Browsing by Author "Reinoso Venegas, Franco"

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    Estudio del efecto de la adición de Sn y Zn a catalizadores de Cu para síntesis de metanol.
    (Universidad de Concepción, 2024) Reinoso Venegas, Franco; Karelovic Burotto, Alejandro Iván
    The hydrogenation of CO2 to methanol is a promising alternative for the reuse of this greenhouse gas as feedstock in the synthesis process. However, the currently used Cu/ZnO/Al2O3 catalyst is not selective enough towards methanol due to the occurrence of the Reverse Water Gas Shift Reaction, which decreases the selectivity. Given the importance of this compound in the chemical industry, it is necessary to explore new materials to synthesize catalysts that are active and selective towards methanol formation through CO2 hydrogenation. With that said, the effect of adding low amounts of promoters was studied, specifically the addition of Zn and/or Sn to the Cu/SiO2 catalyst, where the copper content was kept constant at 10%wt and only the Zn and Sn content were modified. Thus, the molar fractions Zn(and/or Sn)/(Zn(and/or Sn)+Cu) used to study the effect of the low promoter content and compare it with the higher content were 0.01 and 0.2, respectively. Kinetic tests were carried out in a laboratory reactor, operating at 8 bar and at four different temperatures (280 °C,260°C, 240 °C, 220°C). Each sample was characterized by H2-TPR and XRD analysis. Zn was found to decrease the copper reduction temperature and no detectable crystalline phases were formed. For the Sn-containing catalysts, it was found that copper adsorbed much less H2, in addition to the formation of the Cu20Sn6 alloy. In kinetic tests, Zn was found to promote methanol synthesis, whereas Sn-containing catalysts were not active towards methanol. Catalysts with low Zn content achieved 10% higher conversion than the catalyst with higher Zn content, however, the selectivity towards methanol is clearly benefited with Zn loading. As for the Sn catalysts, it is suggested that the lack of methanol production is due to the formation of an alloy with copper or due to the chlorine present in the Sn precursor, which is possibly contaminating the active sites.
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