Efficient Separation Of Carbon Dioxide Research Articles

Efficient separation of carbon dioxide and methane in high-pressure and wet gas mixtures using Zr-MOF-808

The capture and separation of carbon dioxide (CO2) has been the focus of a plethora of research in order to mitigate its emissions and contribute to global development. Given that CO2 is commonly found in natural gas streams, there have been efforts to seek more efficient materials to separate gaseous mixtures such as CO2/CH4. However, there are only a few reports regarding adsorption processes within pressurized systems. In the offshore scenario, natural gas streams still exhibit high moisture content, necessitating a greater understanding of processes in moist systems. In this article, a metal-organic framework synthesis based on zirconium (MOF-808) was carried out through a conventional solvothermal method and autoclave for the adsorption of CO2 and CH4 under different temperatures (45–65 °C) and pressures up to 100 bar. Furthermore, the adsorption of humid CO2 was evaluated using thermal analyses. The MOF-808 synthesized in autoclave showed a high surface area (1502 m2/g), a high capacity for CO2 adsorption at 50 bar and 45 °C and had a low selectivity to capture CH4 molecules. It also exhibited a fine stability after five cycles of CO2 adsorption and desorption at 50 bar and 45 °C − as confirmed by structural post-adsorption analyses while maintaining its adsorption capacity and crystallinity. Furthermore, it can be observed that the adsorption capacity increased in a humid environment, and that the adsorbent remained stable after adsorption cycles in the presence of moisture. Finally, it was possible to confirm the occurrence of physisorption processes through nuclear magnetic resonance (NMR) analyses, thus validating the choice of mild temperatures for regeneration and contributing to the reduction of energy consumption in processing plants.

Carbon Dioxide Capture by Adsorption in a Model Hydroxy-Modified Graphene Pore.

Concerns regarding the environmental impact of increasing levels of anthropogenic carbon dioxide have led to a variety of studies examining solid surfaces for their ability to trap this greenhouse gas (GHG). Atmospheric or post-combustion carbon capture requires an efficient separation of carbon dioxide and nitrogen gas. We used the molecular mechanics MM3 parameter set (previously shown to provide good estimates of molecule-surface binding energies) to calculate theoretical surface binding energies for carbon dioxide ∆E(CO2) and nitrogen ∆E(N2). For efficient separation, differentiation of these two gas-surface adsorption energies is required. Examined structures based on graphene, carbon slit width pore, and carbon nanotube gave ∆E(CO2) to ∆E(N2) ratios of 1.7, 1.8, and 1.9, respectively. To enhance the CO2 adsorption, we developed a model graphene surface pore lined with four hydroxy groups whose orientation allowed them to form hydrogen bonds with the oxygens in CO2. Both the single-layer and double-layer versions of this pore gave significant enhancement in the ability to trap CO2 preferentially to N2. The two-layer version of this pore gave ∆E(CO2) = 73 and ∆E(N2) = 6.8 kJ/mol. The one- and two-layer versions of this novel pore averaged a ∆E(CO2) to ∆E(N2) ratio of 12.

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.

Constructing solubility-diffusion domain in pebax by hybrid-phase MOFs for efficient separation of carbon dioxide and methane

A MIL-88B-on-UIO-66 (Abbreviation for UIO@MIL) hybrid-phase MOFs with rod-to-octahedral structure was obtained by the epitaxial growth method, and was added to Pebax matrix to develop a series of Pebax/UIO@MIL MMMs for CO2/CH4 separation. In UIO@MIL hybrid-phase MOF, CO2 solubility domain is formed in the core of UIO@MIL due to the abundant Zr–OH on the surface of UIO-66. MIL-88B has large pores and special rod-like structure that can entangled with the Pebax chain and adjust the spacing of the Pebax chain to form CO2 diffusion domains in MMMs. The results show that Pebax/UIO@MIL-4 membrane has the best CO2 separation performance, the CO2 permeability is 379.07 ± 10.00Barrer, and the CO2/CH4 selectivity is 38.1 ± 1.33. Therefore, hybrid-phase MOFs fillers provide a novel idea for the design of excellent MMMs.

OCEAN: An Algorithm to Predict the Separation of Biogas Using Zeolites

In this work, we propose the OCEAN algorithm, a method for the analysis and selection of the best performing material and working conditions for an efficient separation of carbon dioxide and methane from biogas. Molecular simulation and intelligent computational techniques joined forces to generate a reliable database of adsorption values with an optimized number of parameters, allowing an accurate prediction of the adsorption behavior of the materials at any working condition (pressure and temperature). The screening over a large number of possibilities leads to the selection of the optimal combination of material and operational conditions for an enhanced biogas purification process.

PH Responsive Carboxymethyl Chitosan/Poly(amidoamine) Molecular Gate Membrane for CO2/N2 Separation.

Efficient carbon dioxide separation is an emerging field of interest in the era of energy scarcity and environmental calamity. The present study focuses on the versatile aspects of carboxymethyl chitosan and dendrimer in terms of CO2 separation. A comprehensive study has been accomplished to inspect the physicochemical properties of the prepared membrane. The mixed gas (CO2/N2) separation performances have been measured varying the temperature (60-110 °C) and sweep/feedwater flow ratio (0.33-3). The blend membrane containing 10 weight (wt.)% dendrimer presented highest CO2 permeance of ∼100 GPU and CO2/N2 selectivity ∼149 on maintenance of sweep/feedwater flow ratio 2.33 and 1.67, respectively, at an operating temperature of 90 °C. The remarkable performance displayed by the membrane has been explained with reference to the dendrimer molecular gate mechanism and the salting out effect offered by carboxymethyl chitosan matrix.

Evaluation of dry acid gas removal process on bench scale test facility coupled with syngas produced by O2/CO2-blown gasifier

Dry acid gas removal test facility that comprises of halide and sulfur control units was coupled with O2/CO2-blown gasifier to demonstrate performance and operability of the dry gas purification process for the oxy-fuel IGCC power generation with efficient carbon dioxide separation. The facility was operated for initial five desulfurization cycles of sequential operation of sulfidation, regeneration, and reduction. The duration of each step was fixed to three hours which includes the purge operation to change the gas condition from syngas to oxidative gas, and vice versa. The test facility has the sulfur removal unit equipped with three fixed-bed reactors. Honeycomb shaped desulfurization sorbent that was improved to prevent harmful carbon deposition was installed in those reactors. The cyclic operation results revealed that the unit could reasonably remove sulfur compounds in the sulfidation steps and released the absorbed sulfur during succeeding regeneration steps for the initial five cycles of operation. The spent sorbent did not suffered with carbon deposition and retained their performance on sulfur removal. The absorbed sulfur in the spent sorbent was adequately released in regeneration steps for further operation of desulfurization cycles. The performance and operability of the dry acid gas removal process was successfully demonstrated in the actual syngas operation test.

Mixed Matrix Membrane Based on Cross-Linked Poly[(ethylene glycol) methacrylate] and Metal–Organic Framework for Efficient Separation of Carbon Dioxide and Methane

The key in preparing mixed matrix membranes for the desired gas separation is to rationally select a suitable combination of inorganic fillers and polymers and to develop fabrication techniques enabling formation of a continuous inorganic phase with dual transport pathway. Herein, we report the facile design of flexible poly[poly(ethylene glycol) methacrylate-co-poly(ethylene glycol) dimethacrylate] membranes containing metal organic frameworks UiO-66 prepared from zirconium chloride and 2-aminoterephthalic and terephthalic acid varying in contents, shapes, and sizes. The surface chemistry effects of both polymer matrix and MOFs on permeability and selectivity were investigated. The bare polymer membrane exhibited a permeability for CO2 of around 117 barrer and a selectivity of up to 15. Addition of glycidyl methacrylate in the polymerization mixture led to membranes that were modified with hexamethylenediamine to provide for basicity. However, this modification did not improve performance of the membrane...

Detailed Investigation of the Binary Adsorption of Carbon Dioxide and Methane in Zeolite Na-ZSM-5 Studied Using in Situ ATR-FTIR Spectroscopy

The separation of carbon dioxide from methane is an important process when purifying biogas and natural gas. Zeolite membranes and adsorbents are among the technologies suggested for efficient separation of carbon dioxide from these gases. In the present work, the adsorption of carbon dioxide and methane from binary mixtures in a low alumina Na-ZSM-5 zeolite film at various gas compositions and temperatures was studied using in situ ATR-FTIR (attenuated total reflection Fourier transform infrared) spectroscopy. Adsorbed concentrations were successfully extracted from infrared spectra. The experimental values of the adsorbed phase mole fraction of carbon dioxide and methane were compared to values predicted using the ideal adsorbed solution theory (IAST). The values predicted with the IAST agreed very well with values determined experimentally. The CO2/CH4 adsorption selectivity was determined, and at 35 °C a selectivity of 15.4 was obtained for an equimolar gas mixture. At the highest (0.9) and lowest (0.03) investigated mole fractions of carbon dioxide in the gas phase, the selectivity was higher compared to the other investigated mole fractions. At 35 °C the highest observed selectivity values were 31.1 and 20.4 for the highest and the lowest adsorbed mole fraction, respectively. At compositions closest to those found in biogas and natural gas, there was a decrease in the selectivity at higher temperatures, indicating that separation of carbon dioxide from methane in biogas and natural gas may be more efficient at low temperatures.

Highly efficient separation of carbon dioxide by a metal-organic framework replete with open metal sites

Selective capture of CO(2), which is essential for natural gas purification and CO(2) sequestration, has been reported in zeolites, porous membranes, and amine solutions. However, all such systems require substantial energy input for release of captured CO(2), leading to low energy efficiency and high cost. A new class of materials named metal-organic frameworks (MOFs) has also been demonstrated to take up voluminous amounts of CO(2). However, these studies have been largely limited to equilibrium uptake measurements, which are a poor predictor of separation ability, rather than the more industrially relevant kinetic (dynamic) capacity. Here, we report that a known MOF, Mg-MOF-74, with open magnesium sites, rivals competitive materials in CO(2) capture, with 8.9 wt. % dynamic capacity, and undergoes facile CO(2) release at significantly lower temperature, 80 degrees C. Mg-MOF-74 offers an excellent balance between dynamic capacity and regeneration. These results demonstrate the potential of MOFs with open metal sites as efficient CO(2) capture media.