Greenhouse Gases: Science and Technology最新文献

Enhanced rock weathering (ERW) is an emerging negative emission technology (NET) with significant potential for mitigating climate change and improving soil health through the accelerated chemical weathering of silicate minerals. This study adopts a critical research approach to review existing ERW experiments, focusing on the mechanisms of soil improvement and CO₂ sequestration, as well as the economic costs and environmental risks associated with its large-scale implementation. The results demonstrate that while ERW effectively enhances soil pH and provides essential nutrients for crops, its CO₂ sequestration capacity is highly dependent on variables such as soil type, rock type, application rate, and particle size. Furthermore, the economic feasibility of ERW is challenged by high costs related to mining, grinding, and transportation, and environmental risks posed by the release of heavy metals like Ni and Cr during the weathering process. Notably, significant discrepancies exist between laboratory experiments and field applications, highlighting the need for extensive in-situ monitoring and adjustment of ERW practices. This study underscores the importance of optimizing ERW strategies to maximize CO₂ sequestration while minimizing environmental impacts. Future research should focus on long-term field experiments, understanding secondary mineral formation, and refining the application techniques to enhance the overall efficiency and sustainability of ERW. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd.

Accelerated weathering of limestone (AWL) process efficiently captures CO₂ from point source emissions. However, despite achieving an outstanding capture efficiency of 73.51 %, lab-grade (LG) limestone with 99.90 % CaCO₃ as an absorbent is costly ($2757.70/t), making commercialization of AWL impractical. This work delves into the viability of utilizing construction-grade (CG) limestone (93.26% purity) for the AWL process facilitated by potable water in an absorption tower for post-combustion capture. The result shows that CG limestone achieves comparable CO₂ capture efficiency of 8.0–74.68% and bicarbonate (Ca(HCO₃)₂) concentration of 0.63–3.10 mM compared with LG limestone. However, LG limestone has 0.29 mol CO₂/mol CaCO₃ higher CO₂ absorption capacity and a faster absorption rate than CG limestone, indicating a somewhat better CO₂ capture performance. Nevertheless, CG limestone offered a more cost-effective alternative, with a $2735.24 lower cost per ton of CaCO₃ and a $2651.63 per ton CO₂ lower CO₂ capturing cost at the highest carbon capture efficiency (HCCE) condition compared to LG limestone. The kinetic analysis shows that the forward reactions in the AWL process are significantly faster at elevated CO₂ concentration, with the mass transfer coefficient affirming that CO₂ dissolves faster than CaCO₃, in line with prior research. Thus, this work validates that CG limestone-based AWL achieves comparable CO₂ capture performance to that of LG limestone, offering a cost-efficient alternative. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd.

Potassium hydroxide and potassium carbonate, being cost-effective and environmentally friendly CO₂ capture solvents, are promising candidates for carbon capture applications. Their slow absorption kinetics, however, necessitate strategies to enhance their rates, thereby reducing the capital costs of absorption equipment and saving energy for regenerating large volumes of solvent. Glycine, a potential additive, is explored for this purpose. While glycine-based solvents are more stable than MEA, their amino functional group renders them susceptible to oxidative degradation. This study investigates the degradation of these solvents and the influence of potassium hydroxide and potassium carbonate on their stability. The experiment was performed under 100% O₂ at 90 °C and 3 bar for about 3 weeks. It was observed that glycinate degraded by 53% for the glycinate-only solution. The results also show that the addition of potassium hydroxide and potassium carbonate to a glycinate-only solution had a mixed effect on the degradation of glycinate. Potassium hydroxide increased degradation by 5% compared to the glycinate-only solution, while potassium carbonate decreased degradation by 4%. This order is supported by the degradation rate constants. Meanwhile, under N₂, no significant change was observed in glycine concentration. Glycine's susceptibility to oxidative degradation is likely attributed to its less compact and rigid structure, resulting in weaker bonding and increased vulnerability to external factors. This instability leads to the formation of formate, carbonate, acetate, and oxalate as the primary degradation products across all studied solutions. A proposed mechanism for glycinate oxidative degradation sheds light on this process. These findings are crucial for informed decision making regarding performance trade-offs in point source carbon capture and direct air capture, where oxygen is a prevalent gas component and potassium-based solutions are commonly employed as absorbents. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd.

This study introduces a novel approach to promote CO₂ absorption by aqueous K₂CO₃ solutions through the in-situ generation of reactive oxygen species (ROS) via the alkali activation of H₂O₂. The superoxide radical anion (O₂^•-) is recognized as a major contributor in this process, with its presence confirmed by UV-Vis (Ultraviolet–visible) spectroscopy through the characteristic diformazan peak formed from the reaction between nitro blue tetrazolium (NBT) and superoxide. CO₂ absorption experiments and ¹³C NMR (Carbon-13 nuclear magnetic resonance) characterization demonstrate the enhanced efficiency of the promoted solution in both CO₂ absorption and the conversion of K₂CO₃ to KHCO₃. Comparative analysis with traditional promoters reveals the superior kinetic performance of the H₂O₂-promoted system at room temperature. Notably, our system yields pure KHCO₃ without by-products, making it highly suitable for carbon capture and utilization (CCU) by enabling versatile subsequent transformation processes. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd.

Carbon dioxide (CO₂) in the supercritical state, being denser yet less viscous, is suitable for long-distance transportation. Despite this well-known principle, implementing an operational scheme with appropriate inlet pressure and mass flow rate for supercritical CO₂ (srCO₂) transportation is challenging due to the complex interplay among state variables, fluid properties, pipeline dimensions and materials, and the intricate boundary and ambient conditions surrounding the pipeline. This paper utilizes PIPESIM software to conduct a feasibility study of srCO₂ transportation over a 10-mile-long model pipeline in the Cook Inlet region of Alaska, USA. The study aims to understand the limitations of operational parameters and develop a scheme for selecting feasible parameters for srCO₂ transportation. Considering geographic location, elevation profiles, and ambient conditions, the simulations calculated pressure and temperature profiles, erosion kinetics, and fluid states for various conditions derived from a combinatorial set of pipeline diameters ranging from 11 to 16 in, inlet pressures between 1,400 and 1,900 psia, and mass flow rates from 10 to 275 lbm/s, with an inlet temperature of 200 °F. The major findings indicate that larger pressure losses are expected in smaller pipelines that are well-insulated and/or operated at lower inlet pressures. Turbulent flow is more likely to occur in smaller pipelines and at higher mass flow rates, potentially altering the state of the transported fluid. The parametric modeling results provide a scenario-driven approach to determining a feasible range of mass flow rates, pipeline inner diameters, and inlet pressures for srCO₂ transportation. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd.

Ventilation air methane (VAM) is one of the main greenhouse gas sources. Owing to the characteristics of low concentration of ventilation air methane and high moisture content, we build an experimental platform and take the oxidative combustion temperature and methane conversion rate as the research indexes, and the systematic research finds that the inhibitory effect of moisture on the oxidative combustion of ultra-low concentration of methane (<1%) is a nonlinear polynomial law. In the meantime, we constructed OH(H₂O)_n+CH₄ and studied its reaction potential energy surface using quantum chemical calculations, which used the most significant primitive reaction of methane combustion, OH+CH₄→H₂O+CH₃, as the theoretical basis. We found that as moisture content increased, so did its reaction energy barrier, making the reactants more stable, strengthening the three-body collision effect, and reducing the number of free radicals, all of which hindered the methane chain reaction. The study aimed to validate the experimental finding that moisture inhibits the oxidative combustion of ventilation air methane by examining the internal mechanism of methane oxidation. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd.

CO₂ separation technology at low pressure is most desirable in carbon capture projects to mitigate global warming. Facilitated transport membranes offer selective and effective CO₂ permeation using a wide range of carbon carriers at low pressure. Porous fillers were recently included as they can carry abundant fixed carriers besides offering open channels for CO₂ permeation. This study investigates the effects of amine-modified zeolitic imidazolate framework-8 (ZIF-8) with well-defined micropores and gas sieving ability in polyvinyl alcohol (PVA) membranes containing an ionic liquid that worked as mobile carriers. The effects of amine-modified ZIF-8 and silica nanoparticles on membrane properties and separation performance were also compared. Fourier transform infrared spectra confirmed the incorporation of ZIF-8, secondary amine, IL anions, and silica nanoparticles in PVA membranes. Energy dispersive analysis showed the good dispersion of inorganic fillers. The amine-modified silica nanoparticles resulted in higher thermal stability compared to the amine-modified ZIF-8 in PVA membranes containing [bmin][Ac] ionic liquid, as shown in the thermogravimetric analysis. However, the CO₂ separation performance of PVA membranes containing [bmim][Ac] ionic liquid was improved more significantly by the amine-modified ZIF-8 with microporous structure. A CO₂/N₂ ideal selectivity of 85.65 and CO₂ permeance up to 4,502.91 GPU were attained. Unlike the CO₂/N₂ ideal selectivity, the CO₂ permeance was not significantly affected either using [bmin][Ac] or [bmin][BF₄]. The humid gas greatly enhanced the CO₂ permeance without much changes in the CO₂/N₂ ideal selectivity due to the promotion of facilitated transport. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd.

Underground biomethanation, which relies on the subsurface microbial activity to convert hydrogen and carbon dioxide into methane, is a promising approach to support carbon capture, utilization, and storage technology. The process involves injecting hydrogen with captured CO₂ into depleted oil and gas reservoirs or aquifers colonized by hydrogenotrophic methanogens that can convert these two substrates into methane. Despite the attractiveness of this technology, there are still uncertainties about the efficiency of the conversion process, particularly the impact of microbial parameters. To investigate the efficiency of the hydrogen conversion process, we relied on a bio-reactive transport model that can mimic microbial growth and decay, consumption of substrates, and transport of reactants and products. It was found that the methane concentration peaks near the injection well when the hydrogen fraction is in the range of 75% to 80% of the injected gas composition. In addition, a noticeable hydrogen sulfide concentration can be produced due to sulfide ions in the brine. Using the Kozeny-Carman relation, an attempt was made to correlate microbial growth with reduced porosity and permeability. It was then revealed that substrate consumption by microbes leads to a drastic increase in the microbial population in the subsurface, which can reduce the petrophysical properties of the reservoir, especially in the near wellbore area. The results obtained from a series of parametric analyses showed that the hydrogen concentration in the injected gas, pressure, well spacing, and injection rate are some of the most important parameters contributing to the biomethanation process. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd.

In this work, an alkali melting-pickling assisted solid phase synthesis method of S-1 zeolite molecular sieve with excellent adsorption properties for CO₂ was successfully developed by using solid waste fly ash. SiO₂ with a purity of up to 97.84% was successfully extracted by using alkaline fusion activation, high temperature calcination and pickling. The CO₂ adsorption capacity of the prepared SiO₂ was 0.51 mmol/g at 298 K and 1 bar. Silicalite-1 molecular sieve was prepared by solid phase synthesis method using SiO₂ extracted from fly ash as silicon source. The results showed that the prepared Silicalite-1 had good morphology and relatively high crystallinity. The specific surface area is 623.30 m²/g, and the total pore volume is 0.31 cm³/g. In addition, the adsorption capacity of CO₂ was 2.05 mmol/g at 298 K and 1 bar. Compared with the prepared SiO₂, the adsorption capacity of CO₂ by Silicalite-1 molecular sieve increased by four times. Moreover, under the test condition of 298 K, it has a high selectivity coefficient for CO₂/N₂ mixed gas, and after 10 times of adsorption-desorption cycle tests, the adsorption capacity of Silicalite-1 molecular sieve for CO₂ does not change significantly, and its adsorption rate can still be as high as 89.31%. The results indicate that Silicalite-1 molecular sieve prepared by solid phase synthesis method has good adsorption selectivity and adsorption–desorption cycle regeneration stability, and can be used in the field of CO₂ adsorption, separation and purification. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd.

During CO₂ storage in deep saline aquifers, the presence of residual water has an important influence on the storage efficiency and safety. In this study, natural rock cores taken from deep reservoirs in the Ordos Basin and Fukang, Xinjiang are used as research objects. Nine groups of core-flooding experiments are performed under different CO₂/N₂ gas mixture ratios to study the influence of rock properties (mineral composition, permeability, porosity and pore structure) on the residual water. Furthermore, the geophysical and chemical properties of rock cores are analyzed by X-ray diffraction, electron microscopy, field emission scanning electron microscopy and piezoelectric mercury method. The results show that residual water saturation is a quantitative power function of drainage time. The residual water saturation is positively correlated with the total amount of quartz and feldspar and increases with increasing permeability. Moreover, both the average and median pore throat radius show a strong inverse correlation with irreducible residual water saturation; as these radius increase, the residual water saturation decreases. In contrast, the porosity and maximum pore throat radius display a weaker correlation with irreducible residual water saturation. This study is of great value for engineering practices such as the site selection of CO₂ storage projects in saline aquifer and improvement of CO₂ storage efficiency. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd.