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Abstract: A bifunctional NiPb/ZnO-diatomite-ZSM-5 (NiPb/ZnO-DZSM-5) catalyst for FCC gasoline upgrading by reactive adsorption desulfurization (RADS) coupling olefin aromatization function was prepared by wet-mixed squeezed method to avoid octane number loss from olefins hydro-saturation in traditional RADS processing. The crystalline structure and textural property of as-prepared adsorbents/catalysts were characterized by X-ray powder diffraction (XRD) and N2 adsorption analysis, respectively. Adsorption desulfurization and aromatization activities evaluation of FCC gasoline and model gasoline over different adsorbents/catalysts were investigated. The results showed directly introducing the composite of aromatization catalyst into the reactive adsorption desulfurization adsorbent is difficult to conquer the loss of gasoline octane number from olefin saturation and sustain the ultra deep desulfurization ability of the reactive adsorption desulfurization process simultaneously. However, the prepared Pb-modified Ni/ZnO-DZSM-5 catalysts (by introducing second metal into Ni/ZnO-DZSM-5 catalyst), exhibited improved aromatization and desulfurization performance with low octane number loss. The aromatic concentration in products increased with the additive amount of ZSM-5 in catalyst composition, meanwhile, as the adding Pb cannot destroy the original crystalline phase, Pb-modified NiPb/ZnO-ZSM-5 catalyst can inhibit olefin saturation effectively with high desulfurization activity. Regenerated bifunctional NiPb/ZnO-DZSM-5 catalyst also exhibits excellent desulfurization and aromatization performance with no octane number loss. [Copyright &y& Elsevier]

• Cationic substitution was used to increase the Co/Mo ratio. • Well-defined new Waugh Co-Mo POM was used to prepare HDS catalyst. • Highly dispersed and stacked MoS 2 was controllably prepared via the POM route. • New reference for the rational design and controllable fabrication of efficient HDS catalysts. In this paper, the Waugh Co-Mo polyoxometalate (POM) (NH 4) 6 [CoMo 9 O 32 ] was prepared and cationic substituted to increase the Co/Mo ratio to 0.44 with Mo and Co atoms in a new Waugh Co-Mo POM molecule. The method was verified by X-ray diffraction, X-ray fluorescence, and infrared spectroscopy. Then, two series of Co-Mo hydrodesulfurization (HDS) catalysts were prepared using the Waugh Co-Mo POMs and traditional precursors, respectively. The HDS evaluation results showed the activities of catalysts prepared from the new Waugh Co-Mo POM is higher than the reference catalysts. For the catalyst prepared from the new Waugh Co-Mo POM, the cationic substitution provides a higher Co/Mo ratio and atomic-level proximity between Mo and Co atoms, leading to shorter and less stacked MoS 2 nano-particles and more exposure of unsaturated edges and corner sites. In addition, a weak interaction between the new Waugh Co-Mo POM and Al 2 O 3 leads to more CoMoS active phases. Catalysts prepared from the new Waugh Co-Mo POM showed excellent HDS performance, demonstrating the new Waugh Co-Mo POM is a superior precursor to construct the efficient HDS catalyst. [ABSTRACT FROM AUTHOR]

• Single dispersion Mo 7 O 24 was achieved by polyoxometalates-ionic liquids self-assembly. • MoS 2 with adjustable size and layer structure derived from (DODA) 6 Mo 7 O 24 by controllable confined-sulfidation effect. • For the first time, MoS 2 catalyst was applied in hydrogen evolution and hydrogenation reactions simultaneously and exhibited excellent catalytic performance. • The same active sites of MoS 2 in hydrogen evolution and hydrogenation reactions were analyzed. In the period of energy conversion, the effective utilization of fossil fuels and the development of new energy sources are becoming extremely imperative. MoS 2 have excellent catalytic activity for fuel hydrogenation and hydrogen production. However, the synthesis of highly dispersed MoS 2 that can expose more active sites has been challenging. Herein, (DODA) 6 Mo 7 O 24 with organic–inorganic core–shell structure was prepared by POMs-ILs (polyoxometalates-ionic liquids) self-assembly. MoS 2 with adjustable size and layer structure derived from (DODA) 6 Mo 7 O 24 by controllable confined-sulfidation effect for hydrogenation and hydrogen evolution reaction (HER). Among them, MoS 2 (T 280 S 1:4 t 30) has the lowest overpotential, and only 200 mV is needed to reach the current density of 10 mA·cm−2. At the same time, it has the optimal hydrogenation performance with the highest selectivity for octahydroanthracene and perhydroanthracene, along with a hydrogenation percentage of 48.04 % in the process of anthracene hydrogenation. Density functional theory demonstrated that the monolayer MoS 2 was more favorable for water molecule dissociation and hydrogen molecule activation, which proves that the MoS 2 has excellent catalytic activity for HER and hydrogenation simultaneously. This work is instructive for the synthesis of MoS 2 and its application in HER and hydrogenation. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Oil-soluble catalyst precursor could be easily obtained. • The precursor shows good solubility and stability in heavy oil. • The precursor could easily decompose to small MoS 2 particles with more active sites. • The obtained catalyst showed excellent hydrocracking activity of vacuum residue. Abstract Herein, a simple method for the preparation of presulfided oil-soluble MoS 2 catalysts was proposed. The catalyst precursor, cetyltrimethyl ammonium heptamolybdate (CTATTM) was easily synthesized by dissolving ammonium tetrathiomolybdate in an aqueous solution containing excess cetyltrimethyl ammonium bromide, which could be directly dissolved in a vacuum residue (VR). The obtained catalyst was evaluated in slurry phase hydrocracking of VR at 410 °C with an initial H 2 pressure of 10 MPa for 1 h. It showed remarkable hydrocracking activity, with a reduction of the resin content from 25.21 to 3.54 wt% and of the C7-asphaltene content from 6.82 wt% to almost zero. With using the catalyst, as the yield of the liquid product increased from 75.03 to 96.43 wt%, yields of the coke and gas would be only 0.19, and 3.38 wt%, respectively, significantly lower than the values of 14.05, and 10.92 wt%, respectively, obtained without using the catalyst. Moreover, with increasing Mo content, hydrodemetalization conversion increased from 42.5 to 83.4 wt%, while hydrodesulfurization conversion increased from 21.6 to 59.2 wt%. In addition, a higher initial H 2 pressure over 10 MPa can more efficiently promote the conversion of VR to light oil products with a significantly lower formation of coke and gas than the cases under conditions below 10 MPa. Multiple techniques, including X-Ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and Fourier-transform infrared spectroscopy (FT-IR), were employed to determine a plausible correlation between the structure and performance. The CTATTM precursor shows good solubility and stability in heavy oil, leading to easy formation of small MoS 2 particles with stacking numbers of 1 and 2, and slab lengths of 5–11 nm. This presulfided oil-soluble MoS 2 catalyst with good hydrocracking activity for VR shows great potential for further industrial applications. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Sulfiding agent could effectively react with the supported Mo oxide to form intermediate thiosalts. • The usage of sulfiding agent could generate mononuclear and polynuclear ammonium thiosulfate. • The sulfiding conditions could modify the final morphology of active phase. • The large number of Mo nuclear would lead to the high stacking of MoS 2 slabs. • The catalyst with optimal Mo dispersion and ratios of edge sites to rim sites showed high HDS activity. Abstract The influence of sulfiding conditions in the ex-situ presulfidation process on the morphology and performances of CoMoS/γ-Al 2 O 3 catalysts was studied in details for hydrodesulfurization (HDS) of dibenzothiophene. Surface and bulk characterization using XRD, HRTEM, XPS, TPR and FT-IR confirmed that the sulfiding agent mixture of (NH 4) 2 S and elemental S effectively react with the supported Mo oxide to form intermediate thiosalts from mononuclear ammonium thiomolybdates to polynuclear ammonium thiomolybdates, namely the formed thiosalts from (NH 4) 2 MoS 4 to (NH 4) 2 Mo 2 S 12 and (NH 4) 2 Mo 3 S 13 ,which weaken the strong interaction between the γ-Al 2 O 3 support and Mo oxide, resulting in maximum sulfidation of Mo oxide species. Mo species tend to agglomerate as the number of Mo nuclear increases, which further induces significant changes in the morphology of MoS 2 particles. Such observation was further correlated with HDS activity and selectivity. The CoMoS/γ-Al 2 O 3 catalyst with (NH 4) 2 Mo 2 S 12 as intermediate exhibits suitable slab lengths and stacking numbers of MoS 2 slabs with optimal compromise between the Mo dispersion and ratios of edge sites to rim sites, and show the highest HDS activity. Therefore, a tailor-made catalyst with excellent HDS performance could be developed by adjusting the sulfiding conditions through ex-situ presulfidation method. [ABSTRACT FROM AUTHOR]

[Display omitted] • Dopant of Ag on MnCeO x promotes the catalytic activity for propane oxidation. • Ag dopant increases Mn4+ and Ce3+ concentrations. • Ag dopant enhances surface oxygen migration capability. • Ag dopant leads to a novel carboxylate formation path. The development of highly active catalysts for eliminating volatile organic compounds (VOCs) at low temperature is desirable but remains challenging. In this study, a series of Ag-loaded MnCeO x catalysts were fabricated. Catalysts with an Ag loading of 5 wt% exhibited the highest catalytic activity (T 90 = 242 °C) and excellent stability in H 2 O, NO 2 , and CO atmosphere. Characterization results revealed that the introduction of Ag increased Mn4+ and Ce3+ concentrations and enhanced surface oxygen migration capability, which is conducive to the adsorption and dissociation of propane and O 2. Combining in-situ diffuse reflectance infrared Fourier transform and discrete Fourier transform calculation revealed a novel propane oxidation pathway on MnCeO x and Ag/MnCeO x. The addition of Ag species can convert propane into propylene in the initial stage and reduce the activation energy. This study supplied a novel insight into Ag-doped catalysts catalytic mechanism for VOCs oxidation reaction. [ABSTRACT FROM AUTHOR]

Binary NiMo, CoMo, NiW, and CoW transition-metal oxide catalyst precursors, were synthesized through a hydrothermal reaction, and highly-loaded hydrodesulfurization (HDS) catalysts were prepared by mixing the precursors with an alumina gel, calcination and sulfidation. The transition-metal oxide catalyst precursors and highly-loaded sulfide catalysts were characterized by XRD, N 2 adsorption–desorption, XRF, and HRTEM. Dibenzothiophene and fluid catalytic cracking (FCC) diesel were employed to evaluate the HDS performance. The crystalline phases of ammonium nickel (or cobalt) molybdate were detected in the NiMo (or CoMo) oxide catalyst precursors, while quasi-amorphous phases were observed for the CoW and NiW oxide precursors. In the sulfided HDS catalysts, typical MoS 2 or WS 2 phases were observed by TEM, while XRD demonstrated that Ni and Co sulfides were present, in accordance with HRTEM results. The catalytic results showed that the binary transition-metal CoMo sulfide catalyst exhibited high direct desulfurization activity and that the NiMo sulfide catalyst had higher HDS and hydrodenitrogenation activities toward the FCC diesel than the other catalysts, with conversions of higher than 99.1% and 99.7%, respectively. [ABSTRACT FROM AUTHOR]

A single-molecule confinement-sulfurization strategy was proposed to construct ultrafine Co-MoS 2 monolayer catalysts, employing oil-soluble POMs as precursors. Well-defined Co 2 Mo 10 -POMs were introduced for regulating CoMoS sites at atomic scale, exhibiting high intrinsic activities in VR HCK. [Display omitted] • Ultrafine Co-MoS 2 monolayer catalysts were controllably fabricated from the oil-soluble polyoxometalate (POM) precursors. • The POM anions were encapsulated and confined by organic surfactant cations at single-molecule level. • Well-defined Co 2 Mo 10 POMs were introduced for regulating CoMoS active sites at atomic scale. • CoMoS active sites show excellent catalytic performance for slurry phase hydrocracking of vacuum residue. • The structures and catalytic mechanisms of CoMoS sites were revealed by coupling XAFS with DFT calculations. Herein, a novel single-molecule confinement-sulfurization strategy was proposed to construct ultrafine Co-MoS 2 monolayer catalysts by using oil-soluble single-molecule polyoxometalates (POMs), (DODA) 6 Co 2 Mo 10 , as precursors. Well-defined Co 2 Mo 10 -POM, acting as molecular pre-assembling platform, is introduced for the atomically precise construction of bimetallic sites. Highly efficient conversion of VR under severe condition is realized with (DODA) 6 Co 2 Mo 10. The origin of prominent catalytic performance can be attributed to the in-situ formation of ultrafine single-layered Mo-based nanosheets with abundant exposed CoMoS active sites. By combining synchrotron radiation-based X-ray absorption spectroscopy and density functional theory calculations, we further discover that there is clearly intimate interaction between Mo and Co atoms and the dissociation of molecular hydrogen at CoMoS phases is energetically preferred, leading to remarkable hydrogenation and coke suppression activity. This work highlights an idea on the rational design and targeted synthesis of ultrafine bimetallic catalysts for slurry phase HCK with dramatically synergistic catalysis. [ABSTRACT FROM AUTHOR]

Highlights: [•] The steric hindrance mainly suppressed the reactivities of S-compounds and olefins. [•] H2S inhibition effect was severe on HDS reactivity, thus decreasing the selectivity. [•] The interconversion of Lewis and Brønsted acid sites explained the H2S inhibition. [•] The HYD pathway of the HDS reaction was principally affected. [•] Catalysts with appropriate acidic sites proportion was effective in selective HDS. [ABSTRACT FROM AUTHOR]

Abstract: Porous ammonium nickel molybdate, a potential precursor for deep hydrodesulfurization catalyst with the formula of (NH4)HNi2(OH)2(MoO4)2, was synthesized by a high-temperature hydrothermal synthesis method. The unsupported NiMoS catalysts with various Ni/Mo ratios were prepared from the precursors. The precursors and catalysts were characterized by nitrogen physisorption, powder XRD, TG–DSC–MS, HRTEM, SEM and evaluated in the continuous HDS of FCC gas oil. The results indicated that the activities of thus-achieved catalysts were much higher than that of commercial NiMo/Al2O3. The catalysts derived from the crystalline ammonium nickel molybdate showed much higher catalytic activity than that obtained from amorphous precursor, which means they could be attractive material system for futural applications. [Copyright &y& Elsevier]

Abstract: Presulfided CoMoS/γ-Al2O3 catalysts with sharp and deep eggshell concentration profiles of Co and Mo were prepared by a simple method and their properties were characterized by EDS, HRTEM, and FT-IR techniques. It was found that the Co eggshell thickness of the as-prepared catalysts could be conveniently regulated by controlled evaporation depth of the pre-soaked n-decane in the outer layer of the catalyst extrudates prior to the impregnation process, and the remaining n-decane in the core of the extrudates could prevent the diffusion of the acetone impregnation solution of Co(NO3)2 into that zone of extrudates. The evaluation results of the catalytic performance in hydrodesulfurization (HDS) of dibenzothiophene (DBT) indicated that the eggshell catalysts showed higher HDS activity than that of the uniform catalyst. That was because the eggshell catalysts could remarkably decrease the internal diffusion limitation effect due to a short diffusion path of the reactant. In addition, the eggshell catalysts could greatly improve the utilization efficiency of the active components. [Copyright &y& Elsevier]

• Detrimental effect of sulfation on CO 2 -capturing capacity in presence of steam. • Understanding of the competitive adsorption mechanism between CO 2 and SO 2. • Detailed reaction paths of carbonation and sulfation when H 2 O molecules exist. • Comparison of CO 2 and SO 2 adsorption energies on various sites of CaO (1 0 0) surface. Calcium looping is a fast-developing second generation CO 2 capture technology. In practical looping of Ca-based sorbents, steam and SO 2 are naturally present in the flue gas subjected to CO 2 capture, due to the combustion of fossil fuels. Until now, the single effect of steam or SO 2 has been reported to have a significant impact on the CO 2 capture of sorbents. However, there are few studies on the synergistic effect of steam and SO 2 on the CO 2 sorption characteristics of sorbents, and it is poorly understood. In this study, experiments and DFT calculation are employed to clearly understand the synergistic effect of steam and SO 2 on the carbonation behaviors of sorbents. Tests were first performed under typical calcium looping (CaL) conditions with and without the presence of steam and SO 2 during the carbonation process. Results indicated that the enhancement of steam on the sulfation is obviously stronger than that on the carbonation as the CaL cycles increased, which is then verified by a series of characterization methods. According to quantitative analysis through DFT calculation, the adsorption energy of SO 2 on CaO (1 0 0) surface was found to be more than that of CO 2 in the presence of steam, indicating the preferential adsorption of SO 2 in the presence of H 2 O molecules on the CaO (1 0 0) surface. Therefore, the experimental results were verified and the competitive adsorption mechanism of SO 2 and CO 2 in the presence of steam during the carbonation process was further understood from microscopic aspect. [ABSTRACT FROM AUTHOR]