Carbon Capture Science & Technology最新文献

The enzyme carbonic anhydrase (CA) has gainned considerable attention from the literature and the industry in the context of CO₂ capture. CA immobilization in gas-liquid membrane contactors, and more specifically, on poly(ionic liquid) (PIL) composite membranes has been demonstrated to be a potential strategy to facilitate its industrial implementation. These membranes were comprised of a PIL layer coating on a porous hydrophobic polymeric support. In this work, the composition of the PIL layer was tuned by anion exchange to yield a variety of enzyme carriers. The following anions were compared: bromide [Br], acetate [Ac], tetrafluoroborate [BF₄], and bis(trifluoromethylsulfonyl)imide [NTf₂]. The surface morphology, chemistry, and properties of these composite membranes were characterized by SEM, EDX, ATR-FTIR, and water contact angle. The activity of the different biocatalytic composite membranes was determined by the p-nitrophenyl acetate hydrolysis model reaction. It was found that the anion exchange salts had a detrimental effect on the immobilized enzyme activity. In light of these results, the enzyme immobilization step was conducted after anion exchange. The resulting biocatalytic membranes displayed slight differences in immobilized enzyme activities and thermal stabilities following the order [Br]>[BF₄]>[Ac]>[NTf₂] and [BF₄]>[Br]≈[Ac]>[NTf₂], respectively. The differences were more pronounced and detrimental for the most hydrophobic anion, [NTf₂]. Parallel trends were noted when the membranes were tested for CO₂ absorption in a gas-liquid membrane contactor set-up suggesting that the CO₂ mass transfer is strongly influenced by the activity of the immobilized enzymes. In addition, the effect of the absorption conditions, i.e., solvent flow rate, solvent saturation, and solvent concentration were evaluated. Under the best conditions, the novel biocatalytic membranes outperformed the commercial PVDF support by about a factor of 4 in terms of overall mass transfer coefficient. Such improvement would result in significant reductions in the required membrane area to capture CO₂ by a gas-liquid membrane contactor.

Sodium zirconate (Na₂ZrO₃) is a promising material for pre-combustion CO₂ capture due to its fast sorption kinetics and excellent cyclic stability at high temperatures under ideal condition (desorption in 100% N₂). Still, there is a lack of study on the performance of Na₂ZrO₃ cyclic capture under harsh condition (desorption in high concentration CO₂). In this study, Na₂ZrO₃ was prepared by wet-mixing and heated-drying, and the difference in the cyclic CO₂ capture performance of the sample was compared between desorption under harsh condition and vacuum condition. The crystal structure of Na₂ZrO₃ was identified during the sorption-desorption cycles. The crystal structure was also modeled and simulated to analyze the reason for the superior capture performance from the monoclinic Na₂ZrO₃. It was found that the special interlocked and multilayered stacked structure of the monoclinic Na₂ZrO₃ allowed for high reactivity with CO₂. It was found that high temperature solely had little help in the desorption of Na₂ZrO₃ under harsh condition, but vacuum condition promoted desorption of Na₂ZrO₃ in high fraction CO₂, and vacuum desorption at 1000 °C-1050 °C resulted in Na₂ZrO₃ with both good capture performance and cycling stability. Vacuum desorption led to more complete reversion of Na₂ZrO₃ to the monoclinic state, benefiting for CO₂ capture. This study attempted to simulate the harsh capture environments of real industrial applications and to explore the possibility of Na₂ZrO₃ as a carbon capture material for pre-combustion capture.

Quantum dots exhibit great potential in photocatalytic CO₂ conversion into value-added fuels to achieve a carbon-neutral society, owing to their unique optical properties and tunable surface chemistry. However, the generation of multi-carbon hydrocarbon products remains a grand challenge. Herein, polyethyleneimine (PEI) coated AgInS₂ quantum dots (AgInS₂@PEI QDs) are designed for the photo-catalytic conversion of CO₂ to C₂ products. It is found that the yield and selectivity of C₂H₆ can be significantly enhanced by regulating the content of Ag and PEI in AgInS₂@PEI QDs. Under the optimal conditions, C₂H₆ yield reaches 63 μmol g^-1, and the electron selectivity is 30.3 %. A mechanistic study reveals that PEI effectively promotes the accumulation of photogenerated electrons, and the CO-enriched local environment caused by Ag boosts CC coupling on asymmetric bimetallic sites. This work offers new insight on the design of efficient quantum dot photocatalysts for CO₂ conversion to C₂ products.

Sodium carbonate solvent absorbent has been widely studied for CO₂ reduction to deal with global warming because of its green, low cost, and non-corrosive advantages. However, in the application of sodium carbonate as an absorbent for CO₂ capture, there is no unified cognition of the mass transfer process, which leads to the lack of guidance for the industrial large-scale process. Moreover, the mechanism of mass transfer enhancement of surfactants, which can effectively improve the mass transfer performance, has not been effectively explored in the literature. Based on this, this paper firstly adopts the molecular dynamics method to analyze the solution characteristics after surfactant addition and optimize the surfactant. Subsequently, a classical dissolved oxygen test method was used to measure the gas-liquid mass transfer coefficient for CO₂ absorption into sodium carbonate solution. And based on this mass transfer coefficient measurement method, the mass transfer process of sodium carbonate solution with surfactant was analyzed. The results showed that the sodium carbonate solution with 5 wt% concentration and 10 wt% concentration at 30 °C did not satisfy the pseudo first-order fast chemical reaction kinetics assumption. To improve CO₂ absorption mass transfer rate, dodecyl trimethyl ammonium chloride (DTAC) surfactant was introduced, which was improved by 119 % compared with non-enhanced solvent at 5 wt% concentration solution, and the assumption of pseudo first order fast chemical reaction was satisfied. After the introduction of surfactant, the barrier effect decreased the liquid phase mass transfer coefficient, but the Marangoni effect happened in the 5 wt% concentration of sodium carbonate solution, which enhanced the liquid-phase mass-transfer coefficient. This finding reveals the mechanism of mass transfer promotion of sodium carbonate by the surfactant DTAC, which is of great engineering significance for the application in the field of decarbonization after the introduction of surfactant.

Direct air capture (DAC) represents an advanced negative carbon emission technology, with the key being high-performance CO₂ adsorbents. First, this work carefully identifies CO₂ physisorption and chemisorption by CaO/HcATP (CaO loaded on acid-modified attapulgite) as DAC adsorbent. The chemisorption of amorphous "CaO" plays a crucial role in both the adsorption capacity and rate, with contributions of 66.8 % and 50.85 %, respectively. The adsorption capacity of CaO/HcATP is only 212.4 ± 25.7 µmol/g via the simple CO₂ physisorption and improved by 426.7 µmol/g owning to the chemisorption of amorphous CaO. Second, the concentration of silanol groups on CaO/HcATP plays a pivotal role in the adsorption process. The concentration of silanol groups decreases to 3.85 OH/nm² after undergoing 30 cycles of adsorption-desorption. Then it increases to 9.54 OH/nm² by adsorbing the moisture in the air, resulting in a recovered adsorption capacity of 90.7 %. Furthermore, the pseudo-first-order adsorption kinetics model effectively predicted the experimental results. Finally, the dual loop of CO₂ capture and regeneration is summarized using the CaO/HcATP as DAC adsorbent. The amorphous "CaO" interacts with the surface silanol of HcATP, synergistically capturing CO₂ in the form of "CaO···CO₂", which reduces desorption energy consumption. The wetting property of HcATP contributes to the regeneration of CaO/HcATP. This work contributes to establishing fundamental principles for designing cost-effective DAC adsorbents.

Aerosol emissions from the CO₂-capture process have a significant impact on both solvent depletion and environmental contamination. This work comprehensively investigated the emissions of AMP (2-amino-2-methyl-1propanol)/PZ (piperazine) from a bench-scale platform and a CO₂-capture pilot plant. The concentration of nuclei in flue gas is a key factor affecting aerosol emissions, and a high nuclei concentration leads to more serious aerosol emission problems. The amine emissions after the absorber in the three different scenarios (no added nuclei, nuclei added, and pilot plant) were 273, 1051, and 1347 mg/Nm³, respectively. Increasing the lean-solvent temperature promoted aerosol emissions, and increasing the liquid/gas ratio and CO₂ loading in the lean solvent suppressed aerosol emissions. In the pilot plant, the effects of four mitigation measures were evaluated, and it was found that dry bed and acid washing had better mitigation effects than did conventional water washing; amine emissions could be reduced to as low as 21 mg/Nm³ PZ and 25 mg/Nm³ AMP. This study provides a reference for the design and optimization of carbon-dioxide-capture systems, which can help to reduce the impact on the environment.

Mixed-matrix membranes (MMMs) leverage the processability of polymers and selectivity of Metal-Organic Frameworks (MOFs). However, they still suffer from poor interfacial compatibility and limited scalability in preparation. In certain polymers, MOFs can bridge the pores within the polymer membrane, enhancing the CO₂ adsorption and solubility properties, thus selectively boosting the CO₂ permeability. In this study, high-performance MMMs were prepared using scalable CALF-20 in combination with PIM-1. MMMs with a 5% doping level achieved CO₂ permeability up to 8003 barrer with 25% improvement in CO₂/N₂ selectivity. This enhancement was attributed to well-designed MMMs, where MOFs matched the abundant non-interconnecting pores in the PIM-1 membrane. This study represents a significant advancement towards scaling up the preparation of high-performance MOF-based MMMs for carbon capture applications.

In this study, a novel composite was engineered by integrating Zr-MOF (NH₂-UIO-66) with MXene layers through electrostatic self-assembly. Under simulated sunlight and at 80 °C, this composite material achieved nearly complete conversion of low-concentration atmospheric CO₂ to CO and CH₄ without additional sacrificial agents or alkaline absorption liquids, marking one of the few reports demonstrating near-complete reduction of low-concentration CO₂ directly from the air. For high-concentration CO₂ in industrial flue gas, the composite utilized residual heat at 80 °C without additional energy input, exhibiting excellent CO₂ reduction efficiency with CO and CH4 production rates of 127 μmol·g^-1·h^-1 and 330 μmol·g^-1·h^-1, respectively, resulting in a total production rate 4.76 times higher than that in the air. Compared to most reports on thermocatalytic CO₂ reduction (>300 °C), this material shows significant advantages below 100 °C. The performance improvement is attributed to the introduction of Zr-MOF, which provides additional active sites and reduces activation energy. Additionally, the localized surface plasmon resonance (LSPR) effect of MXene facilitates the migration of thermal charge carriers to Zr⁴⁺ sites within the MOF. Density Functional Theory (DFT) calculations validate these findings. Overall, Zr-MOF/MXene composite holds potential for reducing CO₂ in air and industrial settings, advancing energy conversion and environmental management.

The integrated CO₂ capture and utilization employs chemical looping approach for suppressing the equilibrium limitations of traditional gas-solid catalytic reactions, enabling efficient conversion of dilute CO₂ into high-value fuels with minimal energy consumption. However, the diminishing cyclic activity of dual-functional materials poses significant challenges to their industrial application. Herein, we tailored a series of magnesium-calcium materials, the influence of coordinated metals on the cyclic performance were quantitatively investigated. Notably, Fe₂Ni₂Ce₂Mg₅Ca₂₀CO₃ achieves a cumulative CO yield of 121.0 mmol/g over 15 cycles at 650°C, with a maximum CO yield of 8.3 mmol/g per cycle and 99.0% CO selectivity, and its CO₂ capture capacity remains stable at 10.6 mmol/g over 37 adsorption/desorption cycles. Experimental results indicate that lattice phase separation is a fundamental mechanism underlying the decline in cyclic activity. The strategic incorporation of transition metal intermediates promotes the formation of dispersed metal-carbonate interfaces, providing surface hydrogenation sites and accelerating the lattice decomposition and reconstruction of CO₃* within a dispersed lattice. This modification mitigates the adsorption/catalytic lattice phase separation, boosts metal migration and deoxygenation activity for cyclic nanoparticle construction. The findings offer valuable strategies for designing highly efficient and stable DFMs in CO₂ capture and utilization.

The growth of coherently engineered porous bimetal (PBM) nanostructures shows great progress in electrochemical carbon dioxide (CO₂) utilization. This is due to their remarkable catalytic and physicochemical merits that present an encouraging approach for CO₂ conversion into valuable products (i.e., fuels and chemicals). Hence, this review presents recent advances in experimental, in-situ analysis and theoretical studies of PBM electrocatalysts, including PBM Cu-based and PBM Cu-free electrocatalysts, toward CO₂ reduction reaction (CO₂RR) and comprehend its fundamental mechanisms. Various synthesis strategies were utilized to construct PBM nanostructures with distinct compositions, morphology, and synergism for excellent CO₂RR activity, stability and product selectivity. As corroborated by theoretical calculations that revealed beneficial electronic features and reaction routes with facile adsorption energies for reactant (CO₂) and intermediate species on the various active sites of PBM nanostructures in easing the CO₂RR. Future research efforts should establish robust framework for experimental, in-situ analysis, theoretical simulations and automated machine learning in developing next-generation electrochemical CO₂ utilization technologies with PBM nanostructures. Finally, this study emphasizes the potential of PBM nanostructures for efficient electrochemical CO₂ utilization and provides a pathway to sustainable and inexpensively viable carbon-neutrality.