Simulated Flue Gas Conditions Research Articles

Cascade Reactions for Enhanced CO2 Capture: Concurrent Optimization of Porosity and N‐Doping

AbstractCarbon capture emerges as a pivotal decarbonization technology for addressing global warming challenges. Porous carbons, despite their cost‐effectiveness and ease of regeneration for CO2 capture, typically exhibit limited capacity owing to insufficient adsorption sites. Here, nitrogen‐doped porous carbons (NPCs) are introduced that overcome the prevalent trade‐offs between specific surface area and N‐doped content in NPCs fabrication through cascade reactions. The optimized NPC, which features hierarchical porosity ranging from ultra‐micropores to macropores, shows a superior CO2 capture capacity of 4.46 mmol g−1, ranking in the top 10% of the reported NPCs. This capacity exceeds that of the NPC fabricated with the conventional method by 58% and surpasses the control porous carbon by 106%. Langmuir adsorption modeling and mathematic correlation analysis revealed that this enhanced capacity is attributed to significantly improved ultra‐micropores volume and nitrogen‐species content. Moreover, this optimized NPC demonstrates exceptional stability, preserving its adsorption performance over 110 adsorption–desorption cycles under simulated flue gas conditions. This research not only highlights the integration of templating and N‐doping within NPCs fabrication but also offers an effective strategy to optimize porosity and nitrogen functionality in carbon materials, advancing beyond conventional methodologies.

Dual Metallosalen-Based Covalent Organic Frameworks for Artificial Photosynthetic Diluted CO2 Reduction.

Directly converting CO2 in flue gas using artificial photosynthetic technology represents a promising green approach for CO2 resource utilization. However, it remains a great challenge to achieve efficient reduction of CO2 from flue gas due to the decreased activity of photocatalysts in diluted CO2 atmosphere. Herein, we designed and synthesized a series of dual metallosalen-based covalent organic frameworks (MM-Salen-COFs, M: Zn, Ni, Cu) for artificial photosynthetic diluted CO2 reduction and confirmed their advantage in comparison to that of single metal M-Salen-COFs. As a results, the ZnZn-Salen-COF with dual Zn sites exhibits a prominent visible-light-driven CO2-to-CO conversion rate of 150.9 μmol g-1 h-1 under pure CO2 atmosphere, which is ~6 times higher than that of single metal Zn-Salen-COF. Notably, the dual metal ZnZn-Salen-COF still displays efficient CO2 conversion activity of 102.1 μmol g-1 h-1 under diluted CO2 atmosphere from simulated flue gas conditions (15 % CO2), which is a record high activity among COFs- and MOFs-based photocatalysts under the same reaction conditions. Further investigations and theoretical calculations suggest that the synergistic effect between the neighboring dual metal sites in the ZnZn-Salen-COF facilitates low concentration CO2 adsorption and activation, thereby lowering the energy barrier of the rate-determining step.

Dual Metallosalen‐based Covalent Organic Frameworks for Artificial Photosynthetic Diluted CO2 Reduction

Directly converting CO2 in flue gas using artificial photosynthetic technology represents a promising green approach for CO2 resource utilization. However, it remains a great challenge to achieve efficient reduction of CO2 from flue gas due to the decreased activity of photocatalysts in diluted CO2 atmosphere. Herein, we designed and synthesized a series of dual metallosalen‐based covalent organic frameworks (MM‐Salen‐COFs, M: Zn, Ni, Cu) for artificial photosynthetic diluted CO2 reduction and confirmed their advantage in comparison to that of single metal M‐Salen‐COFs. As a results, the ZnZn‐Salen‐COF with dual Zn sites exhibits a prominent visible‐light‐driven CO2‐to‐CO conversion rate of 150.9 μmol g−1 h−1 under pure CO2 atmosphere, which is ~6 times higher than that of single metal Zn‐Salen‐COF. Notably, the dual metal ZnZn‐Salen‐COF still displays efficient CO2 conversion activity of 102.1 μmol g−1 h−1 under diluted CO2 atmosphere from simulated flue gas conditions (15% CO2), which is a record high activity among COFs‐ and MOFs‐based photocatalysts under the same reaction conditions. Further investigations and theoretical calculations suggest that the synergistic effect between the neighboring dual metal sites in the ZnZn‐Salen‐COF facilitates low concentration CO2 adsorption and activation, thereby lowering the energy barrier of the rate‐determining step.

Utilizing silica fume and synthetically produced mesoporous silicas for simulated flue gas CO2 adsorption

ABSTRACT Carbon capture and storage (CCS) is crucial in mitigating greenhouse gas emissions. Solid adsorbents, notable for their reusability and corrosion resistance, are gaining attention in CO2 gas separation. This study uses Silica fume as an adsorbent and silica source for SiO2 and MCM-41 silica-based adsorbents. Silica was extracted via an alkaline dissolution method, and adsorbents were synthesized using a CO2-induced precipitation method, chosen for its shorter synthesis time and CO2 utilization. The effects of pore volume, average pore diameter, and specific surface area on amine loading and CO2 adsorption capacity were investigated using CTAB surfactant in SiO2 synthesis, resulting in MCM-41. The synthesized adsorbents were modified with TEPA and DEA amines due to their high affinity for CO2. After determining optimal amine loading, the impact of combining TEPA with DEA was examined. The highest CO2 adsorption capacity under simulated flue gas conditions (15% volume CO2 and 85% volume N2) was 198 milligrams per gram of adsorbent for the SiO2 adsorbent functionalized with 50% by weight amine (28% TEPA and 22% DEA). Variations in CO2 adsorption over time, the influence of adsorbent quantity on adsorption capacity, the affinity of the adsorbent for N2 adsorption, and the adsorption–desorption cycle were investigated. The 28%TEPA-22%DEA-SiO2 adsorbent emerged as the optimal choice due to its large total volume and average pore diameter, absence of a template in its structure, excellent performance in CO2 adsorption, lack of affinity for N2, and robust adsorption–desorption stability.

Sulfonated Chitosan Gel Membrane with Confined Amine Carriers for Stable and Efficient Carbon Dioxide Capture.

Capturing carbon dioxide (CO2) from flue gases is a crucial step towards reducing CO2 emissions. Among the various carbon capture methods, facilitated transport membranes (FTMs) have emerged as a promising technology for CO2 capture owing to their high efficiency and low energy consumption in separating CO2. However, FTMs still face the challenge of losing mobile carriers due to weak interaction between the carriers and membrane matrix. Herein, we report a sulfonated chitosan (SCS) gel membrane with confined amine carriers for effective CO2 capture. In this structure, diethylenetriamine (DETA) as a CO2-mobile carrier is confined within the SCS gel membrane via electrostatic forces, which can react reversibly with CO2 and thus greatly facilitate its transport. The SCS ion gel membrane allows for the fast diffusion of amine carriers within it while blocking the diffusion of nonreactive gases, like N2. Thus, the prepared membrane exhibits exceptional CO2 separation capabilities when tested under simulated flue gas conditions with CO2 permeance of 1155 GPU and an ultra-high CO2/N2 selectivity of above 550. Moreover, the membrane retains a stable separation performance during the 170 h continuous test. The excellent CO2 separation performance demonstrates the high potential of gel membranes for CO2 capture from flue gas.

Against catalyst deactivation during toluene oxidation on CuCeOx in flue gas: High oxidation efficiency and rapid oxidation pathway

The removal of volatile organic compounds (VOCs) from flue gas by a tightly coupled catalytic oxidation process in the NH3-SCR unit is a cost-effective approach. A CuCeOx bimetallic mixed oxide catalyst prepared by the co-precipitation method has demonstrated the ability to completely convert toluene at 350 ℃ under simulated flue gas conditions. Cu oxide is considered as the main active site for toluene oxidation, and the introduction of Ce induced a synergistic effect which enhanced the surface adsorbed oxygen and oxidation performance. The CuCeOx catalyst was found to outperform commercial VOC catalysts (Pt/Al2O3) and SCR catalysts (V2O5-WO3/TiO2) under the influence of different flue gas components. The negative effect of the flue gas on CuCeOx almost diminished at 350 ℃. The mechanism study showed that toluene on CuCeOx underwent a rapid oxidation pathway, thereby avoiding the potential interaction between intermediates and flue gas components. The superior catalytic performance of CuCeOx in the simulated flue gas conditions were attributed to the higher toluene adsorption efficiency and weaker adsorption towards the flue gas components.

High-temperature corrosion behavior of the FeCrAl laser cladding coatings in waste-to-energy superheaters: Influence of Al content

Enhancing the high-temperature corrosion resistance of superheaters in waste-to-energy plants (WTE) is key to improving the efficiency of WTE power generation. The present study employed laser cladding technology to fabricate Fe-13Cr-xAl coatings, and characterized the microstructure, phase structure, and Vickers hardness of the coatings using OM, SEM, XRD, and a Vickers hardness tester. The study investigated the influence of high-temperature corrosion resistance of the coatings under simulated WTE flue gas conditions. This study found that: Al and Cr both exist in the form of solid solution atoms in the laser cladding coatings. The Vickers hardness of the coatings gradually increased with increasing Al content. When the Al content exceeds 10 %, cracks begin to appear in the coatings, and the number and size of cracks increase with increasing Al content. The Fe-13Cr-7Al coatings exhibit the best high-temperature corrosion resistance under simulated WTE flue gas conditions, and it can achieve ∼73 % of the high-temperature corrosion resistance of the Inconel 625 alloy laser cladding coatings. During high-temperature corrosion, phase separation occurs near the grain boundaries, resulting in chromium depletion zones, which promote intergranular corrosion of the coatings. During the process of high temperature corrosion, the reactions between Al, Cl, and S exhibit the lowest Gibbs free energy. The continuous consumption of Al effectively protects the Fe and Cr in the substrate. Additionally, the formation of aluminum oxide in the coating hinders the inward diffusion of Cl2, thereby beneficially impeding the progress of corrosion. Excessive Al contents in the coatings introduced cracks that served as channels for molten salt to penetrate the matrix, thereby reducing the high-temperature corrosion resistance of the coatings.

Hollow microbeads modified with MoS2 for enhanced removal of mercury from coal-fired flue gas

Hollow microbeads, derived from fly ash emitted by power plants, are hollow microbeads composed of various compounds including SiO2 and Al2O3. These microspheres exhibit a high specific surface area and stable chemical properties. In this work, HM-MoS2 was synthesized through a two-step hydrothermal method to address the issues of low adsorption efficiency and high operational costs associated with the utilization of hollow microbeads in actual power plant applications. The experiments demonstrated that under simulated power plant flue gas conditions, the adsorption efficiency of HM-15 for elemental mercury (Hg0) exceeded 96%. Additionally, HM-15 displayed resistance to SO2 and NO gases, indicating its potential as a mercury adsorbent material with promising industrial applications.

Boc Protection for Diamine-Appended MOF Adsorbents to Enhance CO2 Recyclability under Realistic Humid Conditions.

Among the various metal-organic framework (MOF) adsorbents, diamine-functionalized Mg2(dobpdc) (dobpdc4- = 4,4-dioxidobiphenyl-3,3'-dicarboxylate) shows remarkable carbon dioxide removal performance. However, applying diamine-functionalized Mg2(dobpdc) in practical applications is premature because it shows persistent performance degradation under real flue gas conditions containing water vapor owing to diamine loss during wet cycles. To address this issue, we employed hydrophobic carbonate compounds to protect diamine groups in een-Mg2(dobpdc) (een-MOF, een = N-ethylethylenediamine). tert-Butyl dicarbonate (Boc) reacted rapidly with diamines at the pore openings of MOF particles to form dense secondary and tertiary hydrophobic amines, effectively preventing moisture ingress. The Boc-protected een-MOF-Boc1 maintained excellent CO2 adsorption even under simulated flue gas conditions containing 10% H2O. This observation indicates that Boc protection renders een groups intact during repeated wet cycles, suggesting that Boc-protected een groups are resistant to replacement by water molecules. To increase the practicability of the MOF adsorbent, we fabricated een-MOF/PAN-Boc1 composite beads by shaping MOF particles with polyacrylonitrile (PAN). Notably, the composite beads maintained their CO2 adsorption performance even after repeating the temperature swing adsorption process more than 150 times in 10% water vapor. Furthermore, breakthrough tests showed that the dynamic CO2 separation performance was retained under humid conditions. These results demonstrate that Boc protection provides an easy and effective way to develop promising adsorbents with high CO2 adsorption capacity, long-term durability, and the properties required for postcombustion applications.

Enhanced CO2 capture potential of UiO-66-NH2 synthesized by sonochemical method: experimental findings and performance evaluation

The excessive release of greenhouse gases, especially carbon dioxide (CO2) pollution, has resulted in significant environmental problems all over the world. CO2 capture technologies offer a very effective means of combating global warming, climate change, and promoting sustainable economic growth. In this work, UiO-66-NH2 was synthesized by the novel sonochemical method in only one hour. This material was characterized through PXRD, FT-IR, FE-SEM, EDX, BET, and TGA methods. The CO2 capture potential of the presented material was investigated through the analysis of gas isotherms under varying pressure conditions, encompassing both low and high-pressure regions. Remarkably, this adsorbent manifested a notable augmentation in CO2 adsorption capacity (3.2 mmol/g), achieving an approximate enhancement of 0.9 mmol/g, when compared to conventional solvothermal techniques (2.3 mmol/g) at 25 °C and 1 bar. To accurately represent the experimental findings, three isotherm, and kinetic models were used to fit the experimental data in which the Langmuir model and the Elovich model exhibited the best fit with R2 values of 0.999 and 0.981, respectively. Isosteric heat evaluation showed values higher than 80 kJ/mol which indicates chemisorption between the adsorbent surface and the adsorbate. Furthermore, the selectivity of the adsorbent was examined using the Ideal Adsorbed Solution Theory (IAST), which showed a high value of 202 towards CO2 adsorption under simulated flue gas conditions. To evaluate the durability and performance of the material over consecutive adsorption–desorption processes, cyclic tests were conducted. Interestingly, these tests demonstrated only 0.6 mmol/g capacity decrease for sonochemical UiO-66-NH2 throughout 8 consecutive cycles.

Synergistic performance of Ni-Ca based dual functional materials under the coexistence of moisture and oxygen in CO2 source for integrated carbon capture and utilisation

Global warming and climate change require urgent reduction of CO2 emissions. Integrated carbon capture and utilisation combined with dry reforming of methane (ICCU-DRM) has the potential to mitigate greenhouse gas emissions by capturing and converting CO2 and CH4 into valuable syngas. However, the performance and stability of dual-functional materials (DFMs) are unclear under real-world flue gas conditions, particularly in the presence of steam and O2. In this study, we elucidated the mechanisms of the performance of a Ni0.05/CaO0.95 DFM under various flue gas conditions and investigated the combined effects of steam and O2 on CO2 uptake, CO and H2 yields and cyclic stability. Our approach includes the synthesis and evaluation of the DFM using advanced characterisation techniques, such as XRD, in-situ infrared spectroscopy, CH4-TPR, SEM, EXD, FIB-SEM, BET, and XPS, to gain insights into the properties and behaviour of the DFM under different flue gas conditions. The findings show that under the simulated flue gas condition (10.0 % CO2 + 6.0 % H2O + 6.7 % O2/N2), there was a significant deterioration in performance, with CO2 uptake of only 5.7 mmol.g-1, average H2 yield of 11 mmol.g−1 and average CO yield of 6.2 mmol.g−1. While under the ideal condition (10.0 % CO2/N2), the CO2 uptake, average H2 yield and average CO yield were 10.7 mmol.g−1, 16.9 mmol.g−1 and 23.1 mmol.g−1, respectively. FIB-SEM and XPS analysis highlighted the combined effect of steam and O2 on the performance of Ni0.05/CaO0.95 DFM during ICCU-DRM. Notably, the presence of O2 promoted the oxidation of Ni, resulting in decreased catalytic activity and volumetric expansion of Ni particles. Furthermore, the presence of steam promoted CO2 adsorption, inducing additional volumetric expansion of the CaO component of DFM. These synergistic expansions form a dense shell on the surface, hindering the reduction of internal NiO, thereby diminishing DFM performance.

Metal-Doped Mesoporous MnO2-CeO2 Catalysts for Low-Temperature Pre-Oxidation of NO to NO2 in Fast SCR Process

Selective catalytic reduction (SCR) is an effective system for treating nitrogen oxides (NOx; mainly NO), and fast SCR requires the equimolar reactants of NO and NO2. This study focused on catalysts for oxidizing 50% of NO to NO2. A series of catalysts composed of a variety of components, such as mesoporous mMnO2-nCeO2 as carrier catalysts (m:n = 9:1 and 7:3) and transition metals (e.g., Fe, Co, Ni, Cu, and Cr), were synthesized and characterized using N2 adsorption, in situ XRD, TEM, and XPS. All samples had a mesoporous structure with pore size around 8 nm. XPS results demonstrated that addition of cerium ion increased the surface area and provided oxygen vacancy due to the formation of Ce3+ within the structure. NO oxidation activity was tested using a feed (205~300 ppm NO and 6% O2) that simulated typical flue gas conditions. Doped mesoporous mMnO2–nCeO2 has higher NO oxidation activity than pristine mMnO2–nCeO2. The doped mMnO2-nCeO2 catalyzed 50% of NO to NO2 at between 140 and 200 °C resulting in an equivalent amount of NO and NO2. Among the transition metals, Cu, Ni, Co, Fe, and Cr have the highest to lowest oxidation activity, respectively. The precatalytic oxidation of NO can potentially be combined with the current SCR system without changes to existing equipment and can be applied to the exhaust gas treatment for de-NOx.

Influence of transition metal catalysts on the decomposition product distribution of PCBs and PCDD/Fs

In this study, reliable and stable polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) generation systems were used to investigate catalyst performance. The distribution characteristics of PCBs and PCDD/Fs after reaction were evaluated under different simulated flue gas conditions using NiO- and MnO2-loaded γ-Al2O3 and ZSM-5 catalysts. The results showed that the active metal of the catalyst affected mainly the decomposition efficiency, the substrate type affected the distribution characteristics of PCBs, and both the active metal and substrate type jointly determined the fingerprint distribution characteristics of PCBs. Moreover, there was an apparent marginal effect of the active metal loading on the same catalyst and the decomposition efficiency of the pollutants. In the temperature range of 100–350 °C, temperature variation had little effect on the removal efficiency of PCBs, but the gas–solid phase distribution characteristics of the pollutants changed significantly, and large amounts of di- and tri-CBs were generated in the products at 200 °C. A small amount of water generated hydrogen via the water–gas shift reaction at medium temperature, which promoted the hydro-dechlorination reaction of the chlorinated organics. However, excess water in the substrate gas competes with the pollutants for adsorption sites and reduces the reaction activity of the catalyst.

Phenoxazine-based COFs for CO2/N2 separation and organic dye adsorption

CO2 adsorption IAST selectivities of phenoxazine-cored YCOF1 up to 70.97 (237 K) and 30.05 (298 K) under simulated flue gas conditions. High adsorption capacities of 650.14 (YCOF1) and 572.95 (YCOF2) mg g−1 for the dye MG in the aqueous solution.

Upgrading CO2 from simulated power plant flue gas via integrated CO2 capture and dry reforming of methane using Ni-CaO

Integrated CO2 capture and utilisation via dry reforming of methane (ICCU-DRM) represents a promising and profitable route for directly capturing and converting CO2 from various CO2 sources. However, the influence of realistic flue gas conditions on ICCU-DRM remains unknown and challenging. Herein, we investigated the influence of the presence of H2O and O2 in power plant flue gas on integrated CO2 capture and DRM using Ni10-CaO dual functional material (DFM). It is found that H2O promoted the kinetics of CO2 capture, while the O2 oxidised Ni into NiO and prohibited the performance of utilisation of the captured CO2 during DRM. Specifically, the delay of pre-reduction of NiO and the coverage of catalytic sites by the formed CaCO3 decreased the process performance and efficiency. The reduction of NiO would instantly generate CO2 and hinder the contact between CH4 and Ni, resulting in a lower initial catalytic performance during the CO2 utilisation (DRM) of ICCU. Due to the occurrence of CH4 decomposition in DRM, the following CO2 capture step would produce CO in the flue gas, which could be problematic, owing to the carbon gasification reactions. An extra step of carbon steam gasification (CSG) after DRM could effectively remove most of the deposited carbon and by-produce syngas. Subsequently, the small amount of carbon residue after the CSG step could be preferentially combusted by O2 into CO2 in flue gas, and then be captured by CaO instead of generating CO. This study demonstrates the feasibility and challenges of ICCU-DRM under simulated power plant flue gas conditions and provides potential insights for future investigation and deployment of this integrated process.

Migration and control of mercury in hazardous chemical waste incineration

This study evaluated the emission and control characteristics of mercury during hazardous chemical waste incineration. Meanwhile, for the complex flue gas conditions generated by hazardous chemical waste incineration, the commercial activated carbon used in the incineration system was modified with CuBr2, and its Hg0 removal performance was tested. The results showed that the major proportion of Hg was in the fly ash, and the content accounted for 74.53 % of the total Hg. The Hg content in the fly ash increased with decreasing fly ash particle size. In the exhaust flue gas, the Hg content was 11.05 % of the total Hg, in which the mass percentages of Hg2+ and Hg0 were 59.08 % and 40.92 %, respectively. The flue gas purification equipment of the incineration system had a removal efficiency of 92.40 % for HgT. The saturated Hg0 removal capacity of the modified activated carbon was improved by 33.51 times. Under simulated incineration flue gas conditions, the modified activated carbon was able to achieve an Hg0 removal efficiency of 92.85 %. The results can contribute to the understanding of Hg emissions from hazardous chemical incineration systems and provide guidance for efficient Hg removal from activated carbon.

Quaternary ammonium-functionalized polysulfone sorbent: Toward a selective and reversible trap-release of CO2

A novel good performing and selective polymeric sorbent has been synthesized by chemical modification of eco-friendly and inexpensive polysulfone through introduction of quaternary ammonium pendant groups (qPSU). The self-standing film conjugated outstanding thermo-mechanical resistance with high selectivity of adsorption for CO2 over methane, fast capture kinetics and very good stability over multiple adsorption–desorption cycles. Worth notes, the qPSU sorbent exhibited absorption capacity up to 2.21 mmol g-1 under simulated flue gas conditions (humid 6 % CO2, 20 % relative humidity and ambient pressure) and one of the highest amine efficiency reported to date for low-temperature and low-pressure CO2 sorbents. The maximum adsorption capacity can be completely restored under mild conditions (50 °C in pure N2 for 20 min), with only 60.3 kJ mol-1 consumed during sorbent regeneration. 13C NMR characterization revealed carbon dioxide is chemisorbed via formation of bicarbonate ions. The approach may be further extended to a wide range of polymeric systems, and thus might open up new avenues in the development of advanced carbon dioxide sorbents.

Catalytic performance and sulfur resistance of OMS-2 modified by copper for mercury removal at low temperature

Cu-doped manganese oxide molecular sieve catalysts (Cu-OMS-2) are prepared by hydrothermal synthesis method, and their Hg0 removal ability and sulfur resistance are investigated experimentally under simulated flue gas conditions. It indicated that appropriate proportion of Cu doped could increase both the content of Mn4+ active sites on the catalyst surface and the BET specific surface area. The maximum specific surface area of these catalysts is 260.49 m2/g, with the Cu/Mn molar ratio of 0.025. A highest Hg0 removal efficiency of 93.6 % is achieved by the catalyst with Cu/Mn molar ratio of 0.05. SO2 in flue gas significantly inhibits the Hg0 removal ability of OMS-2-H120, but its suppression ability is relatively weak after the addition of Cu to OMS-2-H120. The Hg0 removal efficiency of Cu0.05-OMS-2 can reach 92 % even in the presence of 1000 ppm SO2. The doping of Cu on OMS-2 enhances SO2 adsorbed by CuO, inhibiting the reaction of SO2 with the active center on the catalyst surface. It reduces the generation of sulfate and enhances the sulfur resistance ability of Cu0.05-OMS-2. The process of Hg0 oxidation by O2 over Cu0.05-OMS-2 is found to follow Mars-Maessen mechanism based on the characteristics of fresh and spent catalysts. Elemental mercury is firstly chemisorbed on the Cu0.05-OMS-2 catalyst surface and then oxidized.

Quaternized polyepichlorohydrin-based membrane as high-selective CO2 sorbent for cost-effective carbon capture

A trimethylammonium-functionalized polyepichlorohydrin membrane (TPp) was synthesized using inexpensive, eco-friendly raw materials and easy synthetic steps and evaluated as CO2 sorbent. The polymeric membrane exhibited satisfactory sorbent performance in terms of stability, rapid adsorption, high selectivity and working capacity. The peak capture capability of 1.34 mmol g-1 was achieved at 25 °C under simulated flue gas condition (humidified 10% CO2, 20% RH). The quaternary ammonium groups enable superior amine efficiency (0.95 mmol CO2/mmol N at 25 °C), well exceeding the highest value reported to date for low-temperature CO2 sorbents under simulated flue gas conditions, and reversible trap-release of CO2. De facto, the TPp sorbent can be completely regenerated under mild conditions (50 °C in pure N2 for 20 min), with only 64.8 kJ mol-1 consumed during sorbent regeneration. The low cost, versatility and ease of preparation make the TPp membrane a promising sorbent for scalable and cost-effective CO2 capture.

Rational fabrication of ZIF-8 forests via metal template-guided growth for promoting CO2 chemical transformation

Construction of macroscopic metal–organic frameworks (MOFs) with high processability is crucial for their practical usage. Here, we demonstrate a facile metal template-guided growth approach that exploits the synthesis of forest-like ZIF-8-based material. The 3D self-supported array architecture endows the resultant ZIF-8 forests with efficient exposure of active sites, rapid mass transfer and simple recovery. Under mild catalytic reaction conditions (1 bar CO2, 60 ℃), ZIF-8 forests show remarkable activities toward the coupling of epoxides and CO2 with an excellent cyclic carbonate yield of 96%, surpassing the powdered ZIF-8 crystals. Importantly, the catalytic performance can be well-maintained even after 10 cycles and under both simulated flue gas conditions and full-spectrum light irradiation, demonstrating the potential for practical catalysis. Our work provides a practical guideline to produce macroscopic MOF-based materials with great potential for industrial catalysis.