A facile one-step synthesis of molybdenum carbide-carbon composites for the hydrogenation of naphthalene

A molybdenum carbide-carbon composite (β-Mo2C/C) is prepared by carbonization of an anionic resin with molybdate. The β-Mo2C/C is characterized by X-ray diffraction, N2 physisorption, scanning electron microscopy, and transmission electron microscopy. Characterization indicates that the sample shows a hierarchically microporous, mesoporous, and macroporous structure, and has a large surface area. The nanosized β-Mo2C crystals are highly dispersed in the carbon-based sample. The β-Mo2C/C composite shows high catalytic activity in the hydrogenation of naphthalene to tetralin.

Simple and large-scale synthesis of β-phase molybdenum carbides as highly stable catalysts for dry reforming of methane

The catalytic stability of monometallic β-Mo₂C/CNTs was found to be superior to that of bimetallic Ni/β-Mo₂C under similar reaction conditions.

Simple synthesis of ultrasmall β-Mo2C and α-MoC1−x nanoparticles and new insights into their catalytic mechanisms for dry reforming of methane

Ultrasmall β- and α-molybdenum carbide particles were synthesized by a resin route and they showed different oxidation–recarburization cycles.

Modification of the carbide microstructure by N- and S-functionalization of the support in MoxC/CNT catalysts

Surface modification of a CNT support with S- or N-containing functionalities results in significant modification of the catalytic performance of supported molybdenum carbide in the steam reforming of methanol.

Nanoporous Cathodes for High-Energy Li-S Batteries from Gyroid Block Copolymer Templates

This study reports on a facile approach to the fabrication of nanoporous carbon cathodes for lithium sulfur batteries using gyroid carbon replicas based on use of polystyrene-poly-4-vinylpyridine (PS-P4VP) block copolymers as sacrificial templates. The free-standing gyroid carbon network with a highly ordered and interconnected porous structure has been fabricated by impregnating the carbon precursor solution into the gyroid block copolymer nanotemplates and subsequently carbonizing them. A wide range of analytical tools have been employed to characterize fabricated porous carbon material. Prepared nanostructures are envisioned to have a great potential in myriad areas such as energy storage/conversion devices owing to their fascinating morphology exhibiting high surface area and uniform porosity with interconnected three-dimensional networks. The resulting carbon nanoporous structures infused with elemental sulfur have been found to work as a promising electrode for lithium sulfur batteries demonstrating a high cycling stability over more than 200 cycles.

A novel approach to the synthesis of bulk and supported β-Mo2C using dimethyl ether as a carbon source

A pre-heating (PH) reduction route is more effective than a rapid heating (RH) reduction route for carbide synthesis.

A facile solvent-free route to synthesize ordered mesoporous carbons

A novel solvent-free route is developed to synthesize a series of highly ordered mesoporous carbons (OMCs) and functionalized OMCs from solid raw materials.

Synthesis of renewable diesel with the 2-methylfuran, butanal and acetone derived from lignocellulose

In this work, the hydroxyalkylation/alkylation of 2-methylfuran (2-MF) with acetone and butanal was investigated over a series of solid acid catalysts. Among the investigated candidates, Nafion-212 resin demonstrated the highest activity and stability for both reactions. Butanal is more reactive than acetone in hydroxyalkylation/alkylation, which can be rationalized by the steric and electronic effects of alkyl group. Finally, the hydroxyalkylation/alkylation products as prepared were directly hydrodeoxygenated over Pd/C, Pt/C and Ni-WxC/C catalysts. Evidently higher carbon yields to diesel were obtained when hydroxyalkylation/alkylation product of 2-MF with butanal was used as the feedstock. This can be considered as another advantage of 2-MF-butanal route. It is interesting that Ni-WxC/C catalyst exhibited excellent catalytic performance and good stability in the hydrodeoxygenation of hydroxyalkylation/alkylation products, which made it a promising substitute for the noble metal catalysts.

Ordered mesoporous phenolic resins: highly versatile and ultra stable support materials

Ordered mesoporous phenolic resins and carbons - an advanced class of ultra-stable mesoporous materials - offer potential applications in the field of catalysis, electrodes and adsorbents. This review gives an extensive overview of the main principles and the recent progress made in the synthesis of these innovative materials using the soft-template method. Furthermore, the versatility towards functionalization and the incorporation of hetero-atoms in the organic framework of the mesoporous resins and carbons are considered. Finally, the broad range of potential applications is discussed and future perspectives in the field of mesoporous polymers and carbons are given.

Carbon-supported molybdenum carbide catalysts for the conversion of vegetable oils

Ordered mesoporous carbon (OMC)-supported molybdenum carbide catalysts were successfully prepared in one pot using a solvent-evaporation-induced self-assembly strategy accompanied by a carbothermal hydrogen reduction reaction. Characterization with nitrogen sorption, small-angle XRD, and TEM confirmed that the obtained materials had high surface areas, large pore volumes, ordered mesoporous structures, narrow pore size distributions, and uniform dispersions of molybdenum carbide particles. With nitrogen replaced by hydrogen in the carbothermal reduction reaction, the formation temperature of molybdenum carbide could be reduced by more than 100 °C. By changing the amount of molybdenum precursor added from less than 2 % to more than 5 %, molybdenum carbide structures could be easily regulated from Mo(2) C to MoC. The catalytic performance of OMC-supported molybdenum carbide catalysts was evaluated by hydrodeoxygenation of vegetable oils. Compared with Mo(2)C, MoC exhibited high product selectivity and excellent resistance to leaching in the conversion of vegetable oils into diesel-like hydrocarbons.

Chitosan: a green carbon source for the synthesis of graphitic nanocarbon, tungsten carbide and graphitic nanocarbon/tungsten carbide composites

In this paper, a simple approach was proposed to fabricate graphitic carbon nanocapsules, tungsten carbide and tungsten carbides/graphitic carbon composites by using chitosan, a green and renewable biopolymer, as a carbon source. The route includes, first, fabrication of the precursors that consist of chitosan coordinated with a certain metal ion (or metal complex anion) followed by carbonizing the precursors under N(2) atmosphere. The composition of the final products could be regulated by changing the type and ratio of the metal source (cations or complex anions) combined with the chitosan in the precursors. The experimental results showed that uniform carbon nanocapsules could be obtained when Ni(2+) was introducing in the precursors, while incorporating [PW(12)O(40)](3-) (PW(12)) with chitosan led to the formation of WC nanoparticles. As the Ni(2+) and PW(12) are simultaneously coordinated with chitosan, the composites of tungsten carbide/graphitic carbon were successfully produced. Transmission electron microscopy (TEM) analysis revealed that the graphitic carbon nanocapsules are about 45 nm in diameter; uniform WC nanoparticles with a average size of 40 nm are observed. Moreover, the particle size of WC in the tungsten carbide/graphitic carbon composite is about 10 nm, which is smaller than that of the pure WC particles. Furthermore, the performance of the sample-loaded Pt nanoparticles for methanol electro-oxidation was studied in detail. The results indicated that the samples could act as good carriers for Pt in the methanol electro-oxidation reaction with high effectivity and improved stability.

Silica-templated synthesis of ordered mesoporous tungsten carbide/graphitic carbon composites with nanocrystalline walls and high surface areas via a temperature-programmed carburization route

Ordered mesostructured tungsten carbide and graphitic carbon composites (WC/C) with nanocrystalline walls are fabricated for the first time by a temperature-programmed carburization approach with phosphotungstic acid (PTA) as a precursor and mesoporous silica materials as hard templates. The mesostructure, crystal phase, and amount of deposited graphitic carbon can be conveniently tuned by controlling the silica template (SBA-15 or KIT-6), carburizing temperature (700-1000 degrees C), the PTA-loading amount, and the carburizing atmosphere (CH(4) or a CH(4)/H(2) mixture). A high level of deposited carbon is favorable for connecting and stabilizing the WC nanocrystallites to achieve high mesostructural regularity, as well as promoting the carburization reaction. Meanwhile, large pore sizes and high mesoporosity of the silica templates can promote WC-phase formation. These novel, ordered, mesoporous WC/C nanocomposites with high surface areas (74-169 m(2) g(-1)), large pore volumes (0.14-0.17 cm(3) g(-1)), narrow pore-size distributions (centered at about 3 nm), and very good oxidation resistance (up to 750 degrees C) have potential applications in fuel-cell catalysts and nanodevices.