Estudio de catalizadores basados en compuestos de Ni para la hidrogenación de Co2.
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Date
2025
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Universidad de Concepción
Abstract
En la actualidad, la crisis climática y el calentamiento global, provocados por las emisiones de gases de efecto invernadero (GEI), son una de las principales problemáticas a las que se enfrenta la humanidad. Aproximadamente el 78 % de estas emisiones corresponden a CO 2 captura y utilización de CO 2 . De esta manera, la procedente del aire ambiente ha suscitado un interés creciente. Entre las alternativas más prometedoras destaca la hidrogenación de CO 2 a metanol, para la cual se han estudiado diversos metales (como Cu, Pt y Pd) en combinación con promotores (Ga, Mg, In y La) a nivel de laboratorio. En comparación con los catalizadores de metales nobles, el uso de Ni con promotores dispersos sobre el soporte para la reacción de hidrogenación se considera una de las formas más eficientes debido a su amplia disponibilidad y bajo coste.
Este trabajo estudió el efecto de la adición de Sn en la hidrogenación de CO 2 alterando sólo el porcentaje másico de Sn desde cero hasta 3.4 mediante el método de reducción química húmeda sobre: (i) catalizadores Ni/SiO 2 ; (ii) catalizadores Ni/ZrO 2-monoclínica (m); (iii) catalizadores Ni/ZrO tetragonal (t). Además, se discutió la sinergia bimetálica Ni-Sn y se comparó con la limitada literatura existente sobre este tipo de catalizadores.
La caracterización de los catalizadores tras la adición de Sn se realizó mediante análisis de difracción de rayos X, microscopía por transmisión de electrones de alta resolución, microscopía electrónica de barrido de emisión de campo con espectroscopía de dispersión de energía: catalizadores Ni/SiO 2 Ni/ZrO 2-m y Ni/ZrO 2 , -t presentan partículas de Ni bien dispersas y se forman aleaciones Ni-Sn que estabilizan la presencia metálica de Sn a condiciones ambiente. Por su parte, la cinética se estudió a 8 bar desde 220ºC a 280ºC en un reactor de lecho empacado diferencial.
Adiciones de Sn de 1.7 wt.% y 3.4 wt.%sobre catalizadores Ni/SiO 2 promueven la rWGS. Sin embargo, existe una disminución en la velocidad de formación de CO con respecto al catalizador base, que se atribuye a la disminución de sitios activos por la formación de compuestos intermetálicos Ni Sn. Por otro lado, adiciones de Sn de 1.7 wt.% y 3.4 wt.% sobre catalizadores Ni/ZrO 2 un probable cambio en el mecanismo de reacción inhibiendo la formación de CH 4-m inducirían y promoviendo la rWGS. Además, con la adición de Sn se indujo la formación de metanol con una selectividad máxima de ca. 5.0 %, una tasa de formación de ca. 0.014 mol·g-1·s-1 y una energía aparente de activación de ca. 33 kJ-1 mol.
Currently, the climate crisis and global warming, due to greenhouse gas (GHG) emissions, are among the main problems facing humanity. Approximately 78% of these emissions accounted for by Among the most promising alternatives is the hydrogenation of C02. As a result, the capture and utilization of C02 from the ambient air has attracted growing interest. C02 on the support for C02 hydrogenation to methanol, for which various metals (such as Cu, Pt, and Pd) in combination with promoters (Ga, Mg, In, and La) have been studied at the laboratory setting. Compared to noble metal catalysts, the use of Ni with promoters dispersed represents one of the most efficient methods due to its wide availability and low cost. This work studied the effect of adding Sn in the hydrogenation of C02 by altering only the mass percentage of Sn from zero to 3.4 using the wet chemical reduction method on (i) Si02 catalysts; (ii) Zr02 catalysts; (iii) Ni/ Ni/monoclinic (m)-tetragonal (t) Zr02 catalysts. In addition, the Ni -Sn bimetallic synergy was discussed, and the limited existing literature on this type of catalyst was compared. The characterization of the catalysts after the addition of Sn was performed by X-ray diffraction analysis, high-resolution transmission electron microscopy, and field emission scanning electron -m, microscopy with energy dispersive spectroscopy: Ni/Si 02, Ni/Zr02 and Ni/Zr02 -t catalysts present well-dispersed Ni particles and form Ni-Sn alloys that stabilize the metallic presence of Sn under ambient conditions. Meanwhile, the kinetics were studied at 8 bar from 220°C to 280°C in a differential packed bed reactor. Additions of Sn at 1.7 wt.% and 3.4 wt.% to Ni/Si02 catalysts promote rWGS. However, there is a decrease in the rate of CO formation compared to the base catalyst, which is attributed to the decrease in active sites due to the formation of Ni-Sn intermetallic compounds. On the other hand, additions of Sn at 1.7 wt.% and 3.4 wt.% on Ni/ZrO2-m catalysts would likely induce a change in the reaction mechanism, inhibiting CH4 formation and promoting rWGS. Furthermore, the addition of Sn induced methanol formation with a maximum selectivity of ca. 5.0%, a formation rate of ca. 0.014 µ mol·g-1·s 1 , and an apparent activation energy of ca. 33 kJ mol-1.
Currently, the climate crisis and global warming, due to greenhouse gas (GHG) emissions, are among the main problems facing humanity. Approximately 78% of these emissions accounted for by Among the most promising alternatives is the hydrogenation of C02. As a result, the capture and utilization of C02 from the ambient air has attracted growing interest. C02 on the support for C02 hydrogenation to methanol, for which various metals (such as Cu, Pt, and Pd) in combination with promoters (Ga, Mg, In, and La) have been studied at the laboratory setting. Compared to noble metal catalysts, the use of Ni with promoters dispersed represents one of the most efficient methods due to its wide availability and low cost. This work studied the effect of adding Sn in the hydrogenation of C02 by altering only the mass percentage of Sn from zero to 3.4 using the wet chemical reduction method on (i) Si02 catalysts; (ii) Zr02 catalysts; (iii) Ni/ Ni/monoclinic (m)-tetragonal (t) Zr02 catalysts. In addition, the Ni -Sn bimetallic synergy was discussed, and the limited existing literature on this type of catalyst was compared. The characterization of the catalysts after the addition of Sn was performed by X-ray diffraction analysis, high-resolution transmission electron microscopy, and field emission scanning electron -m, microscopy with energy dispersive spectroscopy: Ni/Si 02, Ni/Zr02 and Ni/Zr02 -t catalysts present well-dispersed Ni particles and form Ni-Sn alloys that stabilize the metallic presence of Sn under ambient conditions. Meanwhile, the kinetics were studied at 8 bar from 220°C to 280°C in a differential packed bed reactor. Additions of Sn at 1.7 wt.% and 3.4 wt.% to Ni/Si02 catalysts promote rWGS. However, there is a decrease in the rate of CO formation compared to the base catalyst, which is attributed to the decrease in active sites due to the formation of Ni-Sn intermetallic compounds. On the other hand, additions of Sn at 1.7 wt.% and 3.4 wt.% on Ni/ZrO2-m catalysts would likely induce a change in the reaction mechanism, inhibiting CH4 formation and promoting rWGS. Furthermore, the addition of Sn induced methanol formation with a maximum selectivity of ca. 5.0%, a formation rate of ca. 0.014 µ mol·g-1·s 1 , and an apparent activation energy of ca. 33 kJ mol-1.
Description
Tesis presentada para optar al título de Ingeniero/a Civil Químico/a.
Keywords
Catalizadores, Níquel, Licuefacción del carbón