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

Abstract

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.