Infrared reflection specrometry of minerals and gemstones

International audienc

The use of a natural Mexican zeolite as support of NiMoW sulphide hydrotreating catalysts

In order to examine the influence of type of metal precursor on the hydrodesulfurization (HDS) activity of synthetized samples, a series of ternary Ni–Mo–W catalysts supported on a natural Mexican zeolite (clinoptilolite) were prepared by sequential wet impregnation of the zeolite support with different thiosalts of W and Mo, and Ni(NO3)2·6H2O. The synthetized samples were characterized by N2 adsorption–desorption isotherms at −196 °C, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX/SEM), high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) techniques. The catalysts activity was evaluated in the HDS of dibenzothiophene (DBT) reaction performed in a batch reactor at 350 °C and 3.1 MPa of total hydrogen pressure. The activity tests demonstrated that the best catalyst was the NiMoW-H/zeo sample synthesized from ammonium thiosalts. The use of tetraalkylammonium thiometalates as metal precursors led to the decrease in the HDS activity. The most active catalyst in the HDS of DBT reaction showed the largest density of active phases on the support surface determined from HRTEM measurements.Dr. R. Huirache-Acuña wants to thank the support of CONACYT CIENCIA BASICA 182191 and CIC-UMSNH 2012-2013 Projects (Mexico) and the valuable assistance of Dr. Eric M. Rivera Muñoz (CFATAUNAM) and financial support of Project DGAPA – UNAM PAPIIT IN107311–3. The authors are grateful to Prof. J.L.G. Fierro (ICP-CSIC, Spain) for stimulating discussion and providing laboratory facilities for the catalyst characterization. This study was partially supported by The Spanish Ministry of Science and Innovation (ENE2010-21198-C04-01) and The Community of Madrid (S2009ENE-1743 project) with financial aid from the Scientific Cooperation FONCICYT Program (FONCICYT-96194 project).Peer Reviewe

Synthesis and characterization of composites NiMo sulfides supported in clinoptilolite ion treated and its application as catalysts in hydrodesulfurization

Trabajo presentado en el XXIV International Materials Research Congress, celebrado en Cancún (México) del 16 al 20 de agosto de 2015.A series of Ni-Mo/Clinoptilolite catalysts for hydrodesulfurization (HDS) of 3-methylthiophene (3MT) were prepared by simultaneous impregnation of HNO3-modified natural zeolite Clinoptilolite with Ni and Mo salts precursors. Before impregnation, the natural Clinoptilolite (from Mexico) was modified by treatment with HNO3 during 24 and 48 h. The catalyst behavior was evaluated in HDS of 3MT carried out in a flow reactor at T=280 ºC and atmospheric H2 pressure. The calcined and fresh sulfided catalysts were characterized by a variety of techniques (SEM, N2 adsorption-desorption isotherms, XRD, TPR, TPD-NH3, DRS UV-Vis EDX/HRTEM and XPS). It was found that zeolite leading during 48 h led to poorer support quality than its leaching during shorter time (24 h). As a consequence the catalysts supported on this substrate were less active in 3MT HDS reaction. This is because the long time leaching (48 h) led to formation of micropores in which reactant molecules can¿t to entry and the loss of support crystallinity. The best catalyst found in this study was the one loaded with a largest Mo wt.% and supported on HNO3-treated zeolite during 24 h. The decrease in catalytic activity observed for the latter catalysts was due to the structural change from amorphous to crystalline and the sintering followed by the decrease of surface area.Peer Reviewe

Structural properties of phosphate-washing waste based geopolymeric mortars

The phosphate ore extraction activities often generate serious environmental problems, particularly those engendered by the phosphate washing waste. The waste was characterized by X ray fluorescence. The powder was calcined at 700 °C. The calcined and uncalcined samples were then investigated by means of X-ray powder diffraction (XRD). The calcined PWW was activated with sodium hydroxide and sodium silicate to produce geopolymeric materials. The reached results prove to reveal that the present phases in the powder appeared to have a remarkable effect on the result of compressive strength