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The catalytic activities of the dispersed NixW(1−x)S2 catalysts were investigated for hydrocracking (HCK) of vacuum residue (VR) at 693 K, 9.5 MPa H2 with the same amount of catalyst loading of 0.113 mmol as a metal basis. The catalysts were prepared in situ in the reaction using nickel acetylacetonate and tungsten hexacarbonyl as Ni and W precursors, respectively. Structural properties of the dispersed catalysts were characterized by extended X-ray absorption fine structure and transmission electron microscopy, which confirmed the formation of a well-dispersed NixW(1−x)S2 phase in the size range 8–10 nm. Moreover, it was demonstrated that the bimetallic metal sulfides of NixW(1−x)S2 feature promotional activity in the VR HCK, showing higher turnover frequency values and less coke formation in VR HCK than monometal sulfides.

CoMoS2/Al2O3 catalysts prepared by adding citric acid (CA) were synthesized and applied tor hydrodesulfurization (HDS) of fluid-catalytic cracking decant-oils (FCC-DO). The HDS of FCC-DO was carried out in an autoclave batch reactor at 653 K and 9.4 MPa H2. The structural properties of the catalysts were characterized by N2 physisorption, X-ray absorption fine structure spectroscopy (XAFS), and transmission electron microscopy (TEM). The S compounds in FCC-DO have been classified into three groups in terms of the reactivity of HDS. The Co K-edge XANES analysis confirmed the formation of the Co-Mo-S phase with the addition of CA, contributing to better activity in the HDS of FCC-DO.

The degradation of amorphous cobalt phosphides (CoPx) as an electrocatalyst for the hydrogen evolution reaction (HER) is studied in the discontinuous operation of alkaline water electrolysis cells (AWEs). Although amorphous CoPx shows a 100-fold enhancement in HER activity over nickel, the kinetic current for the HER is decreased after discontinuous operation. Under the off condition, the cathode potential of the AWE increases close to the equilibrium potential for CoPx oxidation to Co, Co(OH)2, CoOx, and CoPxOy. The irreversible oxide and hydroxide formation induces weaker interactions between Co and P, and thus the degradation of kinetics over CoPx, negatively affecting the HER even though a cathodic current is applied for recovery. A cathodic protection method is devised to mitigate the degradation of CoPx by shifting the electrode potential below the equilibrium potential of Co(OH)2. Mn is chosen as a sacrificial species, and it slows the rate of electrode degradation by negative polarization of the electrode. The results show that the co-deposition of even a small amount of Mn onto the CoPx electrode could limit the loss of HER activity during repeated discontinuous operation of the AWEs. Furthermore, in situ X-ray absorption near edge structure analysis confirms that the CoPx with co-deposited Mn does show the effect on holding the phase of CoPx during discontinuous operation.

Dispersed MoxW(1−x)S2 catalysts were obtained in situ in the hydrocracking (HCK) of vacuum residue (VR) at 693 K at 9.5 MPa H2 with the same metal loading of 0.113 mmol with varying Mo:W ratios. The intrinsic activities of the catalysts were compared based on the H2 consumption rate per the surface site number, i.e. TOFs. The Mo0.75W0.25S2 catalyst showed a superior activity with a high TOFs of 0.6012 s−1 over those of monometallic sulfides of MoS2 (0.4764 s−1) or WS2 (0.2550 s−1). Transmission electron microscopy (TEM) analysis identified that the morphology and average particle size of the MoWS2 catalyst maintains even after three times of recycles. Moreover, extended X-ray absorption fine structure (EXAFS) analysis confirmed homogeneous distribution of Mo and W species in the MoWS2 phase.

NiMoS and CoMoS catalysts were synthesized and applied to hydrotreating (HDT) of FCC light cycle oils (FCC-LCO) in an autoclave batch reactor at 613 K and 8.6 MPa H2. The S and N compounds in LCO were classified into four and three groups, respectively, in terms of the HDT reactivity. The individual and the competitive reactivities of the S and N compounds in the HDS and the HDN were investigated over the conventional CoMoS and NiMoS catalysts using S and N model compounds (dibenzothiophene, DBT, and carbazole, CBZ). In the HDS of DBT, both the direct desulfurization (DDS) and pre-hydrogenation pathway (HYD) were found to proceed, whereas the HYD pathway was favored for the HDN of CBZ. As a result, the NiMoS catalyst that facilitates the HYD pathway showed better activity in the HDN of LCO than the CoMoS (k = 10.20 × 10−2 vs. 1.80 × 10−2 h−1). Indeed, the HDS of LCO over the NiMoS was more favorable than that over the CoMoS catalyst (k = 4.3 × 10−1 vs. 3.6 × 10−1 h−1).

Unsupported bimetallic sulfide catalysts were obtained in situ using Mo(CO)6 and Co octoate as precursors to investigate the promotional effect of Co on the MoS2 catalyst in the hydrocracking (HCK) of vacuum residue (VR). Transmission electron microscopy (TEM) and X-ray absorption fine structure spectroscopy were used to obtain structural properties of the catalysts. The bimetallic CoMoS2 catalyst exhibited high catalytic activity in the VR HCK with respect to the H2 consumption rate and asphaltene conversion as compared with monometallic sulfides such as Co9S8 or MoS2 with the same catalyst loading of 0.113 mmol at 673 K and 9.5 MPa H2. Higher hydrodesulfurization activity was also observed for the CoMoS2 catalyst. Moreover, extended X-ray absorption fine structure and TEM analysis identified the formation of a Co–Mo–S phase in monoslab particles of average particle size 6.7 nm and the maintenance of the morphology during five times of recycle tests. These results thus suggest that the unsupported CoMoS2 catalyst has a promotional effect on VR HCK.

Ni2P catalysts supported on SiO2 and Ga-SiO2 were prepared by incipient wetness impregnation technique, and the effect of the electronic properties of Ni2P on hydrodesulfurization (HDS) performance was studied. X-ray diffraction (XRD), X-ray absorption near edge structure (XANES), and in situ FT-IR with CO adsorption studies were used to examine structural and electronic properties of the supported Ni2P catalysts. The catalytic activity in hydrodesulfurization (HDS) was measured at 3.0 MPa and at three different temperatures of 613, 628, and 643 K in a three-phase fixed bed reactor using a model feed containing 500 ppm S as 4,6-DMDBT, 6000 ppm S as DMDS, 100 ppm N as quinoline, 1 wt% tetralin, and 0.5 wt% n-nonane in n-tridecane balance. In both cases, the HDS conversion was very high over 90%. For the product distributions, the Ni2P/SiO2 maintained a low direct desulfurization (DDS) selectivity at 26.5%, while the Ni2P/Ga-SiO2 exhibited higher DDS selectivity of 32.1% at 643 K. The Ni K-edge XANES and CO-adsorbed FT-IR analysis confirmed the electron enriched property of Ni2P on SiO2, but with the electron deficiency of Ni2P phase supported on Ga-SiO2 support. These results thus suggest that the electron deficient Ni2P favors σ-bonding with S compounds to promote direct desulfurization of 4.6-DMDBT.

Comprehensive series tests on hydrotreating (HDT) and hydrocracking (HDC) of fluid catalytic cracking (FCC) light cycle oil (LCO) into high-value light aromatics rich in benzene, toluene, and xylenes (BTX) were conducted in a fixed-bed down-flow reactor under medium pressure (6 MPa). Two different LCOs, LCO-1 (a full-range LCO) and LCO-2 (340 °C− LCO which contained a smaller fraction of refractory alkyl(C2+)-carbazoles and heavy tri+-aromatics (three and more rings aromatics) than LCO-1), were used as feedstocks. Comparison of NiW-S, NiMo-S, and CoMo-S supported on γ-Al2O3 and a commercial catalyst (for vacuum gasoil hydrodesulfurization) as LCO HDT catalysts revealed that NiMo-S/γ-Al2O3 allowed for highly selective hydrogenation (HYD) of di+-aromatics (two and more rings aromatics) into mono-aromatics with minimal loss of aromatics at high HDN conversion rates. For HDC catalysts, NiMo-S, CoMo-S, and Mo-S were supported on a hybrid zeolite, BZ(x) (a mixture of H-Beta (B) and H-ZSM-5 (Z) (x wt%)). Since Mo-S exhibited moderate HYD power and H-ZSM-5 promoted the dealkylation of alkyl-aromatics into BTX, Mo-S/BZ(10) yielded the largest amount of BTX in the HDC model of tetralin among the three catalyst analyzed. The HDC of hydrotreated LCO-1 (HDT-LCO-1) over Mo-S/BZ(10) catalyst generated a low yield of BTX-rich light aromatics because of the limited conversion of C11+ heavy aromatics. However, during the HDC of HDT-LCO-2, the yield of BTX-rich light aromatics was close to the theoretical yield (48.4 wt%) over a wide temperature range when Mo-S/BZ(10) was used as catalyst, which indicated the highly selective HDC behavior of Mo-S/BZ(10) for this reaction. Therefore, NiMo-S/γ-Al2O3 and Mo-S/BZ(10), which exhibited well-balanced metallic and/or acidic functions, were promising HDT and HDC catalysts, respectively, for the selective conversion of LCOs into high-value BTX-rich light aromatics at high yields.

In order to design a suitable catalyst for hydrocracking (HCK) of vacuum residue (VR), a series of NiMoS/γ-Al2O3 catalysts were prepared with varying Mo loading amounts, Ni addition, P addition, and porosity of γ-Al2O3 support, and were applied for the VR HCK. Activity tests were conducted in an autoclave batch reactor at 693 K and 10 MPa H2 for the VR HCK in the presence of 0.26 wt% catalyst and 33.0 wt% tetralin. X-ray absorption spectroscopy (XAS), N2-physisorption, H2-temperature programmed reduction (H2-TPR), and energy dispersive X-ray fluorescence (ED-XRF) measurements were applied to verify the physical properties of the prepared catalysts. The amount of Mo loadings on γ-Al2O3 was observed most favorable at 8.0 wt% with the asphaltene conversion of 62.9%. The addition of Ni had minimal effect on the VR HCK, but the effect on the hydrodesulfurization (HDS) of VR was significant. It was noteworthy that the increase in porosity of the γ-Al2O3 support played an important role in enhancing the asphaltene conversion to 68.5%.

Oil-dispersed WS2 catalysts were prepared in situ using an oil-soluble W precursor of W(CO)6 in the hydrocracking (HCK) of vacuum residue (VR). Smaller size of WS2 catalyst (WS2-DMDS) was also obtained by the addition of dimethyl disulfide (DMDS) with the W precursor in the VR HCK. The activity tests were performed in a batch reactor at 692 K at 9.5 MPa H2 with the same metal loading of 0.113 mmol. Oil-dispersed MoS2 catalyst was also employed to compare the structure and activity with WS2. Extended X-ray absorption fine structure (EXAFS) and transmission electron microscopy (TEM) analysis were used to examine structural properties of the dispersed catalysts. The activity based upon the H2 consumption rate per lateral metal numbers, TOFS, in the VR HCK turned out that WS2 (0.709 s−1) is better than MoS2 (0.573 s−1), which leads to higher asphaltene conversion for WS2 (39.2%) than MoS2 (35.8%). Moreover, it was noted that the dispersibility of WS2 (58.0%) was found better than MoS2 (3.3%).

Different morphologies of oil-dispersed MoS2 catalysts were obtained by a ligand stabilization method using Mo(CO)6 as a Mo precursor and trioctylphosphine oxide (TOPO) as a coordinating agent to identify the active site of MoS2 in the hydrocracking (HCK) of vacuum residue (VR). Transmission electron microscopy (TEM) and extended X-ray absorption fine structure (EXAFS) spectroscopy were used to obtain structural properties of the dispersed catalyst. It was observed that the MoS2 forms a nanoscaled monolayer from 5 to 10 nm in size. The effect of the oil-dispersed MoS2 catalysts having different morphology on the slurry phase HCK of VR was investigated at 673 K and 9.5 MPa H2. The turnover frequency (TOF) of the dispersed MoS2 catalysts in the VR HCK was found to show a good correlation with the rim-site Mo dispersion of the MoS2 slabs based on the same metal loading of 0.113 mmol at 673 K and 9.5 MPa H2.

The effects of Co, Ni, or Mo precursors having different oil solubility and oxidation state on the slurry phase hydrocracking (HCK) of vacuum residue (VR) was investigated at 673 K and 9.5 MPa H2. X-ray diffraction and extended X-ray absorption fine structure spectroscopy were used to obtain structural properties of the dispersed catalyst. Under standard operating condition, the metal precursors were found to form nanoscaled dispersed particles of MoS2, Co9S8, and Ni3S2, with the following VR HCK performances in the order MoS2 > Co9S8 ≫ Ni3S2, based on the same metal loading of 0.113 mmol. Among the oil-soluble Mo precursors such as Mo-hexacarbonyl, -octoate, and -naphthenate, it was observed that Mo-octoate having an intermediate oxidation state forms the smallest particles of 5.8 nm in size and shows the best activity in the VR HCK.

The effects of tetralin as an H-donor on the reactivity of asphaltenes in a petroleum pitch were investigated under thermal cracking or catalytic hydrocracking conditions at 693 K and 10.0 MPa N2 or H2. Reaction temperatures, pressures, and tetralin contents were varied to examine the reactivity of asphaltenes. Thermal cracking of the petroleum pitch led to a considerable amount of coke formation, close to 53.7 wt%, but the addition of tetralin reduced the coke formation down to 23.6 wt%. The coke formation was considerably reduced to 10.3 wt% in the catalytic hydrocracking condition, and was not formed in the presence of tetralin. Kinetic studies on the catalytic hydrocracking of petroleum pitch in the absence or presence of tetralin demonstrated that the addition of tetralin, showing an increase in the hydrogen transfer capacity, contribute to the marked performance of hydrocracking of the petroleum pitch in the presence of dispersed MoS2 catalyst.

A series of Pt/Nb 2 O 5 catalysts were synthesized at different temperature conditions to investigate metal-support interaction effect on the catalytic activities in the aqueous phase hydrodeoxygenation of 1,6-hexanediol at 523 K and 5.5 MPa. The increase of calcination temperature of Nb 2 O 5 support over 773 K lowered surface area as well as acidity of Nb 2 O 5 , which altered the electron density of the active center Pt as characterized by XANES analysis. It was demonstrated that the bifunctional catalytic nature of Pt/Nb 2 O 5 catalyst having high acidity and electron deficiency could promote the dehydration of 1,6-hexanediol followed by hydrogenation with high selectivity toward n -hexane.

A highly dispersed nickel phosphide catalyst supported on SBA-15 was prepared and tested for the hydrotreating of tire pyrolysis oil (TPO). Physicochemical properties of the prepared catalyst were analyzed by CO uptake chemisorption, BET, TEM, and X-ray diffraction (XRD). An advanced technique with gas chromatography equipped with mass spectrometry and atomic emission detector was applied to investigate carbon-, sulfur-, and nitrogen-containing compounds in TPO. Hydrotreating tests were carried out in a fixed-bed continuous flow reactor at 350 °C, 3.0 MPa, and LHSV of 0.5 h−1. The Ni2P/SBA-15 exhibited an HDS conversion of 89.3% and an HDN conversion of 60.7%, which was comparable to the performance of a commercial NiMoS catalyst under the same conditions.

Catalysts consisting of Ni 2 P placed on low and high surface area siliceous supports, i.e. SiO 2 -L, SiO 2 -H, and Si-MCM-41, were synthesized by TPR (temperature-programmed reduction), and the effect of the sulfur and nitrogen content of the feed on hydrotreating activity was studied. Structural information on the supported Ni 2 P phase after reaction was obtained by XRD (X-ray diffraction) and EXAFS (extended X-ray absorption fine structure) measurements. The catalytic activity in hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) was obtained at 573 and 613 K and a pressure of 3.1 MPa in an upflow, liquid-gas-solid bed reactor with a feed consisting of 4,6-dimethyldibenzothiophene (4,6-DMDBT) and quinoline dissolved in tridecane as solvent. Using reference compositions of 4,6-DMDBT at levels of 500 ppm S, dimethyldisulfide (DMDS) at levels of 6000 ppm S, and quinoline at levels of 200 ppm N, the order of activity was Ni 2 P/SiO 2 -L 2 P/SiO 2 -H 2 P/MCM-41, compared on the basis of equal number of sites (230 mmol) placed in the reactor. The Ni 2 P/MCM-41 gave a notably high conversion in HDS of 98% that was substantially above those of a Ni-Mo-S/Al 2 O 3 commercial catalyst which had an HDS conversion of 81%, on a basis of equal quantity of sites (230 mmol) placed in the reactor. The sites were titrated by pulse CO uptakes for the phosphides and by pulse O 2 adsorption at low temperature for the sulfide. Analysis of the spent samples by EXAFS showed that Ni(2) sites of square pyramidal geometry in Ni 2 P are bound to sulfur, with a lower Ni S coordination, as the particle size decreased, and the order in the number of these sites followed the reactivity Ni 2 P/SiO 2 -L 2 P/SiO 2 -H 2 P/MCM-41. It is thus concluded that the active Ni(2) site on the highly dispersed Ni 2 P is much more tolerant to sulfur than the tetrahedral Ni(1) sites also present in the samples.

Electrochemical water splitting is one of the most promising systems by which to store energy produced from sustainable sources, such as solar and wind energy. Designing robust and stable electrocatalysts is urgently needed because of the relatively sluggish kinetics of the anodic reaction, i.e. the oxygen evolution reaction (OER). In this study, we investigate the anomalous in situ activation behaviour of carbon-supported Ni2P nanoparticles (Ni2P/C) during OER catalysis in alkaline media. The activated Ni2P/C shows an exceptionally high activity and stability under OER conditions in which the overpotential needed to achieve 10 mA cm−2 was reduced from approximately 350 mV to approximately 300 mV after 8,000 cyclic voltammetric scans. In situ and ex situ characterizations indicate that the activity enhancement of Ni2P catalysts is due to a favourable phase transformation of the Ni centre to β-NiOOH, including increases in the active area induced by structural deformation under the OER conditions. These findings provide new insights towards designing transition metal/phosphide-based materials for an efficient water splitting catalyst.

Ni 2 P catalysts supported on nano-sized β (β-N) or micrometer-sized β (β-M) zeolites were prepared by temperature-programmed reduction, and their structural and chemical properties were analyzed by N 2 physisorption, transmission electron microscopy, X-ray diffraction, extended X-ray absorption fine structure, NH 3 temperature-programmed desorption, and CO uptake. The catalytic activity was tested at 653 K and 6.0 MPa in a fixed bed reactor for the hydrocracking of 1-methylnaphthalene (1-MN) into benzene, toluene, and xylene (BTX). In the hydrocracking, Ni 2 P/β-N showed better activity and stability for hydrocracking of 1-MN than Ni 2 P/β-M, with BTX yields of 42.3% and 30.5% for Ni 2 P/β-N and Ni 2 P/β-M, respectively. In addition, Ni 2 P/β-N maintained the stability in terms of catalytic activity and local structure, while Ni 2 P/β-M suffered from coke formation, particularly in the presence of heavy aromatics such as phenanthrene in the feed. The characterization results demonstrated that the β-N has abundant intercrystalline mesopores to provide better dispersion for Ni 2 P catalysts and accessibility toward acid sites, offering the proximity of the hydrogenation active center and the cracking sites. Kinetic analysis for the hydrocracking of 1-MN over the catalysts revealed that the Ni 2 P/β-N catalyst shows superior activity for both hydrogenation and cracking over the Ni 2 P/β-M catalyst.

The effects of various organic solvents having different H-donor index, asphaltene solubility, and alkyl-substitution on the upgrading of vacuum residue (VR) were investigated under thermal cracking or catalytic hydrocracking conditions at 673 K and 10.0 MPa N2 or H2. Molecular dynamics simulations were also adopted to verify physical interaction between asphaltene species with H-donor solvents. Thermal cracking led to a considerable amount of coke formation, close to 29.8 wt.%, but the addition of H-donors reduced the coke formation down to 23.4, 19.0, 12.4, and 4.1 wt.% in the presence of naphthalene, 1-methyl naphthalene(1-MN), decalin, and tetralin, respectively. The coke formation was considerably reduced to 7.2 wt.% in the hydrocracking condition, and further down to 2.9 and 1.2 wt.% in the presence of naphthalene and tetralin, respectively. It was demonstrated that H-donors retaining the H transfer capability coupled with the solubility of asphaltene contributed to the marked performance of VR hydrocracking in the presence of dispersed MoS2 catalyst.

The slurry phase hydrocracking (HCK) of vacuum residue (VR) in the presence of dispersed MoS 2 catalyst was investigated under varying temperature, pressure, and reaction time. Extended X-ray absorption fine structure (EXAFS) measurements were used to obtain structural information about the dispersed MoS 2 phase during the reaction. Under a standard reaction condition of temperature 673 K and pressure 10.0 MPa in an autoclave batch reactor, kinetic analysis for VR HCK confirmed that the reaction occurs in a parallel manner in the production of 77% liquid oils as major products such as vacuum gas oil and distillates with the generation of gas and of 23% coke in the presence of dispersed MoS 2 catalyst (0.113 mmol or 360 ppm Mo). Although temperatures below 653 K at 9.5 MPa were found beneficial in coke reduction to less than 1.0 wt.% in favor of hydrogenation at 33 h of reaction, higher pressures over 15 MPa at 673 K were more influential in accelerating the VR conversion into liquid products, reaching 90% at 4 h of reaction with coke reduction down to 1.2 wt.% than the cases under conditions below 10 MPa. Analysis of the spent catalysts by EXAFS and TEM demonstrated that the nanosized MoS 2 phase was well developed from Mo(CO) 6 in the early stage of the reaction, with lower Mo S and Mo Mo coordination verifying the small MoS 2 particles having more exposed and defect sites as active phases.

The activation and degradation mechanism of Ni-LDH catalysts electrodeposited on low and high-density carbon papers for the oxygen evolution reaction (OER) in alkaline media was investigated using in situ X-ray absorption near-edge structure (XANES) spectroscopy coupled with CV cycles in a potential range of 0–0.9 V (vs Hg/HgO), which allowed proposing two-stage degradation mechanisms with respect to cyclic voltammetry (CV) cycles. The electrodeposited α-Ni(OH)2 is firstly transformed to γ-NiOOH as an active phase in OER. In the reducible potential region, however, γ-NiOOH was partially reduced to β-Ni(OH)2, isolating the rest, which is the first stage of degradation. In the following anodic potential region, β-Ni(OH)2 is readily converted to β-NiOOH, which is mostly reversible, but only a small portion of β-NiOOH is overcharged to unstable γ-NiOOH, being responsible for the second stage degradation. It was noted that Ni(OH)2 catalysts electrodeposited on a low-density carbon paper (Ni-LC) underwent a severe degradation in the first stage, losing at least 56.9 % current density at 0.65 V (vs Hg/HgO), followed by a steady degradation in the second stage, while the use of a high-density carbon substrate (Ni−HC) effectively improved redox stability, maintaining a minimal loss of overpotential less than 5%, particularly with the second stage degradation being negligible even under potential changes, providing an important insight into designing durable and active Ni-LDH catalysts for the OER.

Catalysis plays a fundamental role in the establishment of sustainable chemical technologies that are efficient in terms of energy and atoms [...]

Asphaltene molecules, which consist of differently hydrogenated polyaromatic cores grafted with side alkyl chains of different sizes and grafting densities, were simulated with a solvent mixture of heptane and tetralin using coarse-grained force fields. Starting with the initial configuration of randomly distributed asphaltene molecules and solvents, the asphaltene molecules aggregate because of the attractive force between their polyaromatic cores, but their sizes and shapes differ. The average aggregate size decreases with an increase in the hydrogenated polycyclic core, side-chain length, and tetralin concentration, which agree with experimental observations in the hydrocracking process. The number of side chains also influences the aggregate size but only in the presence of tetralin. In particular, the effect of tetralin addition occurs more significantly for asphaltene molecules with more side chains because side chains sterically block the intermolecular interactions between polyaromatic cores, which makes it easier for the aromatic ring of tetralin to bind to the polyaromatic core of asphaltene. These steric effects of side chains yield different shapes of aggregates, showing parallel stacking (face-to-face) for aromatic cores with many side chains, and T-shape (edge-to-face) or offset-parallel stacking for those with fewer side chains. These findings agree with the experimental observation regarding the effect of tetralin on the solubility of asphaltene, and indicate that the extent of the tetralin effect depends on the number of side alkyl chains, implying that tetralin solvents need to be added with consideration for the structural change of asphaltene under hydrogenation or dealkylation conditions.

Silica-supported Pd and PdSn catalysts were prepared by ion exchange or incipient wetness impregnation and characterized with H 2 chemisorption, X-ray diffraction, in situ Sn K-edge X-ray absorption near edge structure (XANES), and scanning transmission electron microscopy. The activity of the catalysts was evaluated in the deoxygenation of vapor-phase heptanoic acid at 0.1 MPa and 573 K. A Pd catalyst synthesized via ion exchange formed nanoparticles of 1.1 ± 0.4 nm and was more stable in heptanoic acid conversion compared to a Pd catalyst synthesized via incipient wetness impregnation having nanoparticles of 2.4 ± 0.5 nm. The addition of Sn to a Pd catalyst by either co-impregnation of precursors or physical mixing of supported monometallic catalysts improved the overall catalyst stability. Moreover, Sn addition expanded the reaction network from primarily decarbonylation over Pd to include dehydration and decarboxylative ketonization over PdSn. Electron microscopy confirmed the physical migration of Sn during catalytic reaction. In situ XANES analysis during the deoxygenation of a carboxylic acid suggests that partially reduced SnO x is the active Sn phase associated with Pd nanoparticles under reaction conditions.

Although the electrochemical hydrogen evolution reaction (HER) has been intensively investigated for decades as a promising hydrogen production source, its economic feasibility is still questionable because of the high cost of Pt-based electrocatalysts. Transition metal phosphides are potential replacements for Pt; however, a fundamental understanding of the active catalyst site chemistry is still lacking. Such an understanding is crucial to design robust catalytic materials. The aim of this study is to rationalize the HER on the active sites of nickel phosphide (Ni2P) nanowires. Using experimental and theoretical analyses, it can be concluded that the active site of Ni2P nanowires is an exposed Ni3P2 surface generated by the oxygenated Ni3P_P surface created during the HER. This work is a breakthrough in the efficient design of phosphide-based non-Pt catalysts for electrochemical hydrogen production.

Effects of carbon black (CB) additives with dispersed MoS2 catalysts (d-MoS2) on the slurry phase hydrocracking (HCK) of vacuum residue (VR) were studied in an autoclave batch reactor at 693 K and 9.5 MPa H2. For comparison, commercial NiMo catalysts supported on large and small pore volume Al2O3 (-LP, -SP) were also applied for the VR HCK. The structure of the catalysts was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and extended X-ray absorption fine structure (EXAFS). The dispersed MoS2 (d-MoS2) was observed to form nanosized single slabs of 8.4 nm, while in the presence of CB the particle size of the d-MoS2-CB became even smaller (4.8 nm). A series of recycle runs of the VR HCK revealed high activity and stability of d-MoS2-CB followed by d-MoS2 > NiMo-LP > NiMo-SP. The kinetic analysis also demonstrated that the d-MoS2-CB shows a high asphaltene conversion with minimizing coke formation.

The reaction mechanism of the carboxylation of K-2-naphthoxide was investigated by density functional theory calculations and spectroscopic studies. The reaction intermediates and products were confirmed by CO2 adsorbed-FTIR and 1H-NMR measurements. Four steps of the reaction pathway were identified: CO2 activation, electrophilic substitution, CO2-K complex rearrangement, and H-shift, producing 2-hydroxy-1-naphthoic acid (2,1-HNA), 2-hydroxy-3-naphthoic acid (2,3-HNA), and 2-hydroxy-6-naphthoic acid (2,6-HNA). The occurrence of CO2-K complex rearrangement was also confirmed. These energy profiles of reaction pathways for the reaction intermediates were well consistent the experimental results on the carboxylation of K-2-naphthoxide.

The asphaltene hydrocracking (HCK) was carried out at 693 K and 11.0 MPa H2 to examine the phase transformation of V species contained in the asphaltene and the catalytic activity of the resulting V compounds in the HCK. The V K-edge X-ray absorption near edge structure spectroscopy (XANES) was employed to identify the V species dispersed in the asphaltene and the phase transformation with respect to the HCK conditions. The V in asphaltene was observed as a form of the vanadyl-porphyrins (VO-porphyrin) that was converted into V2S3 during the HCK in the presence of tetralin, whereas the VO-porphyrin was not converted fully into the V2S3 in the absence of tetralin due to its isolation within a coke. In addition, the catalytic activity of V2S3 formed from VO-porphyrins in the asphaltene was confirmed by an increase of H2 consumption and asphaltene conversion in the recycle tests of the vacuum residue (VR) HCK at 693 K and 11.0 MPa H2 in the presence of tetralin. The intrinsic catalytic activity of the dispersed V2S3 in the VR HCK was measured at 693 K and 11.0 MPa H2 in presence of the model V precursor of 0.113 mmol VO(acac)2, exhibiting a TOFT of 0.080 s−1 and the asphaltene conversion of 30%. The XANES and TEM analysis confirmed that the V precursor undergoes transformation into nano-scaled V2S3 particles in course of the VR HCK. Therefore, it was demonstrated that the VO-porphyrin in asphaltenes can be converted into the dispersed V2S3 catalysts during the VR HCK.

Nano-scaled NiO particles (nano-NiO) are prepared by a ligand stabilization method and compared with micron-sized NiO particles (micro-NiO) as anodic material of Li-ion battery. The structural and physical properties are characterized by N 2 physisorption, transmission electron microscopy, and X-ray diffraction. The nano-NiO shows uniform spheres with an average particle size of 9 nm with high and stable discharge capacity of 637 mAh g −1 , while the micro-NiO forms irregularly shaped particles with an average particle size of 750 nm with low capacity of 431 mAh g −1 at 0.5C. In situ X-ray absorption near edge structure (XANES) analysis reveals that the capacity and reversibility of the NiO anode is highly affected by the particle size of the NiO. The micro-NiO exhibits a low capacity with absence of phase transformation upon the discharge/charge cycles. In contrast, the nano-NiO exhibits a high capacity with reversible phase transformation between NiO and Ni metal upon the cycle test.

Nano-scaled Ni2P particles were synthesized by ligand stabilization method and applied for hydrogen evolution reaction (HER). X-ray diffraction (XRD), transmission electron microscope (TEM), and X-ray absorption fine structure (XAFS) spectroscopy were employed to examine structural properties of Ni2P nanoparticles. The electrocatalytic HER activity and stability for the Ni2P nanocatalyst were tested in 0.5M H2SO4, and the Ni2P electrocatalyst exhibited a low onset potential for the HER at around −0.02 V vs. RHE, a little more negative compared to the Pt catalyst which shows almost 0 V vs. reversible hydrogen electrode (RHE), and the Tafel slope of 75 mV per decade, i.e. following Volmer step as a rate-determining step. Density functional theory (DFT) calculations for hydrogen adsorption over Ni2P surfaces (0 0 1) and (0 0 2) revealed that the hydrogen adsorption might occur via two reaction pathways: consecutive or simultaneous hydrogen adsorption. The consecutive hydrogen adsorptions on threefold hollow (TFH)-Ni site followed by on P(II) site on a Ni2P (0 0 1) surface led to a lower reaction barrier than simultaneous hydrogen adsorption. These results thus demonstrated that the Volmer step might follow consecutive adsorption mechanism over the Ni2P surface.

The hydrodeoxygenation (HDO) of guaiacol was investigated over SiO2, ZrO2, and active carbon (AC) supported Ni2P catalysts. The physical properties of the catalysts were analyzed by temperature-programmed reduction (H2-TPR), CO-uptake chemisorption, and N2 physisorption. X-ray diffraction and extended X-ray adsorption fine structure spectroscopy were used to obtain structural properties for the supported Ni2P catalysts. The HDO was tested in a batch reactor at 573 K and 30 atm. The Ni2P/SiO2 catalyst underwent a decrease in the HDO conversion from 87 to 30 % for the first and second run of reaction. However, the Ni2P/ZrO2 and Ni2P/AC catalysts showed a little low but stable HDO conversions of 72 and 46 %, respectively. The in situ XAFS analysis revealed that differently from the cases of Ni2P/ZrO2 or and Ni2P/AC catalysts, the local structure of the Ni2P on SiO2 support underwent an oxidation to form nickel phosphate during the reaction, demonstrating that the SiO2 based Ni2P was vulnerable to the water or hydroxyl group of the reactant due to the hydrophilic nature of SiO2 support.

Co 3 O 4 powders as anode active materials for Li-ion battery are synthesized by a simple precipitation method. Physical properties of the prepared Co 3 O 4 are characterized by N 2 physisorption, transmission electron microscopy, and X-ray diffraction. Conversion mechanisms upon the structural changes of Co 3 O 4 anode are thoroughly studied by an in situ X-ray absorption fine structure (XAFS) technique. In the first cycle of discharge/charge, the X-ray absorption near-edge structure of Co reveals that the 1.1 V plateau of the discharging is ascribed to the direct conversion of Co 3 O 4 to Co metal, and the 2.0 V plateau of the charging to the conversion of Co metal to CoO and Co 3 O 4 . In the second cycle of discharge/charge, the XAFS analysis reveals that a part of Co metal phase remains unconverted due to the phase isolation. It is demonstrated that the addition of a conductive material can significantly improve the redox reaction of the Co 3 O 4 anode material by minimizing the phase isolation.

A series of Ni2P/SBA-15 catalysts with different Ni2P loadings were prepared and applied for the hydrotreating of light cycle oil. The loading level of Ni2P was varied from 0.5 to 3.0 mmol Ni2P per 1.0 g of SBA-15 support, resulting in the optimum catalyst loading of 2.0 mmol Ni2P. The physical properties of the catalyst samples were characterized by N2-adsorption–desorption isotherms, CO uptake chemisorption, TPR, and TEM. X-ray diffraction (XRD) and extended X-ray absorption fine structure (XAFS) spectroscopy were used to obtain structural properties for the supported Ni2P catalysts. Hydrotreating tests were performed in a continuous flow fixed-bed reactor at 623 K, 3.0 MPa, and LHSV's of 0.5–1.0 h−1. The 2.0 mmol Ni2P/SBA-15 gave an HDS conversion of 99.0% and an HDN conversion of 92.5%, which were much higher than those of a Ni–Mo–S/Al2O3 catalyst which gave an HDS conversion of 91.9% and an HDN conversion of 65.8% based on the same LHSV of 0.5 h−1. Substantial changes in the composition of aromatic compounds were found for the Ni2P/SBA-15 catalysts from 14.3 wt.% 1-Ar (mono-aromatics), 40.6 wt.% 2-Ar (di-aromatics) and 19.4 wt.% 3+-Ar (tri+-aromatics) in the LCO feed to 46.1 wt.% 1-Ar, 16.3 wt.% 2-Ar and 2.0 wt.% 3+-Ar in the product.

A Ni 2 P/SiO 2 catalyst was prepared by temperature-programed reduction (TPR), and applied for the hydrodeoxygenation of guaiacol. The physical properties of the catalyst samples were characterized by N 2 adsorption/desorption isotherms and CO uptake chemisorption. X-ray diffraction (XRD) and extended X-ray absorption fine structure (XAFS) spectroscopy were used to obtain structural properties for the supported Ni 2 P catalysts. Hydrodeoxygenation (HDO) tests were performed in a continuous flow fixed-bed reactor at 523–573 K, and 1 or 8 atm, and an LHSV of 2.0 h −1 . The Ni 2 P/SiO 2 gave an HDO conversion over 90% with two different reaction pathways being identified; at 1 atm direct deoxygenation was dominant to produce benzene, and at 8 atm prehydrogenation followed by deoxygenation was preferred to produce cyclohexane. A combined X-ray absorption fine structure spectroscopy and density functional theory analysis revealed that the active site of Ni 2 P catalysts is composed of threefold hollow Ni and P sites which lead to adsorption of H or OH groups. These results suggest that relative populations of H or OH groups on Ni or P sites of Ni 2 P surface have an impact on overall reaction pathways of the HDO.

Ni2P catalysts supported on ZSM-5, Beta, and USY zeolites were prepared by temperature-programmed reduction (TPR), applied for the hydrocracking of naphthalene, and characterized by BET, CO uptake, NH3-TPD, TEM, X-ray diffraction (XRD), and extended X-ray absorption fine structure (EXAFS). The catalytic activity was tested at 673 K and 3.0 MPa in a three-phase fixed bed reactor for hydrocracking of naphthalene. The Ni2P/Beta exhibited best activity with a naphthalene conversion of 99%, and a BTX yield of 94.4%. Well-dispersed Ni2P particles combined with moderate acidity and porosity of zeolite Beta contributed to the enhanced hydrocracking activity of naphthalene into BTX.

The synthesis of 2-hydroxy-6-naphthoic acid (2,6-HNA) from carboxylation of alkali-naphthoxide was studied with varying alkali cation types and reaction conditions such as reactant concentration, reaction time, temperature, and pressure. The product selectivity was strongly affected by the types of alkali cation, reaction time, and temperature, while the product yield was governed by reaction pressure. The maximum HNA yield, 28.6%, was achieved with 2,6-HNA selectivity of 81.6% at 6 atm of CO2, 543 K, and 6 h of reaction. The addition of K2CO3 led to further increase in the productivity of 2,6-HNA via suppression of the decarboxylation of HNA.

Six-carbon containing model compounds of 1-hexanol, 1,6-hexanediol and sorbitol for the reforming were employed to study the effect of hydroxyl functional group on the thermodynamic equilibrium product distribution in a wide range of conditions of temperature (300–1300 K), pressure (1–150 atm) and feed composition (H 2 O/carbon = 0.5–30). The increase of hydroxyl group in reactants gave rise to the increase of carbon dioxide with loss of methane in the product in the following order: sorbitol > 1,6-hexanediol > 1-hexanol, while the formation of hydrogen and carbon monoxide was mostly governed by the feed composition (H 2 O/carbon) and pressure rather than the number of hydroxyl group in reactants.

This study focused on the elucidation of the Co phase in NaCo/ZnO catalysts with different Co loadings for ethanol steam reforming. The catalysts were applied for ethanol steam reforming with a feed of 20 wt% ethanol in water at 773 K. The characterizations of catalysts were made by temperature programmed reduction (TPR), X-ray absorption near-edge spectroscopy (XANES) and X-ray diffraction (XRD). The TPR and XANES analysis indicated that a Co loading less than 1 wt% led to the formation of a Co-ZnO composite while Co loadings of 10 wt% gave rise to the formation of Co metal after reduction. The XRD analysis of the oxidic precursors revealed that the ZnO phase was dominant without any Co oxidic phase for the Co loaded samples below 1 wt% due to the formation of Co-ZnO composite, but with evident contribution of Co3O4 being found for the 10 wt% NaCo/ZnO sample. The activity test of the catalysts in ethanol steam reforming showed that the catalysts with Co loadings more than 10 wt% exhibited good and stable activity with an ethanol conversion of 90%. These results demonstrate that the Co metal phase is active for the ethanol steam reforming and viable with Co loadings of 10 wt%.

The amphiphilic phosphotungstic acid catalyst (A-PTA) was prepared with quaternary ammonium salt to apply for the oxidative desulfurization (ODS) of light cycle oil (LCO), resulting in high activity of the ODS conversion of 95%, at H 2 O 2 /S ratio of 10 and 353 K. The model reaction tests for the ODS of refractory sulfur compounds in n-octane demonstrated that the addition of indole drastically reduced overall ODS conversion, while the introduction of 1-methylnaphthalene fully recovered the ODS activity, which were attributed to the high solubility of the oxidized S or N compounds in the 2-ring aromatics.

The gas-phase hydroxylation of benzene by using a mixture of oxygen and hydrogen has been carried out over Cu/ZSM-5 catalysts modified with palladium. In-situ X-ray absorption studies employed in the course of H2-tempereature programmed reduction (H2-TPR) followed by benzene hydroxylation confirmed that the oxidic phase of Cu2+ was transformed to Cu+ during the reaction. The addition of Pd to Cu/ZSM-5 noticeably improved the reducibility of the oxidic Cu phase, which resulted in an increase in the activity of the reaction.

A nickel phosphide (Ni 2 P) catalyst supported on γ-Al 2 O 3 was successfully synthesized by a liquid phase phosphidation (LP) in the presence of trioctylphosphine and trioctylphosphine oxide. Characterizations were made by BET, CO uptake, TPR, 27 Al–NMR, and EXAFS spectroscopy, which revealed that the Ni 2 P phase remained stable during reaction without the formation of AlPO 4 phase. The Ni 2 P/Al 2 O 3 -LP catalyst gave a good and stable activity with a 4,6-DMDBT HDS conversion of 99% at 573 K and 3.1 MPa, which was much higher than the Ni 2 P/Al 2 O 3 -HT catalyst (HDS conversion of 45%) prepared by the conventional temperature-programmed reduction method.