Various TiO2, SiO2, Al2O3, and Nb2O5–Al2O3 supported Pt catalysts have been prepared by urea precipitation method for catalytic hydrodeoxygenation (HDO) of diphenyl ether (DPE) as a 4-O-5 aryl-ether lignin model compound. The selectivity toward deoxygenated product cyclohexane increased obviously with Nb2O5·nH2O decorated, owing to the significant promotion effect of NbOx species and acid sites on C–O bond cleavage. At higher pressure (3.0 MPa H2), DPE underwent a HYD route, while direct hydrogenolysis route occurred at low pressure (0.1 MPa H2). In addition, the reaction rate constants and activation energies were obtained in the temperature range from 160 to 220 °C. Based on the Arrhenius law, the activation energy for the cleavage of the C–O bond in DPE was calculated to be 91.22 kJ/mol. It was noteworthy that the Pt/20Nb–Al2O3 showed higher stability than Pt/Al2O3 for hydrodeoxygenation of diphenyl ether, which can be attributed to its water-tolerant Lewis acid sites.

H-Beta zeolites with various Si/Al ratios have been prepared for the liquid-phase benzylation of various arenes with benzyl chloride (BzCl). 29Si and 27Al MAS NMR spectroscopy revealed the incorporation of Al into the silica framework to form catalytically active Brønsted acid sites (BAS). 1H MAS NMR spectroscopy investigations demonstrated the BAS density increased with reducing Si/Al ratio, while the BAS strength decreased as probed by CD3CN molecules. These H-Beta zeolites are highly selective to desired monobenzylation products depending on the shape-selectivity induced by the suitable channel system. The catalytic performance is in line with the nucleophilicity and proton affinity (PA) of arenes (xylene > toluene > benzene) on the same catalyst, typically for Friedel–Crafts reaction. A shape-selective effect has been observed to dominate the reaction, lowering the performance of mesitylene compared to xylene, as well as being selective to only the monobenzylation product. The benzylation performance is enhanced with increasing the BAS strength of H-Beta zeolites due to the formation of more aryl cation intermediates by attacking electronegative chlorine atom in BzCl. An alternative reaction mechanism based on the activation of arenes by protonating aromatic ring of BAS is proposed to explain the superior benzylation activity of BzCl with less active arenes.

To obtain an effective supported metallic catalyst for aqueous hydrogenation of succinic acid (SA), C-supported Re–Ru catalysts with different Re/Ru ratios were sought by using a convenient and environmentally friendly microwave-assisted thermolytic method. The results indicate that the as-prepared Re–Ru/C catalysts exhibit high dispersion with fairly small average particle size (0.7–1.6 nm) and well-structural properties. During the transformation of SA, the Ru composition is responsible for the hydrogenolysis of SA, while the Re composition favors the hydrogenation of SA. The bimetallic Re–Ru interaction promotes the formation of 1,4-butanediol (selectivity is 70.1% with complete conversion), which could rarely be detected when using Re/C or Ru/C monometallic catalysts. The kinetic study further reveals that the introduction of Ru significantly reduces the apparent activation energy from 62 to 40 kJ mol–1 and increases the saturation ability of hydrogenation intermediates on the surface of catalysts compared with Re/C. A Re–Ru/C bimetallic catalyst accelerates the formation rate of 1,4-butanediol relative to that of tetrahydrofuran. According to a kinetic mechanism, ring opening of γ-butyrolactone is favored at low temperature, while direct hydrogenation is favored at high temperature.

The laminar MgO with high specific area and the organometallic precursor Cu(acac)2 were used for the successful synthesis of Cu/MgO catalysts by metal-organic chemical vapor deposition (MOCVD) method. The copper supported on MgO catalysts were characterized by means of X-ray diffraction, Fourier-transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and N2-physisorption. Characterization results indicated that the organic precursor was successfully deposited onto MgO and the crystal structure of MgO remained intact after deposition. The hydrogenation of γ-valerolactone (γ-GVL) was employed to evaluate the catalytic performance of the Cu/MgO catalysts. It was found that the 18% Cu/MgO catalyst exhibited excellent catalytic activity (90.5%) and selectivity (94.4%) for 1,4-PDO at 473 K and 10 MPa, and the catalytic activity of Cu/MgO did not diminish significantly after cycling for three times.

Pd@MIL-101(Cr) hetero-catalysts have been successfully prepared using the metal–organic chemical vapour deposition (MOCVD) approach, by choosing [Pd(η3-C3H5)(η5-C5H5)] as a volatile precursor, and the hydrothermally stable metal–organic framework, MIL-101(Cr) as a support. The prepared Pd@MIL-101(Cr) hetero-catalysts characterized with various analytical techniques, exhibited highly monodispersed immobilized Pd nanoparticles in the MIL-101(Cr) cavities, while retaining the pristine crystallinity and porosity. The intact hybrid Pd@MIL-101(Cr) has been demonstrated to be an efficient catalyst for 2-butyne-1,4-diol hydrogenation with excellent activity, stability and selectivity (2-butene-1,4-diol (>94%)).

Transition metal carbides have been of great interest because of their noble-metal-like properties. Because of the complexity of their structures, it is crucial to design an experiment that can eliminate the influence of supports, surface carbon contamination and particle sizes when finding the exact catalytic active sites. In this work, phase-pure W2C nanorods (lengths of 2–4 μm and diameters of 100–600 nm) with different amounts of crystal defects were prepared by the pyrolysis of metatungstate and melamine hybrid nanorods with nanoscale periodic structure synthesized in the aqueous phase. The nanoscale alternating structure between tungsten oxide and melamine effectively promotes the reduction of tungsten oxide and the formation of tungsten carbide, avoiding the deposition of carbon on the surface. At the same time, vacancy defects are generated due to the deficiency of carbon. High pyrolysis temperature (900 °C), prolonged pyrolysis time (4 h), introduction of hydrogen and the proper increase of the temperature ramping rate (5 °C min−1) are favorable to the formation of vacancy defects. The activities of different catalysts were evaluated by the hydrodeoxygenation of benzofuran at 320 to 350 °C. The results show that the vacancy defect sites in W2C are the key to the high reactivity of W2C. The vacancy defect sites have favorable properties for the cleavage of carbon–oxygen bonds. The Caromatic–O bond is cleaved in the case of unsaturated aromatic rings, thereby reducing the consumption of hydrogen. In addition, it is found that the apparent activation energy of each chemical bond is linear-like and positively related to its bond dissociation energy.

Carbon-supported Re–M (M = Pt and Rh) bimetallic catalysts with controlled size and composition were synthesized by using a microwave-assisted thermolytic method and evaluated in the aqueous phase hydrogenation of succinic acid. The Re–M interaction contributes to the inhibition of aggregation of particles and to the improvement in the catalytic activity for succinic acid hydrogenation through decreasing the activation energy. The Re–M interaction favors the ring opening of γ-butyrolactone, an intermediate product, to 1,4-butanediol instead of the hydrogenation and dehydration to tetrahydrofuran observed over a Re/C catalyst. The kinetic study proves that the Re–M interaction can increase the relative formation rate of 1,4-butanediol more than that of tetrahydrofuran, while the strength of the Re–M interaction has a limited influence on the product selectivity. It was shown that the Re–Rh interaction can reduce the direct hydrogenolysis of succinic acid, but it cannot avoid the hydrogenolysis of 1,4-butanediol, thus limiting the selectivity to this product. According to the kinetic mechanism, ring opening of γ-butyrolactone is favored at low temperature while direct hydrogenation to tetrahydrofuran is favored at high temperature.

•MoxC nanobelts with high-valence state are synthesized by one-pot pyrolysis method.•MoxC nanobelts exhibit superior HER activity and good long-term stability.•Excellent performance is due to high intrinsic activity of high-valence state Mo.Hydrogen evolution reaction (HER) is considered to be one of the most promising strategies to create hydrogen. Recently, searching high-efficient, stable, and earth-abundant electrocatalysts to replace precious metals for practical utilizations of HER is attracting more and more attentions. Herein, novel molybdenum carbide nanobelts containing Mo of high-valence state derived from MoO3-ethylenediamine inorganic/organic hybrid precursors are successfully synthesized via a facile one-pot pyrolysis method. The molybdenum carbide nanobelts are characterized using XRD, SEM, TEM and XPS. Moreover, the high-valence state Mo and their relative content in the molybdenum carbide nanobelts can be identified by XPS. The high-resolution XPS spectra of Mo 3d indicates in the molybdenum carbide nanobelts the proportion of high-valence state Mo in active Mo components is 51.3%. More importantly, the as-synthesized products exhibit excellent electrocatalytic activity for HER with a low onset overpotential of 50 mV and a small Tafel slope of 49.6 mV dec−1 in acidic medium (0.5 M H2SO4). Besides, the catalysts require only overpotentials of 143 and 234 mV to achieve current densities of 10 and 220 mA cm−2, respectively. Furthermore, they also exhibit good durability after 2000 cycles and constant current density test. Such excellent electrocatalytic HER performance can be ascribed to the high intrinsic activity of high-valence state Mo in Molybdenum Carbide. Synthesizing molybdenum carbide with high-valence state Mo electrocatalysts for HER will open up an exciting alternative avenue to acquire outstanding HER electrocatalytic activity.Download high-res image (215KB)Download full-size image

Spinel ferrites NiFe2O4 supported Ru catalysts have been prepared via a simple sol–gel route and applied for converting biomass-derived furfural to 2-methylfuran. The as-prepared catalysts were characterized by thermogravimetric analysis (TG), N2 adsorption–desorption, X-ray diffraction (XRD), scanning electronic microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Results showed that the catalysts had well-dispersed Ru active sites and large surface area for calcination temperature ranging from 300 to 500 °C. The conversion of biomass-derived furfural into 2-methylfuran was conducted over Ru/NiFe2O4 through catalytic transfer hydrogenation in liquid-phase with 2-propanol as the hydrogen source. A significantly enhanced activity and increased 2-methylfuran yield have been achieved in this study. Under mild conditions (180 °C and 2.1 MPa N2), the conversion of furfural exceeds 97% and 2-methylfuran yield was up to 83% over the catalyst containing 8 wt% Ru. After five repeated uses, the catalytic activity and the corresponding product yield remained almost unchanged. The excellent catalytic activity and recycling performance provide a broad prospects for various practical applications.Download high-res image (138KB)Download full-size imageRu/NiFe2O4 catalysts demonstrated effective hydrodeoxygenation for furfural, which is facilitated by the catalytic transfer hydrogenation using 2-propanol as hydrogen source. High 2-methylfuran (MF) yield was obtained over the Ru/NiFe2O4 catalyst under mild reaction conditions, in which the catalyst can be simply recycled using an external magnetic field.

A series of bimetallic Nb–Ni oxide catalysts with different Nb/Ni molar ratio have been prepared by chemical precipitation method. XRD, Raman and XPS results indicate that amorphous Nb2O5 species exist in the samples with a Nb/Ni ratio about 0.087. The as-synthesized bimetallic Nb–Ni oxides effectively promote the dispersion of NiO active components, as a result effectively inhibit the agglomeration of NiO particles. Ni0.92Nb0.08O sample with the largest surface area of 173 m2/g mainly consists of fold-like nanosheets and the amorphous Nb2O5 species are well-dispersed all over the bulk NiO. After the reduction in hydrogen, the Nb-promoted bulk nickel catalysts display better catalytic performance for hydrodeoxygenation of lignin-derived anisole to biofuels than bulk Ni catalyst. The selectivity to deoxygenated products with using Ni0.92Nb0.08 catalyst increases 2.5 fold to that with bulk Ni catalyst at 160 °C and 3 MPa H2, as a result of the synergistic effect between amorphous Nb2O5 species and metal Ni active sites. In addition, with further increase in the reaction temperature to 200 °C, deoxygenation almost goes quantitatively.High-specific-surface-area Nb–Ni oxides are prepared by using chemical precipitation, and display excellent HDO performance for lignin-derived compounds. Selectivity to deoxygenated products increases 2.5 folds over Ni0.92Nb0.08 than over bulk Ni catalyst.

Hydroisomerization of long chain n-alkanes has been playing an important role in the petroleum industry, in which heavy distillate and residue are converted into value-added products such as gasoline, jet fuel, other middle distillates and lubricant oils. Herein, 10-ring zeolites, including ZSM-22, ZSM-23, ZSM-35, and ZSM-48 were studied for the process. ZSM-35 and ZSM-48 are relatively less studied zeolites as hydroisomerization reaction catalysts though they are expected to display interesting shape selective properties. A higher conversion was obtained over Pt-ZSM-35 and a higher selectivity was obtained over Pt-ZSM-23 at low temperature and short contact time, and a higher selectivity was obtained over Pt-ZSM-48 at high temperature and long contact time, while the mixed catalysts displayed interesting conversion and selectivity. Small differences in the channel system have a notable influence on the product distribution of hexadecane hydroisomerization over 10-ring zeolites. A combination of the evidence of no absence of multibranched products and the length of hexadecane molecular could infer that hexadecane hydroisomerization includes a pore mouth reaction mechanism.

Nanocrystalline Pt–Ce oxides were prepared by citric acid method and impregnation method, and then mounted on cordierites to investigate the catalytic behavior for methane oxidation under scarce oxygen environment. XRD, H2-TPR, TEM, and XPS were employed to investigate the relationship between physicochemical characteristics and catalytic performances. Pt–CeO2 showed good activity for oxygen conversion in fuel rich condition, especially during extinction step, with a huge hysteresis loop. By varying the oxygen concentration, Pt–CeO2 catalysts were poisoned by oxygen along ignition, and the competitive adsorption of oxygen and methane inhibits the activation of methane. Owing to the interaction between Pt and CeO2, and a more homogeneous dispersion of Pt in CeO2 compared with that of Pt/CeO2 prepared by impregnation, Pt–CeO2 catalysts maintained high activity during calcination and pretreatments.

Hydroconversion of fluorene has been conducted over the zeolites and silica–alumina-supported platinum catalysts. The hydrogenation of aromatic rings, the hydroisomerization of the cycloalkanes, and the cracking reaction over the Pt/Y zeolite catalysts are studied to give a detailed hydroconversion reaction network of fluorene through conversion of the synthesized intermediates. Compared to the β-zeolites and silica–alumina supports used, the dispersed platinum catalysts on the Y-zeolites with unique cage structure and acidic properties selectively catalyze the ring-shift isomerization of perhydrofluorene with high yields of the dodecahydrocyclopenta[a]naphthalene and dodecahydrophenalene. Such hydroisomerization reaction is enhanced above 250 °C, while more cleavage of carbon–carbon bond occurs at higher temperatures (280–290 °C) which lead to the great production of single-ring cycloalkanes and more loss in carbons. In the comparative study of the support effect, an examination of the product yields indicates that mild acidity and unique zeolitic structure of Y-zeolites show a major contribution to the selective ring-shift isomerization of saturated aromatic rings. In addition, the generation of mesopores in the Y-zeolite crystals by postsynthesis alkaline treatment facilitates the mass transfer of compounds and provides an improved yield of isomers.

A series of metallic Re/C catalysts were prepared with the microwave-assisted thermolytic method by using decacarbonyldirhenium [Re2(CO)10] as a precursor for the hydrogenation of succinic acid. The results of FT-IR, UV-Vis, XRD, HRTEM, ICP, TPR and CO chemical adsorption showed that the as-prepared catalysts had well-dispersed rhenium nanoparticles on activated carbon. Changing irradiation time or rhenium loadings could effectively adjust the properties of Re/C catalysts which exhibited good catalytic performance for the hydrogenation of succinic acid. There were plenty of active sites on Re/C catalysts for the high concentration hydrogenation of succinic acid, and increasing temperature or pressure improved catalytic activity at a defined scope. From the kinetic study of succinic acid catalytic hydrogenation, there was a certain converting relationship between the different intermediates and the product distribution which could be controlled by variation of reaction time.

The surface of silica with mesopores (SiO2) was post-modified by the deposition of highly dispersed Al2O3 or ZrO2 oxides. Loading of Pt on the modified silica supports yielded higher metal dispersion with respect to the parent silica based on the CO chemisorption and transmission electron microscopy results. Hydrodeoxygenation (HDO) of dibenzofuran (DBF) over the as-prepared Pt catalysts mainly proceeds via the hydrogenation of the aromatic rings, which is followed by the cleavage of the C–O bond to produce oxygen-free hydrocarbons. Preferable hydrogenation of the aromatic rings is observed over the smaller Pt nanoparticles. The relatively strong acidic properties of Al2O3/SiO2 or ZrO2/SiO2, revealed by the NH3-TPD profiles, promote the selective C–O bond cleavage of hexahydrodibenzofuran to alter the HDO reaction pathway. The small sized Pt nanoparticles supported on the Al2O3 or ZrO2 modified silica supports show superior HDO performance with enhanced deoxygenation ability to those over unmodified silica. According to the pseudo-first-order kinetics analysis, the fitted HDO rate constant follows the order: Pt/Al2O3/SiO2 > Pt/ZrO2/SiO2 > Pt/SiO2 under a constant temperature, which is attributed to the cooperative function of the dispersed metal particles and the acidic sites of supports.

Pd-based monolithic catalysts were prepared using cordierites as supports and used as combustion catalysts for methane. The catalytic activity was further promoted by Ce–Zr oxides coatings. Oxides with different Ce/Zr ratios were synthesized via urea co-precipitation method and fully characterized. Catalytic performance of the monoliths was evaluated by oxygen-lean methane combustion through light-off experiments. Steep conversion curves were observed with oxygen completely depleted below 350 °C over all catalysts. Pd supported on ZrO2 ignited the reaction at the lowest temperature while similar activities for total oxygen conversion were observed for Zr-rich monoliths. Zr-embedded oxides promoted the activity on oxygen consumption due to the interaction between Zr and Pd at the interface, dispersing and stabilizing Pd particles on the catalyst surface. The addition of Ce further promoted the stability of the catalysts. Compared with Pd/Zr, Pd/Ce1Zr2 showed little deactivation after three successive light-offs and maintained stability after 500 h time-on-stream test. Core/shell Pd particles model was proposed for the activity. Small Pd metal particles on the surface serve as an activation site for methane whereas wrapped PdO in the core stabilized by the Ce–Zr oxides acts as oxygen donor. The extent of reduction of Pd has significant effect on activity in the reaction conditions. Other impacting factors such as different oxygen concentrations and space velocities were also assessed to investigate the extent of the influence on methane catalytic combustion.

Cleavage of lignin-derived 4-O-5 aryl ethers has been conducted over nickel nanoparticles supported on niobic acid-activated carbon composite under mild conditions. The hydrated niobic acid has been successfully supported and well dispersed on activated carbon. Due to the coexisting Brönsted and Lewis acid sites on the hydrated niobic oxide, the Ni/xNbAC catalysts exhibited higher activities for cleavage of C–O ether bonds and dehydration than those of the Ni/AC catalyst. With increasing content of niobic acid, a larger amount of O-free alkane is obtained owing to niobic acid-promoted removal of oxygen from lignin-derived aryl ethers. The cleavage of C–O ether bonds and dehydration of cyclohexanol to cyclohexane are both favored at high temperature. The direct cleavage of the 4-O-5 aryl ether bond can also be achieved under low H2 pressure, forming phenol and benzene as intermediates, followed by hydrodeoxygenation of phenol to cyclohexane.

Development of highly active and sulfur-tolerant catalysts for deep hydrodesulfurization (HDS) is of great importance in petroleum refining. Here, the discovery of Fe-substituted Ni–Si intermetallic catalysts (Ni1–xFexSi2) that efficiently removes dibenzothiophene (DBT) by HDS is reported. The structure of the catalyst was identified through X-ray diffraction, Mössbauer spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The results showed that Fe atoms substituted Ni atoms in Ni1–xFexSi2 catalysts, which preferentially bond with Ni to form alloy and combine with Si to form silicide. The DBT activity for the Ni1–xFexSi2 has the following order: Ni0.75Fe0.25Si2 > NiSi2 > Ni0.50Fe0.50Si2 ≈ Ni0.25Fe0.75Si2 ≈ Fe–Si. The positive synergistic effect on HDS activity can be correlated to that the formation of Ni–Fe and Fe–Si bonds makes the metal site to have high d-electron density, which promotes the hydrogenation activity. Comparison with the fresh and spent catalysts revealed the stability and sulfur resistance of these catalysts. The present findings suggest that Fe-substituted Ni–Si intermetallics catalysts provide a good starting point for a new catalyst development in the HDS field.

Fe3Si nanoparticles with a size of about 6–9 nm well dispersed on silica have been prepared by pyrolysis of ferrocene–polydimethylsilane composites at 600 °C. Powder XRD patterns, TEM and HRTEM images, and XPS spectra revealed that the average particle size increased with increasing pyrolysis temperature and a new phase, Fe5Si3, appeared when the pyrolysis temperature was above 800 °C. 57Fe Mössbauer spectra, M − H curves and FC and ZFC curves demonstrated that the as-prepared nanoparticles presented superparamagnetic behavior at 27 °C and ferromagnetic behavior at −268 °C, and their particle sizes had a great impact on their magnetic properties. The Fe3Si nanoparticles on silica may find applications in magnetically recording materials, magnetically separable catalysts and electrode materials for spintronic devices.

Cubic Pd nanoparticles were rapidly encapsulated in ZIF-8 through a PVP-assisted synthetic method at room temperature. The obtained PVP–Pd@ZIF-8 exhibited high activity and stability for hydrogenation of 1,4-butynediol, with excellent selectivity to 1,4-butenediol.

Silicon–nickel intermetallic compounds (IMCs) supported on silica (Si–Ni/SiO2), as a highly efficient catalyst for CO methanation, have been prepared by direct silicification of Ni/SiO2 with silane at relatively low temperature in a fluidized bed reactor. The as-prepared materials were characterized by X-ray diffraction, transmission electron microscopy, in situ FT-IR of CO adsorption, and H2-temperature programmed reduction-mass spectrometry (TPR-MS) of CO. The results indicate that uniform NiSix nanoparticles with about 3–4 nm are evenly dispersed on silica. The combined in situ FTIR and TPR-MS results suggest that the Si–Ni/SiO2 catalysts afforded high activity in CO methanation, promoting the formation of CH4 at ca. 240 °C. The catalytic hydrogenation of CO on Si–Ni/SiO2 was investigated in a fixed-bed reactor at GHSVs 48000 mL h−1 g−1 under 1 atm in the temperature interval 200–600 °C. In the higher temperature reaction region (500–600 °C), it is notable that the Si–Ni/SiO2 catalysts present high activity for CO methanation as compared to the Ni/SiO2 catalyst. More importantly, the Si–Ni/SiO2-350 catalyst containing thermally stabile Si–Ni IMCs shows significantly higher resistance to the sintering of Ni particles. Raman characterization of the spent materials qualitatively shows that carbon deposition observed on the conventional Ni/SiO2 catalyst is much higher than that of the used Si–Ni/SiO2-350. It is proposed that small amounts of silicon interacting with Ni atoms selectively prevent the adsorption of resilient carbon species.

Monometallic Pd/C and Re/C and bimetallic Pd–Re/C catalysts with different Re/Pd molar ratios were prepared by incipient-wetness impregnation and characterized by temperature-programmed reduction, X-ray diffraction, CO chemisorption, and transmission electron microscopy. The results indicated that there is a strong interaction between Pd and Re species and that Pd can significantly promote the reduction of rhenium oxide. The hydrogenation of succinic acid to γ-butyrolactone and tetrahydrofuran was investigated over the as-prepared Pd/C, Re/C, and Pd–Re/C catalysts. Pd/C showed a low conversion of succinic acid and a high selectivity to γ-butyrolactone. Adding a small amount of Re evidently enhanced the hydrogenation activity of succinic acid and improved the yield of γ-butyrolactone, whereas more Re increased the yield of tetrahydrofuran. The main reaction pathway for the conversion of succinic acid in aqueous solution on Pd–Re/C catalysts is proposed through hydrogenation of the intermediates, including γ-butyrolactone, 1,4-butanediol, and tetrahydrofuran as the substrates.

Single phase Ni2Si nanoparticles (NPs) have been successfully synthesized by using the Rochow reverse reaction, in which organosilanes ((CH3)nSiCl4−n) are used as the silicon source. The results demonstrate that the crystalline size and phase of nickel silicide can be controlled through changing the organosilanes and reaction time. A formation mechanism of Ni2Si NPs has been proposed, which involved reaction deposition and subsequently diffusion of Si atoms. Magnetism performance tests indicate that the saturation magnetization and coercive field of Ni2Si NPs depend greatly on the environmental temperature and particle size. The blocking temperature (TB) of the materials was found to strongly depend on selecting the organosilanes precursor: in the case of the Ni2Si-0 (148 K) and Ni2Si-2 (336 K). This novel methodology opens a route to prepare other classes of metal silicides with single phase and stoichiometry. The as-prepared single phase Ni2Si nanoparticles can find applications in ferrofluids, imaging, and magnetic separation due to its special magnetic behavior depending on the applied temperature (below or above TB).

Herein, we report an new approach to synthesis of graphene-like MoS2 flakes and tunable layers (from mono- to multi-layer) easily controlled by the thermal decomposition temperature of a single source (Mo(Et2NCS2)4). The approach opens a new way to controlled large-scalable synthesis of graphene-like transition metal sulfides for energy storage, nanoelectronics and optoelectronics.

The conversion of highly concentrated glucose was conducted over a Cu–Cr catalyst with a base in two steps for the first time. Reaction parameters such as reaction time, temperature, and H2 pressure were optimized in each step. On the basis of these results, the corresponding reaction route was proposed. At the low-temperature step, and without a base, glucose was hydrogenated into sorbitol or isomerized and hydrogenated into mannitol. While in the presence of a base, the direct decomposition of glucose was observed because of base-catalyzed retro-aldol condensation. At the high-temperature step, it was found that the addition of a base greatly restrained the formation of oligosaccharides. Compared with CaCO3, Ba(OH)2, KOH, and NaOH, Ca(OH)2 exhibited the best promotion, indicating that the conversion of glucose was relative to not only the concentration of OH– but also the metal ionic radius and electric charge. The addition of a base had no obvious effect on the stability of Cu–Cr catalyst. In the recycling, the catalyst exhibited reasonable recyclability because of the partial deactivation originating from the migration of Cr onto Cu sites and the coverage of carbon species, as shown by X-ray photoelectron spectroscopy measurements.

Nanocrystalline PdO-CeO2 oxides were prepared by solid state grinding method, and then thermal treated at elevated temperatures. XRD, BET, Raman, XPS and TEM were employed to investigate the relationship between physicochemical characteristics and catalytic performances for the oxides. Homogeneous solid solutions are structurally stable up to 700 °C whilst segregation of Pd particles occurs at higher temperature. Monolith catalysts were obtained by wash-coating oxides onto cordierites, attempting to eliminate the scarce oxygen mixed in methane through methane oxidation reactions. Oxides calcined at 800 °C exhibited a higher activity during the first light-off experiment. However, activities improved dramatically for the other catalysts after the first ignition. It is apparent that small Pd particles at ceria surface were responsible for the activation of reactants at lower temperature, whereas well-dispersed Pd in ceria or solid solutions attributed to the total conversion of oxygen. Mars–van Krevelen mechanism was proposed with oxygen activation as the rate-limiting step on the PdCe-500 catalysts.

Hydrodeoxygenation (HDO) of dibenzofuran (DBF) has been carried out over mesoporous silica SBA-15 supported Pt, Pd, and Ru catalysts. The HDO of DBF went through hydrogenation of aromatic rings first, followed by hydrogenolysis of the saturated C–O bond to produce hydrocarbons. The detection of intermediate 2-cyclohexylcyclohexanol over as-prepared Pt catalysts illustrated that the aromatic ring-containing hydrogenated species transformed to the major deoxygenated product bicyclohexane after elimination of the heteroatom oxygen. Among all three catalysts, the Pt/SBA-15 catalysts exhibited the highest hydrogenation activity to yield aromatic ring-containing hydrogenated products. However, the Ru catalysts were more efficient in formation of completely deoxygenated products. Meanwhile, more cleavage of the saturated C–O bond took place at higher reaction temperature in the HDO of DBF. The increase of hydrogen pressure promoted the saturation of aromatic rings with an obvious influence on the conversion of DBF.

Raney Ni–Si catalysts were synthesized by treating Raney Ni with silane in a fluidized bed reactor and tested in the selective hydrogenation of 2-butyne-1,4-diol (BYD) at high concentration. Structural characterizations including XRD patterns, TEM images, and X-ray photoelectron spectroscopy show that Raney Ni–Si catalysts are composed of a Ni core surrounded by nickel silicides. These species transform from Ni-rich silicide (Ni2Si) to Si-rich silicide (NiSi2) with increasing silicification temperature from 250 °C to 450 °C. The insertion of Si atoms into Raney Ni catalysts decreased the catalytic activity, but significantly improved the selectivity to 2-butene-1,4-diol (BED). The beneficial effect of Si on the selectivity hydrogenation of BYD may be caused by the presence of Si at Ni-defect sites, and the formation of the surface nickel silicide that suppress the further hydrogenation of BED. Compared with the traditional Lindlar-type catalysts, such Raney Ni–Si materials can be used extensively in organic synthesis for selective hydrogenation of alkynes, avoiding the associated hazards of toxic additives.

Direct hydrogenolysis of highly concentrated cellulose (up to 15 wt%) into 1,2-propanediol and ethylene glycol without the formation of coke-like precipitates could be performed over CuCr catalysts. Addition of Ca(OH)2 results in a significant increase in the EG yield.

Supported Cu–Cr catalysts were prepared by a non-alkoxide sol–gel route, and characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), H2-temperature programmed reduction (H2-TPR) and X-ray photoelectron spectroscopy (XPS) measurement. Their structures were significantly tuned by the Cu–Cr molar ratio. CuCr2O4, CuCr2O4–CuO and CuCr2O4–Cr2O3 structures were confirmed in CuCr(0.5), CuCr(4) and CuCr(0.25) catalysts, respectively. A direct interaction between CuCr2O4 and CuO or Cr2O3 in CuCr(4) and CuCr(0.25) catalyst was observed by the H2-TPR and XPS results. The catalytic performance of Cu–Cr catalysts with various structures was examined by hydrogenolysis reaction of high concentrated glycerol. Under mild conditions (2.0 MPa and 130 °C) and high concentration (100 wt%), the maximum conversion (52%) was obtained over the CuCr(0.5) catalyst, while the CuCr(4) catalyst gave the highest selectivity of 1,2-PD (up to 100%). This finding will result in the production of less waste water and lower energy consumption in the following separation steps during glycerol hydrogenolysis.

A white Mo(VI)–melamine hybrid solid precipitated immediately when aqueous solutions of (NH4)6Mo7O24 and melamine were mixed. This hybrid proved to be an efficient single-source precursor for single-phase β-Mo2C. Treating the precursor at 650 °C in either Ar or H2 resulted in molybdenum carbides, with H2 being the optimal choice from the perspective of achieving a high-purity carbide. This single-source route successfully inverted the direction of carbon diffusion, thus alleviating the polymerization of carbon species on the carbide surface, which will provide several advantages in catalytic applications. As in the hydrogenation of naphthalene, an ultrahigh selectivity to tetralin was achieved over the resultant β-Mo2C, and its highly purified surface facilitated a steady state with high conversion. With the characteristics of low cost and nontoxicity, the Mo(VI)–melamine hybrid could serve as a green starting material for obtaining highly crystallized β-Mo2C with high purity.

Hydrodeoxygenation (HDO) of dibenzofuran (DBF) with only a hydrogenation (HYD) reaction route was conducted on Pd/COK-12 catalysts with different Pd loadings, which were prepared by metal–organic chemical vapor deposition of [Pd(C3H5)(C5H5)] onto mesoporous silica COK-12. Hydrogenated intermediates with partial or full hydrogenation of the benzene ring were studied in detail. The presence of cycloketones is due to the high selectivity of Pd-based catalysts in the hydrogenation of phenols derived from the C–O bond cleavage of hydrogenated intermediates. The reaction only goes through the HYD reaction route with hardly detected biphenyl, which is further confirmed by HDO of 2-phenylphenol. The increase of Pd loading on the catalysts largely promotes the deoxygenation of saturated oxygen-containing species from hydrogenation of DBF, followed by cleavage of the sp3 C–O bond. Finally, a detailed reaction network of HDO of DBF is proposed according to the detected hydrogenated species and cycloketones.

Ni–Si intermetallics (IMCs) have been designed as promising hydrodesulfurization catalysts with high activity toward HDS and good sulfur tolerance, which is due to the formation of an electron-deficient Ni by the Ni–Si interaction in the Ni–Si IMCs.

The selective hydrogenation of naphthalene to tetralin has been conducted on Mo2C/AC prepared by microwave irradiation, and achieved a lasting high conversion with 100% selectivity up to 60 hours. The choice of activated carbon as a support is critical in gaining an ideal balance between high activity and good stability of the catalyst.

Fe@SiO2 and FeSi2@SiO2 nanoparticles with core@shell structure have successfully been synthesized by direct silane silicification of Fe2O3 nanoparticles. The as-prepared samples were characterized by N2 physisorption, X-ray diffraction, transmission electron microscopy, temperature programmed reduction of H2, X-ray photoelectron spectroscopy, Mössbauer spectroscopy, and superconducting quantum interference magnetometry. It was found that the amorphous SiO2 shell was formed to protect the core against oxidation when the reduced Fe2O3 nanoparticles were silicified by silane. When the reduced Fe2O3 nanoparticles were exposed to air, a Fe2O3 layer was formed. The structure of the core changed from cubic Fe to orthorhombic FeSi2 with increasing silicification temperatures from 350 to 550 °C, due to the dissolution of Si atoms into the iron lattice. The magnetic characterization showed that all samples have ferromagnetic nature and the saturation magnetization values drastically decreased with increasing silicification temperature. This novel methodology can be applied to synthesis of Co@SiO2 and Ni@SiO2 with core@shell structure. The as-prepared Fe@SiO2 and FeSi2@SiO2 nanoparticles with core@shell structure can find applications in magnetically separable catalysts, biomedicines, and magnetically recording materials.

The Cu–Fe catalysts with stoichiometric proportion (Cu/Fe molar ratio was 0.5) were prepared by an epoxide assisted route. The structural properties of Cu–Fe catalysts were determined by X-ray diffraction (XRD), and Mössbauer spectroscopy measurements. These results indicated that a crystalline phase transformation from c-CuFe2O4 to t-CuFe2O4 occurred when elevating the calcination temperature from 500 to 600 °C. The M–H plots exhibited that all Cu–Fe catalysts had ferromagnetic nature and the saturation magnetization values monotonously increased with increasing calcination temperature irrespective of the phases composition. The significant superparamagnetic behavior was observed in the results of magnetic and Mössbauer spectroscopy measurements. The H2 temperature-programmed reduction (H2-TPR) was also conducted for examining the reducibility of Cu–Fe catalysts. The catalytic performance of Cu–Fe catalysts was examined for the hydrogenolysis reaction of glycerol. It is found that the formation of spinel CuFe2O4 greatly enhances the hydrogenolysis activity. The highest glycerol conversion (47%) was obtained over CuFe-500 catalyst, while the selectivity of 1,2-propanediol was maintained at about 92% for all catalysts.

Deposition of Pt, Ru, Pt–Ru alloy, Ru@Pt, and Pt@Ru nanoparticles onto carbon nanotubes (CNTs) has been achieved by chemical reduction of the corresponding RuCl3·3H2O and/or H2PtCl6·6H2O by ethylene glycol in the presence of NaOH. The as-prepared catalysts were characterized by X-ray diffraction, H2-temperature programmed reduction, H2-temperature programmed desorption, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy. Liquid-phase selective hydrogenation of phenylacetylene was used as a probe reaction to evaluate their catalytic performances. The as-prepared Pt, Ru, Pt–Ru alloy, Ru@Pt, and Pt@Ru nanoparticles fell in the range of 1.5–3.0 nm in diameter, and were uniformly dispersed on the CNTs. All the bimetallic catalysts displayed the characteristic diffraction peaks due to a Pt face-centered cubic structure, but the 2θ values were shifted to slightly higher ones, indicating the formation of alloy or core–shell structures. XPS analysis revealed that the catalysts contained mostly Pt(0) and Ru(0), with traces of Pt(II), Pt(IV), and Ru(IV). The Pt@Ru/CNTs and Ru@Pt/CNTs core–shell catalysts showed different catalytic properties in selective hydrogenation of phenylacetylene from the Pt–Ru alloy and the mixed monometallic samples with the correspondingly identical composition.

Nickel–silicon intermetallics have been prepared by a direct silicification method using SiH4 as the silicon source. The prepared nickel–silicon intermetallics were characterized by X-ray diffraction, transmission electron microscopy, temperature-programmed reduction, temperature-programmed desorption, X-ray photoelectron spectroscopy, and CO chemisorption measurements. The catalytic hydrogenation of cinnamaldehyde and phenylacetylene over the nickel–silicon intermetallics was investigated. Nickel–silicon intermetallics presented much higher selectivity to the intermediate product (hydrocinnamaldehyde) than monometallic nickel catalyst, which may be attributed to the repulsive force between the electronegative silicon atoms in the nickel–silicon intermetallics and oxygen atoms in the C═O bond of cinnamaldehyde. In addition, nickel–silicon intermetallics showed excellent selectivity for the hydrogenation of phenylacetylene to styrene (ca. 93%) due to the strong modification of the electronic structure derived from the interaction of nickel and silicon.

Preparation of highly active and excellent sulfur tolerant hydrodesulfurization (HDS) catalysts is very important for the removal the sulfur from the sulfur containing compounds in petroleum. Herein we report on the synthesis and characterization of ferromagnetic nickel–cobalt silicide (Ni1–xCoxSi2) solid solution catalysts having large surface area by the reaction of nickel cobalt oxide solid solutions with SiH4. The catalytic properties of Ni1–xCoxSi2 were investigated for HDS of dibenzothiophene (DBT). The results showed that the saturation magnetization of the Ni1–xCoxSi2 solid solutions with fluorite structure can be controlled by changing the molar ratio of Ni to Co. The nickel-rich Ni0.75Co0.25Si2 catalyst is much more active than that of monometallic silicide (NiSi2 and CoSi2) and significantly improves the hydrogenation property (31.5% HYD selectivity), proving the synergistic effect between the components. X-ray photoelectron spectroscopy (XPS) provided further evidence that the valence electron concentration of the Ni increased with increasing the Co substitution, enhancing the metal–silicon and metal–metal interactions. In addition, the Si sites in the silicides alter the metal coordination, leading to a strong modification of the electronic structure around the Fermi level of the metals. This engenders a high activity for the HDS of DBT and weakens the metal–sulfur bonds, improving the sulfur tolerance.

The highly porous metal organic framework MOF-5 was loaded with the metal–organic compound [Pd(C3H5)(C5H5)] by metal–organic chemical vapor deposition (MOCVD) method. The inclusion compound [Pd(C3H5)(C5H5)]@MOF-5 was characterized by powder X-ray diffraction (PXRD), Fourier-transform infrared (FT-IR) spectroscopy, and solid-state nuclear magnetic resonance spectroscopy. It was found that the host lattice of MOF-5 remained intact upon precursor insertion. The –C3H5 ligand in the precursor is easier to lose due to the interaction between palladium and the benzenedicarboxylate linker in MOF-5, providing a possible explanation for the irreversibility of the precursor adsorption. Pd nanoparticles of about 2–5 nm in size was formed inside the cavities of MOF-5 by hydrogenolysis of the inclusion compound [Pd(C3H5)(C5H5)]@MOF-5 at room temperature. N2 sorption of the obtained material confirmed that high surface area was retained. In the Suzuki coupling reaction the Pd@MOF-5 materials showed a good activity in the first catalytic run. However, the crystal structure of MOF-5 was completely destroyed during the following reaction runs, as confirmed by PXRD, which caused a big loss of the activity.The embedding of palladium nanoparticles into the metal organic framework MOF-5 has been successfully prepared by MOCVD method, and been used as catalyst for Suzuki reaction. The prepared Pd@MOF-5 had a very high BET surface area with Pd particles in size of 2–5 nm. The Pd@MOF-5 was used as a heterogeneous catalyst for the Suzuki coupling reaction and achieved a good activity.Open image in new window

In order to well understand reaction pathways of glycerol hydrogenolysis over Cu–Cr catalysts, hydrogenolysis of glycerol was investigated as a function of the molar ratios of Cu to Cr, reaction time, reaction temperature, hydrogen pressure, and glycerol concentration. The intermediates in glycerol hydrogenolysis were identified under Ar atmosphere or relatively mild condition. Hydrogenolysis of propanediols was also investigated for understanding the formation of propanols as by-products. The structure of Cu–Cr catalysts, prepared by an epoxide-assisted route, was determined by X-ray diffraction and scanning transmission electron microscopy. The high conversion of 85.9% and high selectivity toward 1,2-propylene glycol of 98.5% was achieved over the CuCr(4) catalyst in the hydrogenolysis of glycerol. As expected, extending reaction time, or elevating temperature and hydrogen pressure favored the conversion of glycerol. Interestingly, the conversion of glycerol and the selectivity to 1,2-propanediol increased with increasing the glycerol concentration at the same ratio of catalyst to glycerol. It was found that the hydrogenolysis of glycerol not only involved glycerol directly dehydrated and hydrogenated to 1,2-propanediol (DH route), but also involved glycerol dehydrogenation to glyceraldehyde, which was subsequently dehydrated and hydrogenated to 1,2-propanediol (DDH route), while 1,2-propanediol was further converted to propanol through H+ transfer from alcohol compounds.Graphical abstractHighlights► Hydrogenolysis of glycerol involved DH and DDH reaction pathways. ► Further conversion of 1,2-PD was promoted by H+ transfer from alcohol compounds. ► Conversion and selectivity to 1,2-PD increased with increasing concentration at same cat/subs ratio. ► Conversion of 85.9% and selectivity to 1,2-PD of 98.5% were achieved over CuCr(4) catalyst.

Activated carbon supported Pt, Pd, and Pt–Pd catalysts have been successfully prepared by incipient wet impregnation with a hydrochloric solution of PdCl2 and PtCl4. Hydrodeoxygenation of benzofuran was used as a probe reaction to investigate their catalytic properties. The activated carbon supported Pt–Pd catalyst was confirmed to form Pt–Pd alloy by X-ray diffraction. All the catalysts were active in the hydrodeoxygenation of benzofuran. Pd catalyst did not only give higher hydrogenation activity, but also showed faster deoxygenation rate than the Pt catalyst. The Pt–Pd catalyst with the mole ratio of Pd/Pt = 4 showed the highest catalytic activity among all of the catalysts. 2-Ethylcyclohexanone, which was not observed over the sulfide catalysts, was detected as a new oxygen-containing intermediate in the hydrodeoxygenation of benzofuran over the activated carbon supported Pt, Pd, and Pt–Pd catalysts. A ketone/enol isomerization reaction route is proposed to happen over the activated carbon supported noble metal Pt, Pd, and Pt–Pd catalysts.

MoS2/MCM-41 catalysts have been prepared by thermal decomposition of MCM-41 with cetyltrimethylammonium thiomolybdate, which was synthesized by reaction between ammonium thiomolybdate and cetyltrimethylammonium bromide left in the pore channel of MCM-41. The obtained catalysts exhibit type IV adsorption–desorption isotherms, indicating that MCM-41 mesoporous structure is retained during the synthesis process. With increasing loading of MoS2, the catalytic activity of MoS2/MCM-41 for HDS of DBT first increases, followed by a leveling off above 10 % MoS2 loading, likely due to lack of accessibility to additional active sites. For the first time over MoS2 catalysts, the DDS (i.e., hydrogenolysis) reaction pathway is favored with 100 % selectivity. This unique performance is associated with single layer MoS2 sites stabilized within the pores of the MCM-41 support.

Silica supported CoSi particles were synthesized by metal organic chemical vapor deposition of the Co(SiCl3)(CO)4 precursor carried in hydrogen at atmospheric pressure and moderate temperature in a fluidized bed reactor. In contrast, CoCl2 supported on silica was formed by using argon as the carrier gas. The samples were characterized by X-ray diffraction, transmission electron microscopy, ultraviolet–visible spectroscopy, and thermogravimetric/differential thermogravimetric analysis. The precursor Co(SiCl3)(CO)4 reacted with the hydroxyl groups of amorphous silicavia loss of HCl and introduced cobalt species onto the surface. The decomposition mechanism of the supported precursor on silica was investigated by in situFourier transform infrared spectroscopy from room temperature to 300 °C in a hydrogen or argon atmosphere. The results showed that CO and HCl elimination occurred in a hydrogen atmosphere, while only CO elimination occurred in Ar. All of the results showed that it was possible to prepare supported CoSi at lower temperatures via changing the carrier gas.

The surface areas of Cu−Cr xerogels prepared by an epoxide assisted route are highly dependent on synthetic conditions like gelation temperature, amount of water in the solvent, and gel aging time. Gelation temperature affects the relative rates of hydrolysis and condensation, the amount of water in solution adjusts the solution pH, and the aging process influences the microstructural properties of the xerogels. These factors affect the stability of the sol particles in solution and the final structure of the gel. Thermogravimetric and differential thermogravimetric analysis, specific surface area measurement through nitrogen adsorption, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy are employed to determine particle size distribution and morphology of the different particulate products (i.e., gels, powders) obtained via different synthesis conditions, both before and after thermal treatments. The xerogel surface area can reach up to 230 m2/g by adjusting the operating parameters. Moreover, the results show that the Cu−Cr catalysts with CuCr2O4 and Cr2O3 phases obtained by calcining the as-prepared xerogels in 20% O2 in Ar have better activity for glycerol catalytic conversion than catalysts with Cu and Cr2O3 phases that were obtained by calcination in Ar. In addition, the activity of catalysts increased with the surface areas of xerogels. It is noteworthy that the catalysts have significant selectivity to 1,2-propanediol (54%) and 1-propanol (36%) at 32% conversion of glycerol at 210 °C and 4.1 MPa H2 pressure.

A family of unsupported NiMoW sulfide catalysts have been prepared by thermal decomposition of mechanically ground tetramethylammonium thiomolybdotungstate and Ni(NO3)2 for hydrodesulfurization of dibenzothiophene. The materials were characterized by Fourier transformation infrared spectroscopy, ultraviolet–visible spectroscopy, thermogravimetric analysis, X-ray diffraction, N2 physorption, scanning electron microscopy, and transmission electron microscopy. The results showed that structures and properties of unsupported NiMoW sulfides depend on nickel content and decomposition condition. XRD revealed a decrease in the stacking along the c direction of the MoS2 and/or WS2 crystalline structures as the nickel content was increased, consistent with a higher dispersion of the metal sulfides observed by electron microscopy. The low nickel content in Ni0.5MoWSy catalyst gave a positive effect on the hydrodesulfurization of dibenzothiophene, as indicated by the greatly increased specific catalytic activity per unit surface area. In contrast, the high nickel content in Ni1.5MoWSy catalyst showed a negative effect due to the formation of nickel sulfides. Ni0.5MoWSy catalyst showed the highest activity in the hydrodesulfurization reaction compared to other samples. The results further suggest that unsupported NiMoW sulfide catalysts may be promising candidates for wide application in hydrotreating of fuel oil.Graphical abstractHighlights► Tetramethylammonium trimetallates were obtained by mechanical grinding route. ► Layer and stacking degree of sulfides showed a decreasing trend with increasing Ni content. ► Low Ni content showed greatly enhanced intrinsic catalytic activity per unit surface area. ► The addition of nickel promoted the hydrogenation pathway in the HDS of DBT.

Highly active Pt–WCx/carbon nanotube (CNT) electrocatalysts for the oxygen reduction reaction (ORR) have been developed by the combination of tungsten carbide with CNTs as electrocatalyst supports. The obtained WCx/CNT and Pt–WCx/CNT samples were characterized by XRD, TEM, XPS and electrochemical measurements. The results showed that nanostructured tungsten carbide particles on carbon nanotubes could be prepared by microwave-assisted thermolytic molecular precursor method, and the particle size of tungsten carbide increased with the increase of tungsten loading. The nanostructured WCx/CNTs showed electrocatalytic activity for oxygen reduction reaction. The deposition of Pt nanoparticles on the WCx/CNTs resulted in higher electrocatalytic activity for the oxygen reduction reaction and better immunity to methanol than Pt/CNT catalysts. The unique electrocatalytic properties of the novel Pt–WCx/CNT electrocatalyst were attributed to a synergistic effect between Pt, WCx and the CNTs. The findings also indicated that WCx/CNTs were efficient electrocatalyst supports that could reduce Pt usage while the same electrocatalytic properties were kept for the ORR in direct methanol fuel cells.

A non-alkoxide sol–gel route to highly active and selective Cu–Cr catalysts for glycerol conversion is presented. The addition of propylene oxide to ethanol solutions of Cr(NO3)3·9H2O and Cu(NO3)2·3H2O resulted in the formation of transparent Cu–Cr gels. The resulting gels were converted to the Cu–Cr catalysts by atmospheric drying and calcination. The Cu–Cr catalysts are characterized by X-ray diffraction (XRD), N2 physisorption, temperature-programmed reduction (TPR), and transmission electron microscopy (TEM). The results show that the surface area of the Cu–Cr catalyst is adjusted by the hydrolysis conditions, Cu/Cr molar ratio, and treatment conditions (such as gas atmosphere and final temperature). For the sample with Cu/Cr = 0.5, the surface area of Cu–Cr xerogel can reach 94 m2/g and decreased to only 31 m2/g after calcination at 500 °C. The catalysts show significant catalytic activity and selectivity in glycerol conversion, i.e. above 52% conversion of glycerol and above 88% selectivity to 1,2-propanediol at 210 °C and 4.15 MPa H2 pressure. CuCr2O4 supported Cu catalysts are much more active than Cr2O3 supported Cu catalysts. This indicates a strong interaction between Cu and CuCr2O4 that is significantly improving the effectiveness of the catalyst for glycerol conversion.

Nanostructured Mo2C/CNTs composites have been synthesized by using a novel methodology of microwave-assisted thermolytic molecular precursor with Mo(CO)6 as single source precursor. Pt electrocatalysts supported on the Mo2C/CNTs composites were prepared by using the modified ethylene glycol method. The resulting Mo2C/CNTs and Pt−Mo2C/CNTs were characterized by inductively coupled plasma-optical emission spectroscopy, thermogravimetric analysis, X-ray diffraction, transmission electron microscopy, and energy-dispersive X-ray spectroscopy. The rotating disk electrode experiments were used to measure electrocatalytic activity for oxygen reduction reaction. The results showed highly dispersed sphere-like Mo2C and Pt particles with 3−6 nm can be prepared upon CNTs by the above-mentioned methods. The formation process of Mo2C includes the following steps: decomposition of Mo(CO)6 precursor to the metallic Mo and CO, CO dismutation reaction, formation of the MoOxCy by the metallic Mo and CO, the MoOxCy carburization to Mo2C, and further carburization of Mo2C to Mo3C2. The Pt−Mo2C/CNTs sample gave higher electrochemical surface area and activity for oxygen reduction reaction with a more positive onset potential in acid solution than those of Pt/CNTs under the same condition, which was attributed to the synergistic effect among Pt, Mo2C, and CNTs. The findings indicate that Mo2C is an inexpensive and promising alternative to precious metal and worthy of further exploring for other applications in catalysis.

Silica supported nickel phosphide catalysts with initial Ni/P molar ratios from 0.5 to 2.0 and the sum of NiO and P2O5 loadings from 10 to 40 wt % in their precursors have been prepared by the temperature-programmed reduction method and characterized by means of X-ray diffraction, N2 physisorption, CO chemisorption, and pyridine adsorption with in situ Fourier transform-infrared (FT-IR) spectroscopy. Naphthalene hydrogenation was carried out at 340 °C and 4.0 MPa over the as-prepared Ni2P/SiO2 catalysts. Mutual influences of naphthalene hydrogenation and quinoline hydrodenitrogenation were investigated under similar conditions. The catalyst with Ni/P = 1.25 and 30 wt % loading showed the complete naphthalene conversion as well as 92.1% of selectivity to decalin. It was observed that cis-decalin converted partly into trans-decalin under the studied conditions. Addition of quinoline into naphthalene hydrogenation obviously decreased naphthalene conversion and selectivity to decalin over the Ni2P/SiO2 catalysts due to the strong adsorption of quinoline on active sites. The similar effects of the quinoline hydrogenated compounds on naphthalene hydrogenation were also observed over the Ni2P/SiO2 catalysts. The addition of naphthalene had no effect on quinoline hydrogenation to tetrahydroquinoline but inhibited tetrahydroquinoline hydrogenation to decahydroquinoline. Naphthalene conversion over the Ni2P/SiO2 catalyst in the presence of quinoline and dibenzothiophene decreased with the increase of their contents. It is noteworthy that naphthalene conversion could be recovered after the removal of quinoline while the hydrogenation activity could not in the case of dibenzothiophene.

Cobalt silicide nanoparticles in mesoporous silica SBA-15 were successfully prepared by metal-organic chemical vapor deposition of a single-source precursor and were characterized by nitrogen physorption, X-ray diffraction, temperature-programmed reduction, temperature-programmed desorption, and transmission electron microscopy. The catalytic hydrogenation of naphthalene on the cobalt silicide nanoparticles in mesoporous silica was investigated in a fixed-bed reactor at 340 °C under 4.0 MPa hydrogen pressure. No cobalt silicide was observed in the mesoporous silica without calcination because of the hydrolysis of Co(SiCl3)(CO)4. Highly dispersed and evenly distributed cobalt silicide particles with diameters of 2−4 nm could be formed by adsorption and reduction of Co(SiCl3)(CO)4 in the mesoporous silica with calcination above 500 °C. The cobalt silicide loading in the mesoporous silica depended on both the amount of precursor provided and the amount of hydroxyl groups in the mesoporous silica. A 8.3% CoSi/SBA-15 sample showed lower conversion and higher selectivity to tetralin (about 100%) in the naphthalene hydrogenation, while a 16.1% CoSi/SBA-15 sample showed a higher catalytic activity up to 87% and a lower selectivity to tetralin (35%) than other CoSi/SBA-15 samples, which may be due to the size effect and the strong interaction of CoSi and support.

Interstitial silicide-modified nickel, with high selectivity in some hydrogenation reactions, had been produced by dissolving silicon atoms into the nickel lattices. The metallic nickel was obtained by reducing the as-prepared high surface area NiO, followed by modification of the bulk nickel through silification of silane/H2 at relatively low temperature and atmospheric pressure. The as-prepared materials were characterized by X-ray diffraction, magnetic measurements, X-ray photoelectron spectroscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, and temperature-programmed reduction. The results show nickel silicide formation involves the following sequence as a function of increasing temperature: Ni (cubic) → Ni2Si (orthorhombic) → NiSi (orthorhombic) → NiSi2 (cubic). The insertion of Si atoms into the interstitial sites between Ni atoms resulted in a significant change in the unit cell lattice of nickel. All of the silicide-modified nickel materials were ferromagnetic at room temperature, and saturation magnetization values drastically decreased when Si is present. Silicide-modified nickel develops a thin silicon oxide layer during exposure to air, which can be removed by H2-temperature programmed reduction. The as-prepared bulk silicide-modified nickel showed above 92% styrene selectivity in the hydrogenation of phenylacetylene under 0.41 MPa H2 and at 50 °C for 5 h. In addition, only low conversions were obtained for styrene hydrogenation under the same hydrogen pressure and temperature for 50 min. These results indicate that these novel silicide-modified nickels are promising catalysts for the selective hydrogenation of unsaturated hydrocarbons.

Pd nanoparticle/functionalized CNF composites were synthesized by a two-step chemical vapor deposition of Pd(allyl)(Cp) as precursor at atmospheric pressure. Online mass spectrometry was used to measure the gas fragments during the two-step CVD. The functionalized CNFs and the resulting composites were characterized by temperature-programmed desorption mass spectroscopy, inductively coupled plasma-optical emission spectroscopy, X-ray diffraction, and transmission electron microscopy. The catalytic hydrogenation of cyclooctene on the Pd/CNF nanocomposites was also investigated in a fixed-bed reactor at 40 °C under atmospheric pressure. No palladium deposition was observed on the raw CNFs, as a result of the absence of anchoring sites. The functionalization of CNFs with HNO3 solution resulted in the formation of surface oxygen groups. The Pd(allyl)(Cp) precursor could be dissociatively adsorbed on the surface of the CNF by the reaction between the ligands and the surface oxygen groups. Further reduction in H2 formed the Pd/CNF nanocomposites. The palladium loading on the functionalized CNFs depends on the degree of functionalization of the CNFs and on the amount of precursor provided. TEM and XRD results showed that highly dispersed and evenly distributed Pd particles with diameters of 2−4 nm could be prepared by this two-step CVD method. The Pd/CNF nanocomposite catalysts exhibited high activity and stability in the catalytic hydrogenation of cyclooctene, which can be attributed to the special interaction between the palladium nanoparticles and the CNFs and to the mesoporous nature of the CNFs, which prevents mass transfer limitation. The two-step CVD route has great potential in the controlled synthesis of CNF-supported metal catalysts with high dispersion and uniform distribution.

High-surface-area CexFe1−xO2 solid solutions about 5 nm in size have been successfully prepared by using ultrahigh surface area carbon material as template and cerium and iron nitrates as oxide precursor. The obtained materials were characterized by means of N2 physisorption, X-ray diffraction, Raman spectroscopy, electron paramagnetic resonance, transmission electron microscopy and energy dispersive X-ray spectroscopy. The redox and catalytic properties of the nanoscale CexFe1−xO2 solid solutions were also evaluated by temperature-programmed reduction and ethanol steam reforming. The results confirm the formation of the nanoscale CexFe1−xO2 cubic phase solid solutions with fluorite structure, and the process of Ce4+ substitution by Fe3+ gradually from the surface to the bulk of CeO2. A small addition of Fe into CeO2 resulted in a remarkable increase in the surface area and oxygen vacancy concentration, and decreased the particle size of the solid solution, while further Fe addition decreased the surface area and vacancy concentration of the solid solution, and increased the particle size of the solid solution. The results from temperature-programmed reduction show that addition of Fe into CeO2 not only promotes the reduction of CeO2, but also increases the oxygen vacancy concentration. The CexFe1−xO2 solid solutions show significant catalytic activity toward ethanol steam reforming with above 64% selectivity to hydrogen at 550 °C. The Ce0.90Fe0.10O2 sample presents superior activity and selectivity to hydrogen compared to CeO2, Fe2O3 and other solid solutions. The findings show that the carbon template route may be of great potential in synthesis of other solid solutions, and the CexFe1−xO2 solid solutions are potential materials for oxygen storage and ethanol steam reforming.

CoSi particles on a silica support, synthesized by metal organic chemical vapor deposition (MOCVD) of Co(SiCl3)(CO)4 as a precursor at atmospheric pressure and moderate temperature in a fluidized bed reactor, show high catalytic activity and selectivity in naphthalene hydrogenation.

Microwave heating, in which ZnCl2 was used as activation agent and heating carrier, has been successfully used to prepare activated carbon from wood. The process is simple and only takes a few minutes. The pore structure and surface area of the as-prepared carbon materials can be tuned by simply changing the ratio of ZnCl2 to wood and the microwave heating time.

Nearly monodispersed nanostructured tungsten carbide particles on carbon nanotubes (CNTs) have successfully been synthesized by microwave-assisted metal−organic chemical vapor deposition (MOCVD) at atmospheric pressure in a fluidized bed reactor. The results show that the tungsten carbide particles with 2−5 nm on CNTs can be formed several minutes and the particle sizes increase with the increase of microwave irradiation time. The preoxidation of CNTs is not necessary in the microwave-assisted MOCVD. The resulting materials are active catalysts for hydrazine decomposition and exhibit high selectivity to hydrogen, indicating that nanostructured tungsten carbides on CNTs is an inexpensive and promising alternative to the noble-metal catalysts for hydrazine decomposition. The microwave-assisted MOCVD is of great potential in the controlled synthesis of supported catalytic materials.

A direct strategy for the creation of defects on carbon nanofibers (CNFs) has been developed by steam treatment. Nitrogen physisorption, XRD, Raman spectra, SEM and TEM analyses proved the existence of the new defects on CNFs. BET surface area of CNFs after steam treatment was enhanced from 20 to 378 m2/g. Pd catalysts supported on CNFs were also prepared by colloidal deposition method. The different activity of Pd/CNFs catalysts in the partial hydrogenation of phenylacetylene further demonstrated the diverse surfaces of CNFs could be formed by steam treatment.

ZSM-48 zeolites with various Si/Al ratios were hydrothermally synthesized in the H2N(CH2)6NH2 (HDA)-containing media. The obtained samples were highly crystallized with minor mixed phases as evidenced by X-ray powder diffraction (XRD). The alkaline treated ZSM-48 zeolites maintained its structure under different concentrations of NaOH aqueous solution. Micropores remained unchanged while mesopores with wide pore size distribution formed after the alkaline treatment. The surface area increased from 228 to 288 m2/g. The Brönsted acid sites had little alteration while an obvious increase of Lewis acid sites was observed. The hydroisomerization of hexadecane was performed as the model reaction to test the effects of the alkali treatment. The conversion of hexadecane had almost no change, which was attributed to the preservation of the Brönsted acid sites. While high selectivity to iso-hexadecane with an improved iso to normal ratio of alkanes was due to the mesopore formation and improved diffusivity.The alkaline treated ZSM-48 zeolite maintained its structure, formed mesopores with a wide distribution, and improved the selectivity to iso-hexadecane in hydroisomerization of hexadecane due to overcoming the diffusion limitation.Download full-size image

An enhanced active and selective catalyst consisting of ruthenium supported on dealuminated HY zeolite has been prepared by a wet impregnation method. It was found that BET surface area of Ru/HY catalysts significantly increases after HCl treatment. This treatment also increases the concentration of strong acid sites in the catalyst. The hydrogenolysis of glycerol over 5 wt% Ru/HY catalyst was investigated at 190–220 °C, an initial H2 pressure of 3–6 MPa, and in 20 wt% glycerol aqueous solution. The results indicate that HCl treated Ru/HY catalyst shows higher activity compared with the untreated Ru/HY catalyst, and that the glycerol hydrogenolysis efficiency is influenced by the porosity and acidity of the support. A selectivity to 1,2-PDO of 81.3% at a glycerol conversion of 60.1% under 3 MPa H2 pressure and 220 °C for 10 h was achieved over the modified Ru/HY catalyst with a 1.0 mol/L HCl treatment. It has also been shown that a longer reaction time, a higher temperature and a higher H2 pressure have the positive effects on the glycerol hydrogenolysis efficiency of the enhanced Ru/HY.The ruthenium supported on the dealuminated HY zeolites shows higher conversion and activity in the hydrogenolysis of glycerol simultaneously.Download full-size image

A series of monometallic Pt and Pd and alloyed Pt–Pd catalysts (mole ratio of Pt/Pd = 1, 4, and 0.25) were prepared with silica–alumina as support. CO chemisorption and X-ray diffraction (XRD) were applied to characterize the resulting samples. The performance of the catalysts for hydrodeoxygenation (HDO) for benzofuran (BF) was evaluated in a fixed-bed flow reactor at 280 °C and 3.0 MPa. Only one major route was found for the reaction network of HDO of BF among the catalysts. First, BF was transformed to 2,3-dihydrobenzofuran with the hydrogenation at the heterocyclic ring, followed by further conversion to octahydrobenzofuran at the benzene ring. The main hydrocarbon products are ethylcyclohexane and methylcyclohexane. The silica–alumina-supported catalysts also showed significant cracking activities, with the observation of the production of methylcyclohexane. The activity and product selectivity of Pt, Pd, and bimetallic Pt–Pd catalysts with the influence of the weight time were investigated in detail. Bimetallic Pt–Pd catalysts were higher in activity in the hydrogenation and the removal of oxygen from BF than their monometallic counterparts. The Pd4Pt1 catalyst presented the highest activity, with 99% conversion of BF and 100% selectivity toward 2,3-dihydrobenzofuran among all of the other catalysts at low weight time.

A composite co-crystalline zeolite Eu-1/ZSM-48 was synthesized by a hydrothermal method. The composite materials consist of crystals with intergrowth between the EU-1 (EUO framework type) zeolite and ZSM-48 (MRE framework type) zeolite. The physicochemical properties of EU-1, ZSM-48 and EU-1/ZSM-48 were identified with respect to their crystallinity, textural parameters and acidity by means of X-ray diffraction, N2 adsorption–desorption analysis, scanning electron microscopy, temperature-programmed desorption of ammonia and pyridine adsorption infrared spectroscopy. The catalytic performance of different composite zeolite loaded platinum-based catalysts was studied through the hydroisomerization of hexadecane to isohexadecane as a probe reaction under various reaction conditions. The results indicated that the best performance was obtained over EU-1/ZSM-48 even though EU-1 showed the highest conversion and ZSM-48 showed the highest selectivity. The catalytic performance of EU-1/ZSM-48-200 was significantly different from that of ZSM-48-200 which possessed the same bulk SiO2/Al2O3. The catalytic performance of the EU-1/ZSM-48 intergrowth zeolite improved dramatically compared with the mechanical mixture of pure zeolites. The acidity of the intergrowth zeolite was favorable for the catalytic hydroisomerization of n-hexadecane.

Silica supported CoSi particles were synthesized by metal organic chemical vapor deposition of the Co(SiCl3)(CO)4 precursor carried in hydrogen at atmospheric pressure and moderate temperature in a fluidized bed reactor. In contrast, CoCl2 supported on silica was formed by using argon as the carrier gas. The samples were characterized by X-ray diffraction, transmission electron microscopy, ultraviolet–visible spectroscopy, and thermogravimetric/differential thermogravimetric analysis. The precursor Co(SiCl3)(CO)4 reacted with the hydroxyl groups of amorphous silicavia loss of HCl and introduced cobalt species onto the surface. The decomposition mechanism of the supported precursor on silica was investigated by in situFourier transform infrared spectroscopy from room temperature to 300 °C in a hydrogen or argon atmosphere. The results showed that CO and HCl elimination occurred in a hydrogen atmosphere, while only CO elimination occurred in Ar. All of the results showed that it was possible to prepare supported CoSi at lower temperatures via changing the carrier gas.

High-surface-area CexFe1−xO2 solid solutions about 5 nm in size have been successfully prepared by using ultrahigh surface area carbon material as template and cerium and iron nitrates as oxide precursor. The obtained materials were characterized by means of N2 physisorption, X-ray diffraction, Raman spectroscopy, electron paramagnetic resonance, transmission electron microscopy and energy dispersive X-ray spectroscopy. The redox and catalytic properties of the nanoscale CexFe1−xO2 solid solutions were also evaluated by temperature-programmed reduction and ethanol steam reforming. The results confirm the formation of the nanoscale CexFe1−xO2 cubic phase solid solutions with fluorite structure, and the process of Ce4+ substitution by Fe3+ gradually from the surface to the bulk of CeO2. A small addition of Fe into CeO2 resulted in a remarkable increase in the surface area and oxygen vacancy concentration, and decreased the particle size of the solid solution, while further Fe addition decreased the surface area and vacancy concentration of the solid solution, and increased the particle size of the solid solution. The results from temperature-programmed reduction show that addition of Fe into CeO2 not only promotes the reduction of CeO2, but also increases the oxygen vacancy concentration. The CexFe1−xO2 solid solutions show significant catalytic activity toward ethanol steam reforming with above 64% selectivity to hydrogen at 550 °C. The Ce0.90Fe0.10O2 sample presents superior activity and selectivity to hydrogen compared to CeO2, Fe2O3 and other solid solutions. The findings show that the carbon template route may be of great potential in synthesis of other solid solutions, and the CexFe1−xO2 solid solutions are potential materials for oxygen storage and ethanol steam reforming.

A non-alkoxide sol–gel route to highly active and selective Cu–Cr catalysts for glycerol conversion is presented. The addition of propylene oxide to ethanol solutions of Cr(NO3)3·9H2O and Cu(NO3)2·3H2O resulted in the formation of transparent Cu–Cr gels. The resulting gels were converted to the Cu–Cr catalysts by atmospheric drying and calcination. The Cu–Cr catalysts are characterized by X-ray diffraction (XRD), N2 physisorption, temperature-programmed reduction (TPR), and transmission electron microscopy (TEM). The results show that the surface area of the Cu–Cr catalyst is adjusted by the hydrolysis conditions, Cu/Cr molar ratio, and treatment conditions (such as gas atmosphere and final temperature). For the sample with Cu/Cr = 0.5, the surface area of Cu–Cr xerogel can reach 94 m2/g and decreased to only 31 m2/g after calcination at 500 °C. The catalysts show significant catalytic activity and selectivity in glycerol conversion, i.e. above 52% conversion of glycerol and above 88% selectivity to 1,2-propanediol at 210 °C and 4.15 MPa H2 pressure. CuCr2O4 supported Cu catalysts are much more active than Cr2O3 supported Cu catalysts. This indicates a strong interaction between Cu and CuCr2O4 that is significantly improving the effectiveness of the catalyst for glycerol conversion.

Supported Cu–Cr catalysts were prepared by a non-alkoxide sol–gel route, and characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), H2-temperature programmed reduction (H2-TPR) and X-ray photoelectron spectroscopy (XPS) measurement. Their structures were significantly tuned by the Cu–Cr molar ratio. CuCr2O4, CuCr2O4–CuO and CuCr2O4–Cr2O3 structures were confirmed in CuCr(0.5), CuCr(4) and CuCr(0.25) catalysts, respectively. A direct interaction between CuCr2O4 and CuO or Cr2O3 in CuCr(4) and CuCr(0.25) catalyst was observed by the H2-TPR and XPS results. The catalytic performance of Cu–Cr catalysts with various structures was examined by hydrogenolysis reaction of high concentrated glycerol. Under mild conditions (2.0 MPa and 130 °C) and high concentration (100 wt%), the maximum conversion (52%) was obtained over the CuCr(0.5) catalyst, while the CuCr(4) catalyst gave the highest selectivity of 1,2-PD (up to 100%). This finding will result in the production of less waste water and lower energy consumption in the following separation steps during glycerol hydrogenolysis.

Transition metal carbides have been of great interest because of their noble-metal-like properties. Because of the complexity of their structures, it is crucial to design an experiment that can eliminate the influence of supports, surface carbon contamination and particle sizes when finding the exact catalytic active sites. In this work, phase-pure W2C nanorods (lengths of 2–4 μm and diameters of 100–600 nm) with different amounts of crystal defects were prepared by the pyrolysis of metatungstate and melamine hybrid nanorods with nanoscale periodic structure synthesized in the aqueous phase. The nanoscale alternating structure between tungsten oxide and melamine effectively promotes the reduction of tungsten oxide and the formation of tungsten carbide, avoiding the deposition of carbon on the surface. At the same time, vacancy defects are generated due to the deficiency of carbon. High pyrolysis temperature (900 °C), prolonged pyrolysis time (4 h), introduction of hydrogen and the proper increase of the temperature ramping rate (5 °C min−1) are favorable to the formation of vacancy defects. The activities of different catalysts were evaluated by the hydrodeoxygenation of benzofuran at 320 to 350 °C. The results show that the vacancy defect sites in W2C are the key to the high reactivity of W2C. The vacancy defect sites have favorable properties for the cleavage of carbon–oxygen bonds. The Caromatic–O bond is cleaved in the case of unsaturated aromatic rings, thereby reducing the consumption of hydrogen. In addition, it is found that the apparent activation energy of each chemical bond is linear-like and positively related to its bond dissociation energy.

The surface of silica with mesopores (SiO2) was post-modified by the deposition of highly dispersed Al2O3 or ZrO2 oxides. Loading of Pt on the modified silica supports yielded higher metal dispersion with respect to the parent silica based on the CO chemisorption and transmission electron microscopy results. Hydrodeoxygenation (HDO) of dibenzofuran (DBF) over the as-prepared Pt catalysts mainly proceeds via the hydrogenation of the aromatic rings, which is followed by the cleavage of the C–O bond to produce oxygen-free hydrocarbons. Preferable hydrogenation of the aromatic rings is observed over the smaller Pt nanoparticles. The relatively strong acidic properties of Al2O3/SiO2 or ZrO2/SiO2, revealed by the NH3-TPD profiles, promote the selective C–O bond cleavage of hexahydrodibenzofuran to alter the HDO reaction pathway. The small sized Pt nanoparticles supported on the Al2O3 or ZrO2 modified silica supports show superior HDO performance with enhanced deoxygenation ability to those over unmodified silica. According to the pseudo-first-order kinetics analysis, the fitted HDO rate constant follows the order: Pt/Al2O3/SiO2 > Pt/ZrO2/SiO2 > Pt/SiO2 under a constant temperature, which is attributed to the cooperative function of the dispersed metal particles and the acidic sites of supports.

A series of metallic Re/C catalysts were prepared with the microwave-assisted thermolytic method by using decacarbonyldirhenium [Re2(CO)10] as a precursor for the hydrogenation of succinic acid. The results of FT-IR, UV-Vis, XRD, HRTEM, ICP, TPR and CO chemical adsorption showed that the as-prepared catalysts had well-dispersed rhenium nanoparticles on activated carbon. Changing irradiation time or rhenium loadings could effectively adjust the properties of Re/C catalysts which exhibited good catalytic performance for the hydrogenation of succinic acid. There were plenty of active sites on Re/C catalysts for the high concentration hydrogenation of succinic acid, and increasing temperature or pressure improved catalytic activity at a defined scope. From the kinetic study of succinic acid catalytic hydrogenation, there was a certain converting relationship between the different intermediates and the product distribution which could be controlled by variation of reaction time.

Silicon–nickel intermetallic compounds (IMCs) supported on silica (Si–Ni/SiO2), as a highly efficient catalyst for CO methanation, have been prepared by direct silicification of Ni/SiO2 with silane at relatively low temperature in a fluidized bed reactor. The as-prepared materials were characterized by X-ray diffraction, transmission electron microscopy, in situ FT-IR of CO adsorption, and H2-temperature programmed reduction-mass spectrometry (TPR-MS) of CO. The results indicate that uniform NiSix nanoparticles with about 3–4 nm are evenly dispersed on silica. The combined in situ FTIR and TPR-MS results suggest that the Si–Ni/SiO2 catalysts afforded high activity in CO methanation, promoting the formation of CH4 at ca. 240 °C. The catalytic hydrogenation of CO on Si–Ni/SiO2 was investigated in a fixed-bed reactor at GHSVs 48000 mL h−1 g−1 under 1 atm in the temperature interval 200–600 °C. In the higher temperature reaction region (500–600 °C), it is notable that the Si–Ni/SiO2 catalysts present high activity for CO methanation as compared to the Ni/SiO2 catalyst. More importantly, the Si–Ni/SiO2-350 catalyst containing thermally stabile Si–Ni IMCs shows significantly higher resistance to the sintering of Ni particles. Raman characterization of the spent materials qualitatively shows that carbon deposition observed on the conventional Ni/SiO2 catalyst is much higher than that of the used Si–Ni/SiO2-350. It is proposed that small amounts of silicon interacting with Ni atoms selectively prevent the adsorption of resilient carbon species.

Cubic Pd nanoparticles were rapidly encapsulated in ZIF-8 through a PVP-assisted synthetic method at room temperature. The obtained PVP–Pd@ZIF-8 exhibited high activity and stability for hydrogenation of 1,4-butynediol, with excellent selectivity to 1,4-butenediol.

CoSi particles on a silica support, synthesized by metal organic chemical vapor deposition (MOCVD) of Co(SiCl3)(CO)4 as a precursor at atmospheric pressure and moderate temperature in a fluidized bed reactor, show high catalytic activity and selectivity in naphthalene hydrogenation.

Fe3Si nanoparticles with a size of about 6–9 nm well dispersed on silica have been prepared by pyrolysis of ferrocene–polydimethylsilane composites at 600 °C. Powder XRD patterns, TEM and HRTEM images, and XPS spectra revealed that the average particle size increased with increasing pyrolysis temperature and a new phase, Fe5Si3, appeared when the pyrolysis temperature was above 800 °C. 57Fe Mössbauer spectra, M − H curves and FC and ZFC curves demonstrated that the as-prepared nanoparticles presented superparamagnetic behavior at 27 °C and ferromagnetic behavior at −268 °C, and their particle sizes had a great impact on their magnetic properties. The Fe3Si nanoparticles on silica may find applications in magnetically recording materials, magnetically separable catalysts and electrode materials for spintronic devices.