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Synthesis and Characterization of Hexamethylenediammonium Thiometallates as Precursors of MoS2 and WS2 Catalysts: In situ Activation During HDS of DBT G. Alonso-Nu´n˜ez Æ R. Huirache-Acun˜a Æ F. Paraguay-Delgado Æ J. A. Lumbreras Æ R. Garcı´a-Alamilla Æ A. Castillo-Mares Æ R. Romero Æ R. Somanathan Æ R. R. Chianelli

Received: 27 January 2009 / Accepted: 13 March 2009 / Published online: 28 March 2009 Ó Springer Science+Business Media, LLC 2009

Abstract Hexamethylenediammonium thiometallate (HeDaT) of molybdenum and tungsten were synthesized using the aqueous solution method. This method improved significantly the yield of the catalysts. The HeDaT precursors were in situ activated during the hydrodesulfurization (HDS) of dibenzothiophene (DBT) generating MoS2 and WS2 catalysts. To characterize the precursors Fourier Transform Infra Red (FTIR), Ultraviolet (UV–Vis) and Nuclear Magnetic Resonance (1H NMR) spectroscopy techniques were used to determine their chemical structures. In addition, thermal analysis (TGA-DTA) were performed to study the fragmentation and decomposition behavior of their molecular structures. Catalysts were studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) which showed the shapes of the particles and the characteristic fringes of the layered MoS2 and WS2

phases, respectively. Specific surface areas were determined by the BET method with values of 5 and 19 m2/g with type I and IV adsorption–desorption nitrogen isotherms for both catalysts. The X-ray diffraction study showed poorly crystalline catalysts with weak (002) intensity for the MoS2 and a better-defined (002) reflection for the WS2.

G. Alonso-Nu´n˜ez (&) Universidad Nacional Auto´noma de Me´xico, Centro de Nanociencias y Nanotecnologı´a, C.P. 22800, Ensenada, BC, Mexico e-mail: [email protected]

R. Garcı´a-Alamilla
A. Castillo-Mares Instituto Tecnolo´gico de Ciudad Madero, C.P. 89440, Cd. Madero, Tamps., Mexico

R. Huirache-Acun˜a CFATA-UNAM, Boulevard Juriquilla 3001, C.P. 76230, Juriquilla Quere´taro, Mexico F. Paraguay-Delgado Centro de Investigacio´n en Materiales Avanzados S. C., C.P. 31109, Chihuahua, Mexico F. Paraguay-Delgado National Institute for Nanotechnology, 11421 Saskatchewan Drive, Edmonton, AB T6G 2M9, Canada J. A. Lumbreras Universidad del Istmo Campus Tehuantepec, C.P. 70760, Sto. Domingo Tehuantepec, Oaxaca, Mexico

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Keywords Aqueous solution
Hexamethylenediammonium thiometallates
In situ-activated
MoS2
WS2 catalysts

1 Introduction Thiometallates are widely used as biological systems [1–3] and also as catalyst precursors to produce transition metal

R. Romero Facultad de Ciencias Quı´micas, UABC, C.P. 22390, Tijuana, BC, Mexico R. Somanathan Centro de Graduados e Investigacio´n del ITT, C.P. 22000, Tijuana, BC, Mexico R. R. Chianelli MRTI, University of Texas at El Paso, El Paso, TX, USA

Synthesis and Characterization of Hexamethylenediammonium Thiometallates

sulfide catalysts [4–6]. Ammonium thiometallates (mainly thiomolybdates and thiotungstates) are wel