Thermal and reductive decomposition of ammonium thiomolybdates

Brito, Joaquı́n L.; Ilija, Marcel; Hernández, Petra H.

doi:10.1016/0040-6031(94)02178-q

Cited by 132 publications

(100 citation statements)

References 26 publications

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“…MoS 2 decorated with Ni. higher temperatures (300-500 °C) [35]. The formation of crystalline MoS 2 by a restacking of the sulfide at temperatures above 500 °C has been reported [36], thus explaining the formation of larger crystallites for NiMo/FCNF-600.…”

Section: Nimo Supported Catalysts Characterisationmentioning

confidence: 89%

Carbon nanofibres coated with Ni decorated MoS2 nanosheets as catalyst for vacuum residue hydroprocessing

Pinilla

Purón

Torres

et al. 2014

Applied Catalysis B: Environmental

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Catalysts based on functionalised carbon nanofibers (FCNF) coated with Ni-decorated MoS 2 nanosheets were obtained by direct decomposition of ammonium thiomolybdate and nickel nitrate impregnated on the FCNF under controlled temperature conditions in inert atmosphere. The catalysts were characterised by X-ray Diffraction (XRD), N 2 adsorption, Raman spectroscopy, temperature programmed reduction of sulfur species (TPR-S), NH 3 temperature programmed desorption (NH 3 -TPD) and transmission electron microscopy (TEM). Decomposition temperature was found to have a paramount importance in the formation of uniform MoS 2 slabs, as revealed by the TEM study: at 600 °C, non-uniform covering of the carbon nanofiber (CNF) was observed Higher asphaltene conversions were obtained for the CNF-supported catalysts prepared at 450 °C, which overperformed the Al 2 O 3 -supported benchmark catalyst. However, the catalytic performance in hydrodesulfurisation and hydrodemetallisation of the CNFbased catalysts was slightly lower than that of the benchmark catalyst.

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Section: Nimo Supported Catalysts Characterisationmentioning

confidence: 89%

Carbon nanofibres coated with Ni decorated MoS2 nanosheets as catalyst for vacuum residue hydroprocessing

Pinilla

Purón

Torres

et al. 2014

Applied Catalysis B: Environmental

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“…The thermal behaviour of different tetraalkylammonium thiotungstates was investigated previously in detail [7,9,10,15,16,39,[46][47][48], but in case of the ATT only some studies can be found [5,49,50]. In 1970 Voorhoeve et al [49] investigated the decomposition of ATT in vacuum and H 2 flow by X-ray diffraction (XRD), differential thermal analysis (DTA), optical microscopy and electron spin resonance (ESR).…”

Section: Ws 2 Catalysts Are Promoted Mostly With Cobalt or Nickel Andmentioning

confidence: 99%

Thermal decomposition of ammonium tetrathiotungstate

Hunyadi

Ramos

Szilágyi

2015

J Therm Anal Calorim

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The thermal decomposition of ammonium tetrathiotungstate (ATT), (NH 4 ) 2 WS 4 was studied by SEM, FTIR, XRD, EDX and TG/DTA-MS. The decomposition of ATT involved three steps in inert atmosphere: (i) release of free water between 30-140 °C; (ii) formation of an amorphous WS 3 phase between 170-280 °C, from which (iii) a slightly crystalline WS 2 formed between 330-470 °C. As a difference compared to inert atmosphere, in air in the second step the ATT decomposed into directly WS 2 instead of WS 3 . This WS 2 phase was amorphous, and still contained traces of ATT. Between 260-2 500 °C from the WS 2 monoclinic tungsten oxide crystallized in two steps: at 302 °C a slightly crystalline m-WO 3 formed, which became more crystalline at 471 °C. During the investigation of the effect of the particle size, it was found that the thermal behaviour of ATT crystals was similar to ATT powder, with some shift in the decomposition temperature. The XRD results showed that the WS 2 formed from the ATT powder in N 2 had a higher level of crystallization, compared to the WS 2 obtained from ATT crystals.

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“…Three thiomolybdate complexes of formulas (NH4)zMoS4, (NH4)2M02S12 and (NH4)2M03S13 (monomer, dimer and trimer, respectively) were studied by TG/DTG in both inert and H2 atmospheres and by TPR [12]. The TPR traces were characteristic for each compound and were interpreted, along with the gravimetric data, in terms of the differences in structure between the three crystalline compounds.…”

Section: Resultsmentioning

confidence: 99%

“…Supported oxidic catalysts were prepared, by impregnation of commercial silica gel (Merck) or alumina (Filtrol) with solutions of AHM and NN or CN, followed by drying and calcination [4,5]. Sulfiding was accomplished by heating the samples to 400~ under inert atmosphere before flowing pure H2S for 1 h. The thiomolybdate complexes were synthesized by established methods [6] and employed either pure or impregnated from N,N-dimethyl formamide solutions onto alumina or activated carbon (Merck).…”

Section: Methodsmentioning

confidence: 99%

Thermoanalytical characterization of molybdenum-based catalytic materials

Brito

1997

Journal of Thermal Analysis

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Thermoanalyticai techniques, especially temperature-programmed reduction (TPR), were employed for the characterization of oxidic precursors of molybdenum-based catalysts, sulfides derived from them, and three thiomolybdate compounds, employed as models or precursors of hydrodesulfurization atalysts. Correlations were found between TPR data and the presence of single and mixed oxides of Mo and Ni, Co or Fe, as demonstrated by XRD. The same phases and the thiomolybdates were shown to be present in supported catalytic precursors. Differences between the reducibilities of the mixed oxides of Ni-Mo, Co-Mo and Fe-Mo are easily appreciated from TPR, including those of the ct-and 13-polymorphic modifications of NiMoO 4.

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Thermal and reductive decomposition of ammonium thiomolybdates

Cited by 132 publications

References 26 publications

Carbon nanofibres coated with Ni decorated MoS2 nanosheets as catalyst for vacuum residue hydroprocessing

Carbon nanofibres coated with Ni decorated MoS2 nanosheets as catalyst for vacuum residue hydroprocessing

Thermal decomposition of ammonium tetrathiotungstate

Thermoanalytical characterization of molybdenum-based catalytic materials

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