NiMo Sulfide Research Articles

Solvent free depolymerization of Kraft lignin to alkyl-phenolics using supported NiMo and CoMo catalysts

The catalytic hydrotreatment of Kraft lignin using sulfided NiMo and CoMo catalysts on different acidic and basic supports (Al2O3, ZSM-5, activated carbon (AC) and MgO-La2O3) was studied in the absence of a solvent.

Effect of the textural parameters of the carrier and the preparation procedure of the supported Ni-Mo/Sibunit catalysts on their catalytic activity

The results of studies on the preparation of Ni-Mo sulfide catalysts based on a carbon-carbon composite material of the Sibunit type for the hydrocracking of heavy petroleum residue are reported. The effects of the support texture and the conditions of catalyst preparation on catalytic activity in the model reactions of 1-methylnaphthalene and dibenzothiophene conversion were demonstrated.

Hydroconversion of carboxylic acids using mesoporous SBA-15 supported NiMo sulfide catalysts under microwaves

Hydrogenation of octanoic acid was performed in a continuous manner, using microwaves (MW), and a supported metal sulfide catalyst.

Vacuum gasoil hydrocracking over three-layered packages consisting of supported sulfide NiMo and NiW catalysts

A method for vacuum gas oil hydrocracking using a three-layered package of catalysts is proposed, in which the top layer is NiMo/Al2O3, the middle is NiM/AAS-Al2O3 and the bottom is NiM/Y-Al2O3, where M is molybdenum or tungsten, AAS-Al2O3 is a support with 70% amorphous aluminosilicate (AAS) and 30% aluminum oxide, and Y is an Al2O3 support with 30% zeolite Y and 70% alumina. The acidic properties of the catalysts are studied via the IR spectroscopy of adsorbed CO. The morphology of sulfide particles on a catalyst’s surface is studied by means of transmission electron microscopy. Textural characteristics of the supports and catalysts are studied via nitrogen porosimetry. Packages containing NiMo and NiW catalysts in different combinations are tested in the hydrocracking of vacuum gas oil. It is shown that replacing NiMo/AAS-Al2O3 with NiW/AAS-Al2O3 in a catalyst package containing only NiMo considerably raises the yield of the diesel fraction.

Preparation of NiMoS nanoparticles for hydrotreating

NiMo sulfide nanoparticles were prepared by precipitation using water in oil (w/o) microemulsions, and were characterized by X-ray diffraction (XRD), Dynamic Light Scattering (DLS), X Ray Photoelectron Spectroscopy (XPS) and nitrogen adsorption (BET). They were also tested in the HDS of vacuum gas oil (VGO). Nanoparticles of 3-5nm which produced 50% HDS conversion of a Vacuum Gas Oil (VGO), as well as an enhanced HDN activity (when compared to a NiMo/Al2O3 catalyst), were obtained. After sulfidation of the solids the Ni, at the surface, is mainly decorating the edges of the MoS2 slabs (90at.%), however, an important proportion of the Ni segregates out of this position during the reaction (39%).

Synthesis of NiMo hydrodesulfurization catalyst supported on a composite of nano-sized ZSM-5 zeolite enwrapped with mesoporous KIT-6 material and its high isomerization selectivity

A novel composite material ZSM-5/KIT-6 (ZK-W) was synthesized by enwrapping nano-sized ZSM-5 zeolite crystals with mesoporous KIT-6 silica. This composite was used as catalyst support for NiMo sulfide in the hydrodesulfurization (HDS) of 4,6-dimethyldibenzothiophene (4,6-DMDBT). The NiMo/ZK-W catalyst showed the highest HDS activity and its 4,6-DMDBT conversion was about double that of a conventional NiMo/Al2O3 catalyst at 320°C, 4.0MPa, and LHSV of 150h−1 and on the basis of sulfur. The superior catalytic performance of NiMo/ZK-W is related to the synergistic effect of the excellent diffusion through the hierarchical porous structure and the suitable Brønsted acid sites. 3,6-DMDBT and 3,7-DMDBT, two isomers of 4,6-DMDBT, were identified simultaneously for the first time in the HDS products of 4,6-DMDBT over the NiMo/ZK-W catalyst. The NiMo/ZK-W catalyst exhibited a superior isomerization ability, and 4,4′-dimethylbiphenyl was the main product, indicating that the isomerization pathway is the main reaction route. A new reaction network of 4,6-DMDBT HDS over NiMo/ZK-W catalyst was proposed.

An SEM study of microfossils in the black shale of the Lower Cambrian Niutitang Formation, Southwest China: Implications for the polymetallic sulfide mineralization

The black shale in the Lower Cambrian Niutitang Formation on the southeastern margin of the Yangtze Platform hosts a layer of polymetallic sulfide ores containing extremely high concentrations of Ni (up to 3.8wt.%) and Mo (up to 7.5wt.%). Abundant micrometer-sized microfossils were observed in the Ni–Mo sulfide enriched layer under scanning electron microscopy. The microfossils include vesicles with clear organic wall structures and permineralized internal contents. These structures resemble unicellular green algae. Both biomass-adsorbed transition metals and biological structural protein metals could be accumulated and mineralized from the blooming algae, followed by anoxic microbial reduction and immobilization. The biotic impact may be a substantial mechanism for the massive Ni- and Mo-sulfide deposition in a typical restricted ocean basin environment.

Catalytic upgrading of crude tall oil into a paraffin-rich liquid

Catalytic upgrading via hydrotreatment is an essen- tial method to produce paraffin-range renewable feedstocks from bio-derived oils. This research approach studies the catalytic hydrotreating of crude tall oil (CTO) over a sulfided NiMo catalyst under industrial-relevant conditions in order to produce hydrocarbon fraction, a steam cracker feed with maximum amount of paraffins and high degree of deoxygen- ation. Initial activity of the catalyst (6 h of time on stream) has been investigated, and we report that hydrotreating experiments at most favorable tested conditions (weight hourly space velocity, WHSV=1 h �1 and T=350-400 °C) produces hydrocarbon fraction with 45 wt% of paraffins (n-alkanes+i-alkanes). The highest degree of deoxygen- ation (91 %) was achieved at WHSV=1 h �1 and T=350 °C. Furthermore, the potential of hydrotreated CTO for steam cracking applications has been assessed in this study in view of the achieved product distribution and degree of deoxygen- ation from the hydrotreating of CTO.

Role of support in deoxygenation and isomerization of methyl stearate over nickel–molybdenum catalysts

Microporous SAPO-11 and highly ordered mesoporous AlSBA-15 with different aluminum contents (with Si/Al ratio of 5 and 10) were synthesized. Thus prepared samples were characterized by BET, pyridine-FTIR and NH3-TPD to investigate their structural and acidic properties. The samples were then transformed into bifunctional catalysts by loading with molybdenum and nickel. Their activities were tested in the hydroconversion of methyl stearate using a fixed bed flow reactor system. The sulfided NiMo catalysts exhibited high conversion and deoxygenation activities. High isomerization activities observed for both NiMo/SAPO-11 and NiMo/AlSBA-15 catalysts, similar to the isomerization of light naphtha, was attributed to the acidity of supports. However, the acidity of supports was not the only factor influencing the isomerization of long chain molecules. AlSBA-15 had a large specific surface area that contained more acidic sites inside of its channels, promoting the formation of cracking products; SAPO-11 had a suitable pore size and contained fewer acidic sites inside the pore channels, promoting the formation of mono-branched isomers while suppressing cracking reactions.

Effect of W addition on the hydrodeoxygenation of 4-methylphenol over unsupported NiMo sulfide catalysts

Unsupported NiMo sulfide catalysts modified by tungsten were prepared by a mechanical activation method. They were characterized by XRD, XPS, SEM, TEM and BET specific surface area measurements. The effect of tungsten promoter on the structure and catalytic performance was also discussed. The present work suggested that the addition of tungsten could greatly enhance the hydrodeoxygenation (HDO) activity, and promote the direct deoxygenation (DDO) pathway. Moreover, the addition content affects the mount of active NiMo(W)S phase, resulting in various functions.

Production of Clean Fuel Utilizing the Unsupported Sulfide Catalysts

The sulfur specification for diesel fuel has been tightened exponentially over the years. In this manuscript, the unsupported Ni-Mo (-W) sulfide hydrotreating catalysts were prepared to produce the clean diesel fuel with ultra-low sulfur, nitrogen, and aromatics contents. The X-ray Diffraction (XRD), Low Temperature N2Adsorption (BET method), and High Resolution Transmission Electron Microscope (HRTEM) were applied to characterize the as-prepared catalysts. The characterization results indicate that the unsupported Ni-Mo (-W) hydrotreating catalyst have high specific surface area, large pore volume, high MoS2or WS2stacking layers, and large MoS2or WS2crystal length. The catalysts were evaluated in the micro-reactor using FCC diesel fuel as the raw material. The evaluation results reveal that the unsupported Ni-Mo (-W) catalysts have excellent hydrogenation performance. Utilizing the unsupported Ni-Mo (-W) sulfide catalysts is an efficient method to produce clean diesel fuel. Keywords: clean fuel; Ni-Mo (-W) sulfide; catalyst; hydrogenation

Mechanochemical synthesis of nanocrystalline nickel-molybdenum compounds and their morphology and application in catalysis: III. Catalytic properties of massive Ni-Mo sulfide catalysts synthesized using mechanochemical activation

The precursors of massive Ni-Mo catalysts for hydrotreating processes, which were synthesized by the mechanochemical activation of a mixture of nickel hydroxocarbonate NiCO3·2Ni(OH)2·nH2O and ammonium paramolybdate (NH4)6Mo7O24 · 4H2O, were sulfidized. Their structure was studied by X-ray diffraction analysis and high-resolution electron microscopy. It was found that MoS2 packets, which are characterized by the presence of structural defects and geometric curvature, are the constituents of the massive catalysts. The catalyst also includes a phase of Ni3S2 and regions containing a complex Ni-Mo-S phase. The catalytic tests of the synthesized catalysts in the model reactions of 1-methylnaphthalene and dibenzothiophene conversions showed that the catalyst whose precursor was a heteropoly compound with the Anderson structure after the stage of mechanochemical activation exhibited the highest activity.

Maya crude oil hydrotreating reaction in a batch reactor using alumina-supported NiMo carbide and nitride as catalysts

The hydrotreating (HT) of Maya crude oil was carried out in a Parr batch reactor, using alumina-supported catalysts based on NiMo sulfides, carbides and nitrides, which were synthesized by temperature programmed reaction of the oxidic precursors. The catalysts were characterized by X-ray diffraction, N2 physisorption, scanning- and high resolution transmission-electron microscopy. Next, catalysts with the best performance in thiophene hydrodesulfurization (HDS) were selected to be used in the HT of Maya crude oil. HT reactions were carried out at 320°C and 70–80kg/cm2. All catalysts were sulfided ex situ with a mixture of CS2/H2, prior to reaction. Products of reaction were analyzed by simulated distillation, sulfur and metal contents. Specific weight was also obtained, which was further used to calculate specific gravity and API gravity. Here, it was shown a synergistic effect by using Ni as promoter to Mo carbides and nitrides which is in contrast to previous reports. Moreover, during Maya crude oil HT, it was accomplished the enhancement of API gravity by using NiMo sulfide. Sulfur and metal removal was also successful using these materials, confirming that active phases based on NiMo nitrides and/or carbides could be considered as new HT catalysts for real feedstocks processing.

Oil-soluble Ni-Mo sulfide nanoparticles and their hydrogenation catalytic properties

Oil-soluble bimetallic Ni-Mo sulfide nanoparticles (NiMoS) with narrow size distribution were successfully synthesized through a composite-surfactants-assisted-solvothermal process. The surface functionality and lipophilicity of the Ni-Mo sulfides were shown by transmission electronic microscopy, Fourier transform infrared and ultraviolet spectroscopy. The as-prepared Ni-Mo sulfides supported on activated carbon (NiMoS/AC) exhibited enhanced catalytic activity towards naphthalene hydrogenation instead of cracking. For comparison, CoMoS/AC and MoS2/AC catalysts were also prepared through similar procedures, and it was found that their catalytic performance decreased in the order of NiMoS/AC>CoMoS/AC>MoS2/AC. Furthermore, the activity of the bimetallic NiMoS nanocatalyst can be effectively tuned via variation of the atomic ratio of Ni/(Ni+Mo).

Synthesis and Hydrodesulfurization Performance of NiMo Sulfide Catalysts Supported on γ-Al<sub>2</sub>O<sub>3</sub>

This work presents the synthesis and hydrodesulfurization performance of NiMo sulfide catalysts supported on γ-Al2O3 during the hydrodesulfurization (HDS) of dibenzothiophene (DBT). The catalysts were synthesized by the co-impregnation method using an atomic ratio of Ni=Ni/(Ni+Mo)=0.5. The materials were characterized by N2 physisorption, XRD and HRTEM. This catalyst exhibited the larger pore size and high specific surface area, as well as better morphological properties. The catalytic activity was evaluated using a high-pressure batch reactor at 280 °C and 3.0 MPa. The catalytic activity during HDS-DBT indicated that the NiMoS/γ-Al2O3 catalyst was better than that NiMoS/γ-Al2O3 catalyst. the NiMoS/γ-Al2O3 catalyst exhibits higher DDS selectivity (3.0) than NiMo/γ-Al2O3 catalyst (2.55).

Unsupported Molybdenum Carbide and Nitride Catalysts for Polychlorinated Biphenyls Hydrodechlorination

Unsupported Mo carbide and Mo nitride catalysts have been synthesized by temperature programmed synthesis, and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, H2-temperature programmed reduction and desorption and N2 physisorption. These solid compounds have been tested for the hydrodechlorination (HDCl) of polychlorinated biphenyls (PCBs) at 1 bar in a fixed bed reactor. The Mo carbides and the corresponding Mo nitride phases showed a catalytic activity higher than a conventional HDS catalyst consisting of alumina-supported NiMo sulfides (~35 %). Aroclor 1260 HDCl conversion results were related to spilt-over hydrogen species that were proposed to favor the hydrogenolysis of C–Cl bond on refractory phases. The original PCBs broad distribution changed almost completely to non-chlorinated biphenyl on the carbide and nitride catalysts.

Vacuum gas oil hydrocracking performance of bifunctional Mo/Y zeolite catalysts in a semi-batch reactor

A new approach has been developed to characterize bifunctional catalysts in a complex matrix of hydrotreated vacuum gas oil using a batch reactor test. Triphasic reactions were carried out in a reactor equipped with a stationary basket, hydrogen injection and products sampling systems. Bifunctional catalysts containing different relative amounts of alumina-supported NiMo sulfide and zeolite were tested at 400°C under 120 bars over different reaction times. The repeatability of the test conditions was validated and the lack of mass transfer limitations at phase interfaces was confirmed. Gas and liquid samples were analyzed by one and two-dimensional gas chromatography (GC×GC) respectively to obtain quantitative distributions of linear and branched paraffins, naphthenes and aromatics. The details of the products distribution provided by chromatography were explained using mechanisms of bifunctional catalysis. It has been established that the limiting step defining the total conversion is the scission of the hydrocarbon chains on acid sites of the zeolite. The increase of the molybdenum to zeolite ratio provided an improvement of middle distillate selectivity.

An Efficient Approach to Produce Clean Diesel Fuel: Development of Catalysts With Ultra-High Hydrogenation Performance

The sulfur specification for diesel fuel has been tightened exponentially over the years. To help resolve this question, the authors aimed to develop a novel unsupported Ni-Mo sulfide catalyst with ultra-high hydrogenation performance, for the production of clean diesel fuel. This catalyst was prepared directly with ammonium tetrathiomolybdate and basic nickel carbonate as the catalyst precursors through the low-temperature solid-state surface reaction. XRD and HRTEM characterization results indicate that the stacking number of MoS2 layers is very high in the unsupported Ni-Mo sulfide. The evaluation results of model compound (dibenzothiophene) and FCC diesel fuel demonstrate that the unsupported Ni-Mo sulfide catalyst has excellent hydrodesulfurization activity and ultra-high hydrogenation performance, which can be attributed to the high stacking number of MoS2 layers.

V–Ni–Mo sulfide supported on Al2O3: Preparation, characterization and LCO hydrotreating

The effect of vanadium incorporation on the HDS, HDN, and HDA activities of LCO hydrotreating was investigated on NiMo supported hydrotreating catalysts. The catalysts were characterized by XRD, BET, XPS, NO-chemisorption and evaluated in fixed bed reactor using real LCO as feed. The vanadium promoted NiMo catalyst presented higher HDS and HDN activities, and surprisingly a relatively low activity toward the HDA. This behavior is probably due to a vanadium-mixed active phase, this has superior conversion as compared to NiMo catalyst.

Catalytic hydroconversion of a wheat straw soda lignin: Characterization of the products and the lignin residue

A wheat straw soda lignin was characterized and converted into gases and liquids under H2 pressure, at 350°C over a supported NiMo sulfide catalyst, using tetralin as a hydrogen-donor solvent in a batch autoclave. The aim of this work was to evaluate the transformations occurring during the temperature increasing step to reach a pseudo-t0 and the impact of the catalyst presence in the mixture. A well-developed products separation protocol made possible to isolate and to characterize gases, organic liquid, lignin residue and solids (catalyst and char). A limited quantity of solids (or char) was produced however. As the lignin residue is one of the main intermediates of the lignin conversion pattern, the nature of this material has to be carefully determined. Thanks to several appropriate characterization techniques (GPC, NMR, FTIR), the conversion was followed and the lignin residue was compared to the initial lignin in order to understand the transformations occurring during the process.