Journal of CO2 Utilization最新文献

This study concerns wet carbonation of β-C₂S (Ca₂SiO₄) in a closed system at 23 °C. The progress of carbonation was detected by quantitative X-ray diffraction (QXRD) and thermogravimetric analysis (TGA). Further measurements of pH and ion concentrations as well as modelling carbon species and saturation indices were done. Additionally, stable carbon isotope ratios (δ¹³C) in CO₂, dissolved inorganic carbon (DIC) and carbonate phases were measured. The aim of this study was to investigate δ¹³C isotope values during C₂S carbonation. If a systematic fractionation of carbon isotopes occurs during the reaction, it can help to quantify the carbonation reaction. During the carbonation process over 48 h, we found carbon isotope distributions from the gaseous phase to the solution and ultimately to the solid phase. Calculations confirm the direct relation of δ¹³C values to the carbonation progress. With this, stable isotope measurements offer a promising tool to monitor the reaction progress in-situ.

Lime mud (LM) is a highly alkaline solid waste generated during the papermaking process, and its direct application in cement-based materials can result in insufficient material properties. Pre-carbonation can reduce the alkalinity of LM and improve its ability as a supplementary cementitious material. This study explored the potential of pre-carbonated lime mud (CLM) to partially replace Portland cement under normal and carbonation curing. It was found that CLM absorbed some CO₂ and reduced a small amount of alkalinity after pre-carbonation treatment. Under normal curing conditions, LM can promote the hydration reaction at an early age but inhibit subsequent cement hydration due to its alkalinity. In contrast, CLM significantly alleviated the negative impacts of directly incorporating LM into Portland cement. Under carbonation curing conditions, a significant improvement in the compressive strength of cement-based materials containing LM and CLM was observed. The alkaline properties and nucleation effects of CLM and LM enhanced CO₂ sequestration efficiency. Especially after 14 days of carbonation curing, the sample with CLM exhibited higher CO₂ uptake and better mechanical properties than the sample with LM. This study provides a new solution to improve the resource utilization of LM and mitigates the negative impacts of LM on cement-based materials.

This study investigates the long-term stability and performance in chemical looping reverse water-gas shift reaction (rWGS) of a 50 wt% Fe₂O₃-MgAl₂O₄ material produced using an industrial method. While prior research predominantly focuses on short-term deactivation of lab-scale materials, this research explores the complex relationship between the cycle duration, material performance and stability of an upscaled material. Through comprehensive analyses, successful upscaling is demonstrated. Performance tests on the upscaled material reveal that shorter cycle durations lead to superior CO space-time yield, with a steady-state deactivation rate of 0.07 %/h over 28 days on stream. During the first 225 h of redox time, the equilibrium CO₂ conversion for catalytic rWGS is exceeded. Characterization post-cycling identifies key deactivation mechanisms, underscoring the challenge of maintaining stability over extended cycles. Rietveld refinement and STEM-EDX mapping indicate the formation of Fe_xMg_1-xAl₂O₄ and MgFe₂O₄ phases, the former of which contributes to reduced redox capacity, as indicated by temperature-programmed reduction measurements before and after cycles. Optimal performance was observed with shorter cycles despite lower material utilization, emphasizing the trade-offs between performance and stability. This research provides comprehensive insights for optimizing chemical looping CO₂ utilization processes, vital for advancing scalable and economically viable solutions to combat carbon emissions.

The mechanism of early age accelerated carbonation cured ordinary Portland cement mixtures is evaluated using experimental and thermodynamic modeling. This study considered three early precuring conditions, two carbonation curing periods, four CO₂ concentrations, and a 0.5 w/c ratio. The investigation was conducted using phase profiling of mixtures based on QXRD results and developed a thermodynamic model that simulated the experimental conditions. The mechanical characteristics of carbonation-cured mortar specimens, including compressive strength, elastic modulus, shrinkage, and mass change, were evaluated. The results revealed that short precuring durations hindered carbonation, resulting in lower CO₂ uptake, strength, elastic modulus and higher shrinkage. Increasing the precuring period from six-hours to one or three days resulted significant amount of CaCO₃ precipitation on the surface of the specimen and appropriate mechanical properties. One day precuring followed by one day carbonation with a 10 % CO₂ exposure resulted in a higher calcite precipitation on the surface with less depth of penetration. It was found that a balance between drying-induced degradation and microstructure densification due to calcite precipitation is crucial. An appropriate precuring duration, for each binder type and mix proportion, should be applied to achieve desired properties and CO₂ uptake in carbonation-cured cementitious materials.

Accurate understanding and quantitative characterization of the microscopic distribution and mobilization mechanisms of remaining oil are crucial for further enhancing oil recovery during CO₂ flooding. In this study, miscible CO₂ flooding experiments after water flooding were performed to investigate the mass transfer and microscopic distribution characteristics of remaining oil and CO₂ using micro-computed tomography technique. Additionally, the distribution characteristics of multiphase fluids (oil, water and CO₂) in the pores were comprehensively investigated. Furthermore, the mass transfer effects during the miscible CO₂ flooding process, as well as the CO₂ sequestration ratio (SR) and sequestration factor (SF) were systematically examined. The experimental results show that the ultimate oil recovery factor after miscible CO₂ flooding were 80.9 %, 70.7 %, and 64.7 %, respectively. During the water flooding stage, the produced oil mainly consisted of light hydrocarbons (C₅–C₁₆), followed by medium hydrocarbons (C₁₇–C₂₇). The remaining oil was mainly in cluster and network pattern, followed by multiple and oil film pattern. After miscible CO₂ flooding, the produced gas mainly consisted of CO₂ and CH₄, with a significant increase in the mass fraction of light hydrocarbons (C₅–C₁₆) in the produced oil. The remaining oil was mainly in multiple and singlet pattern, followed by network and film pattern, with a small portion in cluster pattern. The higher the displacement rate, the smaller the SR, but most of the injected CO₂ (SR > 70 %) was retained in the porous media, demonstrating the feasibility of CO₂ geological sequestration during the miscible flooding process.

Constructing stable nanochannels and nanoconfined environments for ionic liquids holds significant application value in gas separation, ion channels, and related fields. The functional polyionic liquid synthesized in this study exhibits a controllable assembly structure and demonstrates liquid crystal properties. Through heating and water treatment, the polyionic liquids crosslink to form multi-hierarchical nanopores, including sub-nanochannels with pore sizes similar to CO₂, without the need for a catalyst. The specific surface area and pore size of the polyionic liquid network (PILC) were adjusted by regulating the self-assembly of polyionic liquids in water. The unique PILC, combining ionic liquid nanopores and liquid crystal structure properties, shows high CO₂ adsorption performance and excellent CO₂/N₂ selectivities, surpassing commonly reported ionic liquid porous materials. Furthermore, PILC-2 exhibits good catalytic performance for CO₂ cycloaddition, and its catalytic activity and selectivity did not significantly decrease after five cycles. This study successfully introduces hierarchical ionic liquid nanochannels into porous networks without involving any inorganic ordered nanomaterials. This provides a simple and effective approach for the highly selective adsorption and separation of CO₂, as well as for the preparation of catalytic materials.

In the present study, the integration of electrochemically mediated amine regeneration (EMAR) with amine thermal swing process is investigated as a novel method for CO₂ capture, utilizing experimental practical data. The aim is to increase the absorption-desorption temperature difference in order to improve the energy efficiency of the capture process and hamper the amine degradation issue at high desorption temperatures. A comprehensive experimental procedure is presented, and an experimental process setup is designed and constructed. As the main novelty of the study a special heating-cooling subsystem is incorporated with the base EMAR process in order to devise a combined electrochemical-thermal system. The performance of the system is evaluated at sequential incremental desorption temperatures while the absorption temperature is kept constant. Relevant data, including the desorbed CO₂ flow, absorbed CO₂ flow, stream points temperature, and cell voltage are collected. Based on the data collected, two performance parameters are calculated, including normalized carbon separation work, and CO₂ desorption density. Based on these performance parameters the system's capability is assessed, and the optimal desorption temperature is ultimately selected. The presented electrochemical-thermal CO₂ separation system, operating with a chloride salt system, demonstrates its best energetics performance at a desorption temperature of 44 °C, resulting in a normalized capture work of 95.2 kJ/molCO₂. Under these optimal conditions, the cell's average voltage is measured to be 0.37 V, and the CO₂ desorption density is determined to be 0.71 l.min⁻¹.m⁻².

The Pressurized Soaking Impregnation Method combines the main advantages of supercritical solvent impregnation and the soaking casting technique. This work studied the impregnation of poly(3-hydroxy-butyrate-co3-hydroxy-valerate) (PHB-HV) sheets with mango leaf extracts using this method for its future use as active packaging. The influence of temperature (35–55 ºC), pressure (10, 20–30 MPa), and depressurization rate (0.1–5 MPa/min) on the impregnation loads, antioxidant capacities, and mechanical properties of the impregnated samples were evaluated. In addition, the morphological characteristics, colour characterization, and release of active compounds in a food simulant of the PHB-HV samples impregnated at 30 MPa were analysed. The results showed higher impregnation loads (7.66 % wt.) at 30 MPa, 55 ºC, and a slow depressurization rate (0.1 MPa/min). However, the impregnation of antioxidant compounds did not show the expected behaviour, reaching values lower than 3 %. In addition, the samples that were impregnated at 30 MPa showed colour differences that were perceptible to the human eye. A non-homogeneous distribution of impregnation, cracks, and pores on the surface were also observed. The release study in the D1 food simulant showed good agreement with the Peleg model and a quasi-Fickian diffusion behaviour according to the Korsmeyer-Peppas model. The contact time study in the impregnation at 30 MPa, 35 ºC and 0.1 MPa/min revealed a slight increase in antioxidant capacity after six hours. Furthermore, samples with a more homogeneous colour distribution were obtained.

In this study, we developed nitrogen-doped carbon supporting materials from biomass-derived fertilizers, offering a sustainable and eco-friendly approach to heterogeneous catalysis for CO₂ hydrogenation. Three types of fertilizers (AA50, AA80, and FV), derived from different biomass sources, were evaluated there potential to prepare the N-doped carbon structure. The synthesis of fertilizer-based supporting materials resulted in an abundant amount and a specific structure of doped nitrogen, essential for immobilizing atomically dispersed Ru catalysts during CO₂ hydrogenation. The catalytic performance of the Ru catalysts supported on optimized fertilizer-derived materials exhibited a turnover number of 2748 over two hours and maintaining 98 % stability across five recycling tests. Analysis of spent catalysts showed that our fertilizer-based supports effectively prevented the sintering and leaching of the Ru catalysts. Moreover, the capability for industrial application was validated through a continuous flow reactor test, achieving an average formate productivity of 697 mmol•g_cat⁻¹h⁻¹ over 100 hours. These results highlight the synthesized Ru catalyst on fertilizer-derived carbon material as a promising solution for eco-friendly CO₂ hydrogenation to formic acid.

Atmospheric-pressure microwave plasma reforming of ethane (C₂H₆)–carbon dioxide (CO₂) mixtures was investigated, potentially for plasma dry reforming of large hydrocarbons. The plasma was characterized using optical emission spectroscopy, and the reforming process was analyzed using gas chromatography and thermocouple measurements. The temperature of the plasma region reached approximately 5000 K, regardless of the specific energy input, which was sufficiently high to initiate the reforming reactions. About 90 % of the C₂H₆-CO₂ mixture was reformed into H₂ and CO with selectivities of about 83 %, at a microwave power and mixture flow rate of 2 kW and 10 slpm, respectively, while the mass flow rate of unmeasured species was less than 1 % of the total. An energy efficiency without any heat recovery schemes was determined to be 49 %, which was slightly higher than that for plasma methane dry reforming because the syngas production becomes favored at a lower temperature for ethane dry reforming. A more detailed analysis was performed by developing a reactor network model. The simulation revealed that the reforming process proceeded as the locally heated plasma flow interacts with its relatively cold surrounding flow through heat and mass transfer. Carbon monoxide (CO) was produced mainly through the reaction H + CO₂ → OH + CO, whereas molecular hydrogen (H₂) was mainly produced through hydrogen (H) abstraction reactions of hydrocarbons. Notably, acetylene (C₂H₂) and ethylene (C₂H₄) were the major by-products due to their higher H abstraction energies.