CO2 Diffusion Research Articles

OsαCA1 Affects Photosynthesis, Yield Potential, and Water Use Efficiency in Rice.

Plant growth and crop yield are essentially determined by photosynthesis when considering carbon dioxide (CO2) availability. CO2 diffusion inside a leaf is one of the factors that dictate the CO2 concentrations in chloroplasts. Carbonic anhydrases (CAs) are zinc-containing enzymes that interconvert CO2 and bicarbonate ions (HCO3-), which, consequently, affect CO2 diffusion and thus play a fundamental role in all photosynthetic organisms. Recently, the great progress in the research in this field has immensely contributed to our understanding of the function of the β-type CAs; however, the analysis of α-type CAs in plants is still in its infancy. In this study, we identified and characterized the OsαCA1 gene in rice via the analysis of OsαCAs expression in flag leaves and the subcellular localization of its encoding protein. OsαCA1 encodes an α-type CA, whose protein is located in chloroplasts with a high abundance in photosynthetic tissues, including flag leaves, mature leaves, and panicles. OsαCA1 deficiency caused a significant reduction in assimilation rate, biomass accumulation, and grain yield. The growth and photosynthetic defects of the OsαCA1 mutant were attributable to the restricted CO2 supply at the chloroplast carboxylation sites, which could be partially rescued by the application of an elevated concentration of CO2 but not that of HCO3-. Furthermore, we have provided evidence that OsαCA1 positively regulates water use efficiency (WUE) in rice. In summary, our results reveal that the function of OsαCA1 is integral to rice photosynthesis and yield potential, underscoring the importance of α-type CAs in determining plant physiology and crop yield and providing genetic resources and new ideas for breeding high-yielding rice varieties.

Storage and diffusion of CO2 in covalent organic frameworks-A neural network-based molecular dynamics simulation approach.

As a consequence of the accelerated climate change, solutions to capture, store and potentially activate carbon dioxide received increased interest in recent years. Herein, it is demonstrated, that the neural network potential ANI-2x is able to describe nanoporous organic materials at approx. density functional theory accuracy and force field cost, using the example of the recently published two- and three-dimensional covalent organic frameworks HEX-COF1 and 3D-HNU5 and their interaction with CO2 guest molecules. Along with the investigation of the diffusion behaviour, a wide range of properties of interest is analyzed, such as the structure, pore size distribution and host-guest distribution functions. The workflow developed herein facilitates the estimation of the maximum CO2 adsorption capacity and is easily generalizable to other systems. Additionally, this work illustrates, that minimum distance distribution functions can be a highly useful tool in understanding the nature of interactions in host-gas systems at the atomic level.

Performance of bacterial mediated mineralization in concrete under carbonation and chloride induced corrosion

Prevention of concrete structures from early deterioration under aggressive environments is a major challenge. The present study investigated the performance of bacterial-treated concrete structures under harsh conditions such as carbonation and chloride exposure. Improvement in the mechanical strength and reduction in penetration properties was recorded in bacterial-treated specimens. The maximum carbonation depth of 18.27 mm and reduction of pH (8.6) were recorded in control specimens during carbonation exposure (5% CO2) for 120 days, whereas significant resistance against CO2 diffusion and much-reduced carbonation depth was observed in BAC specimen (9.28 mm) and BSC (11.13 mm) specimens. Due to accelerated carbonation conditions, further increment in mechanical strength and reduced penetration was observed in control and bacterial treated specimens due to microstructure densification caused by carbonation reaction products. During chloride exposure (5% NaCl) for 120 days, the control specimen showed the initiation of rebar corrosion with Ecorr and Icorr values of −522.2 mV/SCE and 0.34 μA/cm2, respectively. However, bacterial-treated reinforced specimens (BARC and BSRC) significantly resisted the penetration of chloride ions. At the end of chloride exposure, BARC and BSRC specimens showed lower Ecorr values of −203.4 mV/SCE and −301.4 mV/SCE and Icorr values of 0.03 μA/cm2 and 0.02 μA/cm2, respectively. These results suggested that the biogenic treated concrete specimens resisted from the deterioration effects of chloride and carbonation exposure and improved their durability properties.

Simulation of Microscopic Seepage Characteristics of Interphase Mass Transfer in CO2 Miscible Flooding under Multiphysics Field Coupling Conditions.

CO2 miscible flooding in low permeability reservoirs is conducive to significantly improving oil recovery. At present, the microscopic displacement simulation of CO2 miscible flooding is mainly reflected in the simulation of the seepage process, but the pressure control of the seepage process is lacking, and the simulation of the characterization of CO2 concentration diffusion is less studied. In view of the above problems, a numerical model of CO2 miscible flooding is established, and the microscopic seepage characteristics of interphase mass transfer in CO2 miscible flooding are analyzed by multiphysics field coupling simulations at the two-dimensional pore scale. The injection velocity, contact angle, diffusion coefficient, and initial injection concentration are selected to analyze their effects on the microscopic seepage characteristics of CO2 miscible flooding and the concentration distribution in the process of CO2 diffusion. The research shows that after injection into the model, CO2 preferentially diffuses into the large pore space and forms a miscible area with crude oil through interphase mass transfer, and the miscible area expands continuously and is pushed to the outlet by the high CO2 concentration area. The increase in injection velocity will accelerate the seepage process of CO2 miscible displacement, which will increase the sweep area at the same time. The increase in contact angle increases the seepage resistance of CO2 and weakens the interphase mass transfer with crude oil, resulting in a gradual decrease in the final recovery efficiency. When the diffusion coefficient increases, the CO2 concentration in the small pores and the parts that are difficult to reach at the model edge will gradually increase. The larger the initial injection concentration is, the larger the CO2 concentration in the large pore and miscible areas in the sweep region at the same time. This study has guiding significance for the field to further understand the microscopic seepage characteristics of CO2 miscible flooding under the effect of interphase mass transfer.

Enhanced Carbon Monoxide Electroreduction to >1 A cm−2 C2+ Products Using Copper Catalysts Dispersed on MgAl Layered Double Hydroxide Nanosheet House‐of‐Cards Scaffolds

AbstractCu catalysts are most apt for reducing CO(2) to multi‐carbon products in aqueous electrolytes. To enhance the product yield, we can increase the overpotential and the catalyst mass loading. However, these approaches can cause inadequate mass transport of CO(2) to the catalytic sites, which will then lead to H2 evolution dominating the product selectivity. Herein, we use a MgAl LDH nanosheet ‘house‐of‐cards’ scaffold to disperse CuO‐derived Cu (OD‐Cu). With this support‐catalyst design, at −0.7 VRHE, CO could be reduced to C2+ products with a current density (jC2+) of −1251 mA cm−2. This is 14× that of the jC2+ shown by unsupported OD‐Cu. The current densities of C2+ alcohols and C2H4 were also high at −369 and −816 mA cm−2 respectively. We propose that the porosity of the LDH nanosheet scaffold enhances CO diffusion through the Cu sites. The CO reduction rate can thus be increased, while minimizing H2 evolution, even when high catalyst loadings and large overpotentials are used.

Enhanced Carbon Monoxide Electroreduction to >1 A cm-2 C2+ Products Using Copper Catalysts Dispersed on MgAl Layered Double Hydroxide Nanosheet House-of-Cards Scaffolds.

Cu catalysts are most apt for reducing CO(2) to multi-carbon products in aqueous electrolytes. To enhance the product yield, we can increase the overpotential and the catalyst mass loading. However, these approaches can cause inadequate mass transport of CO(2) to the catalytic sites, which will then lead to H2 evolution dominating the product selectivity. Herein, we use a MgAl LDH nanosheet 'house-of-cards' scaffold to disperse CuO-derived Cu (OD-Cu). With this support-catalyst design, at -0.7 VRHE , CO could be reduced to C2+ products with a current density (jC2+ ) of -1251 mA cm-2 . This is 14× that of the jC2+ shown by unsupported OD-Cu. The current densities of C2+ alcohols and C2 H4 were also high at -369 and -816 mA cm-2 respectively. We propose that the porosity of the LDH nanosheet scaffold enhances CO diffusion through the Cu sites. The CO reduction rate can thus be increased, while minimizing H2 evolution, even when high catalyst loadings and large overpotentials are used.

Temperature sensitivity of carbon concentrating mechanisms in the diatom Phaeodactylum tricornutum

Marine diatoms are key primary producers across diverse habitats in the global ocean. Diatoms rely on a biophysical carbon concentrating mechanism (CCM) to supply high concentrations of CO2 around their carboxylating enzyme, RuBisCO. The necessity and energetic cost of the CCM are likely to be highly sensitive to temperature, as temperature impacts CO2 concentration, diffusivity, and the kinetics of CCM components. Here, we used membrane inlet mass spectrometry (MIMS) and modeling to capture temperature regulation of the CCM in the diatom Phaeodactylum tricornutum (Pt). We found that enhanced carbon fixation rates by Pt at elevated temperatures were accompanied by increased CCM activity capable of maintaining RuBisCO close to CO2 saturation but that the mechanism varied. At 10 and 18 °C, diffusion of CO2 into the cell, driven by Pt’s ‘chloroplast pump’ was the major inorganic carbon source. However, at 18 °C, upregulation of the chloroplast pump enhanced (while retaining the proportion of) both diffusive CO2 and active HCO3− uptake into the cytosol, and significantly increased chloroplast HCO3− concentrations. In contrast, at 25 °C, compared to 18 °C, the chloroplast pump had only a slight increase in activity. While diffusive uptake of CO2 into the cell remained constant, active HCO3− uptake across the cell membrane increased resulting in Pt depending equally on both CO2 and HCO3− as inorganic carbon sources. Despite changes in the CCM, the overall rate of active carbon transport remained double that of carbon fixation across all temperatures tested. The implication of the energetic cost of the Pt CCM in response to increasing temperatures was discussed.

Spatial and temporal distribution characteristics of pCO2 and CO2 evasion in karst rivers under the influence of urbanization.

Surface rivers play an essential role in carbon cycle processes in karst regions. However, the CO2 diffusion flux from karst rivers under the influence of urbanization has been scarcely examined in the literature. Along these lines, in this work, the CO2 partial pressure (pCO2) and its degassing in a typical karst river (Nanming River and its tributaries) were thoroughly investigated, which are significantly affected by urbanization in Southwest China. From the acquired results, it was demonstrated that the average values of pCO2 in the main stream of the Nanming River in the wet season, dry season, and flat season were 1975.77 ± 714.45 μatm, 1116.08 ± 454.24 μatm, and 976.89 ± 746.37 μatm, respectively. On the other hand, the tributary showed mean pCO2 values of 1770.46 ± 1120.79 μatm, 1638.13 ± 1121.82 μatm, and 1107.74 ± 824.03 μatm in the three different hydrographic periods. Overall, the pCO2 of the Nanming River basin decreased in the following order: wet season > dry season > flat season, while the mainstream of the Nanming River was slightly higher than that of the tributaries in the wet season. However, it was lower than that of the tributaries in the dry and flat seasons. Additionally, more than 90% of the samples displayed a supersaturated state of CO2, which acted as an important source of CO2 in the atmosphere. From a spatial point of view, pCO2 tended to be higher in the western region than in the eastern region, higher in the middle than in the immediate vicinity, and higher in the south during the three seasons. The higher urban areas showed also relatively higher pCO2 than the lower urban areas. The urban land along with the Nanming River's mainstream exhibited a weaker correlation with pCO2 than the urban land along with the main tributaries due to the mainstream's regular management in recent years. Moreover, the pCO2 was mainly influenced by the carbonate rocks dissolution, aquatic organism metabolic processes, and human activities. In the Nanming River basin, the average CO2 diffusion fluxes in the wet season, dry season, and flat season were 147.02 ± 100.3mmol·m-2·d-1, 76.02 ± 67.45mmol·m-2·d-1, and 119.28 ± 168.22mmol·m-2·d-1, respectively, which indicates high potential CO2 emissions. In addition, it was found that urban construction could increase the pCO2 of karst rivers and cause an increase in the CO2 release flux during the regional urban expansion. In view of the increasing intensive and extensive urbanization in karst regions, our findings are helpful to elucidate the characteristics of carbon dioxide emissions from karst rivers under the disturbance of human activities and further deepen the understanding of the carbon balance in karst river basins.

Grain-Boundary Diffusion of 57Сo in Niobium

The grain-boundary diffusion of Co in Nb has been studied by a layer-by-layer radiometric analysis in the temperature range of 723–873 K. The diffusion annealing modes corresponded to the kinetic C mode, which implies that the diffusion proceeds only along grain boundaries. The coefficients of grain-boundary diffusion of Co in Nb have been determined for several temperatures from diffusion profiles. An expression for the Arrhenius dependence of Co diffusion coefficient along the grain boundaries of Nb has been determined. The temperature dependence of coefficient of grain-boundary segregation of Co in Nb is constructedbased on the temperature dependence of coefficient of grain-boundary diffusion of Co in Nb and the data in the literature on the temperature dependence of the triple product.

Suppression of CO2 induced lithium anode corrosion by fluorinated functional group in quasi-solid polymer electrolyte enabling long-cycle and high-safety Li-CO2 batteries

Given high theoretical energy density and environmental-friendly CO2 fixation ability, rechargeable Li-CO2 battery is explored as a promising energy storage device. However, its cycling stability and safety are challenged by the continuous pulverization of Li anode and the leakage of liquid electrolytes (LEs). Herein, a quasi-solid polymer electrolyte (QSPE) with -CF3 functional groups was designed and in-situ fabricated for Li-CO2 battery. The solidification of electrolyte avoids the leakage of LEs and effectively inhibits the diffusion of the acid CO2 and cathode by-products to etch Li anode. Besides, the introduction of -CF3 can construct a fish scale-like LiF-rich solid electrolyte interface on Li anode, which induces the uniform and dense deposition of Li to inhibit the deeper Li from being further etched. The QSPE also exhibits high ion conductivity (1.98×10−3 S cm−1 at 25°C), enhanced Li+ transport number (0.47), and superb stability (>5.27 V vs. Li/Li+). Consequently, the Li-CO2 battery with QSPE delivers effectively suppressed pulverization of Li anode, extraordinary cyclic stability over 295 cycles (1250 h) at 50 μA cm−2, and lower overpotential (1.05 V) compared to the cells with LE. Moreover, the as-prepared QSPE also demonstrates excellent application potential in other Li metal batteries and flexible electronic devices.

CO2 diffusion in dry and hydrous leucititic melt

Abstract. Using the diffusion couple technique, diffusion of CO2 in a leucititic melt from the Colli Albani Volcanic District in Italy was investigated at temperatures between 1200 and 1350 ∘C in an internally heated pressure vessel at 300 MPa. To examine the effect of dissolved H2O in the melt, experiments were performed for a nominally dry melt (0.18 ± 0.03 wt % H2O) and for a hydrous melt containing 3.36 ± 0.28 wt % H2O. Diffusion experiments were run for 40 to 120 min and terminated by rapid quench. CO2 concentration profiles were subsequently measured via attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and fitted with error functions to obtain individual diffusion coefficients. For the anhydrous and hydrous sample series, seven diffusion coefficients were determined each. Diffusivity was found to increase exponentially with temperature for both melts following an Arrhenius behaviour. The Arrhenius equation for the nominally dry leucititic melt is described by log⁡DCO2=-1.44(±0.24)⋅10000T-1.95(±1.59), where DCO2 is the diffusion coefficient in m2 s−1 and T is the temperature in K. In the experimental temperature range, H2O has an accelerating effect on CO2 diffusion. At 1200 ∘C, diffusivity increases from 1.94 × 10−12 m2 s−1 in the dry melt to 1.54 × 10−11 m2 s−1 in the hydrous melt. The Arrhenius equation for the leucititic melt containing 3.36±0.28 wt % H2O is given by log⁡DCO2=-1.09(±0.30)⋅10000T-3.41(±1.99). The activation energies for CO2 were determined to be 275 ± 47 kJ mol−1 for the anhydrous melt and 209 ± 58 kJ mol−1 for the hydrous melt. The high CO2 activation energy in the leucititic melt indicates that the diffusion might be partly attributed to the carbonate species. At high magmatic temperatures above 1200 ∘C, CO2 diffusivity in the leucititic melt is only slightly lower than CO2 diffusion in rhyolitic and basaltic melts, suggesting that CO2 diffusion in natural melts is relatively independent from the bulk melt composition at such temperatures. CO2 diffuses slower than other volatile components such as halogens and H2O in depolymerized silicate melts. Thus, a fractionation of volatiles can occur during magma ascent and degassing. The experimental data on CO2 diffusion can be used for modelling the degassing mechanisms of ultrapotassic mafic melts.

Evolution of microstructure and CO2 diffusion coefficient of compacted recycled aggregates during carbonation investigated by X-ray tomography

Recycled aggregates compacted in road layers are made of a majority of concrete aggregates which can mineralize atmospheric CO2. Previous studies showed that carbonation modifies the microstructure of recycled concrete aggregates, but little information is available in the case of compacted recycled aggregates. Furthermore, carbonation kinetics depends on CO2 diffusion through the compacted material, which is linked its microstructure. This paper presents an investigation of the evolution of both microstructure and CO2 diffusion coefficient of compacted recycled aggregates during carbonation in two different environments by X-ray tomography. Segmented 3D images were analyzed to fully extract resolved pore structures. In addition, the CO2 diffusion coefficient variations were investigated by calculating the macroscopic diffusivity tensor in the segmented 3D images. We show that the numerical results are very similar to previous experimental results from gas diffusion tests and that the diffusivity coefficients can be estimated by using only the larger pore network (pore size > 5.5 µm). These findings suggest that nondestructive imaging approaches, such as micro-Computed Tomography (µCT), are a relevant alternative to experimental characterization methods.

Nanohybrid Pebax/PEGDA-GPTMS membrane with semi-interpenetrating network structure for enhanced CO2 separations

Polymeric membranes containing polyethylene oxide (PEO) groups are promising CO2 separation materials, but suffer from the trade-off between separation performance and mechanical strength. To overcome this challenge, we combine the merits of semi-interpenetrating polymer network and nanohybrid to maintain a high PEO loading and robust membrane structure. The membranes were prepared by introducing in-situ formed PEO networks with silica nodes into Pebax1657 to produce a semi-interpenetrating network structure. The introduced network and in situ formed silica nanoparticles reduce the chain packing efficiency of Pebax matrix to enhance the CO2 diffusivity, while the increased PEO content enhances CO2 solubility. Under feed gas pressure of 25 bar, nanohybrid membranes containing 40 wt% polymer network display excellent gas separation performance with CO2 permeability of 272.8 Barrer and CO2/N2 selectivity of 79.6 under mixed gas separation tests, surpassing 2008 Robeson upper bound. Moreover, the hybrid membranes showed high mechanical strength, the Young's modulus increases by 1.95 times. This strategy provides a simple route for the design of nanohybrid membranes with high separation performance as well as excellent durability.

Constructing Bi2MoO6/Pomelo-Peel-Derived Carbon 0D/3D Heterojunctions To Enhance Photothermal Catalytic CO2 Reduction in Full Solar Spectrum

The carrier migration limitation has been a key factor restricting the photothermal catalytic CO2 reduction. To further enhance carrier transport, Bi2MoO6 quantum dots (BM QDs) are deposited on the surface of alkali-activated pomelo-peel-derived carbon (CPP-A) to construct CPP-A/BM QDs 0D/3D heterojunctions in this paper. BM QDs have extremely short carrier transport distances and achieve photothermal synergy through the graded utilization of the full solar spectrum. The carbon framework of CPP promotes the high dispersion of BM QDs (3 nm) and allows the local surface temperature of the catalyst to increase rapidly up to 100 °C. The critical role of heat enhances the diffusion, adsorption, and carrier migration processes of CO2 and provides the energy to cross the CO2 activation energy barrier. More importantly, the oxygen-containing groups of CPP and BM QDs form a C–O–Bi interfacial electron bridge, which provides a high-speed channel for carrier transport across the interface, allowing many electrons generated by BM QDs to migrate rapidly to the CPP surface, inducing CPP as a new electron-rich surface for rapid CO2 activation, which results in an ultrahigh CO yield of 61.44 μmol/(g·h) for CPP-A/BM QDs, and the catalytic activity is increased by 9.12 times.

Investigation of density, viscosity and derived thermodynamic properties of CO2-free and CO2-loaded poly(ethylene imine) aqueous systems at different temperatures and 0.1 MPa

In this work, the density and viscosity for poly(ethylene imine) (PEI1800/10000) aqueous systems with and without CO2 over PEI concentrations (wt% = 5, 10, 15, 20, 30) are measured at temperatures from (293.15 to 333.15) K and 0.1 MPa. Based on the experimental data, the thermal expansion coefficient (αp), viscosity activation energy (Eη) and CO2 diffusion coefficient (DCO2) are calculated. The results show that the density and viscosity increase as the PEI concentration and CO2 loading increase. The higher molecular weight samples also give higher density and viscosity. The high viscosity further results in the large activation energy and low CO2 diffusion coefficient. All the experimental results are discussed from the perspective of intermolecular interactions which are further verified by the reaction mechanism and FT-IR spectra.

Swimbladder Function in the European Eel Anguilla anguilla

Eels use the swimbladder for buoyancy control. The ductus pneumaticus connecting the esophagus with the swimbladder is closed soon after initial opening of the swimbladder in the glass eel stage, so that eels are functionally physoclist. Subsequent filling of the swimbladder is achieved by activity of gas gland cells in the swimbladder epithelium and countercurrent concentration in the rete mirabile. Gas gland cells produce and release lactic acid and CO2. In blood, acidification induces a release of oxygen from the hemoglobin (Root effect). The resulting increases in PO2 and PCO2 provide diffusion gradients for the diffusion of oxygen and CO2 into the swimbladder, the main gases secreted into the swimbladder. In addition, the partial pressure of these two gases remains elevated in venous blood leaving the swimbladder epithelium and returning to the rete mirabile. Back-diffusion from venous to arterial capillaries in the rete results in countercurrent concentration, allowing for the generation of high gas partial pressures, required for filling the swimbladder under elevated hydrostatic pressure. The transition of the yellow eel to the silver eel stage (silvering) is accompanied by a significant improvement in swimbladder function, but swimbladder volume cannot be kept constant during the daily vertical migrations silver eels perform during their spawning migration back to the spawning grounds in the Sargasso Sea. Infection of the swimbladder with the nematode Anguillicola crassus significantly impairs the function of the swimbladder as a buoyancy organ.

Study of CO2 solubility enhancement by nanomaterials in carbonated water: Implications for enhanced oil recovery and CO2 storage

Carbonated water injection (CWI) is a promising method for coupled enhanced oil recovery and CO2 geological storage. Nanomaterials can efficiently improve CO2 absorption in conventional absorbents. Therefore, there could be a possibility for using nanomaterials to increase CO2 solubility in carbonated water (CW) and thereby enhance oil recovery and CO2 storage capacity. In this study, the stabilities of different nanofluids and nanomaterial-enhanced CW were examined by the Zeta potential, particle size, high-pressure and high-temperature visual observation, and transmittance measurements. Then, a series of CO2 mass transfer and solubility experiments were conducted in a PVT cell to evaluate the feasibility of enhancing CO2 solubility in CW by nanomaterials and to study the effects of nanomaterial type, concentration, initial pressure, and temperature. Finally, a model was proposed to calculate the diffusion coefficients, pseudo-diffusion coefficient, and CO2 solubility in CW under various conditions. The results revealed that the SiO2-enhanced CW exhibited better stability compared with Al2O3, TiO2, and MWCNT-enhanced CW. For the 0.1 wt% SiO2-enhanced CW at experimental conditions (12 MPa and 30 °C), the ES is 1.17, indicating that the CO2 solubility in SiO2-enhanced CW is enhanced by 17% compared with that in CW because of Brownian motion, shuttle effect, and hydrodynamic effect. Increasing the temperature has a negative influence on the CO2 solubility of SiO2-enhanced CW, while an increase in pressure improved the CO2 solubility capacity. The maximum and average relative error percentages between the calculated and experimental CO2 solubility in SiO2-enhanced CW are 10.65% and 3.18%, respectively, indicating the accuracy of the model to determine the CO2 solubility in SiO2-enhanced CW.

Thermal-Hydraulic-Mechanical Coupling Simulation of CO2 Enhanced Coalbed Methane Recovery with Regards to Low-Rank but Relatively Shallow Coal Seams

CO2 injection technology into coal seams to enhance CH4 recovery (CO2-ECBM), therefore presenting the dual benefit of greenhouse gas emission reduction and clean fossil energy development. In order to gaze into the features of CO2 injection’s influence on reservoir pressure and permeability, the Thermal-Hydraulic-Mechanical coupling mechanism of CO2 injection into the coal seam is considered for investigation. The competitive adsorption, diffusion, and seepage flowing of CO2 and CH4 as well as the dynamic evolution of fracture porosity of coal seams are considered. Fluid physical parameters are obtained by the fitting equation using MATLAB to call EOS software Refprop. Based on the Canadian CO2-ECBM project CSEMP, the numerical simulation targeting shallow low-rank coal is carried out, and the finite element method is used in the software COMSOL Multiphysics. Firstly, the direct recovery (CBM) and CO2-ECBM are compared, and it is confirmed that the injection of CO2 has a significant improvement effect on methane production. Secondly, the influence of injection pressure and temperature is discussed. Increasing the injection pressure can increase the pressure difference in the reservoir in a short time, so as to improve the CH4 production and CO2 storage. However, the increase in gas injection pressure will also lead to the rapid attenuation of near-well reservoir permeability, resulting in the weakening of injection capacity. Also, when the injection temperature increases, the CO2 concentration is relatively reduced, and the replacement effect on CH4 is weakened, resulting in a slight decrease in CBM production and CO2 storage.

High-Throughput Computational Screening of Bioinspired Dual-Atom Alloys for CO2 Activation

CO2 activation is an integral component of thermocatalytic and electrocatalytic CO2 conversion to liquid fuels and value-added chemicals. However, the thermodynamic stability of CO2 and the high kinetic barriers to activating CO2 are significant bottlenecks. In this work, we propose that dual atom alloys (DAAs), homo- and heterodimer islands in a Cu matrix, can offer stronger covalent CO2 binding than pristine Cu. The active site is designed to mimic the Ni-Fe anaerobic carbon monoxide dehydrogenase CO2 activation environment in a heterogeneous catalyst. We find that combinations of early transition metals (TMs) and late TMs embedded in Cu are thermodynamically stable and can offer stronger covalent CO2 binding than Cu. Additionally, we identify DAAs that have CO binding energies similar to Cu, both to avoid surface poisoning and to ensure attainable CO diffusion to Cu sites so that the C-C bond formation ability of Cu can be retained in conjunction with facile CO2 activation at the DAA sites. Machine learning feature selection reveals that the more electropositive dopants are primarily responsible for attaining the strong CO2 binding. We propose seven Cu-based DAAs and two single atom alloys (SAAs) with early TM late TM combinations, (Sc, Ag), (Y, Ag), (Y, Fe), (Y, Ru), (Y, Cd), (Y, Au), (V, Ag), (Sc), and (Y), for facile CO2 activation.

Chitosan-Modified Polyethyleneimine Nanoparticles for Enhancing the Carboxylation Reaction and Plants' CO2 Uptake.

Increasing plants' photosynthetic efficiency is a major challenge that must be addressed in order to cover the food demands of the growing population in the changing climate. Photosynthesis is greatly limited at the initial carboxylation reaction, where CO2 is converted to the organic acid 3-PGA, catalyzed by the RuBisCO enzyme. RuBisCO has poor affinity for CO2, but also the CO2 concentration at the RuBisCO site is limited by the diffusion of atmospheric CO2 through the various leaf compartments to the reaction site. Beyond genetic engineering, nanotechnology can offer a materials-based approach for enhancing photosynthesis, and yet, it has mostly been explored for the light-dependent reactions. In this work, we developed polyethyleneimine-based nanoparticles for enhancing the carboxylation reaction. We demonstrate that the nanoparticles can capture CO2 in the form of bicarbonate and increase the CO2 that reacts with the RuBisCO enzyme, enhancing the 3-PGA production in in vitro assays by 20%. The nanoparticles can be introduced to the plant via leaf infiltration and, because of the functionalization with chitosan oligomers, they do not induce any toxic effect to the plant. In the leaves, the nanoparticles localize in the apoplastic space but also spontaneously reach the chloroplasts where photosynthetic activity takes place. Their CO2 loading-dependent fluorescence verifies that, in vivo, they maintain their ability to capture CO2 and can be therefore reloaded with atmospheric CO2 while in planta. Our results contribute to the development of a nanomaterials-based CO2-concentrating mechanism in plants that can potentially increase photosynthetic efficiency and overall plants' CO2 storage.