Wyniki wyszukiwania - Biblioteka Nauki

Nowa wersja platformy, zawierająca wyłącznie zasoby pełnotekstowe, jest już dostępna.
Przejdź na https://bibliotekanauki.pl

Ograniczanie wyników

Znaleziono wyników: 3

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: molybdenum carbide

Sortuj według:

Ogranicz wyniki do:

Hydroconversion of cetane fraction over molybdenum catalysts.

100%

Walendziewski J. , Pniak B. , Sayag C. , Grzechowiak J.

tom Vol. 10, nr 57

355-360

Carbonization with methane-H2 mixturure and/or hydrogen reduction of 32% MoO3/Al2O3 catalysts gives low activity isomerization catalysts of moderate selectivity, by far lower than it was found for non-supported catalysts described in literature. The main products of isomerization process in the presence of carbonized and reduced catalysts molybdenum catalysts are mono-branched isomers. The hypothetical reason of considerably lower activity of alumina supported molybdenum catalysts in isomerization reaction in comparison to the non-supported ones is reaction of molybdenum compounds with alumina and therefore lower susceptibility of molybdenum for carbonization.

Synthesis and characterization of nanostructured molybdenum & tungsten carbide materials, and study of diffusion model

88%

Covington L. , Munirathinam K. , Islam A. , Roberts K.

Polish Journal of Chemical Technology

2012

tom 14

nr 1

28-34

Powders of two molybdenum carbides (Mo2C and MoC1-x) and tungsten carbide (WC) were prepared by means of temperature programmed reaction (TPR) method. Mo2C and MoC1-x were synthesized by reacting MoO3 with a preselected molar ratio of methane/hydrogen and carbon monoxide/hydrogen gas mixtures respectively. WC was prepared using tungsten oxide (WO3) and a methane/hydrogen gas mixture. These carbides were ultrasonically dispersed in de-ionized water. Samples were characterized using room temperature x-ray diffraction and scanning microscopy. A kinetic diffusion model is also studied to determine diffusivities in solids where the diffusing species desorbs or reacts at the external surfaces, and where the diffusivity does not vary appreciably with concentrations. The method involves measuring the flux of the diffusive species into the solid under the influence of a temperature program.

Analiza procesu syntezy Mo2C w układzie (NH4)6Mo7O24ź4H2O-węgiel aktywny

75%

Sabara M. , Biedunkiewicz A.

tom Vol. 32, nr 4

699-702

Przedstawiono analizę syntezy węglika molibdenu (Mo2C) przy różnych parametrach wyjściowych procesu. Na podstawie diagramów równowagi fazowej układu MoO3-C ustalano skład początkowy próbek. Metodą zol-żel (Stobera) otrzymano próbki do karbotermicznej redukcji. Jako prekursory stosowano (NH4)5Mo7O24ź4H2O i węgiel aktywny. Karbotermiczną redukcję prowadzono w argonie w 1000 i 1250°C w piecu i w aparacie TG. Skład fazowy próbek określono metodą XRD. Na podstawie pomiarów termograwimetrycznych, podczas których identyfikowano także produkty gazowe metodą spektrometrii masowej, przeanalizowano kinetykę procesu.

Analysis of the synthesis of molybdenum carbide (Mo2C) at various initial parameters of the process had been presented. Basing on phase equilibrium diagrams of MoO3-C the composition of initial samples has been determined. Samples to carbothermal reduction was obtained by sol-gel method (Stober). (NH4)5Mo7O24ź4H2O and active carbon were used as precursors. Carbothermal reduction was carried in argon at 1000 and 1250°C in the furnace and in the TG apparatus. Phase composition of samples was determined by XRD method. Basing on thermogravimetric measurements combined with mass spectrometry was determined kinetics of process.