Carbon Capture Science & Technology最新文献

CO₂ separation plays a crucial role in tackling the climate change induced by the greenhouse effects and improving the energy quality of natural gas and biogas. The efficient CO₂ separation technology is highly required. Membrane separation technology is particularly attractive in CO₂ separation processes owing to its advantages. However, the trade-off relationship limited the gas separation efficiency of polymeric membranes in gas separation processes. Therefore, it is necessary to prepare the high-performance membranes such as mixed matrix membranes (MMMs) for CO₂ separation. This review mainly focuses on the preparation methods, the material properties and the CO₂ separation efficiency of the MMMs containing various fillers such as modified ZIFs, MOFs, and GO, and the emerging MOF-based composites, 2D MOFs and 2D MXene. The modified fillers demonstrated higher compatibility with polymer matrix, resulting in enhanced mechanical stability and CO₂ separation efficiency of MMMs. 2D materials could significantly enhance the CO₂ separation efficiency of MMMs, owing to their layered structure and the effective regulation of gas transport ways. Finally, the future direction and conclusions of fillers and MMMs in gas separation processes are provided.

The integrated carbon capture and utilization (ICCU) technology, combined with the reverse water-gas shift reaction (RWGS), is considered a promising strategy for mitigating carbon emissions. This study investigates the limestone calcination and hydrogenation processes under relatively high partial pressures of CO₂ in near-equilibrium conditions, at partial pressures (P) close to the equilibrium pressure (P_eq), relevant to the ICCU-RWGS process, particularly during the in-situ CO₂ conversion stage. The decomposition of CaCO₃ during conventional calcination and hydrogenation under near-equilibrium conditions was initially examined using micro-fluidized bed thermogravimetric analysis coupled with mass spectrometry (MFB-TGA-MS) and a particle-injecting method. The results indicated that limestone decomposition during conventional calcination was inhibited under near-equilibrium conditions, with conversion near 0%. However, during the hydrogenation process, the interaction between H₂ and CaCO₃ further activated the decomposition of limestone. At 750 °C and P/P_eq=0.9, limestone particles took ∼100 s to achieve complete conversion (100%). Given the known self-catalytic activity of CaO in converting carbonate to CO during hydrogenation, a dual-layer limestone hydrogenation process was further conducted using a fixed bed reactor. At 850 °C and a 30 vol.% H₂ atmosphere, the limestone decomposition rate increased significantly and subsequently reacted with H₂ to form CO, resulting in an H₂/CO ratio of approximately 2.5. These findings support the viability of ICCU-RWGS approaches for future commercialization, with the product gas serving as the feedstock for the Fischer–Tropsch Synthesis (FTS) process.

Biodiesel synthesis and purification are critical stages in the production process, continually evolving to address environmental concerns and improve operational efficiency. Currently, biodiesel production has seen significant growth with numerous commercial plants operating worldwide, contributing to the blend of biodiesel with fossil fuels to reduce carbon emissions. Diverse feedstocks, including vegetable oils, animal fats, and waste oils, are increasingly used to enhance the sustainability of biodiesel production. This review examines recent innovations and challenges in biodiesel synthesis and purification, encompassing a diverse range of methodologies. Emphasizing the importance of biodiesel feedstock, the study conducts a comprehensive analysis of various sources contributing to biodiesel production. Synthesis methods, including transesterification, direct use, blending, micro-emulsion, and thermal cracking, are evaluated for their environmental impact and economic feasibility. Furthermore, purification strategies such as wet washing, distillation, adsorption, membrane separation, and solvent-aided crystallization (SAC) are scrutinized for their effectiveness and environmental implications. The review discusses the role of technological advancements in addressing challenges associated with traditional methods, such as high water consumption, energy-intensive processes, and wastewater generation. Moreover, it provides insights into how these innovations can enhance the sustainability, cost-effectiveness, and scalability of biodiesel production. This academically rigorous review offers a nuanced understanding of biodiesel production, combining analysis of feedstock considerations, synthesis methods, and purification strategies to advance discourse on sustainable biofuel production.

To meet temperature goals that limit warming to well below 2 °C requires the removal of hundreds of billions of tonnes of CO₂ from the atmosphere over the course of this century. Effective Carbon Dioxide Removal (CDR) methodologies will be required to reduce net emissions in the near term, counterbalance residual CO₂ emissions to achieve net-zero in the medium term, and contribute to net-negative emissions in the longer term – all of this in a sustainable and safe manner. This paper summarizes the research objectives and selected initial results of a collaborative project to assess CO₂ storage in the upper ocean crust south of Iceland.

The AIMS³ project (www.aims3.cdrmare.de) will deliver new insights, monitoring tools and feasibility assessments for CO₂ storage in young, reactive basalts with little sedimentary cover. Along the flank of the Mid-Atlantic Ridge, we have done geophysical surveys and drilled a transect of boreholes in order to identify fluid migration in the upper ocean crust. Both in situ heat flow and geochemical signatures provide irrefutable evidence for such transport, which will help distributing injected CO₂ in future experiments.

In parallel, our project also has mineralization experiments to assess optimal conditions for injection dissolved, liquid, or supercritical CO₂), numerical modelling for upscaling our results from seagoing work, and development of cost-effective sensors and smart robotic landers for long-term monitoring of the vicinity of the boreholes. We outline the rationale of AIMS³, provide an overview of the activities, and highlight some of the expedition results, with the goal to stimulate communication and collaboration.

In this study, copper- and chromium-based (HKUST-1 and MIL-101(Cr), respectively) metal-organic frameworks (MOF) functionalized with amine groups (HKUST-1‒NH₂ and MIL-101(Cr)‒NH₂, respectively) were directly synthesized using 2-aminoterephthalic acid as an organic linker via hydrothermal method without adding hydrofluoric acid. They were then investigated for their potential applications in dynamic carbon dioxide (CO₂) adsorption and conversion of epoxides with CO₂. The functionalized MOF (HKUST-1‒NH₂ and MIL-101(Cr)‒NH₂) retained their desired textural properties, while gaining a significantly enhanced Lewis basic character for CO₂ capture and catalysis application. Both HKUST-1‒NH₂ and MIL-101(Cr)‒NH₂ not only showed an improved CO₂ uptake capability, but also an excellent and stable regenerability over multiple adsorption-desorption cycles. MIL-101(Cr)‒NH₂ exhibited a higher performance than the parent MOF and HKUST-1‒NH₂ in the transformation of styrene oxide (SO) with CO₂ to styrene carbonate (SC) and carbonate oligomers (COL) due to combined effect of its textural properties and basicity. Under solvent-free system, COL from monomeric SC was directly obtained, up to 72.4 % yield, via in situ oligomerization. Optimization of the solvent-free reaction conditions was carried out to control the selective pathway of CO₂ utilization between cycloaddition and oligomerization. In the presence of acetonitrile, a > 97 % yield of SC was achieved over MIL-101(Cr)‒NH₂ under a mild reaction condition (120 °C and 20 bar of CO₂). Reaction mechanisms for the cycloaddition and oligomerization of SO with CO₂ are also proposed to comprehend the role of MOF, amine group, and co-catalyst. The combined efficient CO₂ adsorption and capability to produce CC and COL makes the synthesized MOF promising materials for CO₂ capture and selective utilization.

In this study, mixed-matrix membranes (MMMs) were fabricated using a composite of UiO-66 and polyaniline (PANI) integrated into a polyether-block-amide (PEBAX) matrix. The successful synthesis of the UiO-66 and PANI@UiO-66 composites and their incorporation into the PEBAX matrix were validated through X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR) Spectroscopy, Brunauer–Emmett–Teller (BET) analysis, and Thermogravimetric Analysis (TGA). Quantitative permeation tests revealed that the CO₂ permeability in UiO-66 based MMMs increased by 90 % at 30 % filler loading (from 82 to 156 Barrer), and by 45 % (from 82 to 119 Barrer) in PANI@UiO-66 based MMMs, alongside substantial improvements in selectivity. For UiO-66 membranes we observed a selectivity drop for both gas pairs (CO₂/CH₄ and CO₂/N₂) that led to our motivation to modify the MOF. The CO₂/CH₄ selectivity of the PANI@UiO-66 based MMMs enhanced from 22 to 29 (34%) and the CO₂/N₂ selectivity from 48 to 57 (18%). Mixed-gas permeation tests further confirmed the efficacy of the membranes in real-world separation scenarios. The diffusivity and solubility results provide insights into the gas transport mechanisms, revealing the synergistic effects of filler incorporation on membrane performance. The integration of UiO-66 and PANI with PEBAX offers a promising pathway for developing efficient and effective gas separation technologies, aligning with the industrial requirements for environmental sustainability and energy efficiency.

Achieving net carbon neutrality is a global goal toward mitigating climate change presumed consequences. The building and construction sector, responsible for approximately 40 % of greenhouse gas emissions, requires innovative zero-carbon technologies. This paper investigates the synergistic potential of combining 3D concrete printing (3DCP) and carbon capture and sequestration (CCS) to advance net carbon neutrality in construction. By implementing different CO2 spraying regimes, this study demonstrates improved carbon dioxide (CO₂) uptake and the crystallinity of precipitated calcium carbonate (CaCO₃). The findings indicate that the method's effectiveness heavily relies on appropriate printing parameters and curing conditions. Chamber-cured samples exhibit the highest CO₂ uptake but the lowest mechanical strength, while ambient-cured samples show the opposite trend. It is also important to note that the duration of CO₂ exposure in this study was relatively short, resulting in limitations in both CO₂ uptake and strength gain. Nevertheless, this study highlights the potential of synergistically combining 3DCP and CCS technologies for net carbon neutrality, emphasizing the critical role of the construction sector in achieving global emission reduction targets.

The reversible CO₂ absorption/desorption of lithium orthosilicate (Li₄SiO₄) sorbents holds potential for high temperature capture of CO₂ from hot flue gases, sorption-enhanced reforming and solar thermochemical energy storage. In this study, we have prepared a series of Li₄SiO₄ sorbents using a combination of K₂CO₃ addition and dry ball-milling procedure to improve the relatively slow kinetics under low CO₂ partial pressure conditions. The synergistic effects of dry ball-milling and K₂CO₃ addition on the intrinsic properties of Li₄SiO₄ sorbents were explored by thermogravimetric analysis and structural characterizations. Thermogravimetric analysis indicate that the highest CO₂ uptakes were achieved with dry ball-milling combined with K₂CO₃ physical addition. The structural characterizations further reveal that this sorbent (P-3K-1.5 M) had the smallest crystallite/particle size, largest surface area, and highest availability of surface alkaline-sites. The kinetics analysis also demonstrates that P-3K-1.5 M exhibited the fastest sorption kinetics during a double process. Additionally, P-3K-1.5 M maintained a high capacity over 10 sorption/desorption cycles. Therefore, this synthesis technique, which is simple, cost-effective, and easily scalable, shows great promise for high-temperature CO₂ capture.

Carbon mineralization is an emerging field of research in carbon sequestration. In this process, dissolved inorganic carbon reacts with mineral cations such as Ca²⁺ and Mg²⁺ to form stable carbonate minerals, enabling permanent carbon sequestration and storage. However, current mineralization methods predominantly rely on physicochemical approaches to expedite the mineralization of carbon. While effective, these methods require substantial chemical and energy consumption and may cause significant environmental impacts. Biomineralization has recently emerged as a sustainable alternative, leveraging biochemical reactions to catalyze CO₂ mineralization. This research focuses on investigating the specific roles of various biomolecules in natural carbon biomineralization and exploring state-of-the-art biomimetic carbon mineralization techniques, including whole-cell microbially induced carbonate precipitation (MICP) and cell-free systems, for carbon sequestration. In addition, we discuss various sources of mineral cations, ranging from natural minerals to industrial waste to seawater, along with their advantages and limitations. Our findings highlight the potential and feasibility of biological carbon mineralization processes to contribute towards sustainable carbon sequestration. However, we also identify challenges and propose future directions to guide further research and the application of these processes.

The preparation of carbon nanotubes (CNTs) from plastics is of great significance for realizing high value utilization of waste and reducing carbon emission. Here, several kinds of real waste plastics were introduced into catalytic pyrolysis, and the process was also optimized. The results showed that the presence of impurities (e.g., adhesive labels) reduced the initial activation energy of the pyrolysis reaction, and the pyrolysis process was extended and could be divided into two stages. During the catalytic process, impurities play a toxic role on the catalyst at higher temperatures and result in the agglomeration of catalyst particles and a decrease in catalytic activity. Less than 10 wt.% carbon fibers were collected from milk cup waste. However, after experimental optimization, the influence of the impurity component was greatly reduced. The toxic effect of organic impurity volatiles on a catalyst was avoided by employing a segmented catalytic pyrolysis process, which led to an increase in solid carbon content of more than 20 % for express package waste. Simultaneously, more uniform and smoother CNTs can be found in the obtained solid carbon. The process of preparing carbon nanotubes with higher yield and better quality is feasible and has important application prospects in the utilization of waste plastics.