Key Takeaways & Executive Findings
- •• • Optimal Ni loading of 12.5% maximizes CH4 and CO2 conversions; excessive 15.0% loading causes activity loss due to Ni agglomeration and pore degradation, underscoring the need for precise metal loading in industrial catalyst formulation. • • Promoter incorporation increases surface active oxygen species (Oβ) to ~60%–68%, enhancing CO2 adsorption/activation and reducing carbon deposition, critical for maintaining catalyst longevity in high-temperature DRM operations. • • After 20 h DRM, Ce-promoted catalyst exhibits minimal Ni particle growth from 6.23 to 8.07 nm (Δ1.84 nm), compared to >5 nm for unmodified catalyst, demonstrating superior sintering resistance essential for extended industrial campaigns. • • Promoter-modified catalysts show substantially reduced carbon deposition and lower carbon graphitization, directly addressing the primary deactivation mechanism in DRM and improving process economics by reducing regeneration frequency.
Abstract
Dry reforming of methane (DRM) converts CH4 and CO2 into syngas, offering a route to mitigate greenhouse gases. Ni-based catalysts suffer from sintering and carbon deposition at high temperatures. This work employs MgO-MgAl2O4 composite supports to regulate Ni loading and introduces Ce, La, and Zr as promoters to investigate their effects on DRM activity, structural stability, and surface oxygen species. Optimal Ni loading of 12.5% yields highest CH4 and CO2 conversions. Promoter introduction slightly suppresses low-temperature activity but substantially modifies support local structure and metal-support interface, improving NiO dispersion and increasing surface oxygen vacancies and active oxygen species (Oβ). These changes enhance CO2 adsorption-activation and suppress carbon deposition. After 20 h DRM, Ce-promoted catalyst shows smallest Ni particle growth (6.23→8.07 nm) and lowest carbon deposition, demonstrating superior stability and anti-coking capability. The study elucidates how Ce, La, and Zr enhance sintering and coking resistance via interfacial electronic modulation and improved oxygen storage/release, guiding rational design of stable Ni-based DRM catalysts.
1. Introduction
Dry reforming of methane (DRM) is a promising route to convert two greenhouse gases, CH4 and CO2, into syngas, yet commercial adoption is hindered by rapid catalyst deactivation from metal sintering and carbon deposition at the required high temperatures (600–1000 °C). Conventional Ni-based catalysts on Al2O3, SiO2, or MgO suffer from severe Ni particle growth and coke formation, leading to short operational lifetimes and frequent regeneration. The challenge lies in designing catalysts that maintain high activity while resisting structural degradation and coking under harsh conditions.
This study addresses the bottleneck by employing MgO-MgAl2O4 composite supports to stabilize Ni dispersion and introducing Ce, La, and Zr promoters to modify the metal-support interface and oxygen mobility. The experimental protocol systematically evaluates the effects of promoter addition on catalytic performance, structural evolution, and carbon deposition, providing quantitative evidence that promoter-induced oxygen vacancies and enhanced Ni-support interactions significantly improve sintering and coking resistance. These findings offer a rational design strategy for durable Ni-based DRM catalysts, potentially enabling more efficient and sustainable syngas production.
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ZHANG Guopei, WANG Cong, ZHANG Xiaoyang, LI Zhaomin (2026). Mechanism of Ce/La/Zr doping on the structure and anti-coking performance of Ni/MgO-MgAl2O4 catalyst. Journal of Fuel Chemistry and Technology. https://doi.org/10.1016/S1872-5813(26)60672-X
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Frequently Asked Questions
What is the optimal Ni loading for maximum DRM activity, and why does higher loading degrade performance?
The optimal Ni loading is 12.5%, which yields the highest CH4 and CO2 conversions. Increasing to 15.0% causes activity loss due to Ni agglomeration and pore structure degradation, which reduces active surface area and hinders reactant access.
How do Ce, La, and Zr promoters affect the catalyst's resistance to sintering and coking?
Promoters strengthen Ni-support interactions and increase surface oxygen vacancies, enhancing CO2 adsorption and activation. This promotes gasification of carbon intermediates, reducing deposition. Ce-promoted catalyst shows minimal Ni growth (6.23→8.07 nm after 20 h) and lowest carbon deposition, indicating superior stability.
What is the role of surface oxygen species (Oβ) in improving DRM performance?
Promoter incorporation increases Oβ proportion to ~60–68%, which facilitates CO2 dissociation and provides active oxygen to oxidize carbonaceous deposits, thereby suppressing coke formation and maintaining catalyst activity.
Does promoter addition compromise catalytic activity at lower temperatures?
Yes, promoter-modified catalysts show slightly suppressed activity in the low-temperature region (below 750 °C). However, this trade-off is offset by significantly enhanced stability and anti-coking performance at typical DRM conditions, making them more durable for industrial use.
What are the implications of these findings for industrial DRM reactor design?
The results indicate that Ce-promoted Ni/MgO-MgAl2O4 catalysts can maintain structural integrity and resist coking for at least 20 h, suggesting potential for extended operation without regeneration. This could reduce downtime and improve process economics, though longer-term tests and scale-up studies are needed.
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