High Concentrations Of Carbon Dioxide Research Articles

Entropy Drives Accelerated Ion Diffusion upon Carbon Dioxide Expansion of Electrolytes.

Carbon dioxide-expanded liquids, organic solvents with high concentrations of soluble carbon dioxide (CO2) at mild pressures, have gained attention as green catalytic media due to their improved properties over traditional solvents. More recently, carbon dioxide-expanded electrolytes (CXEs) have demonstrated improved reaction rates in the electrochemical reduction of CO2, by increasing the rate of delivery of CO2 to the electrode while maintaining facile charge transport. However, recent studies indicate that the limiting behavior of CXEs at higher CO2 pressures is a decline in solution conductivity due to reduced polarity, leading to poorer charge screening and greater ion pairing. In this article, we employ molecular dynamics simulations to investigate the energetic driving forces behind the diffusive properties of an acetonitrile and tetrapropylammonium hexafluorophosphate (TPrAPF6) CXE with increasing CO2 concentration. Our results indicate that entropy drives solvent and electrolyte diffusion with increasing CO2 pressure. The activation energy of ion diffusion increases with higher concentrations of CO2, indicating that increasing the temperature may improve solution conductivity in these systems. This trend in the activation energies is traced to stronger cation-anion Coulombic interactions due to weaker solvent screening at high CO2 concentrations, suggesting that the choice of ion may provide a route to diminish this effect.

Discovery of the first hydrothermal field along the 500-km-long Knipovich Ridge offshore Svalbard (the Jøtul field)

Oceanic spreading centers north of Iceland are characterized by ultraslow spreading rates, and related hydrothermal activity has been detected in the water column and at the seafloor along nearly all ridge segments. An exception is the 500-km-long Knipovich Ridge, from where, until now, no hydrothermal vents were known. Here we report the investigation of the first hydrothermal vent field of the Knipovich Ridge, which was discovered in July 2022 during expedition MSM109. The newly discovered hydrothermal field, named Jøtul hydrothermal field, is associated with the eastern bounding fault of the rift valley rather than with an axial volcanic ridge. Guided by physico-chemical anomalies in the water column, ROV investigations on the seafloor showed a wide variety of fluid escape sites, inactive and active mounds with abundant hydrothermal precipitates, and chemosynthetic organisms. Fluids with temperatures between 8 and 316 °C as well as precipitates were sampled at four vent sites. High methane, carbon dioxide, and ammonium concentrations, as well as high 87Sr/86Sr isotope ratios of the vent fluids indicate strong interaction between magma and sediments from the Svalbard continental margin. Such interactions are important for carbon mobilization at the seafloor and the carbon cycle in the ocean.

Moderate greenhouse climate and rapid carbonate formation after Marinoan snowball Earth

When the Marinoan snowball Earth deglaciated in response to high atmospheric carbon dioxide (CO2) concentrations, the planet warmed rapidly. It is commonly hypothesized that the ensuing supergreenhouse climate then declined slowly over hundreds of thousands of years through continental weathering. However, how the ocean affected atmospheric CO2 in the snowball Earth aftermath has never been quantified. Here we show that the ocean’s carbon cycle drives the supergreenhouse climate evolution via a set of different mechanisms, triggering scenarios ranging from a rapid decline to an intensification of the supergreenhouse climate. We further identify the rapid formation of carbonate sediments from pre-existing ocean alkalinity as a possible explanation for the enigmatic origin of Marinoan cap dolostones. This work demonstrates that a moderate and relatively short-lived supergreenhouse climate following the Marinoan snowball Earth is a plausible scenario that is in accordance with geological data, challenging the previous hypothesis.

Photosynthetic process for removing H2S and CO2 from biogas using the microalgae Chlorella sorokiniana

Biogas is an alternative source of energy that contributes on reducing the emissions of polluting gas in comparison to fossil fuels as well as promoting the treatment of organic waste. However depending on the substrate used in its production, it may have a high concentration of carbon dioxide (CO2) and hydrogen sulfide (H2S); in these cases a treatment is necessary to make its use viable, for comply with current legislation and avoid damage to materials and health. Currently, the most widely used methods are physical-chemical, such as absorption, adsorption, membrane separation, and Pressure Swing Adsorption (PSA), among others. However, these methods are expensive and generate waste that needs to be treated. In this sense, biological methods have proved to be promising alternatives, especially photosynthetic processes using microalgae. This study aimed to evaluate the efficiency in removing CO2 and H2S from biogas through a bench-scale purifier prototype consisting of a photobioreactor and an absorption column, in a continuous biogas flow system. The experiment lasted 240 hours, during which 9 m³ of biogas were treated. In the first 24 hours, the flow rate was 1 L/min, resulting in an average removal of 60.8% of H2S and 20.2% of CO2. Between 24 hours and 240 hours of the study, the average biogas flow rate was 0.54 L/min, and an improvement in removal was observed, reaching 83.4% of H2S and 29.7% of CO2. The system showed efficiency in biogas treatment. However, possibilities for improvement were identified in terms of biogas flow and process, which could further enhance the results presented here.

Effects of high carbon dioxide concentration on emotional processing: Based on multimodal evidence

The effects of CO2 on emotional processing are still incompletely understood, although its effects on cognitive performance are widely recognized. This study hypothesized that elevated CO2 concentration would affect the processing of different valence emotions, which leads to more negative emotions and fewer positive emotions. A within-subject experiment was conducted to compare subjective emotional scores, emotional processing behavioral performance, EEG patterns, and other physiological changes of 30 participants exposed to CO2 concentration at 600 ppm and 5000 ppm. The results suggested that CO2 concentration could affect neural arousal patterns during emotional processing, changes in blood pressure, and salivary cortisol secretion in healthy participants. Emotional experience task performance of participants was also affected by CO2, which was not statistically significant. At the high CO2 concentration, the systolic blood pressure (SBP) level was significantly lower (p = 0.005), while the salivary cortisol level was significantly higher (p = 0.037). Power spectral density analysis showed that there was a significant interaction between CO2 concentration and emotional valence for theta waves in frontal regions (p = 0.029), beta waves in temporal regions (p = 0.017), and gamma waves in frontal-parietal occipital regions (p = 0.013). The present study found that CO2 has a negative effect on emotional processing, such as reducing the speed and accuracy of emotional processing. To some extent, there are also some positive effects, like reducing emotionally-induced increases in blood pressure. This finding warrants further research.

The Living Concrete Experiment: Cultivation of Photosynthetically Active Microalgal on Concrete Finish Blocks

Climate change is a global critical issue. High carbon dioxide emissions and concentrations are important factors. In the construction field, concrete contributes significantly to greenhouse gas emissions. Therefore, a pioneering team of researchers has developed a new “living concrete” construction finish material capable of scrubbing carbon dioxide from the atmosphere. The material consists of ASTM (ASTM is the acronym for American Society for Testing Materials)-certified concrete block(s) with Chlorella vulgaris cultivated on the surface. Chlorella vulgaris is a common micro-algae with photosynthetic activity; these species require water, nutrients, light, and carbon dioxide to live while releasing oxygen in return. The “living concrete” block was developed in dedicated laboratories; its photosynthetic activity was quantified. Proposed as an external application assembly to a new or an existing building envelope—up to 3 m high, i.e., anthropogenic street-level emissions, or installed on roof(s) in horizontal mode—this concrete/biological composite material reverses carbon dioxide emissions and may present itself as a valid solution for climate change issues in urban moderate climates.

EFFECT OF BACK PRESSURE DURING DIRECT PRESETTING OF ALLOY LBTPN D16T

Pipes made of high-strength aluminum alloys with protector thickeners in the middle and at the ends are actively used in the construction of wells for oil and gas. Their light weight and sufficient strength make it possible to build wells of greater depth from lower lifting capacity installations. In addition, aluminum alloy pipes of keyless construction are widely used in cases where there is a high content of carbon dioxide and hydrogen sulfide. This design and material make it possible to significantly increase the service life of pipes in aggressive, corrosive environments. In order to increase the production speed of pipes, it is proposed to use the technology of direct compression with back pressure. You can simulate the manufacturing process using this technology of LBTPN (alloy drill pipe of increased reliability) using a specialized software complex DEFORM, which was done. These aluminum pipes are used in the development of ultra-deep gas and oil wells, as well as horizontal and inclined extended reach wells. LBTPNs were also used in the drilling of ultra-deep Kola, Kryvyi Rih, and Ural wells. It is possible to use compressed pipes with back pressure if the design depth of the well is more than 3000 m. During pressing in the plastic deformation focus, stress transformation is observed: normal growth and drop of tangents and, therefore, a decrease in their total impact; increased level of hydrostatic pressure, all components of deformations and, therefore, also their total impact. Unlike the non-backpressure process, when present and under its action in the gage zone, there is a significant decrease in longitudinal tensile forces, as a result it is possible to carry out the process with higher values of alloy flow rates. Also, pipes made of aluminum alloys of a lock-free design are widely used in cases where there is a high content of carbon dioxide and hydrogen sulfide. This design and material can significantly increase the service life of pipes.

Mitochondria as a key target of molecular hydrogen

The aim of the work was to systematize the data on the biologically significant effects of molecular hydrogen to uncover the mechanisms of its effect on the human body. The paper analyzes the literature on the effect of molecular hydrogen administered in the form of inhalation and hydrogenenriched water on the human body, on laboratory mammals (rats, mice), and on model cell systems in vitro. As a result, a mechanism has been proposed according to which, in addition to the already known effect of hydrogen in neutralizing highly reactive oxygen species, there is at least one other group of molecules that are the target of molecular hydrogen in the body. These are the porphyrins, which are part of the hemoproteins, in particularly the cytochromes of the mitochondrial respiratory chain. In the presence of high concentrations of carbon dioxide, which is formed in the tricarboxylic acid cycle in the mitochondrial matrix, hydrogen damages some of the hemes as a result of covalent binding of the CO group to them. At low doses of hydrogen, this causes a moderate decrease in mitochondrial potential and stimulates the adaptive response of the body, including activation of the transcription factor Nrf2, expression of the heme oxygenase and antioxidant defense enzymes, mitophagy, and renewal of the mitochondrial population in the cell.Conclusion. Molecular hydrogen is an adaptogen that causes mitochondrial hormesis – the renewal and strengthening of the body’s bioenergetic and antioxidant systems.

Integration of network pharmacology and serum medicinal chemistry to investigate the pharmacological mechanisms of QiZhuYangGan Decoction in the treatment of hepatic fibrosis

Ethnopharmacological relevanceQizhuyanggan Decoction (QZD), a traditional Chinese medicine formula, is frequently utilized in clinical practice for managing hepatic fibrosis. However, the specific target and mechanism of action of QZD for hepatic fibrosis treatment remain unknown. Aim of the studyBy combining network pharmacology, serum medicinal chemistry, and experimental validation methods, our study aimed to investigate the therapeutic effects of QZD on hepatic fibrosis, the anti-hepatic fibrosis active ingredients, and the possible mechanism of anti-hepatic fibrosis action. Materials and methodsThe study aimed to investigate the therapeutic effect of QZD on hepatic fibrosis induced by CCl4 in SD rats, as well as its mechanism of action. The rats were anesthetized intraperitoneally using 3% pentobarbital and were executed after asphyxiation with high concentrations of carbon dioxide. Several techniques were employed to evaluate the efficacy of QZD, including ELISA, Western blot, HYP reagent assay, and various pathological examinations such as HE, Masson, Sirius Red staining, and immunohistochemistry (IHC). Additionally, serum biochemical assays were conducted to assess the effect of QZD on liver injury. Network pharmacology, UPLC, molecular docking, and molecular dynamics simulation were utilized to explore the mechanism of QZD in treating hepatic fibrosis. Finally, experimental validation was performed through ELISA, IHC, RT-qPCR, and Western blot analysis. ResultLiver histopathology showed that QZD reduced inflammation and inhibited collagen production, and QZD significantly reduced HA and LN content to treat hepatic fibrosis. Serum biochemical analysis showed that QZD improved liver injury. Network pharmacology combined with UPLC screened six active ingredients and obtained 87 targets for the intersection of active ingredients and diseases. The enrichment analysis results indicated that the PI3K/AKT pathway might be the mechanism of action of QZD in the treatment of hepatic fibrosis, and counteracting the inflammatory response might be one of the pathways of action of QZD. Molecular docking and molecular dynamics simulations showed that the active ingredient had good binding properties with PI3K, AKT, and mTOR proteins. Western blot, ELISA, PCR, and IHC results indicated that QZD may treat hepatic fibrosis by inhibiting the PI3K/AKT/mTOR pathway and suppressing M1 macrophage polarization, while also promoting M2 macrophage polarization. ConclusionsQZD may be effective in the treatment of hepatic fibrosis by inhibiting the PI3K/AKT/mTOR signaling pathway and M1 macrophage polarization, while promoting M2 macrophage polarization. This provides a strong basis for the clinical application of QZD.

An added aroma changes the behaviour of domestic pigs in a novel situation aimed for stunning

The currently most widespread stunning method for pigs is high concentration of carbon dioxide (CO2), but this method is under scrutiny due to animal welfare deficits. One alternative method currently under development with potential to replace CO2 is nitrogen (N2) filled high expansion foam. While N2 does not elicit the same aversive behaviour as CO2, it is currently not known if the high expansion foam itself may be frightening to the pigs. Means to alleviate fear reactions to foam could consist of diverting pigs’ attention using aromas (an odour in combination with taste) of interest to them. The current study aimed to investigate if an added aroma (vanilla aroma) affected pigs’ avoidance and exploratory behaviour when exposed to air-filled high expansion foam in a foam box. The study included 50 pigs (30 females, 20 males) of 14–16 weeks of age, of different crosses between Yorkshire, Hampshire and Duroc. The pigs were randomly assigned to either the treatment with air-filled foam with added aroma or the control treatment with no added aroma, which they were exposed to in a foam box. The results showed that pigs with the aromatised foam expressed significantly more exploration behaviour directed towards the foam and box walls, but not towards the floor or the lid. The aromatised foam also resulted in a higher activity level of the pigs. In contrast to the hypotheses, pigs with aromatised foam expressed more avoidance behaviour, and escape attempts were exclusively observed when pigs were exposed to aromatised foam. Slipping events and frequency of vocalisations did not differ between pigs with and without aroma added to the foam. This study shows that an added aroma (taste and odour in combination) increased pigs’ exploration behaviour towards the foam, and thus could serve as a distraction for the pigs when inside a confined foam box. The results emphasise the importance of taking foam aroma into consideration in the further development of the N2-filled high expansion as a stunning method. The potential anxiety- or stress-reducing effect of any added aroma needs further investigation, and future studies should focus on assessing various types of aromas, and/or odours, as well as different concentrations of the compounds to determine which solution is most efficient in alleviating pig stress and anxiety.

Technology Development for the Pyrolysis of Hydrocarbons in Liquid Metal

AbstractThis article describes the development of a new technology based on the application of liquid metal and aims to produce hydrogen by decarbonization (pyrolysis process) of both natural and artificially synthesized hydrocarbons. When biogas with a sufficiently high carbon dioxide content is used as a feedstock, or by the targeted addition of CO2 to methane, a mixture of hydrogen and carbon monoxide (synthesis gas) can be produced. Furthermore, the paper describes another very interesting application of the technology to create negative emissions. In this scenario, the processes direct air capture, methanation, electrolysis and methane pyrolysis are combined to synthesize solid carbon from atmospheric CO2. The broad range of process options investigated indicates that, when the technology is scaled up to industrial scale, the result will be a process that is flexible in both the use of reactants and the resulting products.

Углекислый газ: проблемы нормирования, контроля и профилактики неблагоприятного воздействия в образовательных организациях

This article is a review of data published in Russian and foreign studies that reflect current problems concerning content of carbon dioxide in spaces of residential and public buildings, including children's educational organizations. We consider: mechanisms of action of high concentrations of carbon dioxide on the human body, which manifests as acute and delayed disruptions of metabolic processes in circulatory, central and respiratory systems; existing carbon dioxide content measurement methods used for indoor spaces; principles of setting microclimate and air quality standards for temporarily and constantly occupied indoor spaces and the respective parameter control principles. This analytical review revealed the need for standard-setting efforts, development and approval of a methodology enabling measurement of the actual carbon dioxide concentration in children's educational institutions, since routine measures adopted for the purpose lack in effectiveness or realization, which prevents normalization and stabilization of all qualitative and quantitative air parameters at the levels making the environment of a classroom safe and optimal for education-related activities given high occupancy of the space.

A review on corrosion of cement-based materials in CO2-rich karst groundwater

In karst areas, groundwater has high concentrations of carbon dioxide. It causes decalcification of cement-based materials by reacting with calcium hydroxide and calcium silicate hydrate. Therefore, the corrosion by CO2-rich groundwater has become a significant concern as it may reduce the service life of concrete structure. Based on the chemical reactions, the corrosion can be divided into leaching corrosion, carbonic acid corrosion, and acid corrosion. Calcium carbonate formation and dissolution are critical steps in corrosion process. The loss of calcium from cement results in cracking and spalling of the cement-based materials. The environmental and material factors had a significant effect on the corrosion rate. Based on the study in simulated karst water, adding supplementary cementitious materials or low-calcium alkali-activated materials can improve the corrosion resistance of the cementitious materials.

Does drought stress eliminate the benefit of elevated CO2 on soybean yield? Using an improved model to link crop and soil water relations

Crop simulation models are indispensable tools that facilitate studies to assess climate impacts and adaptation responses, but have not been adequately tested in terms of accurately predicting crop growth and water stress responses to high carbon dioxide concentrations [CO2]. The soybean model, GLYCIM, previously modified with a coupled leaf-level gas exchange – energy balance model, was integrated with a two-dimensional convective-diffusive root growth module which linked soil and leaf water potentials with the regulation of stomatal conductance. We evaluated the accuracy of this modified GLYCIM using experimental data from a Free-Air CO2 Enrichment (FACE) site, SoyFACE, and used the calibrated model to quantify current and projected elevated CO2 effects on soybean yields in the United States (US) Midwest. The model accurately matched SoyFACE observed data including canopy temperature (RMSE, 2.26 -2.42 °C; IA, 0.89-0.90), photosynthesis rate (RMSE, 6.33 -12.88 µmol m−2 s−1; IA, 0.82-0.92), seasonal LAI (RMSE, 0.96 -1.08 cm2 cm−2; IA, 0.91-0.93), biomass (RMSE, 2.06 -2.34 Mg ha−1; IA, 0.87-0.90), soil water contents (RMSE, 5.42 -7.82 %; IA, 0.80-0.85) and root length (RMSE, 2.12 -5.64 m plant−1; IA, 0.70-0.86). GLYCIM also reproduced the observed declining response of yield to CO2 fertilization with increasing drought. Using an ensemble of five climate model projections, GLYCIM showed that the CO2 fertilization effect on yield was highest in northern counties and declined in southern and the western counties by late 21st century in response to increased drought characterized by higher daily maximum temperature and decreased rainfall. This study highlights the need to continue to test and improve crop models and use geospatially referenced adaptive strategies to capitalize the benefits from elevated [CO2] to better counteract increasing drought.

Thermodynamic analysis of the corrosion of high alumina cement by carbon dioxide

The integrity of the wellbore cement sheath plays a crucial role in the geological utilization and sequestration of carbon dioxide. Although high alumina cement (HAC) is a specialized cement with exceptional performance, additional research is required to assess its capability for long-term carbon dioxide sequestration. In this study, the effects of various corrosion conditions and pozzolanic materials on the corrosion of HAC were investigated by using the Gibbs energy minimization method. And the corrosion resistance of minerals was analyzed based on the multiphase chemical equilibrium theory. The results indicate that C3AH6 in HAC is the most susceptible to corrosion. As the temperature increases, more carbon dioxide is consumed for the complete reaction of the primary minerals in HAC. However, the corrosion of HAC is largely unaffected by system pressure. The high concentration of carbon dioxide in formation water accelerates mineral corrosion rates. In addition, the presence of Mg2+ and SO42− increases the formation of intermediate products during the corrosion of HAC, whereas the rate of mineral corrosion decreases as salinity increases. Fly ash can enhance the corrosion resistance of HAC during the initial stage of carbonization. Increasing the replacement ratio of fly ash to HAC reduces the generation of C3AH6 and increases the formation of C2ASH8. The corrosion resistance of each mineral is different, following the order: Al(OH)3 > C2ASH8 > C4AcH11 > C4Ac0.5H12 > C3AH6.

Molecular characterization of spoilage microbiota in high CO2 refrigerated large yellow croaker (Larimichthys crocea) fillets using metagenomic and metabolomic approaches

Although, the negative role of microorganisms in food safety is well known, the specific role of microorganisms on food is still unclear. The effects of high concentration CO2 on the metabolism of specific spoilage organisms of large yellow croaker and the mechanism of microbial action in the spoilage process of large yellow croaker were investigated. Specific spoilage organisms of large yellow croaker in a refrigerated environment obtained by biodiversity analysis. The effects of spoilage microorganisms on fish fillets were explored using metagenomics and metabolomics approaches. The results showed that the high concentration of carbon dioxide effect prolonged the shelf life of refrigerated large yellow croaker and delayed the deterioration of its quality during storage. Meanwhile, the modified atmosphere packaging with high concentration of carbon dioxide can effectively inhibit the growth of microorganisms, change the structure of spoilage microbial flora, and affect the metabolism of spoilage microorganisms. Pseudomonas spp. and Shewanella spp. had strong spoilage potential and made important contributions to the production of biogenic amines in fish. The contribution of Shewanella spp. to fish spoilage is stronger at high CO2 concentrations. The metabolic capacity of spoilage microorganisms was altered by high CO2 concentration, and the arginine decarboxylase (ADC) pathway was the main pathway for production of putrescine under high CO2 concentration. This study contributes to a better understanding of the role of microorganisms in fish spoilage and provides useful information for the development of new preservation methods.

New metal complexes containing a methyldopa Schiff base for carbon dioxide storage

The high concentration of carbon dioxide in the environment, including from the burning of fossil fuels to meet our energy requirements, is a pressing environmental concern that requires urgent attention. As a result, the development of novel materials for storing gases such as carbon dioxide and hydrogen has garnered greater attention in research. The current work reports the synthesis of a Schiff base derived from methyldopa and its metal complexes. In addition, their effectiveness as carbon dioxide storage materials were assessed. The reaction of methyldopa and 4-hydroxybenzaldehyde in boiling ethanol under acidic conditions for four hours gave the corresponding Schiff base in excellent yield. The reaction of metal (copper, cobalt, and nickel) chlorides and Schiff base in boiling ethanol for three hours gave the corresponding metal complexes in high yields (77–83%). The surface morphology and surface area of the synthesized metal complexes were evaluated. The mesoporous complexes have a surface area that ranges from 3.59 to 7.36 m2/g. The average pores diameter was 7.75–12.27 nm, and the pores volume was 0.0.11–0.014 cm3/g. The carbon dioxide storage capacity of the synthesized mesoporous complexes was 27.4–30.6 cm3/gm. The complex containing nickel was the most efficient towards carbon dioxide uptake (30.6 cm3/cm) possibility due to its relatively high surface area (7.36 cm2/g) and pores volume (0.014 cm3/g) compared to the copper and cobalt complexes.

East Asian summer monsoon variations across the Miocene−Pliocene boundary recorded by sediments from the Guide Basin, northeastern Tibetan Plateau

Records of atmospheric carbon dioxide concentration, sea-surface temperature, and global vegetation show that Earth’s climate and environment changed significantly during the late Miocene−early Pliocene. Understanding the environmental response to insolation forcing during this transitional period may provide insights into future environmental variations resulting from the perturbation of the global carbon cycle caused by fossil fuel combustion. However, terrestrial paleoclimate records capable of resolving orbital time-scale environmental variations are mostly from Europe, especially from the region around the Mediterranean Sea. Here, we present high-resolution records of grain size, black carbon, and geochemistry from a sedimentary sequence from the northeastern margin of the Tibetan Plateau, where precipitation is mainly via the East Asian summer monsoon. We observed increases in sediment accumulation rate and black carbon mass accumulation rate at ca. 5.3 Ma, which we interpret as the result of intensified seasonal precipitation associated with the strengthening of the East Asian summer monsoon; concurrently, precessional and obliquity cycles became more prominent during the early Pliocene. Our results suggest that, in response to current and future high atmospheric carbon dioxide concentrations, changes in the East Asian summer monsoon are likely to result in increased precipitation and seasonality within its region of influence.

New Design of a Separator Unit with Metal Hydride and an Analysis of Its Potential Application in the Process of Hydrogen Separation from a Binary Mixture of Gases

Synthesis gases produced in the processes of the high-temperature gasification of otherwise unusable waste, with the use of technologically efficient and cost-effective separation methods, may represent a reliable source of hydrogen intended for applications in the industry and the transport segments. One of the possible solutions to the separation of hydrogen from a mixture of gases is the use of metal hydride (MH) alloys, which are capable of binding hydrogen into their structure. This is the subject of the present article, in which a new design is presented for a fully functional system and a hydrogen separator unit, and the potential application of a commonly available metal hydride alloy in the separation of hydrogen from a binary mixture containing carbon dioxide and hydrogen is discussed. Load testing of the selected type of metal hydride alloy with a high concentration of carbon dioxide in the mixture, representing 40 vol. % and 4 vol. %, was performed. In addition, testing the alloy’s ability to separate hydrogen from a mixture containing H2 and CO2 was conducted using small alloy samples and a newly designed hydrogen separator unit. The resulting higher purity of hydrogen after the separation was confirmed by an experiment, in which the hydrogen concentration in the resulting mixture increased by 2.7 vol. %. The purity of the desorbed hydrogen amounted to 99.4 vol. %. The testing also confirmed a high degree of degradation of the alloy, caused by the poisoning effect of CO2 on the selected alloy type. There was also a significant decrease in the absorption ability of the alloy—from 1.7 wt. % to 1.2 wt. %—and a significant extension of the absorption time caused by the slower kinetics of the hydrogen storage, which occurred as early as after ten absorption–desorption cycles.

Development of a multi-scale mathematical model for green hydrogen production via biogas steam reforming process

In this work, a dynamic 2D heterogeneous model for catalytic hydrogen production by biogas steam reforming process was developed, considering both the macroscale and the microscale of the system. The partial differential equations (which describe mass and energy balances) of the mathematical model, have been converted into total differential equations, by spatial discretization and implemented in Matlab/Simulink for process simulation. Based on simulation results, the profiles for mass and concentration of the reactants and products were obtained. The developed model has been validated with available literature data. For the conversion of methane, it predicted 72.43% and for the hydrogen percentage on the dry basis, it gave the value of 72.72%. In this study, a special emphasis was placed on highlighting the influence of a high content of carbon dioxide in biogas on the size of the reactor. The developed model is used to study the effects of step and ramp flow inputs disturbances for the methane conversion and hydrogen percentage on the dry basis and to observe how the reactor design parameters change when the CO2 concentration in the feed flow increases. Furthermore, the developed model for biogas reforming was integrated in a green hydrogen plant with CO2 capture feature for overall performance evaluation (e.g., energy efficiency, CO2 capture rate etc.). The decarbonized green hydrogen plant has promising performance indicators (high overall energy efficiency of 54.5% and a high CO2 capture rate 70%).