NiMo Sulfide Research Articles

Unlocking hierarchical hollow nanoblocks of NiMo sulfide with extended interlayer spacing of Mo-S units for high-performance supercapacitor

Molybdenum sulfide (MoS2) has been investigated as electrode of supercapacitor due to its unique structure. However, the restricted availability of active sites and sluggish behavior at the basal surface impede its improvement. Here we propose an unlocking hierarchical hollow strategy to synthesis the bimetallic sulfide heterostructures loaded on the ultrathin carbon (NiS/MoS2@UC). The unlocking hierarchical hollow structure and extended S-Mo layer provide interconnected channels for rapid electrolyte ion transport, while the heterojunction interface promotes the electron transfer and redox reaction. As a result, NiS/MoS2@UC − 2 exhibits a high specific capacitance of 616.7F g−1 at the current density of 1 A/g, which is approximately 10 times higher than that of MoS2@UC and 6 times higher than that of NiS@UC. Moreover, NiS/MoS2@UC − 2 demonstrates a high energy density of 7.7 Wh kg−1 at the power density of 300 W kg−1 with excellent cycling durability.

Performance of sulfided NiMo catalyst supported on pillared bentonite Al and Ti under hydrodeoxygenation reaction of guaiacol

Bio-crude oil is known to be sustainable, eco-environmentally, and an alternative energy source produced by biomass pyrolysis. However, its quality remains relatively low due to a higher oxygen concentration compared to liquid fuels from fossils. Therefore, an upgrading process is necessary through the catalytic hydrodeoxygenation (HDO) process. This work synthesized pillared bentonite using Al and Ti metals as the pillaring agent to produce Al-PILC and Ti-PILC as catalyst support for sulfided NiMo. Their catalytic activity in HDO reaction using guaiacol as a model compound of bio-crude oil were also evaluated. Characterization of the bentonite-pillared materials, including Al-PILC, Mo/Al-PILC, NiMo/Al-PILC, Ti-PILC, Mo/Ti-PILC, and NiMo/Ti-PILC, was performed using Surface Area Analyzer, X-ray Diffractometer (XRD), Temperature-Programmed Desorption of ammonia (NH3-TPD), X-Ray Fluorescence (XRF), and Scanning Electron Microscope (SEM) techniques. The characterization results confirm the pillarization process of bentonite using Al and Ti metals as the pillaring agent, and the preparation of the NiMo catalyst using the stepwise impregnation method was successfully prepared. The NiMo/Ti-PILC catalyst performs a superior conversion value on the HDO guaiacol reaction than other catalysts. A well dispersion of Mo and Ni metals on the surface support (NiMo/Ti-PILC), thus creating numerous active sites of the catalyst after the sulfidation. Variations in time and temperature during the HDO guaiacol reaction significantly affected the conversion.

Making Ternary‐Metal Hydroxysulfide Catalyst via Cathodic Reconstruction with Ion Regulation for Industrial‐Level Hydrogen Generation

AbstractDeep insight into electrochemical reconstruction aids in the decoding of electrocatalytic mechanisms and the development of design principles for advanced catalysts. Despite recent achievements, research concerning cathodic reconstruction is still lacking compared to the anodic variety. This work captures the electroreductive reconstruction dynamics over bimetal Ni–Mo sulfide by various in/ex situ techniques, and whereby cathodic reconstruction is steered with ion regulation to achieve a heterogeneous Ni–Mo–Fe ternary metal hydroxysulfide (NMFSOH) as a robust hydrogen‐evolving catalyst that is competent in industrial‐level water electrolysis. The thermodynamically adaptive heterosynergism in the resultant NMFSOH catalyst can coordinate water dissociation and hydrogenation for the alkaline hydrogen evolution reaction even at high current densities. A flow‐type alkaline water electrolyzer with dual NMFSOH electrodes affords an electricity consumption of 3.99 kW h Nm−3 and an electricity‐to‐hydrogen efficiency of 88.7%, manifesting its competitive cost‐effectiveness toward practical applications. This study showcases ion‐regulatory reconstruction as an effective strategy to construct high‐performance electrocatalysts.

Hydrodeoxygenation of lignin-derived diphenyl ether on in situ prepared NiMoS catalyst: The effect of sulfur addition on catalyst formation

The catalytic activity of unsupported NiMoS catalysts prepared in situ by thermal decomposition of the [(CH3)3S]2Ni(MoS4)2 precursor was studied in the course of diphenyl ether hydrodeoxygenation. The resulting catalysts were characterized using the transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). It was demonstrated that the diphenyl ether conversion naturally decreases with a decrease in the precursor loading. The effect of changes in the amount of the added sulfiding agent on the morphological and structural features of the formed catalysts was studied. It was found that reducing the amount of elemental sulfur from 2.5 to 0.5 wt% results in a more active sulfide NiMo catalyst, which is explained by an increase in the dispersion of the active phase particles from 0.24 to 0.34. A route of diphenyl ether hydrodeoxygenation on unsupported NiMoS catalysts was studied and suggested by varying the reaction time and hydrogen pressure in the system.

Hydrogen Separation from Gas Mixtures by Its Chemical Storage via Hydrogenation of Aromatic Compounds over Dispersed Ni–Mo–Sulfide Catalysts

Hydrogen Separation from Gas Mixtures by Its Chemical Storage via Hydrogenation of Aromatic Compounds over Dispersed Ni–Mo–Sulfide Catalysts

Experimental and computational studies of sulfided NiMo supported on pillared clay: catalyst activation and guaiacol adsorption sites.

We report on intermediate (oxysulfides) and sulfided structures of NiMo supported on aluminium pillared clay (Al-PILC) during the catalyst activation process and the prefered guaiacol adsorption sites on the sulfided catalyst. In situ X-ray absorption fine structure (XAFS) together with density functional theory (DFT) calculations confirm the existence of ill-defined suboxides (MoOx, NiOx) and the well-known subsulfides (Mo2S9, Ni3S2) at the first stage which, at a later stage in the process, transform into MoS2 with two edges, oxygen-decorated Mo and Ni with zero sulfur coverage. The freshly sulfided NiMoS2 catalyst under sulfiding agents is mainly terminated by Mo-edge surface with 50% sulfur coverage (Mo-S50) with a disordered Ni-edge surface that can be assigned as NiMoS (1̄010). When exposed to an inert atmosphere such as He gas, the Mo and Ni edges evolved partially into new structures of Mo and Ni edges with zero sulfur coverage, labelled as Mo-Bare and Ni-Bare. Guaiacol is often used as a model compound for lignin and a series of calculations of guaiacol on the structural edges of a sulfided NiMoS2 catalyst show relatively good agreement between the observed and calculated inelastic neutron scattering (INS) spectra for Mo-S50, Ni-Bare, and NiMoS (1̄010) where guaiacol weakly chemisorbed via oxygen atom of OH group. The results also confirm that guaiacol is physisorbed on the basal plane of NiMoS2 in a horizontal (flat-lying) configuration via van der Waals interaction at a separation of about 3.25 Å.

On Stability of High-Surface-Area Al2O3, TiO2, SiO2-Al2O3, and Activated Carbon Supports during Preparation of NiMo Sulfide Catalysts for Parallel Deoxygenation of Octanoic Acid and Hydrodesulfurization of 1-Benzothiophene

NiMo sulfide catalysts were prepared by the impregnation of high surface area supports with an aqueous solution made of NiCO3·2Ni(OH)2, MoO3 and citric acid, followed by freeze drying and sulfidation in H2S/H2 mixture. N2 physisorption and X-ray diffraction were selected to investigate the amphoteric oxides Al2O3 and TiO2, acidic SiO2-Al2O3 and activated carbon supports, fresh prepared sulfide NiMo catalysts and spent catalysts after model parallel reaction of octanoic acid deoxygenation and 1-benzothiophene hydrodesulfurization. The studied mesoporous amphoteric oxides Al2O3 and TiO2 did not lead to highly active NiMo catalysts due to the low hydrothermal stability of these supports during the preparation of the active sulfide phase and deoxygenation reaction. The most active catalyst based on oxidic support was the NiMo sulfide supported on acidic mesoporous SiO2-Al2O3, which was explained by the increased stability of this support to the water and CO/CO2 mixture during the activation of the sulfidic phase and deoxygenation reaction. The extraordinarily high stability of the activated carbon support led to outstanding activities of the sulfidic NiMo/C catalyst.

Investigation of the hydroisomerization of diesel fractions with different concentration of nitrogen-containing compounds on bifunctional catalysts based on ZSM-23 and non-noble metals

Bifunctional catalysts based on NiMo(W) sulfides and a ZSM-23-Al2O3 composite support have been synthesized. Their properties were studied in the transformations of diesel fractions with different nitrogen content (< 1, 10 and 20 ppm). It was demonstrated that the synthesized catalysts could be used to obtain hydrogenizates with the limiting filterability temperature  –38 °C, which comply with the requirements of GOST R 55475-2013 to the content of gasoline fraction and aromatic compounds, and the derived cetane number. Properties of the developed catalysts based on NiMo and NiW sulfides and characteristics of the corresponding hydrogenizates were compared with each other. In addition, properties of the developed samples were compared with the properties of a foreign commercial platinum catalyst for isodeparaffinization. The synthesized catalysts were found to be less selective than the reference sample, but more stable to N-containing compounds in the feedstock.

Elucidating the role of NiMoS-USY during the hydrotreatment of Kraft lignin

Major hurdles in Kraft lignin valorization require selective cleavage of etheric and C–C linkages and subsequent stabilization of the fragments to suppress repolymerization reactions to yield higher monomeric fractions. In this regard, we report the development of efficient NiMo sulfides and ultra-stable Y zeolites for the reductive liquefaction and hydrodeoxygenation of Kraft lignin in a Parr autoclave reactor at 400 °C and 35 bar of H2 (@25 °C). Comparing the activity test without/with catalyst, it is revealed that NiMo sulfides over ultra-stable Y zeolites (silica/alumina = 30) achieved a significant reduction (∼50 %) of the re-polymerized solid residue fraction leading to a detectable liquid product yield of 30.5 wt% with a notable monocyclic and alkylbenzenes selectivity (∼61 wt%). A physical mixture counterpart, consisting of hydrothermally synthesized unsupported NiMoS and Y30, on the other hand, shows lower selectivity for such fractions but higher stabilization of the lignin fragments due to enhanced access to the active sites. Moreover, an extended reaction time with higher catalyst loading of the impregnated NiMoY30 facilitated a remarkable alkylbenzene (72 wt%) selectivity with an increased liquid yield of 38.9 wt% and a reduced solid residue of 16.4 wt%. The reason for the high yield and selectivity over NiMoY30, according to the catalyst characterization (H2-TPR, XPS, TEM) can be ascribed to enhanced stabilization of depolymerized fragments via H2-activation at a lower temperature and high hydrodeoxygenation ability. In addition, the better proximity of the acidic and deoxygenation sites in NiMoY30 was beneficial for suppressing the formation of polycyclic aromatics.

Catalytic Hydrotreating of Crude Pongamia pinnata Oil to Bio-Hydrogenated Diesel over Sulfided NiMo Catalyst

This work studied the catalytic activity and stability of Ni-MoS2 supported on γ-Al2O3, SiO2, and TiO2 toward deoxygenation of different feedstocks, i.e., crude Pongamia pinnata oil (PPO) and refined palm olein (RPO). PPO was used as a renewable feedstock for bio-hydrogenated diesel production via catalytic hydrotreating under a temperature of 330 °C, H2 pressure of 50 bar, WHSV of 1.5 h−1, and H2/oil (v/v) of 1000 cm3/cm3 under continuous operation. The oil yield from a Soxhlet extraction of PPO was up to 26 wt.% on a dry basis, mainly consisting of C18 fatty acids. The catalytic activity in terms of conversion and diesel yield was in the same trend as increasing in the order of NiMo/γ-Al2O3 > NiMo/TiO2 > NiMo/SiO2. The hydrodeoxygenation (HDO) activity was more favorable over the sulfided NiMo supported on γ-Al2O3 and TiO2, while a high DCO was observed over the sulfided NiMo/SiO2 catalyst, which related to the properties of the support material and the intensity of metal–support interaction. The deactivation of NiMo/SiO2 and NiMo/TiO2 occurred in a short period, due to the phosphorus and alkali impurities in PPO which were not found in the case of RPO. NiMo/γ-Al2O3 exhibited the high resistance of impure feedstock with excellent stability. This indicates that the catalytic performance is influenced by the purity of the feedstock as well as the characteristics of the catalysts.

Characterization and HDS activity of Mo and NiMo sulfided catalyst prepared by thioglycolic acid assisted hydrothermal deposition method

Dispersed NiMo sulfide catalysts were synthesized by hydrothermal deposition method with the assistance of thioglycolic acid (TGA) as sulfiding agent ex situ at 160 °C. The prepared samples were characterized by SBET, XRD, SEM, FTIR, XPS, TPR/TPS, TPD-NH3. The catalyst activity was investigated during hydrodesulfurization (HDS) of thiophene (TH) at 340 °C. XRD and XPS methods showed that this hydrothermal synthesis of Mo and NiMo solids yielded sulfide crystalline phases with high bulk and surface S/Mo ratio. Re-sulfidation of the Ni-containing samples led to an increase in surface area, which was thus able to redisperse the NiMo sulfide active sites. The results of temperature programmed sulfidation measurements combined with mass spectrometric analysis (TPS-MS) of the catalysts revealed the formation of a fraction of TGA species that remained in the pores of the sample with the highest TGA content. In the NiMo catalyst prepared at TGA/Mo molar ratio of four, this TGA enhanced the amount of NiMoS phase in the catalyst and positively affected the HDS activity.

A Facile Strategy to Create Electrocatalysts of Highly Dispersive Ni–Mo Sulfide Nanosheets on Graphene by Derivation of Polyoxometalate Coordination Polymer for Advanced H2 Evolution

A Facile Strategy to Create Electrocatalysts of Highly Dispersive Ni–Mo Sulfide Nanosheets on Graphene by Derivation of Polyoxometalate Coordination Polymer for Advanced H₂ Evolution

Trace element and C-S-Fe geochemistry of Early Cambrian black shales and associated polymetallic Ni-Mo sulfide and vanadium mineralization, South China: Implications for paleoceanic redox variation

Early Cambrian black shales are widely exposed along the southeastern margin of the Yangtze Platform in South China for a length of over 1600 km. The basal part of this sequence host a large spectrum of mineralization, including polymetallic Ni-Mo sulfide, vanadium, phosphorite, barite, as well as combustible shale (stone coal). In particular, the polymetallic Ni-Mo sulfide ore layer is stratigraphically equivalent but geographically separated from the V mineralization. In the Zhangjiajie region in Hunan province, the tenor of the polymetallic Ni-Mo sulfide mineralization in the northeastern segment decreases gradually and grades into vanadium mineralization in the southwestern segment. Based on the stratigraphic correlation, we compared the trace element composition and carbon–sulfur-iron system of the polymetallic Ni-Mo sulfide ore, vanadium ore, and their host black shales.The polymetallic Ni-Mo sulfide and V ores display similar PAAS-normalized REE distribution patterns with negative Ce and positive Y anomalies, similar to present-day seawater. The polymetallic sulfide ores show elevated seawater-like Y/Ho ratios (mean: 52.7 ± 6.8) and the V ores with an average Y/Ho ratio of 40.2 ± 3.8 reflect the influence of terrigenous material. Although both the polymetallic Ni-Mo sulfide ore and the V ore formed under anoxic conditions, the degree of oxygen deficiency was variable, i.e., euxinic condition for the polymetallic sulfide ore but euxinic and suboxic conditions for the vanadium ore. This model is supported by the more elevated redox-sensitive elements (e.g., U and Co) in the polymetallic Ni-Mo sulfide ores compared to the V ores. Excess sulfur of the polymetallic Ni-Mo sulfide ores with S/Fe ratios>1.15 suggests that they formed under iron-limited euxinic conditions. In contrast, the V ores formed under euxinic to suboxic conditions with S/Fe ratios close to or lower than 1.15. The host black shales display positive correlations for TOC and redox-sensitive elements, suggesting that they formed under suboxic conditions. We infer that the polymetallic Ni-Mo sulfide ores formed in a sediment-starved semi-restricted euxinic marine basin. In contrast, the V ores formed under both euxinic and intermittently suboxic to euxinic conditions at the slope of the basin with terrestrial input from enhanced continental weathering. Repeated transgressive–regressive episodes led to the formation of V ores interlayered with suboxic black shale with more subdued oxygen deficiency. The results of this study suggest that exploration for V mineralization should focus on the southeastward lateral stratigraphic equivalents of the polymetallic Ni-Mo sulfide mineralization.

SRGO hydrotreating over Ni-phosphide catalysts on granulated Al2O3

Ni-phosphides present a promising alternative to the conventional hydrotreatment NiMo sulfides. The hydrotreatment catalysts are supported on Al2O3 granules, and the similarly Al2O3 supported Ni-phosphide catalysts provide an interesting case for comparison. In this work the Ni-phosphide catalysts supported on Al2O3 granules were prepared using two procedures: 1) temperature-programmed reduction of “phosphite”-type precursor in hydrogen flow (TPR_I catalyst), 2) treatment of Ni nanoparticles with triphenylphosphine solution at elevated temperature (LP catalyst). The catalysts were characterized by ICP-AES chemical analysis, N2 physisorption, XRD, TEM, XPS, 27Al MAS NMR. The Ni2P particles were found in LP samples, while TPR method gives the mixture of Ni12P5 and Ni2P particles and amorphous AlPO4 on the alumina surface. The behavior of granulated Ni phosphide and conventional sulfided NiMo/Al2O3 catalysts was compared in hydroprocessing of straight-run gas oil (SRGO) at 340 °C, 4 MPa, V(H2)/V(feed) - 400 Nm3/m3, LHSV - 1,5 h−1. Hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) activity of nickel phosphide catalysts were shown to be lower in comparison with NiMo/Al2O3. Hydrotreating of S-containing model compounds (DBT, 4-MDBT, 4,6-DMDBT) was carried out over TPR_I catalyst, and a negative effect of dimethyl disulfide (DMDS) and acridin additions on the HDS activity was observed.

Effects of Water Addition on the Conversion of o-Cresol in the Presence of In Situ Ni–Mo Sulfide Catalysts

Ni-Mo sulfide systems generated in situ from precursor salts were used for the hydrodeoxygenation of o-cresol. After the reaction, the catalysts were recovered and analyzed by transmission electron microscopy and X-ray photoelectron spectroscopy. It was shown that the addition of water into the reaction system affects the composition of the o-cresol conversion product due to a change in the texture and phase composition of the surface layer of the in situ sulfide particles.

Effects of Zn Addition into ZSM-5 Zeolite on Dehydrocyclization-Cracking of Soybean Oil Using Hierarchical Zeolite-Al2O3 Composite-Supported Pt/NiMo Sulfided Catalysts.

Zn-exchanged ZSM-5-Al2O3 (ZA) composite-supported Pt/NiMo (NM) sulfided catalysts were prepared using the conventional kneading method and were tested for dehydrocyclization-cracking of soybean oil. The effects of Zn addition on the activity and selectivity of products were investigated under moderate-pressure conditions of 0.5 and 1.0 MPa H2 in the temperature range of 420–580 °C. At the temperature 500 °C and higher, most of the sample soybean oil was converted at both the pressures of 0.5 and 1.0 MPa. At 1.0 MPa and 500 °C, the effects of Zn addition appeared and increased the yields of aromatics, while the catalyst without Zn produced larger amounts of products with more than C18. Further, at 0.5 MPa and 580 °C, the gas formation was inhibited in comparison to the cases of 1.0 MPa and the effects of the Zn addition also appeared and increased the yields of aromatics, while the catalyst without Zn produced larger amounts of products with more than C18. The Pt/NM/Zn(122)ZA test catalyst produced more than 63% of liquid fuels in the range C5–C18, and the yield of aromatics was 13%, the maximum value in the present study. The following reaction routes were proposed. The structure of triglyceride is converted by hydrocracking to three molecules of aliphatic acids and propane on the surface PtNiMo sulfide on Al2O3 support. The converted aliphatic acids are decomposed through decarboxylation to hydrocarbon fragments, which are further decomposed by cracking on the acid sites of the catalyst, the surface of NiMo sulfide, Al2O3, or ZSM-5. Finally, the formed C3 and C4 olefins are transformed to aromatics through the Diels–Alder reaction on the Zn species of ZnZSM-5. On the other hand, although gases were relatively small in amount, aromatic compounds were formed significantly, suggesting that cyclization might directly occur without conversion to gaseous hydrocarbons to some extent.

Noble metal encapsulated sulfide catalyst for the production of aviation biofuel from the hydroprocessing of non-edible oils

Encapsulation of noble metals inside the zeolite cage has attracted much attention in the area of catalysis due to unique properties, i.e., shape selectivity, higher activity, and product yield. In the combined work, encapsulated Platinum (Pt) inside the sodalite cage combined with sulfided nickel and molybdenum supported on silica-alumina (NiMo(S)/SiO2-Al2O3) is used to improve the catalyst hydrogenation function by providing spillover hydrogen to the nearby active sulfided NiMo sites. Encapsulation ensures the protection of the noble metal sites from poisoning due to the sulfur-containing compounds. They have a higher hydrodynamic diameter than that of the sodalite window cage. Experimental results showed platinum encapsulated sulfided nickel and molybdenum supported on silica-alumina (Pt@SOD-NiMo(S)-SiO2-Al2O3) had a substantial effect on the product composition, yield, and hydrogen consumption compared with the conventional NiMo(S)/SiO2-Al2O3 catalyst for the hydroconversion reaction of jatropha oil to produce carbon–neutral green fuels. Sustainable aviation fuel with lower aromatics and naphthene content (<1%) was produced over the bi-functional Pt encapsulated Ni-Mo(S)/SiO2-Al2O3 catalysts in the reaction temperature range of 380–420 °C. Aromatics and naphthalene obtained in the aviation range product were as much as 15 times lower than the conventional NiMo(S)/SiO2-Al2O3 catalyst. The Pt@SOD-NiMo(S)-SiO2-Al2O3 catalyst showed stable activity for >600 h of the run, whereas state-of-the-art reported catalyst Pt@SOD-NiMo(S)-ZSM-5 had limitations in terms of catalyst life (stable activity only for 350 h).

Aromatics formation by dehydrocyclization-cracking of methyl oleate using ZnZSM-5-alumina composite-supported NiMo sulfide catalysts

In order to investigate the dehydrocyclization-cracking of methyl oleate, one of fatty acid methyl esters, ZnZSM-5-alumina composite-supported NiMo sulfide catalysts were prepared, where the contents of NiMo were changed with the content of alumina. Approximately 100% conversion was achieved for each catalyst even at 450 °C under the 0.5 MPa hydrogen pressure while the selectivity for products changed depending on temperature and the configuration of the composite catalysts. The increase in the content of alumina and the increase in the metal content brought about the increase in the hydrocracking activity. When the content of alumina ratio was low and the metal content decreased, however, the C15–C18 diesel component increased, but hydrocracking did not proceed sufficiently and the larger amount of C19- fraction tended to be formed. The yield of aromatics increased with an optimum combination of amounts of alumina-supported NiMo sulfide and Zn-exchanged ZSM-5, and 9.3NM/Zn(13)Z(24)35A catalysts gave the highest yield of 20 wt%. This catalyst generated relatively smaller amounts of gaseous products and olefins, suggesting that most of the reaction products would be gasified once and then cyclization may occur to produce aromatic compounds. The reaction of methyl oleate started on NiMo/γ-Alumina part in NiMo/ZnZSM-5/γ-Alumina and produced C17 and C18 hydrocarbon fragments through decarboxylation, decarbonylation and hydrodeoxygenation. After successive hydrocracking by NiMo/ZnZSM-5/γ-Alumina and cracking by ZnZSM-5 part, forming smaller alkanes and alkenes, finally C2-C4 olefins and gasoline fractions would be produced. It is likely that C2-C4 olefins would be subjected to selective aromatization to benzene, toluene and xylene on Zn/ZSM-5.

The Hydrodeoxygenation of Glycerol over NiMoSx: Catalyst Stability and Activity at Hydropyrolysis Conditions

AbstractCatalytic activity tests were run to elucidate the chemistry and catalyst stability for the hydrodeoxygenation of glycerol and other aliphatic oxygenates over a NiMoSx/Al2O3 catalyst at different pretreatments at hydropyrolysis conditions in a continuous flow reactor. Reactivity metrics were developed to quantify and compare the reactivity of NiMo for deoxygenation, hydrogenation, and C−C cleavage. Activity experiments showed sulfided NiMo and reduced NiMo catalysts had similar deoxygenation and hydrogenation activity for glycerol HDO at 400 °C and 270 psig H2 with the NiMoSx catalyst showing higher C−C cleavage activity. Without a sulfur co‐feed, both the NiMoSx and NiMoOx catalysts lost &gt;40 % deoxygenation activity over 30 h time on stream. With a 2100 ppm H2S co‐feed the NiMoSx catalyst showed a 12 times decrease in the deactivation rate for deoxygenation and 6 time decrease in the deactivation rate for hydrogenation. The main products at high conversion were propylene, propane, ethylene, methane, CO, methanol, ethanol, and 1‐propanol. At low conversion, the major products were unsaturated allyl alcohol, acrolein, hydroxyacetone, and acetaldehyde. With no H2S co‐feed at short contact times, there was a significant amount of carbon loss possibly due to condensation reactions, while at 2100 ppm H2S in the feed, the carbon balance was 102.4 %. Temperature programmed oxidation of the spent NiMoSx catalysts after 30 h of glycerol HDO without an H2S co‐feed showed that one of the causes of deactivation was coking.

Hydrocarbon biofuel from hydrotreating of palm oil over unsupported Ni–Mo sulfide catalysts

Research on the production of bio-hydrogenated diesel as a green second-generation biodiesel is increasingly attractive for renewable energy utilization in engines, and has potentially been produced from the hydrotreating of vegetable oils. The present work investigated the hydrodeoxygenation of palm oil catalyzed by unsupported nickel-molybdenum (Ni–Mo) sulfide synthesized by a hydrothermal method. The effects of the operating parameters, such as the reaction time (0.5–3 h), temperature (280–320 °C), oil concentration (5–15%) on the n-alkane yield were evaluated. A longer reaction time and higher temperature promoted the reaction via decarboxylation and decarbonylation pathways. Under the appropriate condition (300 °C, 2 h, and initial H2 pressure of 30 bar), the yield of C14–18 alkanes was 75.3 wt%, while the selectivity of n-C15, n-C16, n-C17, and n-C18 alkanes was 21.8, 19.7, 29.6, and 28.1%, respectively. Gas chromatography-mass spectrometry analysis revealed n-alkenes, alcohols, and esters as byproducts. Characterization of catalyst revealed it had a sandwich structure consisting of weakly coupled layers, rim sites and Ni edges, which catalyzed the reaction efficiently. The catalyst could be reused for at least four cycles of palm oil hydrodeoxygenation with retention of a good performance with the decreased 17–25% alkane yield (2nd to 4th cycle with 50.8–57.3% n-C14–18 yield).