Showing papers on "Ammonium tetrathiomolybdate published in 2010"

Preparation method of nanoscale flaky molybdenum disulfide

Abstract: The invention discloses a preparation method of nanoscale flaky molybdenum disulfide, which is characterized by comprising the following steps: ammonium tetrathiomolybdate (ATTM) is used as a molybdenum source and a sulfur source, and oxalic acid is used as a reducing agent; the ATTM and the oxalic acid are added in aqueous solution under the condition of heating and stirring, and then amorphous molybdenum disulfide is obtained by a chemical precipitation process; and then the amorphous molybdenum disulfide is placed into a tube furnace on a quartz boat for heating at a high temperature in a nitrogen atmosphere to obtain the nanoscale flaky molybdenum disulfide. The invention adopts the chemical precipitation process and a high-temperature heating method to prepare the nanoscale flaky molybdenum disulfide which is expected to be produced in a large scale; and the preparation method has available raw materials, low cost and simple process.

Unsupported Ni/Mo(W)S2 Catalysts from Hexamethylenediammonium Thiometallates Precursors: In Situ Activation During the HDS of DBT

Abstract: Unsupported Ni/MoS2 and Ni/WS2 HDS cata- lysts were prepared by in situ activation of hexamethyl- enediammonium thiometallates promoted with Ni. The method involved an aqueous solution reaction of ammo- nium thiomolybdate (ATM) or ammonium thiotungstate (ATT) with Ni(NO3)2� 6H2O and hexamethylenediamine. Ni-promoted precursors were then in situ activated during the hydrodesulfurization (HDS) of dibenzothiophene (DBT) producing Ni/MoS2 and Ni/WS2 catalysts. Solids were analyzed after the in situ activation by scanning electron microscopy, transmission electron microscopy, X- ray diffraction, and for textural properties by using the BET and BJH methods. Catalysts with relatively high surface area and type IV N2 adsorption-desorption isotherms were obtained. The use of the hexamethylene- diammonium precursor led to a significant nickel promo- tion of MoS2 and WS2 catalysts. For Ni/MoS2, the use of this carbon-containing precursor was found to be more beneficial for the final HDS catalytic activity than using the classical ammonium tetrathiomolybdate (ATM) without carbon. For Ni/WS2, compared to tetraalkylammonium thiosalts, the lower amount of carbon in excess formed during the decomposition of the hexamethylenediammo- nium precursor coupled with a lower crystallization rate of WS2 favors a correct nickel accommodation on the WS2 edges.