Key Takeaways & Executive Findings
- •• • Methane pyrolysis offers a dual-output pathway: high-purity hydrogen (combustion value 120 MJ/kg) and functional carbon materials, addressing both energy and material demands. • • Solid catalysts face deactivation from carbon deposition; strategies such as alloying and support optimization can enhance resistance, but molten media systems provide a fundamental solution via dynamically refreshed gas-liquid interfaces. • • Molten media catalytic systems enable continuous carbon separation, overcoming a major bottleneck in solid catalyst processes, as evidenced by studies on bubble dynamics and reactor design. • • The review emphasizes precise control of carbon morphology, which is critical for high-value applications of carbon products, thereby improving overall process economics.
Abstract
The escalation of global warming and climate change necessitates the development of clean energy carriers. Hydrogen, with a high combustion value of 120 MJ/kg and net-zero carbon emissions, is a promising alternative. Catalytic methane pyrolysis offers a route to produce high-purity hydrogen and functional carbon materials simultaneously. However, challenges persist in catalyst deactivation due to carbon deposition and the efficient separation and valorization of carbon byproducts. This review systematically examines recent progress in solid and molten-medium catalysts for methane pyrolysis. It highlights strategies to enhance catalyst stability, including precise control of active sites, alloying, support optimization, and tuning the carbon-catalyst interface. The introduction of molten media catalytic systems, which feature dynamically refreshed gas-liquid interfaces, can fundamentally mitigate deactivation and facilitate continuous carbon separation. The paper discusses reaction mechanisms, catalytic performance, and control of carbon morphology, along with strategies for efficient separation and purification of carbon products in molten media. High-value applications of the produced carbon materials are also explored. The review underscores the potential of methane pyrolysis as a low-carbon technology for hydrogen production, while identifying key research directions for industrial scalability.
1. Introduction
The global imperative to limit temperature rise to 1.5°C has intensified the search for zero-carbon energy carriers. Hydrogen, with its high gravimetric energy density and zero combustion emissions, is a leading candidate. However, conventional hydrogen production via steam methane reforming generates significant CO2 emissions, undermining its environmental benefits. Methane pyrolysis offers a compelling alternative, decomposing methane into hydrogen and solid carbon, thereby avoiding direct CO2 emissions. Yet, the technology has been hindered by catalyst deactivation due to carbon fouling and the challenge of economically valorizing the solid carbon byproduct.
This review addresses these bottlenecks by examining two catalytic approaches: solid catalysts and molten media systems. Solid catalysts, while active, suffer from rapid deactivation; strategies such as alloying and support engineering can improve resilience but do not eliminate the issue. In contrast, molten media systems exploit a continuously refreshed gas-liquid interface, which prevents carbon accumulation and allows for in-situ carbon separation. This paradigm shift could enable continuous operation and enhance the economic viability of methane pyrolysis. The review synthesizes recent advances, focusing on reaction mechanisms, catalytic performance, and carbon morphology control, to provide a roadmap for scaling this technology toward industrial deployment.
Loading authentic research manuscript (Pages 1–5)...
ZHOU Luyuan, WANG Yang, SUN Yu, HUO Kaixuan, DONG Pei, WU Mingbo (2026). Research Progress on Hydrogen and Carbon Materials Production from Methane Pyrolysis. Journal of Fuel Chemistry and Technology. https://doi.org/10.1016/S1872-5813(26)60681-0
Research & Educational Purpose Only: The translations, structured abstracts, analytical annotations, and data reports provided by SinoGreenTechare intended exclusively for academic research, internal corporate R&D, and educational benchmarking. They do not constitute formal engineering, chemical safety, legal, or professional advice.
Copyright & Intellectual Property Notice: Original copyright of the underlying source articles and experimental data remains with the respective authors, institutions, and original publishing journals. SinoGreenTech claims intellectual property only over its proprietary translations, analytical syntheses, and AEO structured enhancements in accordance with international fair use and academic citation principles.
Frequently Asked Questions
What are the primary mechanisms of catalyst deactivation in solid catalysts for methane pyrolysis, and how do alloying strategies mitigate this?
Deactivation primarily results from carbon deposition that encapsulates active sites and blocks pores. Alloying, such as adding Fe or Co to Ni, can alter the carbon solubility and diffusion, promoting the formation of filamentous carbon that detaches from the catalyst, thereby maintaining activity. For instance, bimetallic catalysts have shown enhanced stability compared to monometallic Ni.
How do molten media systems overcome the carbon separation challenge that plagues solid catalysts?
Molten media, such as molten metals or salts, provide a liquid phase with a continuously refreshed interface. Carbon particles, being less dense, float to the surface and can be skimmed off, enabling continuous operation. This eliminates the need for periodic regeneration and allows for steady hydrogen production.
What are the typical operating temperatures for methane pyrolysis, and how do they affect hydrogen yield and carbon morphology?
Typical temperatures range from 800°C to 1000°C for catalytic pyrolysis. Higher temperatures increase methane conversion but also promote carbon graphitization, which may be less desirable for certain applications. The choice of catalyst and temperature can be tuned to produce carbon nanotubes or amorphous carbon, each with distinct market values.
What are the main challenges in scaling up molten media reactors for industrial hydrogen production?
Challenges include reactor design to handle high temperatures and corrosive media, efficient heat transfer, and maintaining uniform bubble distribution for optimal gas-liquid contact. Additionally, the separation and purification of carbon products from the molten media must be cost-effective. Research on bubble hydrodynamics and reactor engineering is addressing these issues.
How does the economic viability of methane pyrolysis compare to steam methane reforming when considering carbon byproduct valorization?
While steam methane reforming is cheaper per kg of hydrogen, it emits CO2. Methane pyrolysis can be competitive if the carbon byproduct is sold at a premium, such as carbon nanotubes for composites or battery anodes. The review highlights that controlling carbon morphology to produce high-value materials is key to improving the overall process economics.
Related Chinese Research & Cross-Citations
Recent Advances in Carbon-Based Materials for CO2 Capture and Utilization
CO2 capture and utilization (CCU) technologies are critical for mitigating global warming and promoting resource circularity. Carbon-based materials, with tunable pore structures, abundant active sites, high specific surface area, and excellent chemical stability, show significant potential for CO2 capture and conversion. This review systematically analyzes the adsorption behaviors and performance variations of activated carbon, porous carbon, graphene, and carbon nanotubes in CO2 capture. For utilization, recent advances in catalytic applications for methanation, reverse water-gas shift (RWGS), dry reforming of methane (DRM), and alcohol synthesis are emphasized. The benefits and drawbacks of carbon materials regarding adsorption capacity, catalytic activity, and stability are evaluated, and their potential in integrated CCU technologies is discussed. Key strategies for enhancing performance through structural modulation and surface modification are elucidated. This review provides theoretical guidance for future development and large-scale implementation of carbon-based materials in CCU.
Fabrication and Microwave Absorption Performance of FexOy/TiO2/C Composites Derived from Red Mud
Red mud, an industrial solid waste from alumina production, poses severe environmental challenges. This study presents a resource-efficient strategy to convert red mud into high-performance microwave absorbing materials. FexOy/TiO2/C composites were synthesized via a sol-gel method using starch as carbon source, followed by carbothermal reduction. The phase composition and microstructure were optimized by adjusting calcination temperature and raw material ratio. The optimal sample, RmCT-5.4-700, exhibited a minimum reflection loss (RLmin) of -30.2 dB at 14.0 GHz with an effective absorption bandwidth (EAB) of 5.3 GHz at a coating thickness of 2.0 mm. The superior absorption performance is attributed to the synergistic effects of dielectric components (TiO2, graphitized carbon) and magnetic components (Fe3O4/Fe). Carbothermal reduction introduces defects that induce dipole polarization, while the conductive network formed by graphitized carbon and Fe3O4/Fe particles enhances conductive loss. Heterogeneous interfaces between Fe3O4, Fe, TiO2, and the red mud matrix promote interfacial polarization. The magnetic loss of Fe3O4/Fe improves impedance matching, facilitating electromagnetic wave penetration and absorption. This work not only provides a novel route for red mud valorization but also contributes to the high-value utilization of solid wastes.
Damage Mechanism of High Chromia Refractory in the Slag Tapping Hole of Commercial Entrained-Flow Gasifiers
The service life of refractory bricks in the slag tapping hole of entrained-flow gasifiers is a critical bottleneck for long-term stable operation. This study investigated the damage mechanism of high chromia refractories in four commercial coal-water slurry gasifiers by analyzing gasification coal samples and corroded refractory bricks. Slag characteristics, including crystallization and viscosity-temperature behavior, were evaluated. Results revealed that low-viscosity slag induces more severe refractory damage. To mitigate slag crystallization risk, a safe slag tapping temperature range is recommended as tICT−t2.5 when tICT exceeds t25. Interior morphology of corroded bricks exhibited cracks, primarily attributed to molten slag penetration and subsequent reactions with refractory material. SEM-EDS analysis of slag-aggregate and slag-matrix interfaces identified reduction in Cr2O3 content as the earliest damage characteristic. XRD detected no zirconium-containing spinel in cracks, indicating that thermal expansion mismatch between newly formed phases and the refractory matrix drives crack propagation. A damage mechanism is proposed: initial Cr2O3 depletion compromises both matrix and aggregate, facilitating slag ingress and new phase formation, ultimately leading to structural failure. Early detection or prevention of Cr2O3 reduction is essential to prolong refractory service life.
Research advances in the pyrolysis recycling of waste wind turbine blades
The global energy landscape is undergoing a profound transformation, with wind energy gaining increasing prominence due to its clean and renewable nature. However, as installed wind power capacity expands, disposal of waste wind turbine blades (WWTB) has emerged as a significant challenge. These blades are predominantly composed of epoxy resin (EP) polymers, carbon fibers (CFs), and glass fibers (GFs). Improper disposal exacerbates environmental concerns and leads to loss of valuable resources, particularly carbon-based materials. Pyrolysis technology, a versatile and environmentally sustainable method for resource recovery, has garnered considerable attention for WWTB disposal. This work presents a comprehensive review of pyrolytic recycling of WWTB, focusing on principles and classifications of pyrolysis technology, key factors influencing the pyrolysis process, as well as pyrolysis methods, equipment, products, and their applications. Through in-depth analysis of current research, this review identifies critical unresolved issues and provides a forward-looking perspective on emerging research trends. The review highlights that pyrolysis can effectively recover glass fibers and carbon fibers with mechanical property retention depending on process conditions, and that catalytic pyrolysis can enhance the quality of recovered products. Economic analysis indicates that collaborative disposal methods can improve cost-effectiveness. Future research should focus on optimizing process parameters for large-scale industrial application and developing more efficient catalysts to improve product selectivity and fiber quality.
Citric Acid-Modified HUSY Zeolite Catalyzes Alkylation of Phenol with Cyclohexanol for High-Density Aviation Fuel Precursors
Lignin-derived oxygenated aromatics, particularly phenols and aromatic ethers, are promising feedstocks for synthesizing high-density, high-heat-sink aviation fuels via alkylation-hydrogenation processes. This study systematically evaluates the catalytic performance of various zeolites (Hβ, HZSM-5, MCM-41, and HUSY) in the alkylation of phenol with cyclohexanol. Characterization demonstrates that HUSY zeolite exhibits superior catalytic activity due to its favorable pore architecture and well-balanced acid site distribution, which synergistically facilitate molecular diffusion and catalytic transformations. To further enhance catalytic properties, HUSY was modified with citric acid at various concentrations and compared with NaOH and oxalic acid treatments. Results reveal that citric acid treatment preserves crystallinity while modulating acidity and pore structure. All modified zeolites enhance phenol alkylation activity. Notably, HUSY-0.5M, exhibiting the highest medium-strong acid to total acid ratio, achieves superior performance: 80.4% phenol conversion and 99.6% selectivity for alkylation products. The catalyst also shows high activity for various lignin-derived compounds (p-cresol, anisole, guaiacol), demonstrating broad applicability. This work provides a new strategy for valorizing lignin-derived phenols into high-value fuel precursors through alkylation.
Hydrogen Production and Structure Evolution Mechanism during Thermochemical Conversion of Microalgae Pellet in Molten Hydroxide Salts
This study investigates the thermochemical conversion behavior of microalgae pellets in a molten hydroxide salt (80% NaOH-20% Na2CO3) system and its influence on hydrogen production. By comparing temperature evolution, gas release characteristics, and structural evolution of pellets with and without molten salt, and integrating char alkalization experiments, the regulatory mechanism of molten salt on reaction pathways and hydrogen production was systematically analyzed. Results indicate that molten salt significantly enhances internal heat transfer efficiency, achieving a central heating rate of 177 °C/s, effectively alleviating thermal hysteresis. Concurrently, molten salt promotes pore development through penetration, erosion, and catalytic effects, resulting in a porosity increase of 53.2%–104.3% after 10 s of reaction. Conversion efficiency is markedly improved, with the dominant reaction pathway shifting to char alkalization after only 70 s. Furthermore, when heating rate is increased above 600 °C, hydrogen yield from char alkalization improves more significantly, primarily attributed to the synergistic promotion of molten salt catalysis and rapid heating on volatiles reforming. This study provides a theoretical foundation for understanding efficient hydrogen production from biomass in molten hydroxide salts.