Industrial CO2 Research Articles

Environmental performance evaluation in the forest sector: An extended stochastic data envelopment analysis approach

This study addresses the global concern about undesirable outputs in the Forest Sector. We propose two innovative models, namely a directional weak disposable DEA model and an extended stochastic DEA model, to measure environmental efficiency. These models make a significant contribution to the field by specifically assessing the uncertain environmental efficiency of the forest sector. We validated our proposed models by conducting an empirical application using the United Nations Economic Commission for Europe (UNECE) forest sector dataset. The study examines important outputs such as above ground biomass stock, export unit prices of industrial roundwood, wood removals (desirable outputs), and CO2 emissions from wildfires (undesirable output). The results demonstrate that our novel stochastic weak disposability DEA model outperforms traditional approaches when the second scenario is applied. Specifically, the average technical efficiency (TE) score decreases to 0.92, and the number of efficient units reduces to 27, representing an approximate improvement of 55 %. Furthermore, the reduction rate of CO2 emissions is 4.09 % lower than the benchmark. Hence, our extended novel stochastic weak disposability DEA approach enhances the assessment of efficiency and inefficiency in decision-making units, contributing to the mitigation of risk and uncertainty. It also improves overall environmental performance in forest management.

Strategic CO2 management in the energy and petroleum sector for the production of low-carbon LNG: A Qatar Case Study

The imperative to mitigate industrial CO2 emissions amidst global climate change has led to the development of innovative strategies that align economic growth with environmental sustainability. This study introduces a comprehensive CO2 allocation and utilisation framework, designed to reduce the environmental impact on the production of Liquefied Natural Gas (LNG). Demploying a multi-objective Linear Programming (LP) approach, the study introduces a system that dynamically allocates CO2 from a major source to several sinks, each with unique characteristics and requirements. Focusing on the State of Qatar, a major player in the global LNG market, advanced simulation tools, such as Aspen HYSYS and QASR Simulator are utilised to define the parameters of these sinks, ensuring precise and efficient CO2 allocation. An integral component of the model is the incorporation of a carbon tax, considered for both the source and the sinks. The results demonstrate that the profit maximisation objective generated a $23.6 billion annual profit, although with high emissions of 23.37 Mt/year. In contrast, the emission minimisation objective curbed emissions to 19.01 Mt/year at a profit of $1.4 billion. The multi-objective approach garnered $18.6 billion annually with emissions at 22.37 Mt/year. The CO2/LNG metric was used to gauge LNG's environmental footprint. Objective 1 yielded a ratio of 0.3033, while objective 2 achieved the best score at 0.2463. The multi-objective approach balanced both, with a ratio of 0.2905. These findings illuminate the feasibility of optimising industrial practices for producing low-carbon LNG through deliberate CO2 allocation and within a circular economy framework.

Development of a new laboratory-scale reduction facility for the hydrogen plasma smelting reduction of iron ore based on a multi-electrode arc furnace concept

Steel production accounts for a significant share of industrial CO2 emissions. The HPSR process is a possible alternative to reduce these emissions massively if not completely negate them. In principle, Fe-ore is reduced at high temperatures in the plasma of a DC electric arc. hydrogen reacts with the oxidic melt at the gas-liquid interface. Various concepts for the hydrogen plasma reduction of iron ore have been investigated, but the process technology has not yet surpassed the demonstration scale (TRL5). Experimental setups for charging masses from a few grams to a few hundred kilograms have been realized. Further investigations on the process stability and the reaction kinetics are still necessary. An improved laboratory-scale furnace concept shall provide the basis for the fundamental research. An existing laboratory facility is the starting point for designing and constructing the new plasma furnace. There are several problems with this experimental setup. Mainly, the reactor’s dimensions and power supply limitations restrict the arc’s length. The first leads to problems with excessive refractory wear, while the latter limits the variation of process parameters. Strong cooling when using Fe crucibles and the unstable nature of the arc complicate the process control. A promising concept to deal with the problem of arc stability is the use of multiple electrodes in a direct current arc furnace. Together with an optimized furnace geometry, new potential for further investigations can open. Using a multi-cathode furnace is also promising to further explore ferroalloy production via hydrogen plasma reduction. An electric arc furnace was designed based on the requirements for the planned plasma reduction facility. The energy requirement was based on assumptions for heat transfer from the arc to the melt, walls, and lid and continuous transfer through the individual furnace parts. Considerations of power supply, hearth dimensions, refractory design, controlled gas atmosphere, and the implementation of auxiliary equipment were central to creating an ideal basis for various experimental setups.

Could environmental regulation effectively boost the synergy level of carbon emission reduction and air pollutants control? Evidence from industrial sector in China

In response to the pressure of combating climate change and enhancing air quality, China has tightened environmental regulations. In China, reducing carbon emissions and air pollutants together has become a critical target for environmental protection. However, no literature explores the impact of environmental regulation on the synergy level of reducing CO2 and air pollutants in the industrial sector. Therefore, this study explores whether environmental regulation could effectively boost the synergy level of carbon emission reduction and air pollutants control in China's industrial sector. We first construct an evaluation indicator system for synergistic emission reduction of CO2 and air pollutants (SO2, NOx, PM), then employs the coupled coordination model to evaluate the synergy level of emission reduction. Furthermore, we explore the impact pathway of environmental regulation on the synergy level of emission reduction. The results indicate that: (1) On the whole, the synergy level shows a slow upward trend, but remains insufficient from 2011 to 2020. (2) Overall, environmental regulation significantly boosts the synergy level of carbon emission reduction and air pollutants control. Regarding the impact pathway, industrial structure has a completely promoting effect, while technical progress exerts a suppressing effect. (3) In regions with higher economic development, environmental regulation has a greater positive influence on synergy level, and the suppressing effect of technical progress is weaker than in less developed regions. These findings could provide helpful references for policy making on synergistic emission reduction of industrial CO2 and air pollutants in China.

Improving Energy Efficiency of Carbon Capture Processes with Heat Pumps

Carbon capture based on chemical absorption in amine-based solvents is the most relevant technology option to reduce CO2 emissions from hard-to-abate industrial CO2 sources and power plants. Because of the energy consumption of the carbon capture process, which is mainly attributed to heating the desorber, carbon capture has a negative impact on the efficiency of the process where CO2 is removed. Heat pumps allow for heat recovery and provide high temperature process heat. Due to recent developments, heat pumps are now capable of supplying steam and providing high temperatures enabling new applications. This contribution investigates the integration of heat pumps into the carbon capture process of a furnace for steel processing to determine the most suitable heat sources and sinks and the achievable energy savings. The energy consumption of the carbon capture process can be lowered by 50% due to the integration of steam generating heat pumps. The cost analysis shows that the costs of steam have the highest influence on the costs of captured CO2.

Towards the Use of Renewable Syngas for the Decarbonization of Industry.

In this article we analyze how syngas produced in a renewable way can replace fossil-fuel based syngas production and thereby play an essential role in the decarbonization of industry. We show that in essentially all industrial applications renewable H2 and/or CO can replace syngas from fossil fuel feedstocks, and quantify the flows of these chemical building blocks required for the transformation of industry towards a net-zero emitting sector. We also undertake a techno-economic analysis, in which we demonstrate that under specific assumptions for the learning rates of some of the key process components, renewable syngas can become cost-competitive with that produced from fossil fuels. Cost competitiveness, however, only materializes for four of the five routes when natural gas prices are at least around 3 €/GJ and carbon taxes increase from 90 €/tCO2 today to 300 €/tCO2 in 2050.

Facile and efficient amine@AD-SiO2 adsorbents from coal fly ash: Comparison of various amines for CO2 adsorption capacity and cyclic stability

Solid amine adsorbent is recognized as an efficient CO2 capture route for globe climate change mitigation. The pore structure of nano supports generally plays a crucial role in the CO2 adsorption performance of solid amine adsorbents; however, the involving of costly and toxic pore-expanding agents limited their scalable application. Herein, an azeotropic-distillation nano-SiO2 (AD-SiO2) support was recycled from coal fly ash (CFA) using the CO2-assisted precipitation and n-butanol AD methods, and possessed a super pore volume of 2.52 cm3·g−1 and an average pore size of 36.6 nm. After impregnating the triethyltetramine, tetraethylenepentamine, pentaethylenehexamine (PEHA), or polyethyleneimine, the synthesized amine@AD-SiO2 adsorbents achieved the excellent adsorption capacity of 3.50–6.13 mmol·g−1 and the fast adsorption kinetics, owing to the superior pore structure of AD-SiO2 support. Based on the viscosity, TGA and liquid-NMR characterization, we explained that the large amine molecule would block the CO2 diffusion channel and thus restrict the active sites, while the small amine molecule would evaporate during the regeneration process. Inspiringly, the PEHA@AD-SiO2 adsorbent possessed the excellent cyclic stability with merely 0.18 % decay per cycle and achieved a final CO2 uptake of 4.24 mmol·g−1 over 50 cycles. This study notably improved the long-term adsorption capacity of solid amine adsorbents via the pore-expanded AD-SiO2 support from CFA, thereby is a low-carbon technology for large-scale industrial CO2 capture.

How to effectively achieve air pollutant reduction and carbon mitigation in China's industrial sector? A study based on decomposition analysis and scenario simulation.

Reducing air pollutant and carbon emissions in the industrial sector is crucial for the ecological civilization construction in China. In this study, we first employ the generalized Divisia index method to analyze the driving factors of industrial CO2 and SO2 emissions, incorporating fixed asset investment and R&D input. The key sub-sectors that exert significant impact on emissions of the whole industrial sector are identified. And then, scenario analysis and Monte Carlo simulation are utilized to predict future trends and potential for reducing CO2 and SO2 emissions. Furthermore, the carbon peaking time of the industrial sub-sectors is investigated. The results indicate that fixed asset investment and R&D input both have played positive roles in CO2 and SO2 emissions. Emission reduction is mainly driven by investment emission intensity, output emission intensity, and R&D emission intensity. Sub-sectors S09, S10, S11, S12, and S18 present substantial potential for reducing air pollutant and carbon emissions. Although SO2 emissions from the industrial sector are projected to decrease in the future, the peak of CO2 emissions have not been reached. The carbon peak time for the whole industrial sector is predicted in 2025, with the peak of 7892.33 Mt. The five key sub-sectors are anticipated to reach the respective carbon emission peaks at different times. Therefore, to effectively implement industrial air pollutant and carbon reduction, the role of fixed asset investment and R&D input should be fully utilized, and high-energy consumption and high-emission sub-sectors should be prioritized for action.

Impact of reservoir quality on the carbon storage potential of the Bunter Sandstone Formation, Southern North Sea

The Lower Triassic Bunter Sandstone Formation is a major prospective reservoir for carbon capture, utilization and storage in the UK Southern North Sea, and is likely to play a pivotal role in the UK reaching mid-century Net Zero targets. A knowledge gap in reservoir quality exists between previous detailed, but highly focused front-end engineering and development projects, and large-scale regional analysis. This study integrates a regional approach with locally derived reservoir characterization, offering a holistic analysis of the prospectivity of the Bunter Sandstone Formation for subsurface CO 2 storage. Petrophysical analysis of ninety-six wells across the UK Southern North Sea is coupled with seismic interpretation to understand spatial variations of reservoir thickness, facies and quality that underpin theoretical CO 2 storage capacity models. Electrofacies classification is employed to identify and correlate baffles and barriers to permeability over areas currently licensed for geological carbon storage. Our findings point to variable, but broadly favourable reservoir conditions, though identification and correlation of laterally extensive intraformational mudstones and halite-cemented horizons will likely present challenges to CO 2 injection. Within carbon storage license blocks CS001, CS006 and CS007, the Bunter Sandstone Formation has the potential to store 5700 MCO 2 t, the equivalent of seventy-nine years of the UK's 2022 business and industrial CO 2 emissions. A further 434 MCO 2 t is offered by Triassic closures within license CS005, with many neighbouring moderate (100–1000 MCO 2 t) and small (<100 MCO 2 t) closures forming part of newly awarded carbon storage licenses that will likely form part of the UK SNS CCUS portfolio in the future. Supplementary material: well-correlation panels and tabulated velocity and storage capacity modelling parameters are available at https://doi.org/10.6084/m9.figshare.c.7027450

Accelerated carbonation of recycled concrete aggregate in semi-wet environments: A promising technique for CO2 utilization

The practical implementation of accelerated carbonation for recycled waste concrete is impeded by sluggish carbonation efficiency. In contrast to previous carbonation enhancement schemes using high-pressure gas and/or complex pre-/post-processing, this study introduces a novel semi-wet carbonation method that achieves high-efficiency carbonation of recycled concrete aggregates (RCA) in a practically simple way. A noteworthy carbonation degree of 10.6 % was achieved within 30 min at room temperature and ambient pressure, which enhanced the RCA by reducing the water absorption rate and porosity by 3.6 % and 20 % respectively. The formed CaCO3 is primarily in calcite form with poorer crystallinity and smaller grain size and the formed silica gel features a lower polymerization degree compared with those formed in wet carbonation. It is due to that the carbonation reactions for the semi-wet scenario happen at the spatially confined water film of the solid-liquid interface. Moreover, the addition of sodium bicarbonate significantly accelerated the semi-wet carbonation, which is due to the weak alkaline environment lowering the CO2 speciation free energy as revealed by reactive molecular dynamics simulations. The proposed semi-wet carbonation method provides a promising way of pushing industrial CO2 capture and utilization.

Role of Environmental Policy Stringency on Sectoral CO2 Emissions in EU-5 Countries: Disaggregated Level Evidence by Novel Quantile-Based Approaches

Consistent with the increasing awareness of environmental problems, countries have applied various measures to combat climate change by preventing environmental degradation of the environment. In this context, a set of measures in different areas and sectors have been taken. Although it is possible to consider each of them, instead, using a more comprehensive index, such as the Environmental Policy Stringency Index, can be appropriate in examining the effects of environmental measures in curbing emissions. Accordingly, this research examines the effect of Environmental Policy Stringency Index on sectoral carbon dioxide (CO2) emissions in the European Union Five countries (namely, Germany, Spain, France, United Kingdom, and Italy) by using data for the period 1990/Q2-2020/Q4, performing novel quantile-based approaches. The outcomes show that at higher quantiles, Environmental Policy Stringency Index provides (a) a decrease in building sector CO2 emissions in France, the United Kingdom, and Italy; (b) a decline in industrial combustion sector CO2 emissions in France and Italy; (c) a curb power sector CO2 emissions in Germany, Spain, and France; (d) a decrease in transport sector CO2 emission in Germany and France; (e) there are causalities from Environmental Policy Stringency Index to sectoral CO2 emissions across quantiles except for some ones; (f) the outcomes are verified as robust. The outcomes prove the differentiating effects of Environmental Policy Stringency Index across sectors under the empirical examinations, quantiles, and countries. Thus, the study discusses various policy endeavors, such as consideration of the varying structure of environmental measures, application of nonlinear approaches, and focusing on some sectors to go fast in curbing sectoral CO2 emissions.

Recent Progress in Hollow Fiber Gas Diffusion Electrodes for CO2 Electroreduction

CO2 electroreduction (CO2RR) to high‐value chemicals by renewable energy is a promising route for achieving carbon cycling. Traditional two‐dimensional planar electrodes applied in CO2RR are faced with problems of high mass transfer resistance, carbonate precipitation, flooding, and complicated structures, seriously limiting their CO2RR efficiency and application. Three‐dimensional hollow fiber gas diffusion electrodes (HFGDEs) are promising candidates due to their rich specific surface area, low mass transfer resistance, simplified component, and no flooding trouble, which are beneficial for achieving high current density as well as high CO2RR efficiency. In this review, we provide inspirations and positive paradigms for the rational design of HFGDE toward CO2RR by following part: 1. The mechanism of CO2RR. 2. The classification of the typical metal‐based CO2RR catalysts. 3. The preparation process of HFGDEs. 4. Recent advanced HFGDE studies for CO2RR. 5. Challenges at this stage and future development of HFGDEs towards accelerating application of industrial CO2 reduction electrolyzers.

Adaptive laboratory evolution of Clostridium autoethanogenum to metabolize CO2 and H2 enhances growth rates in chemostat and unravels proteome and metabolome alterations.

Gas fermentation of CO2 and H2 is an attractive means to sustainably produce fuels and chemicals. Clostridium autoethanogenum is a model organism for industrial CO to ethanol and presents an opportunity for CO2-to-ethanol processes. As we have previously characterized its CO2/H2 chemostat growth, here we use adaptive laboratory evolution (ALE) with the aim of improving growth with CO2/H2. Seven ALE lineages were generated, all with improved specific growth rates. ALE conducted in the presence of 2% CO along with CO2/H2 generated Evolved lineage D, which showed the highest ethanol titres amongst all the ALE lineages during the fermentation of CO2/H2. Chemostat comparison against the parental strain shows no change in acetate or ethanol production, while Evolved D could achieve a higher maximum dilution rate. Multi-omics analyses at steady state revealed that Evolved D has widespread proteome and intracellular metabolome changes. However, the uptake and production rates and titres remain unaltered until investigating their maximum dilution rate. Yet, we provide numerous insights into CO2/H2 metabolism via these multi-omics data and link these results to mutations, suggesting novel targets for metabolic engineering in this bacterium.

A thorough assessment of mineral carbonation of steel slag and refractory waste

Escalating industrial CO2 emissions necessitate innovative carbon capture and utilization strategies. This study explores the potential of mineral-carbonation of steelmaking slags, particularly White Slag (WS) and various Refractory Wastes (RWs), to mitigate CO2 emissions and valorize industrial wastes. Experiments were performed with waste materials from the production lines at CELSA (Barcelona, Spain). We delved into direct aqueous carbonation, evaluating the performance and characteristics of these wastes under different experimental conditions. Our findings reveal that all slags can effectively sequester CO2. This process is effective not only for pure CO2 but also for diluted flue gases under mild conditions (≤ 100 ºC, ≤ 6 bar). Specifically, WS exhibited peak CO2 sequestration capacities (SC) of 359.79 gCO2/kgslag (pure CO2) and 276.65 gCO2/kgslag (diluted flue gas). In contrast, the RWs presented different kinetic, reaching a maximum SC of 311 gCO2/kgslag after prolonged times. Given the large inhomogeneity of RWs, individual analysis of distinct RW fractions revealed significant variations in carbonation performance. Tundish RW exhibited the highest CO2 sequestration capacity, emphasizing the importance of waste source and mineral composition in the carbonation. Chemical and morphological evaluations confirmed the transformation of CaO to CaCO3, with MgO remaining largely inert. Additionally, the process indicated potential environmental benefits by reducing the mobility of toxic metals, particularly Pb, suggesting an ancillary avenue for waste treatment. This study underscores the utility of CO2 mineralization as a dual-benefit approach within the circular economy framework, offering insights into its application for sustainable waste management and CO2 emission reduction in the steel industry.

CO2 capture using silica-immobilized dicationic ionic liquids with magnetic and non-magnetic properties

The need to find alternative materials to replace aqueous amine solutions for the capture of CO2 in post-combustion technologies is pressing. This study assesses the CO2 sorption capacity and CO2/N2 selectivity of three dicationic ionic liquids with distinct anions immobilized in commercial mesoporous silica support (SBA- 15). The samples were characterized by UART-FTIR, NMR, Raman, FESEM, TEM, TGA, Magnetometry (VSM), BET and BJH. The highest CO2 sorption capacity and CO2/N2 selectivity were obtained for sample SBA@DIL_2FeCl4 [at 1 bar and 25 °C; 57.31 (±0.02) mg CO2/g; 12.27 (±0.72) mg CO2/g]. The results were compared to pristine SBA-15 and revealed a similar sorption capacity, indicating that the IL has no impact on the CO2 sorption capacity of silica. On the other hand, selectivity was improved by approximately 3.8 times, demonstrating the affinity of the ionic liquid for the CO2 molecule. The material underwent multiple sorption/desorption cycles and proved to be stable and a promising option for use in industrial CO2 capture processes.

A life cycle assessment of clinker and cement production in Ethiopia

Cement production is a major consumer of energy and the largest source of industrial CO2 emissions. This study aims to perform an environmental life cycle assessment of clinker and cement production in Ethiopia, using ReCiPe impact assessment method. Inventory data (material, energy, and transportation) is collected from seven major Ethiopian cement industries. The midpoint analysis identified nine hotspot environmental concerns: global warming, ozone formation (human health and terrestrial ecosystem), particulate matter formation, terrestrial (acidification and ecotoxicity), freshwater eutrophication, human carcinogenic toxicity, and fossil resource scarcity. Human health emerged as the most significantly affected endpoint damage category by the midpoint impacts. Among the process stages included in clinker system boundary, clinker production phase (kiln emissions) is a significant contributor to the total score of the hotspot impacts, ranging from 60.7% to 91.8%. The clinker system is responsible for over 81.03% of the overall environmental burden of cement. The sensitivity analysis reveals that a 5% change in kiln energy consumption and transportation burden could lead to a reduction in hotspot impacts ranging from 1.8% to 5%. To foster reliability of this study, uncertainty analysis is also conducted. Overall, the findings indicate the need to enhance environmental sustainability in Ethiopian cement production.

Coupled Oxygen-Enriched Combustion in Cement Industry CO2 Capture System: Process Modeling and Exergy Analysis

The cement industry is regarded as one of the primary producers of world carbon emissions; hence, lowering its carbon emissions is vital for fostering the development of a low-carbon economy. Carbon capture, utilization, and storage (CCUS) technologies play significant roles in sectors dominated by fossil energy. This study aimed to address issues such as high exhaust gas volume, low CO2 concentration, high pollutant content, and difficulty in carbon capture during cement production by combining traditional cement production processes with cryogenic air separation technology and CO2 purification and compression technology. Aspen Plus® was used to create the production model in its entirety, and a sensitivity analysis was conducted on pertinent production parameters. The findings demonstrate that linking the oxygen-enriched combustion process with the cement manufacturing process may decrease the exhaust gas flow by 54.62%, raise the CO2 mass fraction to 94.83%, cut coal usage by 30%, and considerably enhance energy utilization efficiency. An exergy analysis showed that the exergy efficiency of the complete kiln system was risen by 17.56% compared to typical manufacturing procedures. However, the cryogenic air separation system had a relatively low exergy efficiency in the subsidiary subsystems, while the clinker cooling system and flue gas circulation system suffered significant exergy efficiency losses. The rotary kiln system, which is the main source of the exergy losses, also had low exergy efficiency in the traditional production process.

Electrocatalytic reduction of simulated industrial CO2 and CO mixtures: Revising chronoamperometry to enable selective gas mixture reduction via cyclic voltammetry

While substantial advancements have been achieved in the electrocatalytic reduction of pure CO2 or CO, the reduction of carbon oxide mixtures remains underexplored, a key limitation in scaling the technology for industrial applications. This underexplored domain gains practical importance by considering carbon oxide mixtures, given that CO and CO2 together constitute a large proportion of diverse industrial gas streams. However, the simultaneous reduction of mixed CO and CO2 poses a potential challenge due to their differing optimal reduction potentials, which complicates an efficient reduction process. While cyclic voltammetry (CV) is typically used for characterization, which involves sweeping between positive and negative potentials, we utilized it to conduct reduction reactions within a defined negative potential window. This approach, serving as an alternative to conventional chronoamperometry that maintains a constant potential, ensures a continuous reduction reaction throughout the entire cycling process. By employing cycling between the optimized reduction potentials of CO2 (−1.4 V) and CO (−1.6 V), CV achieved an increase in production efficiency, ranging from 25 % to 40 % for predominant products (HCOOH and C2H4), in comparison to chronoamperometry. Meanwhile, the results underscored the dependency of performance enhancement on the scan rate of cycling, revealing plausible correlations with mass transfer and electrode surface dynamics. Furthermore, the findings indicated that the selectivity towards HCOOH and C2H4 is closely related to the CO2/CO ratios of gas sources. This provides insight into the potential for modulating selectivity of industrial gas reduction for improved product quality and customization.

CO2-Philic Nanocomposite Polymer Matrix Incorporated with MXene Nanosheets for Ultraefficient CO2 Capture.

The incorporation of two-dimensional (2D) functional nanosheets in polymeric membranes is a promising material strategy to overcome their inherent performance trade-off behavior. Herein, we report a novel nanocomposite membrane design by incorporating MXene, a 2D sheet-like nanoarchitecture known for its advantageous lamellar morphology and surface functionalities, into a cross-linked polyether block amide (Pebax)/poly(ethylene glycol) methyl ether acrylate (PEGMEA) blend matrix, which delivered exceptional CO2/N2 and CO2/H2 separation performances that are critical to industrial CO2 capture applications. The finely dispersed Ti3C2Tx nanosheets in the blend polymer matrix led to an expansion of the free volume within the resultant mixed matrix membrane (MMM), giving rise to a substantially enhanced CO2 permeability of up to 1264.6 barrer, which is 102% higher than that of the pristine polymer. Moreover, these MXene-incorporated MMMs exhibited preferential sorption for CO2 over light gases, which contributed to an exceptional CO2/N2 and CO2/H2 selectivity (64.3 and 19.2, respectively) even at a small loading of only 1 wt %, allowing the overall performance to not only surpass the latest upper bounds but also exceed many previously reported high-performance nanosheet-based nanocomposite membranes. Long-term performance tests have also demonstrated the good stability of these membranes. This composite membrane design strategy reveals the remarkable potential of combining a blend copolymer matrix with ultrathin MXene nanosheets to achieve superior gas separation performance for environmentally important gas separations.

Development of Industrial CO<sub>2</sub> Refrigeration Unit - Its Energy Saving Effects and Effective Utilization of Waste Heat

Development of Industrial CO<sub>2</sub> Refrigeration Unit - Its Energy Saving Effects and Effective Utilization of Waste Heat