The continuous rise in atmospheric CO 2 concentrations has made the development of efficient carbon capture technologies particularly urgent. Among various solid adsorbents, lithium orthosilicate (Li 4 SiO 4 ) stands out as an ideal candidate for high-temperature CO 2 capture due to its high theoretical adsorption capacity (36.7 wt%), excellent thermal stability, and superior thermodynamic properties compared to calcium-based adsorbents. However, industrial fluidized-bed reactors require adsorbents in the form of mechanically robust granules rather than fine powders. Granulation and high-temperature sintering processes typically lead to structural densification, which reduces specific surface area and increases internal CO 2 diffusion resistance, thereby slowing adsorption rates and lowering cyclic conversion efficiency.
Sacrificial pore-forming agents are commonly employed to improve gas transport within Li 4 SiO 4 granules. However, conventional additives often yield only relatively uniform pores, lacking the interconnected hierarchical pore structures essential for efficient diffusion; furthermore, they primarily act as physical templates without chemically activating the adsorbent, and the use of synthetic polymers adds to production costs and environmental burdens. Alkali metal doping can enhance ion mobility—and thus accelerate the carbonation reaction—through the formation of eutectic molten salts, but this usually necessitates additional chemical precursors and processing steps. Consequently, developing a single additive capable of both pore formation and chemical activation is of significant importance.
Th is team published their work in Journal of Advanced Ceramics on Ju ne 22 , 202 6 .
To address these challenges, our team has developed a one-step strategy to fabricate high-strength Li 4 SiO 4 granules using spent coffee grounds (SCG) as a multifunctional modifier. By adjusting the SCG dosage, we elucidated a synergistic enhancement mechanism involving hierarchical pore formation, in-situ potassium doping, and the generation of oxygen vacancies. Unlike traditional methods that introduce these characteristics separately, SCG integrates structural, chemical, and defect-engineering functions into a single biomass-derived additive; this approach offers a scalable pathway for the high-value utilization of waste in the production of high-performance CO 2 adsorbents.
Research indicates that spent coffee grounds (SCGs) exhibit morphological characteristics featuring roughness, irregularity, and a broad particle size distribution. These attributes facilitate the formation of an interconnected hierarchical pore structure during sintering, thereby reducing the resistance to CO 2 diffusion within the particles. Furthermore, the high potassium (K) content in SCG ash allows K to incorporate into the Li 4 SiO 4 system during high-temperature sintering, forming a localized molten carbonate phase that promotes ion transport.
Among the various SCG addition levels tested, the 50 wt% loading demonstrated superior overall performance. The CO 2 adsorption capacity of LSO-50 reached 0.275 g/g, representing a significant improvement over unmodified particles. Upon the further addition of Na 2 CO 3 , the adsorption capacity of LSON-50 increased to 0.330 g/g, with high capacity retention observed after 50 cycles. Additionally, LSON-50 exhibited an attrition loss of less than 10%, indicating a combination of high adsorption performance and excellent mechanical stability.
Overall, this study introduces a novel method for simultaneously modulating pore structure, alkali metal doping, and oxygen vacancies using spent coffee grounds. This approach is characterized by a simple process, low-cost raw materials, and environmental sustainability. The findings not only enhance the high-temperature CO 2 capture performance of Li 4 SiO 4 ceramic adsorbents but also open up new avenues for the application of biomass waste in advanced functional ceramic materials.
About Author
Ruichong Chen , PhD in Science, is currently a distinguished researcher at Chengdu University. His main research interests include structural design and performance optimization of solid tritium breeders in the field of magnetic confinement nuclear fusion, and controllable preparation of hollow target pellets for B4C ignition in the field of laser inertial confinement nuclear fusion.
Jianqi Qi , PhD, currently a doctoral supervisor at Sichuan University. His main research directions are the design and preparation of advanced functional materials, research on the service performance of materials under extreme conditions, and design and regulation of material systems and microstructures.
Zhangyi Huang , He holds a joint Ph.D. degree from Sichuan University and Nanyang Technological University (Singapore).
Funding
This work was supported by the National Natural Science Foundation of China under Grant No. 12505192.
DOI Link: https://doi.org/10.26599/JAC.2026.9221339
About Journal of Advanced Ceramics
Journal of Advanced Ceramics (JAC) is an international academic journal that presents the state-of-the-art results of theoretical and experimental studies on the processing, structure, and properties of advanced ceramics and ceramic-based composites. JAC is Fully Open Access, monthly published by Tsinghua University Press, and exclusively available via SciOpen . JAC’s 2025 IF is 14, ranking in Top 1 (1/34, Q1) among all journals in “Materials Science, Ceramics” category, and its 2025 CiteScore is 24.6 (6/133) in Scopus database. ResearchGate homepage: https://www.researchgate.net/journal/Journal-of-Advanced-Ceramics-2227-8508
Journal of Advanced Ceramics
Spent coffee grounds as multifunctional modifiers for triple-synergistic enhancement of Li4SiO4 ceramic sorbents in high-temperature CO2 capture
22-Jun-2026