Key Takeaways & Executive Findings
- •• • LaNiO3/CeO2 achieved 23.6% CO2 conversion at 300 °C with ~100% CH4 selectivity, demonstrating superior low-temperature activity for power-to-gas applications. • • In situ reduction of LaNiO3 yielded highly dispersed Ni0 particles with average diameter 12.6 nm, providing abundant active sites and mitigating sintering. • • CeO2 support exhibited high oxygen vacancy concentration (Ce3+/(Ce3++Ce4+) = 9.2%, ID/IF2g = 0.35), which facilitates CO2 activation and enhances catalytic performance. • • The catalyst's surface basicity (weak and moderate basic sites) and oxygen vacancies synergistically promote CO2 adsorption and methanation, offering a benchmark for designing efficient Ni-based catalysts.
Abstract
Perovskite-type catalysts show promise for CO2 methanation, yet their low-temperature performance and mechanisms remain unclear. Here, a LaNiO3/CeO2 catalyst was synthesized via sol-gel and impregnation. In situ reduction decomposed the perovskite into highly dispersed Ni0 particles (average 12.6 nm) on CeO2, which provided abundant oxygen vacancies (Ce3+/(Ce3++Ce4+) = 9.2%) and weak/moderate basic sites. This synergy enhanced CO2 adsorption and activation. At 200–300 °C, the catalyst achieved ~100% CH4 selectivity and CO2 conversion up to 23.6% at 300 °C. Comparative studies with LaNiO3, LaCeNiO4, Ni/CeO2, and La-Ni/CeO2 revealed that the perovskite pre-structuration and in situ reduction optimize Ni dispersion and metal-support interactions, stabilizing Ni0 and tuning surface basicity and oxygen vacancies. This work provides a design strategy for efficient low-temperature CO2 methanation catalysts.
1. Introduction
CO2 methanation is a key route for converting captured CO2 into synthetic natural gas, but the reaction is kinetically limited by the inertness of CO2. Conventional Ni-based catalysts suffer from Ni sintering and agglomeration at the elevated temperatures required for practical conversion, leading to rapid deactivation. Lanthanum promotion has been shown to improve Ni dispersion and surface basicity, yet the underlying mechanisms, especially at low temperatures (200–300 °C), remain poorly understood.
This study addresses the bottleneck by employing a perovskite pre-structuration strategy: LaNiO3 is deposited on CeO2 and then reduced in situ to generate highly dispersed Ni0 nanoparticles. The CeO2 support provides oxygen vacancies and basic sites that enhance CO2 adsorption and activation. By systematically comparing LaNiO3/CeO2 with reference catalysts, the authors elucidate how the perovskite structure and CeO2 synergy govern low-temperature activity, offering a rational design pathway for efficient and stable methanation catalysts.
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LIU Ji, ZHANG Xuguang, LIU Mengfan, ZHOU Zhi, LI Wentao, HU Bin, ZHANG Zhenxi, LU Qiang (2026). Mechanistic Insights into Low-Temperature CO2 Methanation over LaNiO3/CeO2 Perovskite Catalyst. Journal of Fuel Chemistry and Technology. https://doi.org/10.1016/S1872-5813(26)60662-7
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Frequently Asked Questions
What is the specific role of the perovskite pre-structuration in enhancing Ni dispersion and catalytic activity?
The perovskite LaNiO3 acts as a structural precursor that, upon in situ reduction, decomposes into highly dispersed Ni0 particles with an average size of 12.6 nm. This pre-structuration prevents Ni agglomeration, providing a high density of active sites. The intimate contact with CeO2 further stabilizes these particles, leading to enhanced CO2 conversion (23.6% at 300 °C) and ~100% CH4 selectivity.
How do oxygen vacancies and surface basicity of CeO2 contribute to the methanation mechanism?
CeO2 exhibits a Ce3+/(Ce3++Ce4+) ratio of 9.2% and an ID/IF2g ratio of 0.35, indicating abundant oxygen vacancies. These vacancies act as active sites for CO2 adsorption and dissociation, while weak and moderate basic sites facilitate CO2 activation. The synergy between Ni0 and these surface defects promotes the hydrogenation pathway, enhancing low-temperature activity.
What are the main deactivation mechanisms for Ni-based CO2 methanation catalysts, and how does LaNiO3/CeO2 mitigate them?
Common deactivation mechanisms include Ni sintering, carbon deposition, and sulfur poisoning. The perovskite-derived Ni0 particles are highly dispersed (12.6 nm) and strongly anchored to CeO2, reducing sintering. The oxygen vacancies and basic sites also help suppress carbon formation by promoting CO2 activation and gasification of carbon intermediates, as evidenced by stable performance at 200–300 °C.
How does the catalytic performance of LaNiO3/CeO2 compare with conventional Ni-based catalysts in terms of selectivity and conversion?
LaNiO3/CeO2 achieves nearly 100% CH4 selectivity and a CO2 conversion of 23.6% at 300 °C, which is competitive with or superior to many reported Ni-based catalysts. The perovskite pre-structuration and CeO2 synergy enable high activity at lower temperatures (200–300 °C), reducing energy input and improving process economics.
What are the scalability prospects for the sol-gel and impregnation synthesis method used for LaNiO3/CeO2?
The sol-gel and impregnation methods are well-established and scalable for industrial catalyst production. The synthesis yields a homogeneous perovskite structure and uniform Ni dispersion, which are critical for reproducible performance. The use of relatively inexpensive Ni and CeO2 precursors makes this catalyst cost-effective for large-scale CO2 methanation applications.
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