Dataset Information

Photo- and Thermocatalytic CO₂ Methanation: A Comparison of Ni/Al₂O₃ and Ni-Ce Hydrotalcite-Derived Materials under UV and Visible Light.

ABSTRACT: Catalysts derived from Ni/Al/Mg/Ce hydrotalcite were prepared via a co-precipitation method, varying the Ce/Al atomic ratio. All of the catalytic systems thus prepared were tested for CO₂ methanation under dark and photocatalytic conditions (visible and ultraviolet) under continuous flow with the light intensity set to 2.4 W cm^-2. The substitution of Al by Ce formed a solid solution, generating oxygen vacancies and Ce³⁺/Ce⁴⁺ ions that helped shift the dissociation of CO₂ towards the production of CH₄, thus enhancing the activity of methanation, especially at lower temperatures (<523 K) and with visible light at temperatures where other catalysts were inactive. Additionally, for comparison purposes, Ni/Al₂O₃-based catalysts prepared via wetness impregnation were synthesized with different Ni loadings. Analytical techniques were used for the characterization of the systems. The best results in terms of activity were as follows: Hydrotalcite with Ce promoter > Hydrotalcite without Ce promoter > 25Ni/Al₂O₃ > 13Ni/Al₂O₃. Hydrotalcite, with a Ce/Al atomic ratio of 0.22 and a Ni content of 23 wt%, produced 7.74 mmol CH₄ min^-1·g_cat at 473 K under visible light. Moreover, this catalyst exhibited stable photocatalytic activity during a 24 h reaction time with a CO₂ conversion rate of 65% and CH₄ selectivity of >98% at 523 K. This photocatalytic Sabatier enhancement achieved activity at lower temperatures than those reported in previous publications.

SUBMITTER: Canales R

PROVIDER: S-EPMC10488339 | biostudies-literature | 2023 Aug

REPOSITORIES: biostudies-literature

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Publications

Photo- and Thermocatalytic CO2 Methanation: A Comparison of Ni/Al2O3 and Ni-Ce Hydrotalcite-Derived Materials under UV and Visible Light.

Canales Rafael R Barrio Victoria Laura VL

Materials (Basel, Switzerland) 20230829 17

Catalysts derived from Ni/Al/Mg/Ce hydrotalcite were prepared via a co-precipitation method, varying the Ce/Al atomic ratio. All of the catalytic systems thus prepared were tested for CO2 methanation under dark and photocatalytic conditions (visible and ultraviolet) under continuous flow with the light intensity set to 2.4 W cm-2. The substitution of Al by Ce formed a solid solution, generating oxygen vacancies and Ce3+/Ce4+ ions that helped shift the ...[more]

PMID: 37687600

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Project description:In this work, various amounts of Ce were added to TiO2 to form a mixed oxide support; Ce x Ti1-x O2 (x = 0, 0.003, 0.05, 0.10 and 0.15) and then those synthesized supports were impregnated by 10 wt% Ni to produce a catalysts. The 10 wt% Ni-Ce x Ti1-x O2 (x = 0, 0.003, 0.05, 0.10 and 0.15) catalysts were tested for CO2 methanation reaction by using a fixed-bed reactor in the temperature range of 100-500 °C. The sample was pretreated at 450 °C under H2 and then a mixed feed gas of CO2 and H2 was switched into the reactor to start the reaction. The results showed that 10 wt% Ni-Ce0.003Ti0.997O2 catalyst (the lowest Ce content) exhibited the highest CO2 conversion and CH4 yield. Moreover, 10 wt% Ni-Ce0.003Ti0.997O2 showed highly stable during the stability test (50 h.). The results indicated that upon addition of small amount of Ce into TiO2-supported Ni, the surface, structural, electrical and redox properties of the catalyst were improved to the extent that these properties can promote the catalytic activities for CO2 methanation. The Ce addition can improve the CO2 methanation catalytic activity by several ways. First, higher dispersion of Ni on catalysts surface upon addition of Ce was observed which resulted in higher adsorption rate of H2 on this metal active site. Second, formation of a larger amounts of oxygen vacancies as well as basicity improvement upon addition of Ce were occurred which can increase the CO2 adsorption on catalyst surface. Third, incorporation of Ce resulted in improving of a starting reduction temperature of Ni2+ to Ni0 for TiO2-supported Ni catalyst which can indicate that the reducibility of Ce-doped TiO2-supported Ni catalyst was enhanced and then alter its catalytic activity. However, increasing of Ce content led to lowering of CO2 methanation activities which resulted from increasing of basicity by Ce addition. The excess amounts of adsorbed CO2 would lead to competitive adsorption to H2 and then lead to a decrease of catalytic activity. Therefore, an appropriate amount of H2 and CO2 adsorption ability on catalyst surface was a prominent factor to dominate the catalytic activity.

Dataset Information

Photo- and Thermocatalytic CO₂ Methanation: A Comparison of Ni/Al₂O₃ and Ni-Ce Hydrotalcite-Derived Materials under UV and Visible Light.

Publications

Photo- and Thermocatalytic CO<sub>2</sub> Methanation: A Comparison of Ni/Al<sub>2</sub>O<sub>3</sub> and Ni-Ce Hydrotalcite-Derived Materials under UV and Visible Light.

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