 and HY zeolite were synthesized and characterized systemically. The characterization results disclosed that hydrogen spillover existed in the NiMo and CoMo catalysts, and decreasing Ni/Mo and Co/Mo ratios could reduce hydrogen spillover. Meanwhile, the naphthalene hydrocracking behaviors over different catalysts were investigated and compared. The higher yield of cyclane for CoMo/AY catalysts demonstrated that hydrogen spillover could deeply hydrogenate naphthalene into cyclane. The combined catalysts of Ni/[email protected]/A, Ni/[email protected]/A and Ni/[email protected]/A showed relatively lower conversions of naphthalene but higher yields of valued

A novel micro-/mesoporous composite material W-MCM-41 was synthesized through self-assembly of the zeolite W nanocrystal precursor. The hierarchical structure material inherited the combining advantages of the ordered mesopores of MCM-41 and the modulated acid properties of zeolite W. Different crystallization times of zeolite W and various molar ratios of CTAB/SiO2 were optimized to achieve good physicochemical properties of micro-/mesoporous materials, which were used to prepare the corresponding CoMo-supported catalysts. Various characterization methods were adopted to analyze the relationship between the catalytic performance and physicochemical properties of series catalysts. The CoMo/WMA catalyst presented the highest hydrodesufurization activity (93.4%) and the best octane number preservability (ΔRON = −1.3 unit), which could be attributed to desirable texture of support, moderate metal–support interaction, and highest sulfidation degree of active phases. The distribution of sulfide compounds in hy...

Advanced microwave absorption (MA) materials have attracted widespread attention to meet the challenges of electromagnetic (EM) pollution. Herein, MgFe

The CoMo type and NiMo type catalysts with high amounts of Bronsted (B) acid sites, referred to as FHUDS-5 and FHUDS-6 respectively, were investigated for their hydrogenation performances including alkylation, hydrodesulfurization (HDS), and hydrodenitrogenation (HDN). The results demonstrated that, as hydroprocessing different diesel feedstocks, appropriate types of catalyst or their stacking system should be considered to achieve optimal HDS performance. As processing the feedstock with high sulfur content but low contents of nitrogen and aromatics, the CoMo type FHUDS-5 exhibited the highest HDS efficiency. On the other hand, the NiMo type catalyst FHUDS-6 presented the highest HDS and HDN efficiency as processing the feedstock with high amounts of nitrogen and aromatics. As processing the feedstock with medium contents of nitrogen and aromatics, the catalysts stacking system of FHUDS-6/FHUDS-5 presented the highest HDS efficiency due to their synergistic effects. The commercial applications for these hydroprocessing catalysts for the ultra-deep HDS on diesel at different refinery plants were also reported.

Hydrocracking of vacuum gas oil (VGO) is a commonly used process to produce more high-quality transportation fuels and chemicals. In this work, effects of four different operation modes, i.e., SSOT...

A series of γ-Al 2 O 3 materials with different textural properties and acidities were synthesized from the boehmite sol by tuning the aging temperatures. NiMo supported catalysts were prepared by using γ-Al 2 O 3 as the supports, then the catalytic HDS performance were evaluated by using DBT and 4,6-DMDBT to be the probe molecules. The physico-chemical properties of γ-Al 2 O 3 supports and the corresponding NiMo catalysts were characterized by XRD, N 2 -physisorption, Py-IR, UV–Vis DRS, laser Raman spectra, H 2 -TPR, XPS, HRTEM methods. The characterization results showed that NiMo/γ-363 catalyst possessed a large pore size (12.0 nm), open pore volume (0.86 cm 3 g − 1 ), moderate acidity and appropriate MSI. The NiMo/γ-363 catalyst presented the highest DBT and 4,6-DMDBT conversions at all the WHSVs. The NiMo/γ-363 catalyst showed highest k HDS and TOF values of the 4,6-DMDBT HDS, which could be ascribed to the synergistic effect of excellent textural properties, appropriate acidity and suitable MSI of the NiMo/γ-363 catalyst, moderate dispersion degree, high sulfidation degree and desirable stacking morphology of the MoS 2 crystallites. The highest HYD/DDS ratio (1.51) of the 4,6-DMDBT HDS over the NiMo/γ-363 catalyst indicated that the HYD pathway was the main reaction route. Furthermore, a possible reaction network for 4,6-DMDBT HDS over the series of NiMo/γ-Al 2 O 3 catalysts was proposed.

A series of aluminum modified Al-SBA-16 materials with different Si and Al molar ratios (50, 40, 30, 20, and 10) were successfully synthesized through a two-step preparation method using aluminum isopropoxide as Al source. Meanwhile, the corresponding catalysts were prepared by impregnating Ni and Mo active metals on the as-synthesized samples. The hydrogenation performances of the obtained catalysts were tested under the same conditions in a fixed-bed microreactor by using FCC diesel as feedstock. Furthermore, the hydrogenation reaction conditions over the NiMo/AS-20 (Al-SBA-16 with a Si/Al ratio of 20) catalyst were studied and optimized. The as-synthesized materials and their corresponding NiMo catalysts were characterized by N2 adsorption and desorption, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, 27Al MAS NMR, UV–vis diffuse reflectance spectroscopy, temperature-programmed reduction, Pyridine Fourier transform infrared sp...

Mesoporous Al2O3 (MA) materials with different crystal forms were synthesized from the boehmite sol. A series of MA materials were used as supports for sulfided NiMo catalysts in the hydrodesulfurization (HDS) of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT). The as-synthesized MA materials with different crystal forms and the corresponding NiMo catalysts were characterized using XRD, nitrogen physisorption, FTIR, pyridine FTIR, UV–vis, Raman, H2 TPR, XPS, and HRTEM characterization methods. The NiMo/δ-Al2O3 (NiMo/δ-MA) catalyst exhibited the highest DBT and 4,6-DMDBT conversion at all the weight hourly space velocities (WHSVs); moreover, its DBT conversion (99.6%) was about twice that of the commercial NiMo/Al2O3 (NiMo/C-MA) catalyst (50.2%), while its 4,6-DMDBT conversion (65.8%) was more than four times that of the NiMo/C-MA catalyst (15.5%) at 613 K, 4.0 MPa, 200 ml/ml, and 150 h−1. The superior catalytic performance of the NiMo/δ-MA catalyst could be ascribed to the synergistic effect of desirable textural properties, moderate acidity, suitable metal–support interaction, appropriate dispersion, and excellent stacking morphology of the active phases. 4,6-DMDBT HDS over the NiMo/δ-MA catalyst showed the highest HYD/DDS ratio (3.08), indicating that the HYD pathway was the main reaction route. Furthermore, an HDS reaction network was proposed for 4,6-DMDBT over NiMo/δ-MA.

A series of mesostructured SBA-16 materials with different morphologies were prepared by templating method using triblock copolymer pluronic F127 (EO 106 PO 70 EO 106 ) as surfactant and tetraethyl orthosilicate (TEOS) as silicon source. The influences of inorganic salt KCl and the synthesis temperature (temperature of the synthesis process before hydrothermal treatment) from 25 to 55 °C on the morphologies of SBA-16 materials were also investigated. The obtained materials were characterized by various techniques, including X-ray diffraction (XRD), small-angle X-ray scattering (SAXS), scanning electron microscope (SEM), transmission electron microscopy (TEM), N 2 adsorption–desorption, UV–visible diffuse reflectance spectrum (UV–vis DRS), H 2 temperature-programmed reduction (H 2 -TPR), Raman and X-ray photoelectron spectra (XPS) measurements. The SAXS, SEM and TEM results demonstrated that the SBA-16 materials possessed a body-centred cubic Im3m mesostructure. Five kinds of morphologies were found for the as-prepared SBA-16 materials, while sphere SBA-16 particles were obtained at the synthesis temperatures of 25 °C and 30 °C; mixed states of decahedral together with sphere were obtained at 38 °C; decahedral together with dodecahedral was obtained at 45 °C; hexagonal prisms was obtained at 50 °C; and tetrakaidecahedron was obtained at 55 °C. Moreover, aluminium isopropoxide was incorporated into the SBA-16 materials with a Si/Al molar ratio of 20 through the post-synthesized method, and the corresponding hydrodesulfurization (HDS) activities of NiMo supported catalysts on dibenzothiophene (DBT) were also performed in a micro reactor at T =340 °C and P =4 MPa with different weight hourly space velocities (WHSV). These NiMo catalysts were denoted as NiMo/S-x. S referred to Al modified SBA-16 supports, and x signified the synthesis temperatures from 25 to 55 °C. The synthesis mechanism of SBA-16 exhibiting different morphologies was proposed. Meanwhile, the DBT (500 ppm) HDS performance over NiMo/S-50 catalyst exhibited the highest conversion of 95.2% at the WHSV of 20 h −1 .

Density functional theory calculations are performed to investigate the hydrodesulfurization (HDS) mechanisms of different sulfur-containing compounds, such as thiophene, benzothiophene, dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) on the brim and CUS sites. Based on the systematic calculations, the dominant reaction pathway of different molecules are explored, and the structure-activity relationship of brim and CUS sites is mainly discussed under the real reaction conditions (p(H2) = 4 MPa, T = 650 K). According to the DFT calculation results, brim site is more favorable for the HDS reactions of thiophene and benzothiophene. However, both brim and CUS sites are considered to participate in the DBT and 4.6-DMDBT HDS processes. The brim site provides the hydrogenation active sites, and the CUS site promotes the removal of sulfur atoms. The proposed mechanism strongly supports that the brim and CUS sites act in synergistic effect for the HDS reaction of the highly refractory organic sulfides.

Serial Al-Ti-SBA-16 materials with highly ordered degree were successfully synthesized by a simple two-step method. The characterization results showed that incorporation of Al and Ti atoms into SBA-16 silica could obtain the supports with different acidities and modulate the distribution and dispersion of active phases for NiMo catalysts. The dibenzothiophene (DBT) hydrodesulfurization (HDS) evaluation results disclosed that the synergistic effect of enhancing acidity and properties of active metals could significantly improve the HDS performance. Importantly, it was the first time that the ratios of S-edge and Mo-edge concentrations were found to be well linked with the hydrogenation pathway (HYD)/direct desulfurization pathway (DDS) ratios. The HDS result showed that the acidity of S-H groups in S-edge sites could be promoted by B acid and further facilitated the DDS selectivity. As the Al and Ti contents in the support were 7.5% and 2.5% respectively, the NiMo/AT-7.5 catalyst exhibited the highest HDS performance due to its appropriate acidity, highest proportion of MoS2 phase and concentration of S-edge sites with high efficiency. Finally, the kinetic and thermodynamic analyses were applied to investigate the intrinsic HDS reactivity for various catalysts. The results confirmed the existence of synergistic effect in the DBT HDS reaction. It was also discovered that the B acid sites could further increase the desulfurization route (DS) of THDBT to CHB. In addition, the S-edge/Mo-edge ratio and kDDS/kHYD could also be well linked.

Serial Al-Zr-SBA-16 composites are successfully prepared through a two-step synthetic method. The influences of Al and Zr species on the properties of Al-Zr-SBA-16 composites and NiMo corresponding catalysts are investigated by various measurements. The results showed that a series of Al-Zr-SBA-16 supports maintained the intact structure and highly ordered degree. Al and Zr modification could increase the proportion of inactive Mo (Td) and Mo(Oh) species, respectively. The DBT HDS evaluation results revealed that NiMo/AZ-2.5 presented the highest HDS efficiency of 96.2%. The reasons should be ascribed to the factors that the higher dispersion degree of active metals, the highest proportion of MoS2 and NiMoS active phases over NiMo/AZ-2.5 sulfide catalyst, and the highest selectivity of hydrogenation (HYD) route. In addition, principle of hierarchical reaction steps in HYD route was also proposed to explain the reason why the HYD/DDS (direct desulfurization) ratio and HDS efficiency were the highest for NiMo/AZ-2.5 catalyst.

Mesoporous FDU-12 silicas with different morphologies have been synthesized under static and stirring conditions in a water bath. Furthermore, a series of mesoporous FDU-12 silicas modified by different amounts of titania have been synthesized, through a two-step method of prehydrolysis of TEOS followed by addition of titanium butoxide as a titanium precursor. Their respective NiMo supported catalysts were also prepared and characterized to elucidate the effects of titania, on the characteristics of the Mo surface species and their hydrodesulfurization (HDS) activities on dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT). The composites were characterized by various techniques (XRD, SEM, TEM, FT-IR, UV-vis, 29Si NMR, Raman, XPS and N2 adsorption–desorption); meanwhile, the catalysts were also tested in a higher pressure HDS reactor at T = 340 °C and P = 4 MPa with different liquid hourly space velocity (LHSV) values. The results show that the two-step synthetic route can prepare well-ordered mesoporous composites with high surface areas and large pore sizes and volumes. Obvious differences in the Mo species can be observed on the sulfided NiMo/Ti-FDU-12 catalysts. This showed that appropriate Ti loading could facilitate the dispersion of molybdena and the formation of the MoS2 and NiMoS phases, which are the important factors for the HDS reaction. All of the catalysts presented high HDS activity, and when the Si : Ti molar ratio was increased to 5, the HDS activities on DBT and 4,6-DMDBT could reach as high as 97% and 65% respectively.