Browsing by Author "Siriporn, Jongpatiwut"

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    Catalytic oxidation of sulfur compounds over Ce-SBA-15 and Ce-Zr-SBA-15
    (2021) Rivoira, Lorena Paola; Vallés, Verónica Alejandra; Martínez, María Laura; Yanika, Sa-ngasaeng; Siriporn, Jongpatiwut
    The catalytic oXidation of different sulfur compounds, commonly present in liquid fuel, was studied over a series of ceria and ceria-zirconium based oXidation mesoporous catalysts. SBA-15 was synthesized using sol-gel method and Ce and Ce-Zr were added by two different procedures: i) directly during the synthesis and ii) via post- synthesis method. The catalysts were characterized by XRD, N2 adsorption isotherms, XPS, DRUV-Vis, TEM, SEM and Py-FTIR. Low angle XRD, N2 isotherms and TEM confirmed that the structure was not changed after metal incorporation. Wide angle XRD, UV–vis-DRS, XPS and TEM determined that the catalysts prepared by direct synthesis presented higher dispersion of Ce oXides, smaller particle size and isolated Zr4+ species. FTIR of adsorbed/desorbed pyridine indicated that zirconium as promoter increases the Lewis acidity of the catalysts, especially during direct synthesis. Ce-Zr-SBA-15 catalyst prepared by direct synthesis was very active in the oXidation of dibenzothiophene, 4,6-dimethyl dibenzothiophene and benzothiophene using hydrogen peroXide (H2O2) as oXidant agent and acetonitrile as polar solvent. The effect of acidity in the catalyst, hydrogen peroXide concentration and temperature was studied. The deactivation test demonstrated that the catalyst is stable and adequate for the industrial process.
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    HDT of the model diesel feed over Ir-modified Zr-SBA-15 catalysts
    (2018) Vallés, Verónica Alejandra; Yanika, Sa-ngasaeng; Martínez, María Laura; Siriporn, Jongpatiwut; Beltramone, Andrea Raquel
    Iridium catalyst using different zirconium modified-SBA-15 supports were tested in the HDT of tetralin and typical sulfur and nitrogen compounds present in diesel feed. The zirconium modified-SBA-15 supports were synthesized by sol-gel method using two sources of zirconium, zirconyl chloride and zirconium (IV) propoXide. Regarding XRD, N2 adsorption isotherms and TEM, we obtained better textural and structural properties using the alkoXide, especially when lactic acid was added in order to decrease the hydrolysis rate of zirconium propoXide. In addition, XPS and DRUV-Vis demonstrated that zirconium was incorporated mainly as tetrahedral Zr4+ species NH3-TPD showed that higher acidity is observed when tetrahedral Zr4+ species are present. Iridium dispersion was determined by TEM and H2-chemisorption and reducibility by XPS and TPR. Among the catalysts prepared, the catalyst synthesized using zirconium propoXide and lactic acid presented the highest dispersion, lowest cluster size and lowest reduction temperature. Consequently, this was the most active catalyst for the hydrogenation of tetralin, the HDN of indole and quinoline and the HDS of dibenzothiophene (DBT) and 4,6- dimethyldibenzothiophene (4,6-DMDBT). The presence of Zr+4 had a remarkable effect on the dispersion and reducibility capacity of the iridium actives species. In addition, the presence of moderate acidity in this material gives the best catalyst for HDN and HDS in the studied conditions. The inhibition effect of the sulfur and nitrogen compounds over tetralin hydrogenation was studied using individual feeds and a miXture feed. We observe that 4,6-DMDBT and quinoline were the most refractory compounds and they showed the highest inhibition effect. Tetralin hydrogenation was stronger inhibited when using the miXture feed compared with the individual feeds. This can be explained in terms of the competition between the different compounds that retard the rate of hydrogenation of tetralin. However, a high conversion of tetralin was achieved even when 300 ppm of S or N was