A Review on CO2 Capture Technologies with Focus on CO2-Enhanced Methane Recovery from Hydrates

Dissociation line and driving force for nucleation of the nitrogen hydrate from computer simulation. II. Effect of multiple occupancy

In this work, we determine the dissociation line of the nitrogen (N2) hydrate by computer simulation using the TIP4P/Ice model for water and the TraPPE force field for N2. This work is the natural extension of Paper I, in which the dissociation temperature of the N2 hydrate has been obtained at 500, 1000, and 1500 bar [Algaba et al., J. Chem. Phys. 159, 224707 (2023)] using the solubility method and assuming single occupancy. We extend our previous study and determine the dissociation temperature of the N2 hydrate at different pressures, from 500 to 4500 bar, taking into account the single and double occupancy of the N2 molecules in the hydrate structure. We calculate the solubility of N2 in the aqueous solution as a function of temperature when it is in contact with a N2-rich liquid phase and when in contact with the hydrate phase with single and double occupancy via planar interfaces. Both curves intersect at a certain temperature that determines the dissociation temperature at a given pressure. We observe a negligible effect of occupancy on the dissociation temperature. Our findings are in very good agreement with the experimental data taken from the literature. We have also obtained the driving force for the nucleation of the hydrate as a function of temperature and occupancy at several pressures. As in the case of the dissociation line, the effect of occupancy on the driving force for nucleation is negligible. To the best of our knowledge, this is the first time that the effect of the occupancy on the driving force for nucleation of a hydrate that exhibits sII crystallographic structure is studied from computer simulation.

Emerging bio-capture strategies for greenhouse gas reduction: Navigating challenges towards carbon neutrality

Greenhouse gas emissions are significantly contributing to climate change, posing one of the serious threats to our planet. Addressing these emissions urgently is imperative to prevent irreversible planetary changes. One effective long-term mitigation strategy is achieving carbon neutrality. Although numerous countries aim for carbon neutrality by 2050, only a few are on track to realize this ambition. Existing technological solutions, including chemical absorption, cryogenic separation, and membrane separation, are available but tend to be costly and time intensive. Bio-capture methods present a promising opportunity in greenhouse gas mitigation research. Recent developments in biotechnology for capturing greenhouse gases have demonstrated both effectiveness and long-term benefits. This review emphasizes the recent advancements in bio-capture techniques, showcasing them as dependable and economical solutions for carbon neutrality. The article briefly outlines various bio-capture methods and underscores their potential for industrial application. Moreover, it investigates into the challenges faced when integrating bio-capture with carbon capture and storage technology. The study concludes by exploring the recent trends and prospective enhancements in ecosystem revitalization and industrial decarbonization through green conversion techniques, reinforcing the path towards carbon neutrality.

Utilization of plant-derived wastes as the potential biohydrogen source: a sustainable strategy for waste management

The sustainable economy has shown a renewed interest in acquiring access to the resources required to promote innovative practices that favor recycling and the reuse of existing, unconsidered things over newly produced ones. The production of biohydrogen through dark anaerobic fermentation of organic wastes is one of the intriguing possibilities for replacing fossil-based fuels through the circular economy. At present, plant-derived waste from the agro-based industry is the main global concern. When these wastes are improperly disposed of in landfills, they become the habitat for several pathogens. Additionally, it contaminates surface water as a result of runoff, and the leachate that is created from the waste enters groundwater and degrades its quality. However, cellulose and hemicellulose-rich plant wastes from agriculture fields and agro-based industries have been employed as the most efficient feedstock since carbohydrates are the primary substrate for the synthesis of biohydrogen. To produce biohydrogen from plant-derived wastes on a large scale, it is necessary to explore comprehensive knowledge of lab-scale parameters and pretreatment strategies. This paper summarizes the problems associated with the improper management of plant-derived wastes and discusses the recent developments in dark fermentation and substrate pretreatment techniques with the goal of gaining significant insight into the biohydrogen production process. It also highlights the utilization of anaerobic digestate, which is left over after biohydrogen gas as feedstock for the development of value-added products such as volatile fatty acids (VFA), biochar, and biofertilizer.

Breakthrough applications of porous organic materials for membrane-based CO2 separation: a review

Over the last decades, porous organic materials (POMs) have been extensively employed in various industrial approaches including gas separation, catalysis and energy production due to possessing indisputable advantages like great surface area, high permeability, controllable pore size, appropriate functionalization and excellent processability compared to traditional substances like zeolites, Alumina and polymers. This review presents the recent breakthroughs in the multifunctional POMs for potential use in the membrane-based CO2 separation. Some examples of highly-selective membranes using multifunctional POMs are described. Moreover, various classifications of POMs following with their advantages and disadvantages in CO2 separation processes are explained. Apart from reviewing the state-of-the-art POMs in CO2 separation, the challenges/limitations of POMs with tailored structures for reasonable application are discussed.

Transformation of Diffusion and Local Structure of CH4 , CO2 , SO2 and H2 O Mixtures in Graphene Under Wide Temperature and Pressure Range: A Molecular Dynamics Simulation Study

As a material with high specific surface area and excellent chemical stability, graphene exhibited remarkable adsorption and separation performance as well as a wide range of potential applications. The graphene layer played a significant role in influencing gas transmission. In this study, we employed molecular dynamics simulation to investigate the diffusion characteristics and local structures of a mixed system consisting of CH4 , CO2 , SO2 and H2 O. Additionally, we further examined the transformation of the behavior of these mixtures within graphene layers. The order of diffusion coefficients of the four molecules without graphene was H2 O>SO2 >CO2 ≫CH4 . However, in the double-layer graphene, the order changed to CH4 >CO2 ≫H2 O>SO2 . Higher temperatures and lower pressures were found to facilitate gas diffusion. Temperature and pressure had great effects on the local structures of CH4 , CO2 and SO2 , while their impact on H2 O was limited due to the extensive network of hydrogen bonds formed by H2 O molecules. The statistical results of average coordination number revealed that CH4 tended to aggregate with itself, whereas CO2 and SO2 exhibited a tendency to aggregate with H2 O. The graphene structure enhanced the separation and transportation of CH4 from mixed systems.

Carbon dioxide capture from air leading to bis-[N-(5-methyl-1H-pyrazol-3-yl-κN2)carbamato-κO]copper(II) tetra-hydrate

A mononuclear square-planar CuII complex of (5-methyl-1H-pyrazol-3-yl)carbamate, [Cu(C5H6N3O2)2]·4H2O, was synthesized using a one-pot reaction from 5-methyl-3-pyrazolamine and copper(II) acetate in water under ambient conditions. The adsorption of carbon dioxide from air was facilitated by the addition of di-ethano-lamine to the reaction mixture. While di-ethano-lamine is not a component of the final product, it plays a pivotal role in the reaction by creating an alkaline environment, thereby enabling the adsorption of atmos-pheric carbon dioxide. The central copper(II) atom is in an (N2O2) square-planar coordination environment formed by two N atoms and two O atoms of two equivalent (5-methyl-1H-pyrazol-3-yl)carbamate ligands. Additionally, there are co-crystallized water mol-ecules within the crystal structure of this compound. These co-crystallized water mol-ecules are linked to the CuII mononuclear complex by O-H⋯O hydrogen bonds. According to Hirshfeld surface analysis, the most frequently observed weak inter-molecular inter-actions are H⋯O/O⋯H (33.6%), H⋯C/C⋯H (11.3%) and H⋯N/N⋯H (9.0%) contacts.

Stochastic Cellular Automata Modeling of CO2 Hydrate Growth and Morphology

Carbon dioxide (CO₂) hydrates are important in a diverse range of applications and technologies in the environmental and energy fields. The development of such technologies relies on fundamental understanding, which necessitates not only experimental but also computational studies of the growth behavior of CO₂ hydrates and the factors affecting their crystal morphology. As experimental observations show that the morphology of CO₂ hydrate particles differs depending on growth conditions, a detailed understanding of the relation between the hydrate structure and growth conditions would be helpful. To this end, this work adopts a modeling approach based on hybrid probabilistic cellular automata to investigate variations in CO₂ hydrate crystal morphology during hydrate growth from stagnant liquid water presaturated with CO₂. The model, which uses free energy density profiles as inputs, correlates the variations in growth morphology to the system subcooling ΔT, i.e., the temperature deficiency from the triple CO₂-hydrate-water equilibrium temperature under a given pressure, and properties of the growing hydrate-water interface, such as surface tension and curvature. The model predicts that when ΔT is large, parabolic needle-like or dendrite crystals emerge from planar fronts that deform and lose stability. In agreement with chemical diffusion-limited growth, the position of such planar fronts versus time follows a power law. In contrast, the tips of the emerging parabolic crystals steadily grow in proportion to time. The modeling framework is computationally fast and produces complex growth morphology phenomena under diffusion-controlled growth from simple, easy-to-implement rules, opening the way for employing it in multiscale modeling of gas hydrates.

Advances in the catalyzed photo-fermentative biohydrogen production through photo nanocatalysts with the potential of selectivity, and customization

Photo nanocatalyst have shownpromise in a variety of fields, including biohydrogen production where their catalytic efficiency is related to size, surface-to-volume ratio, and increasing the number of atoms on the surface. They can harvest solar light to create electron-hole pairs which is the key mechanism to define its catalytic efficiency, thus requiring suitable excitation wavelength, band energy, and crystal imperfections. In this review, a discussion on the role of photo nanocatalysts to catalyze biohydrogen production has been carried out. Photo nanocatalysts feature a large bandgap, andhigh defect concentration, thus having the ability to be tuned for their characteristics. Customization of the photo nanocatalyst has been addressed. Mechanism of the photo nanocatalysts in catalyzing biohydrogen has been discussed. Limiting factors of photo nanocatalysts were highlighted and several recommendations have been made to enhance the effective utilization of these photo nanocatalysts to enhance photo-fermentative biohydrogen production from biomass wastes.

Evaluation of Relative Permeability Curves in Sandstone Core Flooding Using Computational Fluid Dynamics

Geological carbon sequestration is a proven method of safely storing carbon dioxide in formations, thereby reducing atmospheric carbon imprint and mitigating global warming. The relative permeability to carbon dioxide versus brine/water in geological formations determines flow characteristics of one fluid in the presence of another. The objective of this research is to evaluate the relative permeability to carbon dioxide in both the gas phase and the supercritical state in the presence of water in a Vedder sandstone core sample. The sandstone sample used is medium- to fine-grain arkosic artenite containing primarily quartz, potassium feldspar, plagioclase, and biotite. The effect of the viscosity ratio between the non-wetting phase and the wetting phase, on the relative permeability to the non-wetting phase, is studied. Computational fluid dynamics (CFD) is used for this study. Results show that with the same amount of irreducible water fraction, the endpoint relative permeability to the non-wetting phase is approximately one order of magnitude lower for supercritical carbon dioxide than for gaseous carbon dioxide. The endpoint relative permeability does not change significantly with the change in inlet pressure for gaseous carbon dioxide. Additionally, the endpoint relative permeability to the non-wetting phase increases with an increase in the viscosity ratio. Results suggest that CFD can be effectively used to study relative permeability, precluding expensive experiments.

A Review on Green Hydrogen Valorization by Heterogeneous Catalytic Hydrogenation of Captured CO2 into Value-Added Products

The catalytic hydrogenation of captured CO2 by different industrial processes allows obtaining liquid biofuels and some chemical products that not only present the interest of being obtained from a very low-cost raw material (CO2) that indeed constitutes an environmental pollution problem but also constitute an energy vector, which can facilitate the storage and transport of very diverse renewable energies. Thus, the combined use of green H2 and captured CO2 to obtain chemical products and biofuels has become attractive for different processes such as power-to-liquids (P2L) and power-to-gas (P2G), which use any renewable power to convert carbon dioxide and water into value-added, synthetic renewable E-fuels and renewable platform molecules, also contributing in an important way to CO2 mitigation. In this regard, there has been an extraordinary increase in the study of supported metal catalysts capable of converting CO2 into synthetic natural gas, according to the Sabatier reaction, or in dimethyl ether, as in power-to-gas processes, as well as in liquid hydrocarbons by the Fischer-Tropsch process, and especially in producing methanol by P2L processes. As a result, the current review aims to provide an overall picture of the most recent research, focusing on the last five years, when research in this field has increased dramatically.

Techno-Economic Optimization of Multistage Membrane Processes with Innovative Hollow Fiber Modules for the Production of High-Purity CO2 and CH4 from Different Sources

Within the current climate emergency framework and in order to avoid the most severe consequences of global warming, membrane separation processes have become critical for the implementation of carbon capture, storage, and utilization technologies. Mixtures of CO₂ and CH₄ are relevant energy resources, and the design of innovative membranes specifically designed to improve their separation is a hot topic. This work investigated the potential of modified polydimethylsiloxane and ionic liquid–chitosan composite membranes for separation of CO₂ and CH₄ mixtures from different sources, such as biogas upgrading, natural gas sweetening, or CO₂ enhanced oil recovery. The techno-economic optimization of multistage processes at a real industrial scale was carried out, paying special attention to the identification of the optimal configuration of the hollow fiber modules and the selection of the best membrane scheme. The results demonstrated that a high initial content of CH₄ in the feed stream (like in the case of natural gas sweetening) might imply a great challenge for the separation performance, where only membranes with exceptional selectivity might achieve the requirements in a two-stage process. The effective lifetime of the membranes is a key parameter for the successful implementation of innovative membranes in order to avoid severe economic penalties due to excessively frequent membrane replacement. The scale of the process had a great influence on the economic competitiveness of the process, but large-scale installations can operate under competitive conditions with total costs below 0.050 US$ per m³ STP of treated feed gas.

Emerging Solvent Regeneration Technologies for CO2 Capture through Offshore Natural Gas Purification Processes

It is estimated that 40% of natural gas reservoirs in the world are contaminated with acid gases (such as hydrogen sulfide and carbon dioxide), which hinder exploitation activities. The demand for natural gas will increase by 30% from 2020 to 2050, with the rise of industrial activities and the lifting of travel restrictions. The long-term production of these high acid-gas fields requires mitigation plans, which include carbon capture, utilization, and a storage process to reduce carbon emissions. Absorption is one the most established technologies for CO2 capture, yet it suffers from extensive energy regeneration and footprint requirements in offshore operations. Therefore, the aims of this paper are to review and analyze the recent developments in conventional and emerging solvent regeneration technologies, which include a conventional packed-bed column, membrane contactor, microwave heating, flash drum, rotating packed bed, and ultrasonic irradiation process. The conventional packed column and flash drum are less complex, with minimum maintenance requirements, but suffer from a large footprint. Even though the rotating packed-bed column and microwave heating demonstrate a higher solvent flexibility and process stability, both technologies require regular maintenance and high regeneration energy. Membrane contactor and ultrasonic irradiation absorption systems are compact, but restricted by various operational issues.

Chemical Looping Combustion: A Brief Overview

The current development of chemical looping combustion (CLC) technology is presented in this paper. This technique of energy conversion enables burning of hydrocarbon fuels with dramatically reduced CO2 emission into the atmosphere, since the inherent separation of carbon dioxide takes place directly in a combustion unit. In the beginning, the general idea of the CLC process is described, which takes advantage of solids (so-called oxygen carriers) being able to transport oxygen between combustion air and burning fuel. The main groups of oxygen carriers (OC) are characterized and compared, which are Fe-, Mn-, Cu-, Ni-, and Co-based materials. Moreover, different constructions of reactors tailored to perform the CLC process are described, including fluidized-bed reactors, swing reactors, and rotary reactors. The whole systems are based on the chemical looping concept, such as syngas CLC (SG-CLC), in situ Gasification CLC (iG-CLC), chemical looping with oxygen uncoupling (CLOU), and chemical looping reforming (CLR), are discussed as well. Finally, a comparison with other pro-CCS (carbon capture and storage) technologies is provided.

Hardware and Software Implementation for Solar Hot Water System in Northern Regions of Russia

Acceleration of energy transition will become the crucial social, political and technical challenge of the 21st century and will be largely associated with the growing use of renewable energy sources, including solar power. This study provides some experimental results of using solar hot water systems (HWS) embedded in apartment buildings located in the energy-efficient district called Zhatay in Yakutsk city, in the Republic of Sakha (Yakutia). The low annual solar fraction of HWS was found for 2019. It is equal to 0.2869 and caused by thermal energy loss from the hydraulic circuit during the nighttime. The study suggests increasing solar fraction in HWS and implementing a software and hardware system. The experimental evaluation of these studies was performed by testing a solar water heating pilot plant in Kaftanchikovo village in Tomsk Region (Western Siberia). As a result of HWS testing, it was found that the annual solar fraction can be significantly increased by preventing the heating agent from night freezing in hydraulic circuits of tube collectors, even when the outdoor temperature is below its freezing point.

Growth Rate and Morphology Study of Tetrahydrofuran Hydrate Single Crystals and the Effect of Salt

For an advanced gas hydrate management strategy in flow assurance as well as the application of a gas hydrate technology (e.g., desalination), it is important to understand the kinetics and...

Assessment of DFT approaches in noble gas clathrate-like clusters: stability and thermodynamics

We have assessed the performance and accuracy of different wavefunction-based electronic structure methods, such as DFMP2 and domain-based local pair-natural orbital (DLPNO-CCSD(T)), as well as a variety of density functional theory (DFT) approaches on He@(H₂O)_N cage systems. We have selected representative clathrate-like structures corresponding to the building blocks present in each of the sI, sII and sH natural gas clathrate hydrates, and we have carefully studied the interaction between a He atom with each of their individual cages. We reported well-converged DFMP2 and DLPNO-CCSD(T) reference data, together with interaction and cohesive energies of four different density functionals (two GGA, revPBE and PW86PBE, and two hybrids, B3LYP and PBE0), including diverse dispersion correction schemes (D3(0), D3(BJ), D4 and XDM) for both He-filled and empty clathrate-like cages. After the analysis of the results, we came to the conclusion that the PW86PBE functional, with both XDM and D4 corrections, and the PBE0-D4 functional present reasonably adequate approaches to describe the guest-host noncovalent interactions that take place in such He clathrate hydrates. Taking into account that the He@sII is the only helium clathrate that scientists have been able to synthesize recently, we have performed a thermodynamic study on the individual 5¹² and 5¹²6⁴ cages present in the sII crystal. We determined the change in enthalpy, ΔH, and in Gibbs free energy, ΔG, at various temperatures and pressures, and we found out that in the range of experimental conditions the reactions associated with the encapsulation of the He atom inside the cages are exothermic and spontaneous. Finally, we highlighted the importance of an accurate description of the interaction in He@water mixtures, as a crucial component in construction of reliable data-driven models.

Thermodynamic Analysis of Negative CO2 Emission Power Plant Using Aspen Plus, Aspen Hysys, and Ebsilon Software

The article presents results of thermodynamic analysis using a zero-dimensional mathematical models of a negative CO2 emission power plant. The developed cycle of a negative CO2 emission power plant allows the production of electricity using gasified sewage sludge as a main fuel. The negative emission can be achieved by the use this type of fuel which is already a “zero-emissive” energy source. Together with carbon capture installation, there is a possibility to decrease CO2 emission below the “zero” level. Developed models of a novel gas cycle which use selected codes allow the prediction of basic parameters of thermodynamic cycles such as output power, efficiency, combustion composition, exhaust temperature, etc. The paper presents results of thermodynamic analysis of two novel cycles, called PDF0 and PFD1, by using different thermodynamic codes. A comparison of results obtained by three different codes offered the chance to verify results because the experimental data are currently not available. The comparison of predictions between three different software in the literature is something new, according to studies made by authors. For gross efficiency (54.74%, 55.18%, and 52.00%), there is a similar relationship for turbine power output (155.9 kW, 157.19 kW, and 148.16 kW). Additionally, the chemical energy rate of the fuel is taken into account, which ultimately results in higher efficiencies for flue gases with increased steam production. A similar trend is assessed for increased CO2 in the flue gas. The developed precise models are particularly important for a carbon capture and storage (CCS) energy system, where relatively new devices mutually cooperate and their thermodynamic parameters affect those devices. Proposed software employs extended a gas–steam turbine cycle to determine the effect of cycle into environment. First of all, it should be stated that there is a slight influence of the software used on the results obtained, but the basic tendencies are the same, which makes it possible to analyze various types of thermodynamic cycles. Secondly, the possibility of a negative CO2 emission power plant and the positive environmental impact of the proposed solution has been demonstrated, which is also a novelty in the area of thermodynamic cycles.

Integrated biohydrogen production via lignocellulosic waste: Opportunity, challenges & future prospects

Hydrogen production through biological route is the cleanest, renewable and potential way to sustainable energy generation. Productions of hydrogen via dark and photo fermentations are considered to be more sustainable and economical approach over numerous existing biological modes. Nevertheless, both the biological modes suffer from certain limitations like low yield and production rate, and because of these practical implementations are still far away. Therefore, the present review provides an assessment and feasibility of integrated biohydrogen production strategy by combining dark and photo-fermentation as an advanced biochemical processing while using lignocellulosics biomass to improve and accelerate the biohydrogen production technology in a sustainable manner. This review also evaluates practical viability of the integrated approach for biohydrogen production along with the analysis of the key factors which significantly influence to elevate this technology on commercial ground with the implementation of various environment friendly and innovative approaches.

Capture and Reuse of Carbon Dioxide (CO2) for a Plastics Circular Economy: A Review

Plastic production has been increasing at enormous rates. Particularly, the socioenvironmental problems resulting from the linear economy model have been widely discussed, especially regarding plastic pieces intended for single use and disposed improperly in the environment. Nonetheless, greenhouse gas emissions caused by inappropriate disposal or recycling and by the many production stages have not been discussed thoroughly. Regarding the manufacturing processes, carbon dioxide is produced mainly through heating of process streams and intrinsic chemical transformations, explaining why first-generation petrochemical industries are among the top five most greenhouse gas (GHG)-polluting businesses. Consequently, the plastics market must pursue full integration with the circular economy approach, promoting the simultaneous recycling of plastic wastes and sequestration and reuse of CO2 through carbon capture and utilization (CCU) strategies, which can be employed for the manufacture of olefins (among other process streams) and reduction of fossil-fuel demands and environmental impacts. Considering the previous remarks, the present manuscript’s purpose is to provide a review regarding CO2 emissions, capture, and utilization in the plastics industry. A detailed bibliometric review of both the scientific and the patent literature available is presented, including the description of key players and critical discussions and suggestions about the main technologies. As shown throughout the text, the number of documents has grown steadily, illustrating the increasing importance of CCU strategies in the field of plastics manufacture.

A Process for Carbon Dioxide Capture Using Schiff Bases Containing a Trimethoprim Unit

Environmental problems associated with the growing levels of carbon dioxide in the atmosphere due to the burning of fossil fuels to satisfy the high demand for energy are a pressing concern. Therefore, the design of new materials for carbon dioxide storage has received increasing research attention. In this work, we report the synthesis of three new Schiff bases containing a trimethoprim unit and the investigation of their application as adsorbents for carbon dioxide capture. The reaction of trimethoprim and aromatic aldehydes in acid medium gave the corresponding Schiff bases in 83%–87% yields. The Schiff bases exhibited surface areas ranging from 4.15 to 20.33 m2/g, pore volumes of 0.0036–0.0086 cm3/g, and average pore diameters of 6.64–1.4 nm. An excellent carbon dioxide uptake (27–46 wt%) was achieved at high temperature and pressure (313 K and 40 bar, respectively) using the Schiff bases. The 3-hydroxyphenyl-substituted Schiff base, which exhibited a meta-arrangement, provided the highest carbon dioxide uptake (46 wt%) due to its higher surface area, pore volume, and pore diameter compared with the other two derivatives with a para-arrangement.