Insights into the Active Sites of Al2O3-Supported NiMo Catalysts in the Hydrodenitrification Reaction

2021 ◽  
Author(s):  
Zhanglong Guo ◽  
Hua Xu ◽  
Yanfei Wang ◽  
Wei Liu ◽  
Hao Yu ◽  
...  
Keyword(s):  
Active Sites ◽  
Nimo Catalysts

Relation between sulfur coordination of active sites and HDS activity for Mo and NiMo catalysts

2009 ◽  
Vol 309 (1-2) ◽  
pp. 79-88 ◽  
Author(s):  
Bas M. Vogelaar ◽  
Narinobu Kagami ◽  
Thomas F. van der Zijden ◽  
A. Dick van Langeveld ◽  
Sonja Eijsbouts ◽  
...  
Keyword(s):  
Active Sites ◽  
Nimo Catalysts

scholarly journals Effects of pore size, mesostructure and aluminum modification on FDU-12 supported NiMo catalysts for hydrodesulfurization

2020 ◽  
Vol 17 (6) ◽  
pp. 1737-1751
Author(s):  
Pei Yuan ◽  
Xue-Qin Lei ◽  
Hong-Ming Sun ◽  
Hong-Wei Zhang ◽  
Chun-Sheng Cui ◽  
...  
Keyword(s):  
Active Sites ◽  
Pore Diameter ◽  
Electron Tomography ◽  
Spherical Shape ◽  
Hydrothermal Temperature ◽  
Highly Active ◽  
Hds Catalysts ◽  
Nimo Catalysts ◽  
Isomerization Pathway ◽  
The Relationship

AbstractA series of NiMo/FDU-12 catalysts with tunable pore diameters and mesostructures have been controllably synthesized by adjusting the synthetic hydrothermal temperature and applied for the hydrodesulfurization of dibenzothiophene and its derivative. The state-of-the-art electron tomography revealed that the pore sizes of FDU-12 supports were enlarged with the increase in the hydrothermal temperature and the mesostructures were transformed from ordered cage-type pores to locally disordered channels. Meanwhile, the MoS2 morphology altered from small straight bar to semibending arc to spherical shape and finally to larger straight bar with the change of support structures. Among them, FDU-12 hydrothermally treated at 150 °C possessed appropriate pore diameter and connected pore structure and was favorable for the formation of highly active MoS2 with curved morphology; thus, its corresponding catalyst exhibited the best HDS activity. Furthermore, it was indicated that the isomerization pathway could be significantly improved for HDS of 4,6-dimethyldibenzothiophene after the addition of aluminum, which was expected to be applied to the removal of the macromolecular sulfur compounds. Our study sheds lights on the relationship between support effect, active sites morphology and HDS performance, and also provides a guidance for the development of highly active HDS catalysts.

scholarly journals Effect of the Gallium and Vanadium on the Dibenzothiophene Hydrodesulfurization and Naphthalene Hydrogenation Activities Using Sulfided NiMo-V2O5/Al2O3-Ga2O3

Catalysts ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 894 ◽  
Author(s):  
Esneyder Puello-Polo ◽  
Yina Pájaro ◽  
Edgar Márquez
Keyword(s):  
Elemental Analysis ◽  
Rate Constants ◽  
Active Sites ◽  
Sol Gel ◽  
Synthesis Method ◽  
Textural Properties ◽  
Elemental Mapping ◽  
Sulfided Catalysts ◽  
Nimo Catalysts ◽  
Sol Gel Synthesis

The effect of Ga and V as support-modifier and promoter of NiMoV/Al2O3-Ga2O3 catalyst on hydrogenation (HYD) and hydrodesulfurization (HDS) activities was studied. The catalysts were characterized by elemental analysis, textural properties, XRD, XPS, EDS elemental mapping and High-resolution transmission electron microscopy (HRTEM). The chemical analyses by X-ray Fluorescence (XRF) and CHNS-O elemental analysis showed results for all compounds in agreement, within experimental accuracy, according to stoichiometric values proposed to Mo/Ni = 6 and (V+Ni)/(V+Ni+Mo) = 0.35. The sol-gel synthesis method increased the surface area by incorporation of Ga3+ ions into the Al2O3 forming Ga-O-Al bonding; whereas the impregnation synthesis method leads to decrease by blocking of alumina pores, as follows NiMoV/Al-Ga(1%-I) < NiMoV/Al-Ga(1%-SG) < NiMo/Al2O3 < Al2O3-Ga2O3(1%-I) < Al2O3-Ga2O3(1%-SG) < Al2O3, propitiating Dp-BJH between 6.18 and 7.89 nm. XRD confirmed a bulk structure typical of (NH4)4[NiMo6O24H6]•5H2O and XPS the presence at the surface of Mo4+, Mo6+, NixSy, Ni2+, Ga3+ and V5+ species, respectively. The EDS elemental mapping confirmed that Ni, Mo, Al, Ga, V and S are well-distributed on Al2O3-Ga2O3(1%-SG) support. The HRTEM analysis shows that the length and stacking distribution of MoS2 crystallites varied from 5.07 to 5.94 nm and 2.74 to 3.58 with synthesis method (SG to I). The results of the characterization sulfided catalysts showed that the synthesis method via impregnation induced largest presence of gallium on the surface influencing the dispersion V5+ species, this effect improves the dispersion of the MoS2 phase and increasing the number of active sites, which correlates well with the dibenzothiophene HDS and naphthalene HYD activities. The dibenzothiophene HDS activities with overall pseudo-first-order rate constants’ values (kHDS) from 1.65 to 7.07 L/(h·mol·m2) follow the order: NiMoV-S/Al-Ga(1%-I) < NiMo-S/Al2O3 < NiMoV-S/Al-Ga(1%-SG), whereas the rate constants’ values (k) of naphthalene HYD from 0.022 to 2.23 L/(h·mol·m2) as follow: NiMoV-S/Al-Ga(1%-SG) < NiMo-S/Al2O3 < NiMoV-S/Al-Ga(1%-I). We consider that Ga and V act as structural promoters in the NiMo catalysts supported on Al2O3 that allows the largest generation of BRIM sites for HYD and CUS sites for DDS.

Effect of Chitosan Addition on NiMo/Al2O3 Catalysts for Dibenzothiophene Hydrodesulfurization

2012 ◽  
Vol 10 (1) ◽  
Author(s):  
Guillermina Ríos-Caloch ◽  
Víctor Santes ◽  
José Escobar ◽  
Maiby Valle-Orta ◽  
María C. Barrera ◽  
...  
Keyword(s):  
Active Sites ◽  
Batch Reactor ◽  
Kinetic Constant ◽  
Co Adsorption ◽  
Surface Concentration ◽  
Lower Surface ◽  
Organic Additive ◽  
Order Kinetic ◽  
Hno3 Solution ◽  
Nimo Catalysts

Abstract A series of supported NiMo catalysts were prepared by impregnating ammonium heptamolybdate and nickel nitrate (at 12 and 3 wt% of Mo and Ni, respectively) over chitosan (Chi) modified Al2O3 carrier. Alumina substrate was first impregnated with the organic additive (in acidic aqueous HNO3 solution, given the insolubility of chitosan at neutral pH) at concentrations corresponding to Chi/Ni mol ratios of 0.5, 1 and 2. Lower Mo dispersion in materials prepared over Chi-modified alumina was observed by Raman spectroscopy. Also, in those samples formation of hardly reducible aluminum molybdates (due to acidic conditions used during chitosan deposition) was evidenced by thermal analysis. Sulfided (under H2S/H2 flow, at 400 °C) catalysts were tested in dibenzothiophene hydrodesulfurization (HDS, at 72.4 kg/cm2, 320 °C, batch reactor, n-hexadecane as solvent) where no improved activity (in pseudo first order kinetic constant basis) was registered for chitosan-modified samples. However, increased selectivity to the product from direct desulfurization route (biphenyl) suggested enhanced promotion of MoS2 phase (by Ni) in catalysts prepared with organic additive. CO adsorption at -173 °C (followed by infrared spectroscopy) showed lower concentration of NiMoS active sites over catalysts prepared over chitosan-impregnated alumina carrier pointing out to the existence of highly efficient sites, in spite of their lower surface concentration. The present investigation opens the possibility of using chitosan, a sub-product from seafood industry, as efficient HDS catalyst additive.

scholarly journals Catalytic Conversion of Lignin in an Isopropanol/formic Acid Medium With Nimo Catalyst Promoted by W Species

2021 ◽  
Author(s):  
Xinyu Lu ◽  
Hossain Mahmud Robin ◽  
Haoquan Guo ◽  
Dandan Wang ◽  
Pengcheng Xiu ◽  
...  
Keyword(s):  
Formic Acid ◽  
Active Sites ◽  
Chemical Properties ◽  
Acid Sites ◽  
Hydrolysis Lignin ◽  
Remarkable Effect ◽  
Product Evolution ◽  
Stable Chemical ◽  
Nimo Catalysts

Abstract Background: Large amounts of enzymatic hydrolysis lignin (EHL) are generated with the production of cellulosic bioethanol. Efficient degradation and upgrading of EHL is significant for the sustainable and stable development of energy supply.Results: In this study, hydrodeoxygenation (HDO) of EHL to biofuels was carried out promoted by the in situ hydrogen donor produced from the decomposition of formic acid over NiMo catalysts. Results showed that active sites (derived from the support SiO2, W, and NiMo species) had remarkable effect on lignin conversion, and the highest oil yield (57.2 wt%) was gained over NiMo/W-SiO2 catalyst. Conclusions: The product evolution demonstrated that active metal sites (derived from NiMo species) favored hydrogenolysis and deoxygenation via leading in situ hydrogen to attack C-O-C bonds, while acid sites (derived from the support) adsorbed and activated chemical bonds in lignin, resulting in the linkage cleavage caused by the heating program. The obtained bio-oil was rich in alkyl guaiacols (6.7 wt%), containing stable chemical properties and high quality.

What catalysis needs from the electron microscopist

1988 ◽  
Vol 46 ◽  
pp. 694-695
Author(s):  
Alexis T. Bell
Keyword(s):  
Active Sites ◽  
Heterogeneous Catalysts ◽  
Catalyst Deactivation ◽  
Surface Composition ◽  
Internal Surface ◽  
Active Phase ◽  
Atomic Scale ◽  
Metal Catalyst ◽  
Internal Surface Area ◽  
Porous Support

Heterogeneous catalysts, used in industry for the production of fuels and chemicals, are microporous solids characterized by a high internal surface area. The catalyticly active sites may occur at the surface of the bulk solid or of small crystallites deposited on a porous support. An example of the former case would be a zeolite, and of the latter, a supported metal catalyst. Since the activity and selectivity of a catalyst are known to be a function of surface composition and structure, it is highly desirable to characterize catalyst surfaces with atomic scale resolution. Where the active phase is dispersed on a support, it is also important to know the dispersion of the deposited phase, as well as its structural and compositional uniformity, the latter characteristics being particularly important in the case of multicomponent catalysts. Knowledge of the pore size and shape is also important, since these can influence the transport of reactants and products through a catalyst and the dynamics of catalyst deactivation.

Scanning luminescence x-ray microscopy: Progress toward selective staining using microspheres

1994 ◽  
Vol 52 ◽  
pp. 74-75
Author(s):  
C. Jacobsen ◽  
J. Fu ◽  
S. Mayer ◽  
Y. Wang ◽  
S. Williams
Keyword(s):  
Visible Light ◽  
Active Sites ◽  
Light Emission ◽  
Chinese Hamster ◽  
Polystyrene Spheres ◽  
Good Resistance ◽  
X Ray ◽  
Selective Staining ◽  
Visible Light Emission ◽  
Specific Labelling

In scanning luminescence x-ray microscopy (SLXM), a high resolution x-ray probe is used to excite visible light emission (see Figs. 1 and 2). The technique has been developed with a goal of localizing dye-tagged biochemically active sites and structures at 50 nm resolution in thick, hydrated biological specimens. Following our initial efforts, Moronne et al. have begun to develop probes based on biotinylated terbium; we report here our progress towards using microspheres for tagging.Our initial experiments with microspheres were based on commercially-available carboxyl latex spheres which emitted ~ 5 visible light photons per x-ray absorbed, and which showed good resistance to bleaching under x-ray irradiation. Other work (such as that by Guo et al.) has shown that such spheres can be used for a variety of specific labelling applications. Our first efforts have been aimed at labelling ƒ actin in Chinese hamster ovarian (CHO) cells. By using a detergent/fixative protocol to load spheres into cells with permeabilized membranes and preserved morphology, we have succeeded in using commercial dye-loaded, spreptavidin-coated 0.03μm polystyrene spheres linked to biotin phalloidon to label f actin (see Fig. 3).

The design and catalytic performance of molybdenum active sites on an MCM-41 framework for the aerobic oxidation of 5-hydroxymethylfurfural to 2,5-diformylfuran

2019 ◽  
Vol 9 (3) ◽  
pp. 811-821 ◽  
Author(s):  
Zhao-Meng Wang ◽  
Li-Juan Liu ◽  
Bo Xiang ◽  
Yue Wang ◽  
Ya-Jing Lyu ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Active Sites ◽  
Aerobic Oxidation ◽  
Catalytic Performance ◽  
Mcm 41

The catalytic activity decreases as –(SiO)3Mo(OH)(O) > –(SiO)2Mo(O)2 > –(O)4–MoO.

A novel ligand with –NH2 and –COOH-decorated Co/Fe-based oxide for an efficient overall water splitting: dual modulation roles of active sites and local electronic structure

2020 ◽  
Vol 10 (18) ◽  
pp. 6266-6273
Author(s):  
Yalan Zhang ◽  
Zebin Yu ◽  
Ronghua Jiang ◽  
Jung Huang ◽  
Yanping Hou ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Water Splitting ◽  
Energy Demand ◽  
Active Sites ◽  
Electrode Materials ◽  
Global Energy ◽  
Overall Water Splitting ◽  
Local Electronic Structure ◽  
Electrochemical Water Splitting

Excellent electrochemical water splitting with remarkable durability can provide a solution to satisfy the increasing global energy demand in which the electrode materials play an important role.

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