Amine Absorption Research Articles

Amine Infused Fly Ash Grafted Acrylic Acid/Acrylamide Hydrogel for Carbon Dioxide (CO2) Adsorption and Its Kinetic Analysis.

In most carbon dioxide (CO2) capture processes, chemical absorption using an amine solvent is widely used technology; however, the solvent is prone to solvent degradation and solvent loss which leads to the formation of corrosion. This paper investigates the adsorption performance of amine-infused hydrogels (AIFHs) to increase carbon dioxide (CO2) capture by leveraging the potency of amine absorption and adsorption properties of class F fly ash (FA). The solution polymerization method was used to synthesize the FA-grafted acrylic acid/acrylamide hydrogel (FA-AAc/AAm), which was then immersed in monoethanolamine (MEA) to form amine infused hydrogels (AIHs). The prepared FA-AAc/AAm showed dense matrices morphology with no obvious pore at the dry state but capable of capturing up to 0.71 mol/g CO2 at 0.5 wt% FA content, 2 bar pressure, 30 °C reaction temperature, 60 L/min flow rate, and 30 wt% MEA contents. Cumulative adsorption capacity was calculated and Pseudo-first order kinetic model was used to investigate the CO2 adsorption kinetic at different parameters. Remarkably, this FA-AAc/AAm hydrogel is also capable of absorbing liquid activator that was 1000% more than its original weight. FA-AAc/AAm can be used as an alternative AIHs that employ FA waste to capture CO2 and minimize the GHG impact on the environment.

High-Pressure Adsorption of CO2 and CH4 on Biochar-A Cost-Effective Sorbent for In Situ Applications.

The search for an effective, cost-efficient, and selective sorbent for CO2 capture technologies has been a focus of research in recent years. Many technologies allow efficient separation of CO2 from industrial gases; however, most of them (particularly amine absorption) are very energy-intensive processes not only from the point of view of operation but also solvent production. The aim of this study was to determine CO2 and CH4 sorption capacity of pyrolyzed spruce wood under a wide range of pressures for application as an effective adsorbent for gas separation technology such as Pressure Swing Adsorption (PSA) or Temperature Swing Adsorption (TSA). The idea behind this study was to reduce the carbon footprint related to the transport and manufacturing of sorbent for the separation unit by replacing it with a material that is the direct product of pyrolysis. The results show that pyrolyzed spruce wood has a considerable sorption capacity and selectivity towards CO2 and CH4. Excess sorption capacity reached 1.4 mmol·g-1 for methane and 2.4 mmol·g-1 for carbon dioxide. The calculated absolute sorption capacity was 1.75 mmol·g-1 at 12.6 MPa for methane and 2.7 mmol·g-1 at 4.7 MPa for carbon dioxide. The isotherms follow I type isotherm which is typical for microporous adsorbents.

Determination of adsorption capacities of N2 and CO2 on commercial activated carbon and adsorption isotherm models

In today’s technologies of gas purification systems, adsorption processes offer more advantages than traditional processes (amine absorption and cryogenic distillation). Thanks to advantages such as high efficiency, low energy consumption and ease of operation, the adsorption process plays an important role in today’s natural gas purification and carbon capturing processes. In order to bring natural gas to the usage standards and to ensure carbon capture in the emission sources (coal mines, landfills, agricultural activities, etc.) that emit CO2-CH4 as a result of human activities, it is extremely important to purify impurities such as CO2 and N2, which are highly present in the gas mixture. In the study, the adsorption of N2 and CO2 gases on activated carbon and the effect of pressure and temperature on adsorption were examined. The operating conditions pressure range was 1-6 bar and temperatures below room temperature. Experimental studies were carried out in laboratory scale adsorption cell system. As a result of the studies, it was determined that the adsorption capacity of activated carbon N2 and CO2 increased with pressure. N2 adsorption capacities were determined between 0.4-7.8 mmol/g and CO2 adsorption capacities were determined in the range of 2.7-7.4 mmol/g. In addition, Langmuir and Freundlich isotherm models were created, model parameters were examined and the adsorption behaviour of activated carbon for CO2 and N2 gases was obtained.

Research progress of CO2 separation technology by solvent absorption

The combustion of fossil fuels emits a large amount of CO2, which causes the greenhouse effect and leads to global warming and poses a serious threat to life on earth. CO2 capture technology can effectively reduce the concentration of CO2 in the atmosphere, alleviate the greenhouse effect, and improve the environment. CO2 capture technologies include absorption, membrane separation and adsorption separation, among which chemical absorption and separation have the advantages of high efficiency, low cost and easy availability of materials. In this paper, the advantages and disadvantages of three main chemical absorption and separation methods (inorganic reagents, organic amines and ionic liquids) adsorb CO2 are summarized. Among inorganic adsorbents, NH3·H2O can achieve rapid and efficient absorption of CO2, and it is relatively stable and not easy to degrade. Common types of organic amine adsorbents are monoethanolamine, methanolamine, and sterically hindered amine. However, it is difficult for a single organic amine adsorbent to meet the requirements of high absorption rate, high absorption capacity and low reaction heat at the same time. Therefore, mixing organic amine absorbents with different characteristics can improve their performance in absorbing CO2. Ionic liquids have the advantages of good thermal stability, very low saturation vapor pressure, and designable structure, and are a new type of CO2 adsorbent, but ionic liquids have high viscosity themselves. Combining ionic liquids with organic or inorganic porous materials to form loaded ionic liquid materials, which can be used as CO2 adsorbent not only to improve the separation effect, but also to avoid the problem of high viscosity caused by direct absorption of ionic liquids, thus improving CO2 adsorption efficiency.

Thermochemical model for evaluating CO2 regeneration energy for amine absorbents

We present a thermochemical model for evaluating CO2 regeneration energies for aqueous solutions of monoethanolamine (MEA), diethanolamine (DEA), 2-amino-2-methyl-1-propanol (AMP), and 2-(isopropylamino)ethanol (IPAE). The regeneration heat consists of the reaction heat, the sensible heat, and the vaporization heat. We calculated the reaction heat using a thermochemical model. We calculated the concentrations of all chemical species present in the CO2 absorption state at 40 °C and the CO2 release state at 120 °C. We calculated the reaction heat by summing enthalpies of associated reactions and reacted molar quantities derived from the concentration changes between the absorption and release states. For sterically hindered amines AMP and IPAE, the contribution of the protonation reaction to the reaction heat is large, whereas the contributions of protonation and carbamate hydrolysis are large for MEA and DEA. In the regeneration heat, the sensible heat is much larger than the reaction and vaporization heats.

Entropy enthalpy compensation in the SO2 absorption reaction and the optimal capture temperature range with amine alkyl siloxane as absorbent

In the present work, a kind of amine alkyl siloxane N-butyl-N-((1,1,3-trimethyl-3,3-diphenyldisiloxaneyl)methyl)butan-1-amine (BTDMBA) was synthesized and used to capture SO2. Its thermal decomposition temperature is 160℃, which is comparable with that of Ionic liquids (ILs), but its viscosity is only 125 mPa∙s at 25℃ after the absorption of SO2, which is much lower than that of ILs. The reaction mechanism is that BTDMBA reacted with SO2 to form charge transfer complex BTDMBA∙SO2. The reaction enthalpy and entropy change are −83.95 kJ/mol and −240.48 J·mol−1·K−1, respectively, which are more negative than that of ILs. By comparing the enthalpy and entropy change of amine alkyl siloxane and absorbents reported in literatures, an unexpected entropy enthalpy compensation phenomenon was discovered and the isokinetic temperature was found to be 371 K. Based on this phenomenon and the optimization objective function, it was also found that with the decrease of entropy change, the optimal absorption and desorption temperature difference increased initially and decreased afterwards. The maximum of entropy changes is −201 J·mol−1·K−1 for absorbent to achieve recycle absorption capacity 0.79 mol/mol under the condition of absorption pressure 0.002 bar and desorption pressure 1 bar.

Experimental and Thermodynamic Investigation on CO2 Absorption in Aqueous MEA Solutions

The vapor-liquid equilibrium (VLE) of CO2 in a reactive solvent is essential for the proper simulation and design of CO2 absorption processes. This work presents a systematic investigation on CO2 absorption in various aqueous monoethanolamine (MEA) solutions. CO2 solubility in MEA was measured at 298, 313, 333, and 353 K with CO2 partial pressure ranging from 34.5 to 78.0 kPa. A modified Kent-Eisenberg model was developed based on the measured solubility data, showing good predictions over the liquid phase speciation for the CO2-H2O-MEA system. We presented a new analysis based on the first-order difference curve of distribution profiles of the species. Based on the main reactions that occurred, the CO2 absorption process was demonstrated to be divided into four regions with increasing CO2 loading from 0 to 1. Accordingly, kinetic study was proposed to be conducted in the first region, whereas measuring of mass transfer in the first three regions. The findings in this work extend the existing knowledge of CO2 absorption process in terms of speciation and can provide important guidance for further study of the process characteristics using aqueous amine absorbents.

(Invited) Opportunities and Challenges for Biopolar Membrane-Based Electrosynthesis

Over the last 3 decades, research on CO2 abatement technologies centered solely on carbon capture and storage (CCS). Here, technology focus is in the design of separations technologies to capture CO2 from concentrated point (e.g. flue gas) or dilute distributed sources (e.g. atmosphere) using amine absorption, adsorption, and membranes. Most of these technologies involve adsorbing or absorbing CO2 gas, releasing this gas, and then pressurizing it for storage. Thus, a number of different subsystems and specialized new equipment are needed resulting in high capital and operating costs. As a result, CO2 capture for CCS is economically unfavorable in the absence of utilization routes for the captured CO2. Electrolysis of CO2 is a viable potential pathway toward attaining utilization; however, carbon loss in traditional electrolysis architectures is a large limitation. To overcome this challenge, movement toward bipolar-membrane (BPM) based electrolysis cells have been proposed as a viable option. BPMs contain an anion and a cation exchange layer. At the interface of these membranes, a junction potential forms when a electric field is applied across the membrane. Thus, within a BPM electrolysis cell, charge balancing occurs through water electro dissociating at the interface of the anion and cation membrane, thereby forming charge carriers in the form of OH- and H+. The production of acid and base in situ allows for a continuous process with low carbon losses. The primary aim of this talk is to discuss the challenges and opportunities that exist with the development of proper catalyst and membranes for these systems for carbon capture and electrofuel production.

Perstraction of Heat-Stable Salts from Aqueous Alkanolamine Solutions

Amine absorption processes designed to remove acid gases from gas streams generally face a major challenge of solvent degradation. This degradation leads to the formation of heat-stable salts (HSS), corrosive agents that irreversibly bind free alkanolamine. The present study proposes, for the first time, a method for HSS perstraction using a liquid–liquid membrane contactor that allows HSS to transfer through porous membranes from the solvent into a hydrophobic extractant represented by a methyltrioctylammonium solution in 1-octanol. The perstraction provides selective extraction of HSS anions without direct mixing of liquid phases or the formation of stable emulsions of the solvent and the extractant. For this purpose, a number of industrial and laboratory porous membrane samples fabricated from polyvinylidene fluoride, polypropylene, and polysulfone were investigated. Their chemical and morphological stability, surface properties, and transport properties were tested under prolonged (>600 h) contact with a model solvent (an aqueous monoethanolamine solution) and with the components of the selective extractant. The feasibility of HSS perstraction was demonstrated using the formic acid (as an HSS model) extraction from the model solvent. The most promising results were obtained for a system with a polyvinylidene fluoride membrane: up to 50% of formic acid was extracted over 18 h.

DEVELOPMENT OF TECHNOLOGICAL METHODS FOR OBTAINING AMINE ABSORBENTS BASED ON LOCAL RAW MATERIALS FOR OIL AND GAS PROCESSING PLANTS

For oil and gas refineries, the development of technological methods for obtaining amine absorbents based on local raw materials will make it possible to more thoroughly clean hydrocarbon gases. The chemical reagent that replaces the import will be localized and the currency allocated for it will be saved.

Direct, efficient and selective capture of low concentration of CO2 from natural gas flue gas using a high temperature tubular carbon capture membrane

Natural gas (NG) fired power plants emit low concentration (4–5%) of CO2, which presents additional technical and economic challenges to the current benchmark amine absorption technology. The newly emerged high-temperature multiphase membranes operated on molten carbonate (MC) chemistry for CO2 capture/separation/conversion have been demonstrated with great potential to meet this challenge. In this study, we report on the CO2 capture performance of such a membrane in tubular geometry from a mockup NG flue gas. The membrane is comprised of a mixture of Gd0.20Ce0.80O1.95 (GDC) and MC, in which GDC forms a porous skeleton to contain MC. We show that the membrane with a dimension of 6.1 mm in outer diameter, 5.1 mm in inner diameter and 5 cm in effective length (resulting in 4 cm2 effective surface area) can achieve a CO2 flux density of 0.46–0.55 mL/min·cm2 at 650 °C, capturing 97% pure CO2 at a rate of 37–42% from 5%CO2–N2 using moistened Ar as the sweep gas. The level of performance demonstrated by this study suites the membrane well for stationary CO2 capture from NG power plants.

On Solvent Losses in Amine Absorption Columns

The current work was dedicated to developing a novel model based on the mass transfer theory in combination with classical nucleation theory in order to predict the amount of solvent loss in the amine absorption columns. The work was adopted to consider the physical mechanisms leading to amine loss, including mass transfer, aerosol formation, and evaporation of the amine. Aspen Plus simulator and MATLAB software were integrated to make such simulations possible through a round–trip interaction. The model predictions for the temperature and concentration of different components were compared with the literature experimental data, and a fair agreement was seen. Then, the effects of some parameters such as the inlet stream temperature, particle concentration, and diameter on the amine loss were investigated. The results of this study may help engineers and practitioners properly design the amine absorption columns to reduce amine consumption.

Computational fluid dynamics modelling of expanded metal porous matrix heat exchangers for intensified carbon capture applications

Expanded Metal Porous Matrix Heat Exchangers (EM-PMHE) use a fin structure based on stacked sheets of expanded metal. This fin structure creates a three-dimensional flow that also enhances heat transfer. EM-PMHEs are of interest for potential applications in carbon-capture processes. Their compact design could intensify heat exchange processes in the amine absorption cycle. The transport properties of EM-PMHEs are also of interest for applications in rotating packed beds, where expanded metal can make an effective packing material. This work examines a EM-PMHE using computational fluid dynamics. The heat transfer prediction of the model is validated against experimental data from literature. A simple 1D model is also presented for comparison. The model is used to evaluate the potential of EM-PMHEs in amine-based carbon-capture applications. The modelling results indicate that EM-PMHEs could be used to achieve intercooling in the rotating packed bed absorber. This would allow amine concentrations to be increased to 70 wt% in the carbon-capture process, achieving 2x volume reduction in comparison to conventional amine concentrations. Elsewhere in the carbon-capture process, EM-PMHEs could also achieve an 10x size reduction in the lean/rich heat exchanger, a major item of plant equipment in the carbon capture process.

The Effect of MDEA/AMP and Span-80 in Water-in-Oil (W/O) Emulsion for Carbon Dioxide Absorption

Emulsion liquid membrane (ELM) has been widely studied as an alternative method for amine absorption technology in the removal of acid gases such as carbon dioxide (CO2) and hydrogen sulphide (H2S). However, searching for stable ELM formulation with an enhanced CO2 absorption remains as challenge. Therefore, in this study, the aqueous solution containing a mixture of methyl diethanolamine (MDEA) and 2-amino-2-methyl-1-propanol (AMP) in sodium hydroxide (NaOH) solution was introduced as a dispersed phase, kerosene as continuous phase and Span-80 acts as a surfactant for the formation of water-in-oil (W/O) emulsion. In this study, the dispersed phase consists of 8% v/v MDEA and 4% v/v AMP and the continuous phase which contains 6% v/v Span-80 produced a stable emulsion and exhibited 65.2% of CO2 removal. This study indicates that the introduction of blended amine able to produce stable emulsion with an enhanced CO2 removal.

Enhancing CO2 absorption with amino acid ionic liquid [N1111][Gly] aqueous solution by twin-liquid film flow: Experimental and numerical study

• The rheological response of [N 1111 ][Gly] aqueous solution during CO 2 capture. • Twin-liquid film behavior with [N 1111 ][Gly] aqueous solution and its mass transfer performance. • Film thickness is reduced and film velocity is improved for high viscosity [N 1111 ][Gly] aqueous solution by twin-liquid film. • Accommodation of the twin-liquid film to fluid viscosity by modulating window dimensions. Tetramethylamine glycine ([N 1111 ][Gly]) (ILs) is a potential substitute for the alcohol amine absorbent. However, its high viscosity restricts industrial CO 2 absorption due to poor mass transfer performance. Surface renewal is the key to enhance interfacial mass transfer for highly viscous fluids. Considering the rheological response of the [N 1111 ][Gly] aqueous solution during CO 2 capture, the twin-liquid film is suggested for the [N 1111 ][Gly] aqueous solution. The behavior of the twin-liquid film has been investigated by flow experiments and numerical simulation. Reduction of film thickness and improvement of surface velocity can be achieved by the interplay between the twin films, which enhances surface renewal frequency. The accommodation of the twin-liquid film to fluid viscosity can be satisfied by modulating window dimensions. The enhanced mass transfer performance of the twin-liquid film with [N 1111 ][Gly] aqueous solution, illustrated by enhanced surface renewal frequency, proves it a feasible way for industrial CO 2 capture.

Fabrication of nickel oxide functionalized zeolite USY composite as a promising adsorbent for CO2 capture

Adsorption process is considered to be the most promising alternative for the CO 2 capture to the traditional energy-intensive amine absorption process, and the development of feasible and efficient CO 2 adsorbents is still a challenge. In this work, the NiO@USY (ultrastable Y) composites with different NiO loadings were prepared for the CO 2 adsorption using Ni(NO 3 ) 2 as the precursor. The composites were characterized by X-ray photoelectron spectroscopy, X-ray diffraction, nitrogen adsorption–desorption test, scanning electron microscopy analysis, and thermogravimetric analysis, and were evaluated for the CO 2 adsorption capacity, CO 2 /N 2 adsorption selectivity and CO 2 cycle adsorption capacity. The characterization results show that after the activation at 423 K, the Ni(NO 3 ) 2 species were well dispersed into the surface of zeolite USY, and after the further activation at 823 K, Ni(NO 3 ) 2 could be converted into highly dispersed NiO. The adsorption results show that the presence of the active component NiO plays an important role in improving the CO 2 adsorption performance, and the NiO@USY composite with a NiO loading of 1.5 mmol·g −1 USY support displays a high adsorption capacity and adsorption selectivity for CO 2 , and shows a good cycle stability. In addition, the Clausius–Clapeyron equation was used to evaluate the isosteric heat of adsorption of CO 2 on the NiO(1.5)@USY composite, and the heat of adsorption was 17.39–38.34 kJ·mol −1 .

Review of carbon capture absorbents for CO2utilization

AbstractCarbon capture technologies have been recognized as a potential alternative to alleviate global warming. Carbon capture and storage (CCS) is preferred over carbon conversion and utilization (CCU) due to its lower operating costs and higher CO2reduction capability. Nevertheless, CO2utilization has the potential to be more economical if value‐added products are produced. This highlights the importance of assessing CO2utilization routes and alternatives in carbon management. This review paper aims to evaluate the carbon utilization potential of major CO2‐capturing absorbents including amine, hydroxide, ionic liquid, amino acids and carbonate absorbents. All absorbents show potential application for CO2utilization except for ionic liquids (ILs) due to their unclear CO2capture mechanisms. Absorbents that require a desorption process for CO2utilization include MEA, MDEA, K2CO3and Na2CO3due to their high absorption capacity. Industries have utilized the desorbed CO2as chemical feedstocks, enhanced oil recovery (EOR) and mineral carbonation. For hydroxide absorbents and CaCO3, desorption of CO2is unnecessary as the absorbed CO2can be directly utilized to produce construction materials. Apart from that, the incorporation of advanced technologies and business models introduced by the fourth industrial revolution are plausible considerations to accelerate the development of carbon capture technologies. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd.

Conjugated Boron Porous Polymers Having Strong p−π* Conjugation for Amine Sensing and Absorption

Conjugated Boron Porous Polymers Having Strong p−π* Conjugation for Amine Sensing and Absorption

CO2 capture-driven thermal battery using functionalized solvents for plus energy building application

Renewable energy has the drawback of intermittent power generation, and it should be linked to an energy storage system. However, the efficiency and density of the conventional thermal energy storage technologies are low. Herein, for building applications, CO2 capture-driven thermal battery has been developed using solvents composed of amine-functionalized mesoporous silica (3-APTES-SBA-15) and an amine absorbent (MEA). The thermal energy is discharged through the exothermic reaction of amine-CO. When the renewable energy is supplied to the battery, amine-CO2 bonds are broken, which corresponds to charging process. 3-APTES-SBA-15/MEA presents a superior energy storage density of 2.187 kJ/g and an efficiency of 91.5%. It is sufficient for producing heating/hot water considering the discharging temperature, and there is no loss even if stored for a long time. The thermal battery system presents a coefficient of performance of 0.66 and a thermal energy storage density of 0.57 kJ/g. When the thermal battery is combined with solar thermal energy harvesting system, the thermal and electric energy consumptions are reduced by 22.0% (477.9 MJ/m2) and 19.6% (156.9 MJ/m2), respectively. The CO2 capture-driven thermal battery will contribute to manage renewable energy and reduce grid energy consumption for building applications.

Flexible CO2 capture for open-cycle gas turbines via vacuum-pressure swing adsorption: A model-based assessment

As energy systems require flexible and responsive power generators to combat network imbalances, CO2 post-combustion capture (PCC) technologies need to be capable of transient operation. However, currently only amine absorption has been investigated for its efficacy in Flexible-PCC.Within this study we develop and validate a vacuum-pressure swing adsorption (VPSA) process model, capable of processing 33.8 kg/s of exhaust flow from a small-scale open-cycle gas turbine (OCGT). The Flexible response scenario is based on realistic load changes of OCGTs during a 5-h period. To handle the size of flow the system is split into two identical two bed four step VPSA processes, both using Zeolite 13X as the adsorbent material. Included in the Flexible-VPSA operation is the start-up, ramping, and shutdown procedures. Flexible-VPSA showed minute deviations in CO2 purity and recovery rate, and despite the specific energy demand increasing, results show no technical limitations to transient operation. The Flexible VPSA simulations are compared against the benchmark MEA solvent, with both technologies performing similarly when processing highly transient flue gas flowrate. Thus, VPSA is potentially an attractive alternative technology for Flexible-PCC.