Stable molybdenum blue nanoparticles dispersions were synthesized using ammonium heptamolybdate and ascorbic acid. The effect of molar ratios of reducing agent/Mo and acid/Mo on the speed of formation and stability of the disperse system has been demonstrated. The particles were characterized by UV/vis, infrared (FTIR), nuclear magnetic resonance (NMR) spectroscopy, and dynamic light scattering (DLS) methods. The X-ray photoelectron spectroscopy (XPS) method confirmed the presence of reduced MoV in the structure of molybdenum oxide nanoclusters, the proportion of which was 30%.
In recent years, the development of methods for the synthesis of Mo2C for catalytic application has become especially important. In this work a series of Mo2C samples was synthesized by thermal decomposition of molybdenum blue xerogels obtained using ascorbic acid. The influence of the molar ratio reducing agent/Mo [R]/[Mo] on morphology, phase composition and characteristics of the porous structure of Mo2C has been established. The developed synthesis method allows the synthesis to be carried out in an inert atmosphere and does not require a carburization step. The resulting molybdenum carbide has a mesoporous structure with a narrow pore size distribution and a predominant pore size of 4 nm.
Molybdenum blue dispersions were synthesized by reducing an acidic molybdate solution with glucose, hydroquinone and ascorbic acid. The influence of the H/Mo molar ratio on the rate of formation of molybdenum particles was established. For each reducing agent, were determined the rate constant and the order of the particle formation and were established the conditions for the formation of aggregative stable dispersion with the maximum concentration of particles. The dispersed phase is represented by toroidal molybdenum oxide nanoclusters, which was confirmed by the results of UV/Vis, FTIR, XPS spectroscopy and DLS.
In recent years, much attention has been paid to the development of a new flexible and variable method for molybdenum carbide (Mo2C) synthesis. This work reports the applicability of nano-size clusters of molybdenum blue to molybdenum carbide production by thermal treatment of molybdenum blue xerogels in an inert atmosphere. The method developed made it possible to vary the type (glucose, hydroquinone) and content of the organic reducing agent (molar ratio R/Mo). The effect of these parameters on the phase composition and specific surface area of molybdenum carbides and their catalytic activity was investigated. TEM, UV–VIS spectroscopy, DTA, SEM, XRD, and nitrogen adsorption were performed to characterize nanoparticles and molybdenum carbide. The results showed that, depending on the synthesis conditions, variants of molybdenum carbide can be formed: α-Mo2C, η-MoC, or γ-MoC. The synthesized samples had a high specific surface area (7.1–203.0 m2/g) and meso- and microporosity. The samples also showed high catalytic activity during the dry reforming of methane. The proposed synthesis method is simple and variable and can be successfully used to obtain both Mo2C-based powder and supports catalysts.