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

Recent Progress on Phase Engineering of Nanomaterials

As a key structural parameter, phase depicts the arrangement of atoms in materials. Normally, a nanomaterial exists in its thermodynamically stable crystal phase. With the development of nanotechnology, nanomaterials with unconventional crystal phases, which rarely exist in their bulk counterparts, or amorphous phase have been prepared using carefully controlled reaction conditions. Together these methods are beginning to enable phase engineering of nanomaterials (PEN), i.e., the synthesis of nanomaterials with unconventional phases and the transformation between different phases, to obtain desired properties and functions. This Review summarizes the research progress in the field of PEN. First, we present representative strategies for the direct synthesis of unconventional phases and modulation of phase transformation in diverse kinds of nanomaterials. We cover the synthesis of nanomaterials ranging from metal nanostructures such as Au, Ag, Cu, Pd, and Ru, and their alloys; metal oxides, borides, and carbides; to transition metal dichalcogenides (TMDs) and 2D layered materials. We review synthesis and growth methods ranging from wet-chemical reduction and seed-mediated epitaxial growth to chemical vapor deposition (CVD), high pressure phase transformation, and electron and ion-beam irradiation. After that, we summarize the significant influence of phase on the various properties of unconventional-phase nanomaterials. We also discuss the potential applications of the developed unconventional-phase nanomaterials in different areas including catalysis, electrochemical energy storage (batteries and supercapacitors), solar cells, optoelectronics, and sensing. Finally, we discuss existing challenges and future research directions in PEN.

Selective hydrogen production from formic acid decomposition over Mo carbides supported on carbon materials

The support influenced the carbide phase obtained so that a higher ratio of defective carbon favoured the formation of β-Mo₂C phase vs. MoO_xC_y. Redox transformations during the reaction might be responsible of the transformation of β-Mo₂C into MoO_xC_y.

Molybdenum carbide as an efficient and durable catalyst for aqueous Knoevenagel condensation

Molybdenum carbide showed an efficient performance for the Knoevenagel condensation in aqueous media at room temperature, affording the corresponding products in high yields within a short reaction time.

Acetic Acid/Propionic Acid Conversion on Metal Doped Molybdenum Carbide Catalyst Beads for Catalytic Hot Gas Filtration

Catalytic hot gas filtration (CHGF) is used to precondition biomass derived fast pyrolysis (FP) vapors by physically removing reactive char and alkali particulates and chemically converting reactive oxygenates to species that are more easily upgraded during subsequent catalytic fast pyrolysis (CFP). Carboxylic acids, such as acetic acid and propionic acid, form during biomass fast pyrolysis and are recalcitrant to downstream catalytic vapor upgrading. This work developed and evaluated catalysts that can convert these acids to more upgradeable ketones at the laboratory scale. Selective catalytic conversion of these reactive oxygenates to more easily upgraded compounds can enhance bio-refinery processing economics through catalyst preservation by reduced coking from acid cracking, by preserving carbon efficiency, and through process intensification by coupling particulate removal with partial upgrading. Two metal-doped molybdenum carbide (Mo2C) supported catalyst beads were synthesized and evaluated and their performance compared with an undoped Mo2C control catalyst beads. For laboratory scale acetic acid conversion, calcium doped Mo2C supported catalyst beads produced the highest yield of acetone at ~96% at 450 °C among undoped and Ca or Ni doped catalysts.

Effects of graphitization of carbon nanospheres on hydrodeoxygenation activity of molybdenum carbide

The hydrodeoxygenation catalytic activity and stability of carbon supported molybdenum carbide catalysts could be improved by graphitizing their carbon supports.

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.

Synthesis of mesoporous WO3/TiO2 catalyst and its excellent catalytic performance for the oxidation of dibenzothiophene

DBT could be completely oxidized to DBT sulfone (DBTO₂) with the help of WO₃/TiO₂ catalyst and H₂O₂.

Catalytic hydrodeoxygenation of palmitic acid over a bifunctional Co-doped MoO2/CNTs catalyst: an insight into the promoting effect of cobalt

HDO of palmitic acid into C₁₆ hydrocarbons was successfully achieved over Co doped MoO₂/CNTs catalysts at a much lower temperature. Co could promote the formation of Lewis acidic sites, oxygen vacancies and Mo₂C particles, which are all decisive factors for better catalytic activity.

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.

Catalytic deoxygenation on transition metal carbide catalysts

We highlight the evolution and tunability of catalytic function of transition metal carbides under oxidative and reductive environments for selective deoxygenation reactions.

Exploration of the electrochemical mechanism of ultrasmall multiple phases molybdenum carbides nanocrystals for hydrogen evolution reaction

Ultrasmall multiple phases molybdenum carbides nanocrystals (down to 2.5 nm) on graphene support were synthesized by a simplein situmethod. These hybrids show extraordinary high HER activity in acid media.

Highly dispersed molybdenum carbide nanoparticles supported on activated carbon as an efficient catalyst for the hydrodeoxygenation of vanillin

Characterized by XRD and TEM, highly dispersed molybdenum carbide (Mo₂C) nanoparticles with a diameter of 1–4 nm were effectively synthesized on activated carbon at 700 °C.

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.

Selective hydrodeoxygenation of biomass-derived oxygenates to unsaturated hydrocarbons using molybdenum carbide catalysts

Which cleavage do you prefer? With a combination of density functional theory (DFT) calculations, surface science studies, and reactor evaluations, Mo(2)C is identified as a highly selective HDO catalyst to selectively convert biomass-derived oxygenates to unsaturated hydrocarbons through selective C-O bond scissions without C-C bond cleavage. This provides high-value HDO products for utilization as feedstocks for chemicals and fuels; this also reduces the overall consumption of H2 .