Key Takeaways & Executive Findings
- •• The nature of surface hydroxyl groups (Al–OH vs. Si–OH) dictates distinct deactivation pathways for supported PEI adsorbents, with Al–OH promoting oxidative degradation and Si–OH promoting urea formation. • PEG modification effectively suppresses urea formation on Si–OH supports, but does not prevent oxidation on Al–OH supports, highlighting the need for tailored support design. • The optimized 40PEI-20PEG-SBA-15 adsorbent exhibits exceptional stability with 2.45 mmol g−1 CO2 capacity over 1000 cycles and negligible loss after one month in simulated flue gas. • This work provides mechanistic insights essential for designing ultra-stable solid amine adsorbents for practical post-combustion CO2 capture.
Abstract
Although supported solid amine adsorbents have attracted great attention for CO2 capture, critical chemical deactivation problems including oxidative degradation and urea formation have severely restricted their practical applications for flue gas CO2 capture. In this work, we reveal that the nature of surface hydroxyl groups (metal hydroxyl Al–OH and nonmetal hydroxyl Si–OH) plays a key role in the deactivation mechanisms. The polyethyleneimine (PEI) supported on Al–OH-containing substrates suffers from severe oxidative degradation during the CO2 capture step due to the breakage of amine-support hydrogen bonding networks, but exhibits an excellent anti-urea formation feature by preventing dehydration of carbamate products under a pure CO2 regeneration atmosphere. In contrast, PEI supported on Si–OH-containing substrates exhibits excellent anti-oxidative stability under simulated flue gas conditions by forming a robust hydrogen bonding protective network with Si–OH, but suffers from obvious urea formation during the pure CO2 regeneration step. We also reveal that the urea formation problem for PEI-SBA-15 can be avoided by the incorporation of an OH-containing PEG additive. Based on the intrinsic understanding of degradation mechanisms, we successfully synthesized an adsorbent 40PEI-20PEG-SBA-15 that demonstrates outstanding stability and retention of a high CO2 capacity of 2.45 mmol g−1 over 1000 adsorption–desorption cycles, together with negligible capacity loss during aging in simulated flue gas (10% CO2 + 5% O2 + 3% H2O) for one month at 60–70 °C. We believe this work makes great contribution to the advancement in the field of ultra-stable solid amine-based CO2 capture materials.
1. Introduction
Post-combustion carbon dioxide (CO2) capture, which can be retrofitted into existing industrial facilities, is a “must-have” technology to both combat climate change and drive toward a net zero society [1–5]. The use of supported solid amine adsorbents for CO2 capture from actual flue gas streams of large point sources is a promising technology [6, 7]. However, this huge commercial potential will only be realized if the long-term cycling stability issue can be solved. During the CO2 adsorption and desorption operations, supported amines exposed to complex atmospheres (O2/CO2/H2O/N2) and varied temperatures (60–150 °C) are susceptible to degradation through multiple chemical pathways, including oxidative deactivation during CO2 capture period and urea formation during CO2-rich regeneration period [8]. Currently, most literature reports generally focus on one certain deactivation issue, lack of systematic evaluation under various conditions. However, for practical applications, a satisfied adsorbent should prevent both oxidative degradation and urea formation. Under certain conditions, the influence of H2O in the flue gas also needs to be considered. Therefore, mechanistic insights into different deactivation processes are highly demanded, which is essential for the design of ultra-stable supported solid amine adsorbents.
It is widely recognized that the interaction between amine and support is crucial for the performance and lifetime of solid amine adsorbents. Thus, to address the above-mentioned deactivation drawbacks, substantial efforts have been devoted to the exploration of appropriate substrates such as silica and alumina [9–12]. Early studies predominantly employed porous silica supports [13], but it was not considered as a good substrate due to the severe ...
Loading authentic research manuscript (Pages 1–5)...
Meng Zhao, Liang Huang, Yanshan Gao, Ziling Wang, Shuyu Liang, Xuancan Zhu, Qiang Wang, Hong He, Dermot O’Hare (2025). Design of Ultra-Stable Solid Amine Adsorbents and Mechanisms of Hydroxyl Group-Dependent Deactivation for Reversible CO2 Capture from Flue Gas. Nano-Micro Letters. https://doi.org/10.1007/s40820-025-01664-w
Research & Educational Purpose Only:The translations, structured abstracts, analytical annotations, and data reports provided by SinoTechIntel are 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. SinoTechIntel 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 main deactivation mechanisms for solid amine adsorbents?
The main deactivation mechanisms are oxidative degradation during CO2 capture and urea formation during CO2-rich regeneration, both influenced by the support's surface hydroxyl groups.
How do surface hydroxyl groups affect adsorbent stability?
Al–OH groups promote oxidative degradation due to breakage of hydrogen bonding networks, while Si–OH groups enhance oxidative stability but lead to urea formation; PEG modification can mitigate urea formation on Si–OH supports.
What is the performance of the optimized adsorbent 40PEI-20PEG-SBA-15?
It shows outstanding stability with a CO2 capacity of 2.45 mmol g−1 over 1000 adsorption–desorption cycles and negligible capacity loss after one month in simulated flue gas.
Why is long-term cycling stability important for CO2 capture?
Long-term stability is crucial for practical applications to reduce costs and ensure consistent performance, as degradation can lead to capacity loss and increased operational expenses.
What is the significance of this study?
This study provides mechanistic insights into deactivation pathways and demonstrates a strategy to design ultra-stable solid amine adsorbents, advancing the field of CO2 capture materials.
Related Technical Papers & Translations
Direct Repair of the Crystal Structure and Coating Surface of Spent LiFePO4 Materials Enables Superfast Li-Ion Migration
The rapid accumulation of spent LiFePO4 (LFP) cathodes from retired lithium-ion batteries necessitates the development of effective and environmental-friendly recycling strategies. In this context, direct regeneration has emerged as a promising approach for reclaiming LFP cathode materials, offering a streamlined pathway to restore their electrochemical functionality. We report an integrated regeneration protocol that simultaneously repairs the degraded crystal structure and reconstructs the damaged carbon coating in spent LFP. The regenerated cathode material had superfast lithium-ion diffusion kinetics and a stable cathode–electrolyte interface, giving a remarkable rate capability with specific capacities of 122 mAh g−1 at 5C and 106 mAh g−1 at 10C (1C = 170 mA g−1). It also maintained capacities of 110.7 mAh g−1 (5C) and 84.1 mAh g−1 (10C) after 400 cycles. It could be used in harsh environments and could be stably cycled at subzero temperatures (−10 and −20 °C) and in solid-state electrolyte batteries. Life cycle assessment combined with economic evaluation using the EverBatt model reveals that this direct regeneration approach has high economic and environmental benefits.
Oxide Semiconductor for Advanced Memory Architectures: Atomic Layer Deposition, Key Requirement and Challenges
Oxide semiconductors (OSs), introduced by the Hosono group in the early 2000s, have evolved from display backplane materials to promising candidates for advanced memory and logic devices. The exceptionally low leakage current of OSs and compatibility with three-dimensional (3D) architectures have recently sparked renewed interest in their use in semiconductor applications. This review begins by exploring the unique material properties of OSs, which fundamentally originate from their distinct electronic band structure. Subsequently, we focus on atomic layer deposition (ALD), a core technique for growing excellent OS films, covering both basic and advanced processes compatible with 3D scaling. The basic surface reaction mechanisms—adsorption and reaction—and their roles in film growth are introduced. Furthermore, material design strategies, such as cation selection, crystallinity control, anion doping, and heterostructure engineering, are discussed. We also highlight challenges in memory applications, including contact resistance, hydrogen instability, and lack of p-type materials, and discuss the feasibility of ALD-grown OSs as potential solutions. Lastly, we provide an outlook on the role of ALD-grown OSs in memory technologies. This review bridges material fundamentals and device-level requirements, offering a comprehensive perspective on the potential of ALD-driven OSs for next-generation semiconductor memory devices.
Laser powder bed fusion of biodegradable Zn-4Cu alloy: Processing, microstructure and properties
Zn's natural degradability and biocompatibility make it a promising candidate for implants, however, its mechanical properties remain insufficient for bone applications. In this study, the performance of Zn was enhanced by developing Zn-Cu alloys via laser powder bed fusion (LPBF). Optimal LPBF parameters for forming stable tracks were achieved by adjusting laser power and scanning speed. Under optimized conditions of 100 W and 100 mm/s, high-density (99.58%) Zn-Cu alloys with improved hardness (68.2HV) and yield strength (160 MPa) were achieved. These improvements are attributed to solid solution strengthening, segregation strengthening, and grain refinement. The Zn-Cu alloys also demonstrated favorable degradation behavior, with a rate of 0.16 mm/year. This degradation is primarily driven by micro-galvanic corrosion between the CuZn5 phase and Zn matrix, along with refined grains and increased grain boundary density. This work demonstrates a viable strategy for fabricating Zn-based implants with enhanced structural integrity and mechanical performance via LPBF.