Adsorptive desulfurization of fuels using ZSM-35 impregnated with molybdenum. Doctoral Thesis, UFRN, Posgraduate Program in Chemical Engineering, Natal –RN.
adsorptive desulfurization, adsorption kinetics, molybdenum, ZSM-35.
The search for cleaner technologies for the removal of sulfur compounds in fuels is a constant, since the commercial desulphurization process currently used is characterized by high hydrogen consumption and severe temperature and pressure operating conditions, in addition to not meeting the future demands of environmental legislation. In this work it was evaluated the use of zeolite ZSM-35 modified with molybdenum in different concentrations (2.5%, 5%, 10% w / w) applied in an adsorptive desulfurization process at low temperature and pressure. The materials were prepared by wet impregnation and characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), thermal analysis (TG / DTG) and scanning electron microscopy (SEM). The adsorptive desulfurization was carried out in a batch system at temperatures ranging from 30 ° C to 50 ° C under a stirring speed of 140 rpm using a model fuel containing 800 ppm of sulfur. The sulfur contained in the samples was quantified according to the ASTM D5443 standard. The adsorption kinetics was evaluated by the kinetic models of pseudo-first order, pseudo-second order, intraparticle diffusion and Elovich. The results showed that the adsorbents obtained had their structures little affected by the metallic impregnation process and that the thermal stability of the adsorbents was affected by the concentration of molybdenum in the structure, with the lowest mass loss observed being 10.1% (sample 2,5MZ35). In the adsorption desulfurization process for the evaluated systems, the yield varied from 10.03% (2.5% Mo at 30 ° C) to 21.41% (10% Mo at 50 ° C) and that the capacity of adsorption was influenced by temperature and metal concentration in the zeolitic structure. The adsorption experimental data, in general, they were better adjusted to the pseudo-second order kinetic model. The adsorbents obtained showed a good potential for application in desulphurization processes of fuels by adsorption.