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Ammonium heptamolybdate
About: Ammonium heptamolybdate is a research topic. Over the lifetime, 553 publications have been published within this topic receiving 11058 citations. The topic is also known as: Ammonium heptamolybdate.
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TL;DR: In this article, a 2 wt% Mo/ZSM-5 catalyst was used for the dehydroaromatization of methane to benzene in the absence of an added oxidant.
448 citations
TL;DR: One-dimensional nanostructures of orthorhombic molybdenum trioxide (α-MoO3) have been synthesized in the forms of ribbons or rods via acidification under hydrothermal conditions at 140−200 °C as mentioned in this paper.
Abstract: One-dimensional nanostructures of orthorhombic molybdenum trioxide (α-MoO3) have been synthesized in the forms of ribbons or rods via acidification under hydrothermal conditions at 140−200 °C The reaction path has been revealed with our kinetic investigations, which shows the following sequence: (i) from the starting compound (NH4)6Mo7O24·4H2O to (ii) formation of intermediate compound ((NH4)2O)00866·MoO3·0231H2O, and then to (iii) final α-MoO3 nanoribbons or nanorods in 100% phase purity The optimal growth temperature is in the range of 170−180 °C under the current experimental settings At higher reaction temperatures, this transformation can be accelerated, but with poorer crystal morphological homogeneity It has been found that the dimensions of these rectangular nanorods are about 50 nm in thickness, 150−300 nm (mean value at 200 nm) in width, and a few tens of micrometers in length The crystal morphology can be further altered with inorganic salts such as NaNO3, KNO3, Mg(NO3)2, and Al(NO3)3
344 citations
TL;DR: In this article, the supercapacitive behavior of MoS2 nanostructures prepared by a facile one-pot hydrothermal approach using ammonium heptamolybdate and thiourea as starting materials is investigated.
224 citations
TL;DR: In this paper, the XPS binding energy (BE) values of all the metals in the mixed oxide supports as well as Mo-containing catalysts are found to shift from the values of individual metal component oxides.
Abstract: X-ray photoelectron spectroscopy technique was employed to characterize TiO 2 –ZrO 2 , TiO 2 –SiO 2 , TiO 2 –Al 2 O 3 , SiO 2 –ZrO 2 , and SiO 2 –TiO 2 –ZrO 2 mixed oxide supported MoO 3 catalysts. The investigated mixed oxide supports are obtained by a homogeneous coprecipitation method using urea as hydrolyzing agent. Molybdena (12 wt.%) was impregnated over these calcined (773 K) mixed oxide supports by a wet impregnation method from aqueous ammonium heptamolybdate solution. The XPS binding energy (BE) values of all the metals in the mixed oxide supports as well as Mo-containing catalysts are found to shift from the values of the individual metal component oxides. The shift in BE suggests that the Zr in TiO 2 –ZrO 2 and Ti in TiO 2 –Al 2 O 3 acquire more negative charge after doping with MoO 3 on these supports. The observed BE shifts, due to variation in the lattice potential, are explained in terms of Kung’s model. The XPS atomic intensity ratio measurements show that the interaction between Mo and Al is strong and the dispersion of molybdena is more on Al 2 O 3 portion of the TiO 2 –Al 2 O 3 mixed oxide. In the case of MoO 3 /TiO 2 –ZrO 2 and MoO 3 /SiO 2 –TiO 2 –ZrO 2 samples, the Mo:Ti and Mo:Zr ratios show that the Ti 4+ and Zr 4+ both contribute equally in the dispersion of molybdenum on these corresponding mixed oxides. The FWHM values indicate the presence of different Mo(VI) species on TiO 2 –Al 2 O 3 , and a homogeneous distribution on TiO 2 –ZrO 2 and TiO 2 –SiO 2 mixed oxide surfaces.
220 citations
TL;DR: The results demonstrated that the efficiency of visible light assisted MB degradation using h-MoO3 NCs can be effectively enhanced by catalyst loading, light intensity, and operating temperature, however, the efficiency declined with the increase in initial dye concentration.
Abstract: A detailed study on visible light photocatalytic degradation of methylene blue (MB) has been investigated in aqueous heterogeneous media containing hexagonal phase molybdenum oxide (h-MoO3) nanocrystals (NCs) which was identified as a new material for visible light driven photocatalysis. A simple and template-free solution based chemical precipitation method was employed to synthesize h-MoO3 NCs by reacting ammonium heptamolybdate tetrahydrate (AHM) with nitric acid. The formation and growth mechanism of h-MoO3 microstructures was explained. In addition, by annealing the h-MoO3 sample, the phase stability of hexagonal was retained up to 410 °C and showed an irreversible phase transition from hexagonal (h-MoO3) to highly stable orthorhombic phase (α-MoO3). Finally, the photocatalytic activities of h-MoO3 and α-MoO3 samples were evaluated using the degradation of MB, representing an organic pollutant of dye wastewater. The effects of various experimental parameters such as catalyst loading, initial dye concentration, light intensity, and operating temperature were analyzed for the degradation of MB. The results demonstrated that the efficiency of visible light assisted MB degradation using h-MoO3 NCs can be effectively enhanced by catalyst loading, light intensity, and operating temperature. However, the efficiency declined with the increase in initial dye concentration. Optimum conditions for higher photocatalytic performance were recognized as a catalyst loading of 100 mg L−1, a dye concentration of 12 mg L−1, a light intensity of 350 mW cm−2, and an operating temperature of 45 °C.
191 citations