As global awareness about the detrimental effects of climate change intensifies, the scientific community is urgently pursuing innovative solutions to mitigate greenhouse gas emissions. Among these, carbon dioxide (CO₂) capture technologies have emerged as critical tools for reducing atmospheric CO₂ levels, thereby slowing the progression of global warming. One promising method—sorption-enhanced water-gas shift reactions—requires highly efficient sorbents to sequester CO₂ from fossil fuel-derived streams. Despite their potential, conventional sorbents have struggled with drawbacks such as diminished capacity, structural degradation, and mechanical fragility, limiting their widespread adoption. Addressing these challenges, researchers at Taiyuan University of Technology have pioneered a revolutionary granulation strategy to produce alkaline metal salt-promoted magnesium oxide (MgO) sorbent pellets with enhanced CO₂ capture capability and mechanical resilience.
Traditional MgO-based sorbents exhibit excellent affinity for CO₂, especially when promoted with alkaline metal salts that improve sorption kinetics and capacity. However, these materials tend to suffer from pore collapse and powder elutriation during repeated capture and regeneration cycles, largely due to weak mechanical integrity and loss of porous architecture. Consequently, the operational lifespan of these sorbents is markedly curtailed, creating significant obstacles for their practical implementation in industrial carbon capture units. The research team at Taiyuan University of Technology confronted these issues head-on by integrating a sophisticated granulation method combining ball milling and extrusion granulation processes, supplemented with carefully selected granular promoters.
The granulation promoters selected by the researchers fulfill distinct roles within the pellet fabrication process, synergistically enhancing the structural and functional properties of the sorbent pellets. Sodium polyacrylate (SP) serves as an extrusion aid, facilitating the formation of well-shaped pellets by improving material flowability under mechanical pressure. Pseudo-boehmite (PB), a metastable aluminum oxyhydroxide phase, acts as a binder, imparting adhesive strength and contributing to the eventual formation of a γ-AlOOH sol-gel network within the pellet matrix. Nitric acid (NA) functions as a gum solvent to modulate the binder’s distribution and ensure uniform pellet cohesion. Finally, microcrystalline cellulose (MC) operates as a pore-forming agent, imparting a controlled pore architecture upon its pyrolysis during high-temperature treatment of the pellets.
Employing the Response Surface Methodology with Box-Behnken Design (RSM-BBD), the team quantitatively investigated the effects of individual promoters and their interactive terms on the initial CO₂ capture capacity of the MgO-GA sorbent pellets. This robust statistical model enabled precise optimization of the promoter content, revealing that the interaction between pseudo-boehmite and nitric acid plays a pivotal role in dictating sorbent performance. The experimentally optimized composition—1.01 weight percent SP, 1.95 weight percent PB, 15.08 weight percent NA, and 10.05 weight percent MC—resulted in a pellet formulation that achieved a balance between sorption efficiency and mechanical robustness, as predicted with remarkable fidelity by the model.
Characterization of the optimized MgO sorbent pellets unveiled a significant enhancement in CO₂ uptake capacity, reaching 11.46 mmol·g⁻¹ initially, nearly identical to the RSM-BBD model’s predicted value of 11.47 mmol·g⁻¹. This capacity represents a notable improvement over unpromoted pellets, directly correlating with the intricate pore network created by the pyrolytic decomposition of the cellulose and other promoters. Nitrogen adsorption–desorption analysis confirmed the critical role of porosity and surface area in facilitating efficient gas-solid interactions, which are paramount for rapid and extensive CO₂ capture.
Moreover, the mechanical strength of the pellets soared to an impressive 11.14 MPa, which is almost triple that of the baseline samples lacking granulation promoters. This remarkable enhancement is credited primarily to the strategic formation of a γ-AlOOH sol-gel cluster skeleton in situ during pellet fabrication, induced by the presence of pseudo-boehmite and nitric acid. This network not only binds the MgO particles firmly but also safeguards the internal pore architecture from collapse under operational stress.
The long-term durability of sorbent pellets is crucial for industrial applications where repeated adsorption-desorption cycles can severely impair performance. The research team subjected the optimized pellets to twenty successive CO₂ capture cycles, simulating real-world operational conditions. Encouragingly, the sorbents maintained a robust CO₂ uptake capacity of 8.71 mmol·g⁻¹ after these cycles, alongside a mechanical strength retention of 8.92 MPa. This sustained efficiency underscores the practical viability of the granulation method in producing industrial-grade sorbents capable of enduring cyclic thermal and chemical stresses.
Fundamental insights gleaned from this study provide a transformative pathway for advancing MgO-based CO₂ sorbents toward commercial scalability. By meticulously tuning the granulation promoters and their interactions, the researchers successfully surmounted longstanding limitations such as pore collapse and powder loss. This dual enhancement of sorption capacity and mechanical integrity is poised to accelerate the deployment of sorption-enhanced water-gas shift processes and other carbon capture technologies integral to decarbonizing industrial emissions.
In conclusion, the work carried out by Taiyuan University of Technology represents a significant breakthrough in sorbent engineering, marrying detailed materials chemistry with pragmatic fabrication techniques. Their approach elegantly bridges laboratory-scale optimization with the demands of industrial application, signaling a major step forward in sustainable carbon capture. As industries worldwide grapple with stringent emission regulations and mounting environmental concerns, such innovative sorbent technologies will be instrumental in achieving net-zero carbon goals and mitigating the climate crisis.
Their research findings, published on December 5, 2025, in the prestigious journal Frontiers of Chemical Science and Engineering, offer a highly reproducible and scalable methodology that can be adapted for various sorbents and promoters. Future exploration may expand upon these foundations by incorporating novel additives or alternative processing routes to further elevate sorbent performance.
The credibility of this breakthrough is bolstered by comprehensive experimental validation, thorough characterization, and advanced statistical modeling techniques. Such interdisciplinary rigor fortifies confidence among practitioners and policymakers alike that this sorbent technology can substantially enhance the effectiveness and durability of industrial CO₂ capture systems, underpinning a cleaner and more sustainable energy future.
Article Title: Granulation mechanism and CO2 capture performance of alkaline metal salt-promoted MgO sorbents
News Publication Date: 5-Dec-2025
Web References:
http://dx.doi.org/10.1007/s11705-025-2576-8
Image Credits: HIGHER EDUCATION PRESS
Keywords
Carbon dioxide capture, MgO sorbents, alkaline metal salts, granulation promoters, sodium polyacrylate, pseudo-boehmite, nitric acid, microcrystalline cellulose, sorption-enhanced water-gas shift, pore structure, mechanical strength, sol-gel clusters
Tags: alkaline metal salt promotionbioethanol recovery methodscarbon capture innovationsclimate change mitigation strategiesCO₂ capture challengesgreenhouse gas reduction techniqueshigh-efficiency membrane technologyindustrial carbon capture applicationsmagnesium oxide sorbentsmechanical resilience in sorbentssorption-enhanced water-gas shift reactionssustainable energy solutions
