Carbon Dioxide Separation Research Articles

Grand canonical Monte Carlo simulation of the adsorption and separation of carbon dioxide and methane using functionalized Mg-MOF-74

Grand canonical Monte Carlo (GCMC) simulations were used to analyse the effect of -O-Li, -NH2, -SH, -F, -COOH, and -NO2 functional groups on the adsorption and separation of pure CO2 and a mixture of CO2 and CH4. The metal–organic framework (MOF) skeleton was structurally optimized using the Forcite and Dmol 3 modules. First, the GCMC method was employed to simulate the adsorption of pure CO2 by functionalized Mg-MOF-74 at 298 K and 10–3000 kPa. The results illustrated that -O-Li, -NH2, and -SH groups increased the CO2 adsorption below 101 kPa and followed the order Li-O-Mg-MOF-74 > NH2-Mg-MOF-74 > SH-Mg-MOF-74. When the pressure was >101 kPa, the adsorption capacity of Mg-MOF-74 was higher than that of functionalized Mg-MOF-74. Then, the adsorption capacity and selectivity of functionalized Mg-MOF-74 in the CO2/CH4 mixture were investigated at 298 K and 10–3000 kPa. The results showed that the introduction of -O-Li, -NH2, and -SH groups increased the CO2 selectivity of Mg-MOF-74 within the range of 10–1440 kPa and followed the order Li-O-Mg-MOF-74 > NH2-Mg-MOF-74 > SH-Mg-MOF-74.

Application of Hollow Fiber Membrane for the Separation of Carbon Dioxide from Atmospheric Air and Assessment of Its Distribution Pattern in a Greenhouse

Research on carbon management is fueled by the growing concern over rising carbon dioxide (CO2) levels in the atmospheric air and its possible impacts on the climate. In this study, we proposed a method of CO2 separation from atmospheric air. This study aimed to investigate the effects of CO2 enrichment on the air temperature inside a greenhouse using a hollow fiber (HF) membrane system. The experiment was conducted over a period of 30 days in two experimental conditions: 15 days without CO2 enrichment (WCS) and 15 days with CO2 enrichment (CS). Results showed that the mean CO2 concentration and air temperature were highest inside the greenhouse during the CS period, with values of 1120 ppm and 37.42 °C, respectively. Regression analysis revealed a positive correlation between CO2 concentration and temperature during the CS period (R2 = 0.628). The HF membrane system was found to be effective in increasing both the CO2 concentration and air temperature inside the greenhouse. However, the system also has limitations, including the cost, maintenance, and suitability for all types of crops. Further experiments are needed to address these limitations and determine the optimal CO2 concentration for different kinds of crops growing in greenhouses.

Mixed matrix membranes incorporated with zeolite AlPO-18 for CO2/CH4 separation

Mixed Matrix Membranes (MMMs) have garnered a lot of interest in carbon dioxide (CO2) and methane (CH4) gas separation due to their advantages over pure polymeric membranes. In the present work, various Aluminophosphate-18 (AlPO-18) loadings was incorporated into Polysulfone (PSf) matrix to fabricate MMMs for CO2 gas permeation and separation. The MMMs were subjected to characterization including Fourier Transform Infrared (FTIR), X-ray Diffraction (XRD) and Field Emission Scanning Electron Microscope (FESEM) to study the spectroscopic, crystallographic and morphological characteristics of the developed membranes. CO2 and CH4 gas permeation were conducted to evaluate the effect of different AlPO-18 loading on the gas permeation and separation performance of the membrane. FTIR and XRD analysis proved the incorporation of zeolite AlPO-18 particles on the polymeric matrix. Notable improvements in gas permeation and separation were obtained for MMMs incorporated with 1 wt% AlPO-18 (1AlPO-18/PSf MMMs), with the ideal selectivity increasing by 22% in comparison to the pristine PSf membrane.

Techno-economic analysis of a biogas-to-methanol process: Study of different process configurations and conditions

Bio-methanol produced from renewable resources, such as biogas, represents an interesting low carbon energy carrier due to its versatility. Few publications are available on the topic and techno-economic assessments focusing on the production of renewable methanol are needed to properly design such plants and understand their potential. To this purpose, a detailed techno-economic analysis of a 20 MWLHV biogas to methanol process via steam reforming is presented in this work. The process was designed to treat biogas produced via anaerobic digestion of municipal solid waste and be autonomous from a thermal viewpoint. The analysis included the comparison of three different process configurations, differing in the presence and position of the carbon dioxide separation unit. Sensitivity analyses were carried out on key process parameters, namely MeOH synthesis loop Recycle Ratio (RR, in the interval 3−7), methanol reactor pressure (pMeOH; 50–95bar) and Gas Hourly Space Velocity (GHSV,4000−8000; Nm3h·mCAT3). The best plant configuration was achieved when carbon dioxide separation was performed upstream of the reformer, which allowed to achieve higher carbon and fuel efficiencies. In the base case (RR=5, pMeOH=95bar, and GHSV=4000Nm3h·mCAT3), such configuration produced 2480kg/h of methanol, with a carbon and fuel efficiency equal to 51.4% and 72.2% respectively and a levelized cost of methanol of 378.0€/t. Reactor pressure considerably affected process profitability, whereas GHSV and RR had little impact on process economics. When methanol reactor pressure was decreased to 50bar, methanol production kept almost constant, but overall costs were remarkably lower. This led to a higher profitability, with a levelized cost of methanol of about 357.7€/t.

Covalent Organic Frameworks: The Rising-Star Platforms for the Design of CO2 Separation Membranes.

Membrane-based carbon dioxide (CO2 ) capture and separation technologies have aroused great interest in industry and academia due to their great potential to combat current global warming, reduce energy consumption in chemical separation of raw materials, and achieve carbon neutrality. The emerging covalent organic frameworks (COFs) composed of organic linkers via reversible covalent bonds are a class of porous crystalline polymers with regular and extended structures. The inherent structure and customizable organic linkers give COFs high and permanent porosity, short transport channel, tunable functionality, and excellent stability, thereby enabling them rising-star alternatives for developing advanced CO2 separation membranes. Therefore, the promising research areas ranging from development of COF membranes to their separation applications have emerged. Herein, this review first introduces the main advantages of COFs as the state-of-the-art membranes in CO2 separation, including tunable pore size, modifiable surfaces property, adjustable surface charge, excellent stability. Then, the preparation approaches of COF-based membranes are systematically summarized, including in situ growth, layer-by-layer stacking, blending, and interface engineering. Subsequently, the key advances of COF-based membranes in separating various CO2 mixed gases, such as CO2 /CH4 , CO2 /H2 , CO2 /N2 , and CO2 /He, are comprehensively discussed. Finally, the current issues and further research expectations in this field are proposed.

Ethylene Recovery via Pebax-Based Composite Membrane: Numerical Optimization

Membrane technology, particularly polymeric membranes, is utilized in major industrial ethylene recovery owing to the very convenient and robust process. Thus, in this paper, a composite membrane (CM) comprising SAPO-34 and Pebax-1657 was employed to conduct a separation performance under two operating conditions, including temperatures and pressures, ranging from 25.0–60.0 °C and 3.5–10.0 bar, respectively. CO2 permeability and CO2/C2H4 ideal selectivity values that ranged from 105.68 to 262.86 Barrer and 1.81 to 3.52, respectively, were obtained via the experimental works. The separation of carbon dioxide (CO2) from ethylene (C2H4) has then been optimized using response surface methodology (RSM) by adopting a central composite design (CCD) method. As a result, the ideal operational conditions were discovered at a temperature of 60.0 °C and pressure of 10.0 bar with the maximum CO2 permeability of 233.62 Barrer and CO2/C2H4 ideal selectivity of 3.22. The typical discrepancies between experimental and anticipated data for CO2 permeability and CO2/C2H4 ideal selectivity were 1.67% and 3.10%, respectively, demonstrating the models’ validity. Overall, a new combination of Pebax-1657 and SAPO-34 composite membrane could inspire the latest understanding of the ethylene recovery process.

Fabrication of Pebax/4A Zeolite Nanocomposite Membrane to Enhance CO2 Selectivity Compared to Pure O2, N2, and CH4 Gases

The separation of carbon dioxide is essential for the environment. Using membranes to separate this gas is economical, but the weakness in permeability and mechanical strength has prevented their commercialization. Robeson proved that permeability and selectivity have the opposite relationship and provided an upper limit for pairs of gases. Worth to be mentioned that any membrane placed above this limit could be commercialized. Scientists proposed mixed matrix membranes to overcome this problem. These membranes contain two phases, polymer, and inorganic. This research focuused on membrane technology and aimed to prepare a membrane that has a good performance for CO2 separation and at the same time its cost is economical, so by adding a reasonable price zeolite available in the market named 4A to the Pebax1657 polymer and changing the operating conditions of the process, permeability and Selectivity was measured. Pebax polymer and 4A zeolite were selected as respectively the polymer and mineral phases for membrane fabrication. The fabricated membranes were evaluated by XRD, FT-IR, FE-SEM, BET, EDAX, TGA/DSC, and mechanical strength tests. Finally, the selectivity of CO2 compared to N2, O2, and CH4 improved by 53, 67, and 75%, respectively, and obtained a good position on the Robeson diagram.

Recent Advances in the Applications of Green Synthesized Nanoparticle based Nanofluids for the Environmental Remediation.

With the ever-growing importance of green technology, the utilization of inorganic metal oxide nanoparticles and their nanofluids against microorganisms garnered more attention than organic metal oxides in recent years. Therefore, using safer, energy and cost-effective natural raw materials, stabilizing agents, and solvents are the fundamental considerations of the greener process. Due to their unique properties, larger surface area to volume ratio, higher stability and selective toxicity towards microbial pathogens, ZnO, TiO2 and silver nanoparticles are considered environmentally friendly and cost-effective antimicrobial agents. Furthermore, amine-based silica nanoparticles and carbon nanotubes are used for the carbon dioxide and hydrogen sulfide separation. The review mainly focuses on the green synthesis of the various nanoparticles to form nanofluids and their application in environmental remediation. In this light, the current paper briefly summarizes the preparation methods and the prospective environmental remediation applications of various nanofluids in the field of microorganisms controlling mechanisms, wastewater treatment methods and harmful gaseous removal methods.

高分子ガス膜技術でCO2 ネットゼロ経済を

We identified ways to stop the dissociative swelling of graphene oxide membranes in the presence of humidity by incorporating nanodiamonds. The stabilization phenomenon is identified as an enhanced electrostatic interaction between the negatively charged graphene oxide sheets and the positively charged carbonaceous nanodiamonds. Essentially, through the introduction of nanodiamonds, water is prevented from (a) absorbing within the graphene oxide structures, (b) blocking the pathways for hydrogen transport, and (c) irreversibly re–organizing the nanolaminated graphene oxide galleries. Of notable interest, the overall permaselective performance of the membrane was found to exceed that of any reported membrane material performance for the separation of carbon dioxide from hydrogen. For comparison, we surveyed best–in–class performances reported for silicas, polymers and metal and covalent organic frameworks.

Advances in organic microporous membranes for CO2 separation

This Perspective focuses on innovation and advanced design of membranes for carbon dioxide separation, triggered by new organic microporous materials.

Increasing the heating value of natural gas by reducing CO2 concentration using vortex tube: A new method

Natural gas (based on methane) is one of the most popular fossil fuels used in the world's energy industries, so, any progress in increasing its heating value can have impressive impacts on the energy efficiency around the world and specially on global warming. Separation of carbon dioxide is one of the most important actions that can increase the heating value of natural gas. For the first time, this experimental investigation is designed to apply thermodynamic performance of a vortex tube for improving the heating value of natural gas through the separation process. Furthermore, this research investigates the effects of the internal structural parameters of the navigator on the separation level of CO2 from the injected natural gas (Pin = 0.5, 0.7 and 0.9 MPa). The considered structural factors are; the middle part diameter (Ø=12, 13 and 14 mm), the convergence angle (θ = 0°, 1°, 2°, 3° and 4°) and the divergence angle (β = 0°, 1°, 2°, 3° and 4°), and the results show that there are optimum values (Ø=13 mm, θ = 3°, β = 1°) which lead to the maximum level of carbon dioxide separation from the natural gas stream. The results show that the optimum VT decreases the concentration of CO2 at the cold outlet to 1.30 % (P = 0.5 MPa), 1.16 % (P = 0.7 MPa) and 0.79 % (P = 0.9 MPa) via the thermodynamic separation process.

A review on facilitated transport membranes based on π-complexation for carbon dioxide separation

The emission of CO2 from human activities is the principal reason for global warming. Membrane separation technology has been extensively regarded as a tremendous potential option for mitigating CO2 emissions when utilizing fossil fuels as a major source of energy. As an important group of CO2 separation membranes, the fixed CO2 carrier-facilitated transport membrane guided by π-complexation reactions is a rising research field and has attracted much attention in the last ten years due to its desirable CO2 separation performance in the dry state and high resistance to oxidation. In this review, facilitated transport theories derived from π-complexation reactions are discussed for an in-depth understanding, rational design and tunable fabrication of facilitated transport membranes. According to the different fixation methods of metal ions (CO2 active carrier), polymer electrolyte membranes and mixed matrix membranes are discussed in detail as two strategies for fabricating CO2-facilitated transport membranes. Future perspectives toward π-complexation reaction-facilitated transport membranes are proposed.

Landfill gas upgrading using amine-functionalized silica sorbents

ABSTRACT Separation of acid gases such as CO2 from biogas is a key step for its purification before biomethane is used in various applications such as injection into a pipeline or use as a vehicle fuel. In this study, the single step purification of real biogas (locally collected landfill gas) was demonstrated using (3-Aminopropyl) triethoxysilane (APTES)-grafted SBA-15. The sorbent was optimized between amine amount and accessibility to adsorption sites. In studies using a surrogate mixture of CH4/CO2 the sorbent recorded an adsorption capacity of 0.85 mmolCO2/gads under dry conditions and this decreased to 0.72 mmolCO2/gads when the surrogate biogas was saturated with steam. Even though the capacity was further decreased to 0.55 mmolCO2/gads using real landfill gas, it remained fairly stable over 5 cycles despite the presence of impurities, namely hydrogen sulfide (68 ppm). In all cases, the capacity was regenerated with a thermal treatment in inert gas at 100°C. The results suggested possibilities for a single step purification unit to remove acid gasses and water and provide potential for a streamlined operation for the separation of carbon dioxide from biogas. The enhanced economics should propel the move toward a green energy future.

Combination of genetic algorithm and CFD modelling to develop a new model for reliable prediction of normal shock wave in supersonic flows contributing to carbon capture

Carbon dioxide separation and capture using green and efficient methods is an important issue in studies related to climate change. The supersonic separator is one of the efficient and reliable methods that can be used to separate impurities, including carbon dioxide, from gas streams. Reliable estimation of normal shock wave position plays a vital role in the proper design and simulation of supersonic separators. Many studies have used a one-dimensional theoretical (ideal) model of a normal shock wave for the estimation of the shock position and pressure recovery, but the accuracy of the ideal model of normal shock may be insufficient in some situations, as reported in the literature. A novel approach is presented in this paper to provide new equations for normal shock waves by the combination of computational fluid dynamics (CFD) and genetic algorithm. The comparison of the proposed model with several experimental data and the ideal model of a normal shock wave indicate that the present model provides more accurate predictions than the traditional model of a normal shock wave. The present model showed an average absolute relative deviation (AARD) of 1.80%, which is about six times less than AARD of the ideal model, indicating the robustness of the proposed model. Consequently, the present model can be employed as an accurate and efficient tool for the prediction of shock position and design of converging–diverging nozzles.

Development of stabilized zirconia–alkali salts dual membranes for carbon dioxide capture

AbstractMolten Na2CO3–K2CO3 (NKC, 56–44 mol%) eutectic compositions were vacuum‐impregnated, at the eutectic temperature, into two porous ZrO2:8.6 mol% MgO (magnesium‐partially stabilized zirconia, MgPSZ) and ZrO2:8 mol% Y2O2 (yttria‐fully stabilized zirconia, 8YSZ) ceramics. Thermogravimetric analyses were performed in mixtures of that composition with MgPSZ and 8YSZ ceramic powders. Before impregnation, porosity was achieved in the two compounds by addition and thermal removal of 30 vol.% NKC. To ascertain the carbonates had filled up through the ceramic body, both sides of the parallel and fracture surfaces of the disk‐shaped impregnated compositions were observed in a scanning electron microscope and analyzed by energy‐dispersive X‐ray spectroscopy. The electrical conductivity of the two ceramics, before and after impregnation, was evaluated by electrochemical impedance spectroscopy in the 5 Hz–13 MHz frequency range from approximately 530 to 740°C. The permeation of the carbonate ions through the membranes via the eutectic composition was assessed by the threshold temperatures of the onset of the carbonate ion percolation. The objectives were to prepare dual‐phase membranes for the separation of carbon dioxide and for the development of carbon dioxide sensors.

Experimental and COSMO-RS analysis of CO2 solubility in novel aqueous blends of 1-butyl-3-methyl-imidazolium tetrafluoroborate activated by 2-aminoethyl piperazine and bis(3-aminopropyl) amine for post combustion carbon capture

Analysis of available technologies and exploration of new ones are an integral approach for studying the efficient separation of carbon dioxide (CO2) from large point sources. Anew proposed aqueous solvent blends of 1-butyl-3-methyl-imidazolium tetrafluoroborate ([bmim] [BF4]) and 1-(2-aminoethyl) piperazine (AEP) /bis (3-aminopropyl) amine (APA) are studied theoretically using COSMO-RS and experimentally for CO2 capture application. The molecules are studied for describing relationship amid sigma-potential and sigma-surface with CO2 solubility. Important thermodynamic properties such as vapor pressure, Henry’s constant have been evaluated using COSMO-RS method and compared with available experimentally obtained values. Essential binary interaction parameters of vapor liquid equilibrium of the solvents are estimated using NRTL and UNIQUAC 2 models. The work considers the measurements and modelling of CO2 solubility in conferred solvents over (303.15˗323.15) K and (1−244) kPa, respectively. The investigational CO2 solubility data are associated with feed forward neural network model. Thermophysical properties of viscosity, and density have also been measured and modelled employing recognised models.

Preparation and characterization of activated carbon modified by potassium for carbon dioxide/methane adsorption and separation

AbstractIn this study, potassium nitrate, which was confirmed feasible to improve the adsorption capacity of carbon dioxide and separation of carbon dioxide/methane mixture, was utilized to modify the commercial coconut shell activated carbon. Three parameters, including potassium ion concentration, modification temperature and modification time, were investigated. The best sample is obtained when impregnating in potassium nitrate solution of 0.1 mol L−1 at 55 °C for 12 h according to its adsorbed amount capacity and separation effect. The saturated adsorbed amount of carbon dioxide on the optimal sample reaches up to 12.25 mmol g−1. In addition, the selectivity for a binary mixture with volume ratio of 60/40, 50/50 and 40/60, which is considered in the range of typical landfill gas, are 6.86, 6.62 and 6.39, increasing by 45.9 %, 43.6 % and 41.4 %, respectively. The adsorbent obtained in this study is promising in the adsorption and separation of carbon dioxide and methane industrially. Moreover, the method of modifying by potassium ion provides a potential way in improving the property of the adsorbents.

Life cycle assessment of a biomass based chemical looping combustion

Chemical looping combustion (CLC) is a promising technology that generates energy while inherently separating carbon dioxide from air using oxygen carriers. This allows for an efficient and cost-effective means of carbon capture and storage. Current CLC systems use coal with metal oxides for combustion in the fuel reactor, thus, resulting in some environmental impacts. Recent life cycle assessment (LCA) of CLC studies have indicated the environmental impacts of conventional coal-based CLC, especially on the global warming potential. To mitigate these environmental impacts, this study proposes the use of a biomass-based CLC and evaluates its impacts using LCA. A case study in the Philippines is adopted where rice husks are used as biomass feedstock. A kilowatt-hour of electricity generated from the CLC plant is utilized as the functional unit. A relative comparison of environmental impacts was considered between the coal-based power plant, the coal-based CLC plant, and the biomass-based CLC plant. The single score results have shown that the biomass-based CLC has the least environmental impacts relative to the coal-based power plant and the coal-based CLC plant. However, it is noted that water consumption is the main drawback of utilizing rice husks as CLC biomass feedstock. The majority of the environmental impacts of the coal-based CLC and the coal-based power plant were derived from upstream processes such as coal mining and processing. With the use of rice husks as CLC biomass feedstock, net negative emissions were achieved.

Modeling and optimal design of multicomponent vacuum pressure swing adsorber for simultaneous separation of carbon dioxide and hydrogen from industrial waste gas

Modeling and optimal design of multicomponent vacuum pressure swing adsorber for simultaneous separation of carbon dioxide and hydrogen from industrial waste gas

Deep eutectic solvent functionalized mesoporous silica SBA-15 based mixed matrix polymeric membranes for mitigation of CO2 (Extended Version)

The carbon dioxide (CO2) separation can be enhanced by using modified materials like a deep eutectic solvent (DES) modified mesoporous silica SBA-15 in polymeric support i.e polysulfone via mixed matrix membranes (MMMs). The pure SBA-15 and DES are potential candidates for the CO2 capturing and their combination has not been reported yet. In this work, a fresh DES was synthesized by combining equal concentrations of Decanoic acid and choline chloride by mass. MMMs were fabricated by DES functionalized SBA-15 (DES-SBA) filler. The DES-SBA-based polymeric MMMs of different compositions, from 5% to 20% with the difference of five each, were developed and subjected to the gas permeation analysis to evaluate relative selectivities and permeabilities of membranes. The DES-SBA-based MMMs were characterized by SEM and FTIR to obtain distribution analysis of filler in the polymer matrix as well as the cross-sectional and surface morphology and the structural analysis of membranes, respectively. The gas permeation evaluations have been utilized to mixed and pure gas samples and the findings of selectivities for CO2/N2 and CO2/CH4 and permeabilities of synthesized MMMs are being reported. The performance of the MMMs has been enhanced via functionalization of SBA-15 by DES as compared to the neat polysulfone (PSF) based simple membrane.