Carbon Dioxide Capture Process Research Articles

Performance enhancement of desorption reactor in the electrochemically mediated amine regeneration CO2 capture process: Thru modelling, simulation, and optimization

The electrochemically mediated amine regeneration (EMAR) carbon dioxide (CO2) capture process has significant potential in mitigating CO2 emissions. A suitable desorption reactor plays a pivotal role in realizing the efficient utilization of the EMAR technology. This study concentrates on the simulation and improvement of the desorption reactor for the EMAR process. To begin with, a comprehensive multi-physics model was developed to simulate the desorption process within a laboratory flat-plate reactor. The concentration distributions of reactive ions and the effect of CO2 bubbles in the electrolyte were analyzed. Results indicated that shortening electrode length is a practical measure to enhance desorption reactor efficiency. The study also explored the impact of critical operational variables, including electrolyte flow direction, flow rate, copper ions loading, and applied potential. Notably, controlling the applied potential proved highly effective for regulating desorption performance, with optimal adjustment maximizing overall efficiency. Based on these findings and the characteristics of the EMAR process, a novel multi-electrode partitioned EMAR desorption reactor was proposed as an enhancement to the flat-plate reactor. By applying distributed potential, improved desorption performance was obtained, resulting in a 20.05% increase in the CO2 desorption rate with only a 4.04% increase in the unit desorption energy consumption. These findings provide significant insights for optimizing the design and implementation of the EMAR desorption reactor.

Structure–activity relationship of a dual-function amine-based electrolyte for integrated CO2 capture and electrochemical conversion

Integrated carbon dioxide (CO2) capture and electrocatalytic reduction processes through dual-function amine-based electrolytes and their integration into a single reactor can lead to significant energy savings, simplified process flow, and reduced transportation risks. This work investigates the structure–activity relationship of dual-functional amine-based electrolytes for CO2 capture and electrocatalytic reduction and develops an efficient dual-functional amine-based electrolyte system. We investigated 10 different amine-based solutions for their CO2 capture and reduction performances. The substituents on the nitrogen atom of the intermediate carbamate and the positions of the hydroxyl and branched groups affect the capture and electrochemical reduction. The 1,3-propanediamine system demonstrated enhanced CO2 solubility uptake (58.1 %), Faradaic efficiency (10.6 %), and current density (52.1 %) compared with the monoethanolamine system, indicating its potential as a dual-function amine-based electrolyte. Furthermore, density functional theory calculations indicated that the charge distribution of carbamate and the dissociation of C–N bonds directly influence the adsorption of carbamates on the electrode surface and the Faradaic efficiency of the reduced products. In addition, reaction path analysis based on the zwitterionic mechanism indicated that intermediates (carbamate R1R2NCOO-) with higher electronegativity are more conducive to adsorb onto the electrode surface and inhibit hydrogen generation from protonated amines (R1R2NHH+). The results suggest that the selection or design of dual-functional amine-based electrolytes should prioritize amines with straight alkanol chains rather than branched ones, which do not form intramolecular hydrogen bonds or heterocyclic structures. This work provides directions and guidance for designing and developing dual-functional electrolytes for integrated carbon capture and electrocatalytic conversion technologies.

Utilization of accelerated weathering of limestone captured carbon dioxide (CO2) with cement kiln dust to produce building material

The accelerated weathering of limestone (AWL) process is an inexpensive and eco-friendly carbon dioxide (CO2) capture process with comparable performance to amine-based systems. However, the generated calcium bicarbonate (Ca(HCO3)2) solution lacks an effective utilization alternative. Aside from that, the current solid waste utilization alternatives (i.e., carbon mineralization and partial replacement of conventional binders) lack the capability to effectively curb the tremendous production rate of solid waste (i.e., cement kiln dust (CKD)). To address both gaps, this study developed a novel Ca(HCO3)2 solution utilization alternative with CKD as the sole binder to produce a building material termed CKD-bicarbonate lime mortar (BLM). This work aims to identify the optimal mix ratio for CKD-BLM to achieve maximum compressive strength via a series of studies; (i) liquid medium, (ii) Ca(HCO3)2 solution volume, and (iii) sand:CKD mix ratio. From the findings, it was found that CKD-BLM at the optimal CKD:sand:Ca(HCO3)2 mix ratio of 1:0.45:0.29 exhibits the highest compressive strength of 2.09 MPa, surpassing the compressive strength standard of 1.70 MPa set by the ASTM C141 while having acceptable workability of 118 % which is within the standard workability range of 105–155 % set by ASTM C270. However, the CKD-BLM sample exhibits high leaching of Ca, Si, Na and Cl which does not meet the environmental regulation. This was resolved by applying a waterproof coating that effectively curbed the leaching by 28.84–99 %. Overall, this study successfully developed a building material with industrial wastes (i.e., Ca(HCO3)2 solution and CKD) that surpasses the performance of conventional lime mortar while utilizing up to 0.22 kg CO2.kg CKD-BLM_1:0.45:0.29−1.

Unlocking new potentials in energy-efficient carbon dioxide capture: How catalyst-phthalocyanine is leading the way

Addressing the high energy demand of amine-based carbon dioxide capture systems is crucial for achieving carbon neutrality. While enhancing energy efficiency with solid acid catalysts in amine regeneration is promising, developing more efficient catalysts remains a critical challenge. In this study, we introduce the innovative use of a robust, metal-free phthalocyanine as a catalyst to facilitate amine regeneration. Distinctively, phthalocyanine features a macrocyclic ring with an extensive π-conjugated system that functions as Lewis acid sites, diverging from conventional methods that rely on metal atoms for this role. Additionally, the nitrogen and hydrogen atoms on the macrocyclic ring act as Brönsted base sites and Brönsted acid sites, respectively. These sites collectively contribute to a significant acceleration in the CO2 desorption rate, achieving an increase of 1679% at approximately 67 ℃, which far surpasses the performance of previously investigated catalysts. Furthermore, phthalocyanine catalyzes the decomposition of carbamate and protonated monoethanolamine more efficiently than bicarbonate. This research lays the groundwork for next-generation catalysts in amine solvent regeneration of the carbon dioxide capture process.

A novel intercooling carbon dioxide capture process using ionic liquids with ultra-low energy consumption

This study focuses on the use of ionic liquids as solvents for carbon dioxide capture due to their low energy demand. We screened an ideal ionic liquid, 1-ethyl-3-methylimidazolium bis[trifluoromethylsulfonyl]imide ([emim][Tf2N]), based on its excellent absorption capacity and low viscosity. We performed thermodynamic modeling of the gas-liquid phase equilibrium to lay the foundation for process simulation. A basic process was designed for benchmarking performance, and various cases were compared by adjusting key operating parameters such as pressure and temperature. The results showed that the lowest specific capture energy achieved was 1.12 GJ/t at 20 bar and 5 °C. However, further improvements in energy performance were constrained by reduced absorption capacity and increased viscosity resulting from lower operating pressures and temperatures. To address these constraints, we proposed a novel process that optimized the temperature profile in the absorption column by dividing it into two sections with intercooling. This approach did not require significant changes to the base case but offered multidimensional benefits, including reduced energy demand and associated equipment costs. The specific capture energy was further reduced to 1.04 GJ/t. Economic analysis indicated that the capture cost at a production scale of 13.7 kt/a was 206 $/t but had the potential to be reduced to 82 $/t. The costs associated with compressors were found to be the major contributors to both equipment and capture costs. The proposed novel process demonstrates promising benefits and highlights the importance of further investigation into low-pressure operation.

T–x diagrams for the CO2–H2O system: The importance of water content in CO2 transportation for carbon capture and storage

AbstractWhen water is present in a CO2 pipeline, corrosion or plugging can occur due to the formation of liquid water or gas hydrate, respectively. Understanding how corrosion and hydrate plugging can be avoided is important for enhanced oil recovery and carbon dioxide capture and storage processes. If the CO2 is sufficiently dried prior to transportation, the formation of these problematic free‐water phases can be avoided. In this work, isobaric T–x diagrams were developed from the P–T diagram for the CO2–H2O binary system. Pressures ranging from just below the lower quadruple point to above the lower critical end point were studied. These diagrams are meant to give the reader a better conceptual understanding of how the water composition in CO2–H2O mixtures will influence phases that form at different temperatures and pressures. The diagrams are analyzed from the perspective of flow assurance in CO2 transportation.

Techno-economic and life cycle analysis of two different hydrogen production processes from excavated waste under plasma gasification

Focusing on expanding and maturing the technology of excavated waste-to-energy pathways can promise a renewable energy production process in addition to reducing land occupation and greenhouse gas emissions. A very scarce comprehensive literature had covered the exergetic performance, life cycle analysis, and financial feasibility of hydrogen-from-excavated-waste technologies based on the plasma gasification process. This article aims to provide a comprehensive comparison under the exergy, techno-economic, and life cycle environmental analyses for two different hydrogen-from-excavated waste pathways. In this regard, two different configurations (under an innovative methodological and analytical approaches) have been proposed for conceptual design and comparative study of hydrogen fuel generation from excavated waste based on plasma gasification, sorption enhanced/gas-water shift, and gas-water shift processes. The techno-economic and life cycle environmental analyses were compared at two levels (i.e., refuse derived fuel-to-hydrogen and excavated waste-to-hydrogen pathways), which had not been reported in most of the literature. From the outcomes, the proposed excavated waste-to-hydrogen process integrated with the carbon dioxide capture and storage process can provide superior environmental (especially in terms of impacts on human health) and thermodynamic performances compared to the standalone-plasma gasification process. Furthermore, the financial feasibility of the proposed project is completely affected by the selling price of hydrogen. The article's achievements can be competitive with similar pathways and provide attractive design and investment conditions to stakeholders and engineers.

Highly efficient separation and equilibrium recovery of H2/CO2 in hydrate-based pre-combustion CO2 capture

Gas hydrate-based CO2 capture processes have attracted considerable attention due to their potentials for energy-efficient pre-combustion CO2 capture. Recent investigations have explored the use of tailored-wettability porous silica gels, highlighting benefits in thermodynamic and kinetic efficiencies, specifically characterized by low energy requirements and rapid formation. However, achieving high purity levels for both H2 and CO2 is crucial for practical implementation. Consequently, identifying and optimizing an effective separation route becomes imperative. In this study, we examined the thermodynamic stability, gas uptake, and separation factors of THF (5.56 mol%) + H2 + CO2 hydrates with varying compositions (H2:CO2 = 80:20, 60:40, 30:70, or 20:80 mol%) in C0 and C1 silica gel (functionalized by monofunctional alkylsilanes (X-(CH3)2-Si-Cn)) systems with SDS (0 or 500 ppm). Pressure-composition diagrams for THF + H2 + CO2 systems in C0 and C1 silica gel were meticulously measured. Notably, the C1 silica gel system without SDS demonstrated good thermodynamic stability, substantial gas uptake, and a significant separation factor. Based on the pressure-composition diagram of the C1 silica gel system, we proposed a highly efficient route for separating H2 and CO2. This proposed cyclic process involves a three-stage reactor and achieve to gas hydrate-based pre-combustion CO2 capture, yielding a purity of approximately 91 % H2 and 94 % CO2. The present findings provide valuable insights into optimizing the wettability of porous media and efficient separation routes, demonstrating the feasibility of a gas hydrate-based pre-combustion carbon dioxide capture process.

Carbon Dioxides Capture by Metal-Organic Frameworks Membranes and the Mixed-Matrix Membranes

The growing concern over carbon dioxide emissions has garnered substantial attention globally, as the relentless progression of technology continues to contribute to an increase in the production of this greenhouse gas. Consequently, the capture of carbon dioxide has emerged as a crucial mission to counteract the deleterious influences of climate change, which is exacerbated by the rising temperature across the world. This may also lead to various natural hazards, such as the melting of icebergs and the subsequent rise in sea levels. To address these issues, there is no denying the importance of the carbon dioxide capture process. This article will explore some of the methods of capturing carbon dioxide, including the utilization of metal-organic frameworks membranes and Mixed-Matrix Membranes, encompassing the design of such membranes and the strategies employed for their synthesis. To elucidate these techniques, the article will illustrate their processes through multiple examples and empirical findings, accompanied by relevant data.

An Integrated Carbon Dioxide Capture and Methanation Process

An Integrated Carbon Dioxide Capture and Methanation Process

Integrated CO2 capture and reduction catalysis: Role of γ-Al2O3 support, unique state of potassium and synergy with copper

Carbon dioxide capture and reduction (CCR) process emerges as an efficient catalytic strategy for CO2 capture and conversion to valuable chemicals. K-promoted Cu/Al2O3 catalysts exhibited promising CO2 capture efficiency and highly selective conversion to syngas (CO + H2). The dynamic nature of the Cu-K system at reaction conditions complicates the identification of the catalytically active phase and surface sites. The present work aims at more precise understanding of the roles of the potassium and copper and the contribution of the metal oxide support. While γ-Al2O3 guarantees high dispersion and destabilisation of the potassium phase, potassium and copper act synergistically to remove CO2 from diluted streams and promote fast regeneration of the active phase for CO2 capture releasing CO while passing H2. A temperature of 350℃ is found necessary to activate H2 dissociation and generate the active sites for CO2 capture. The effects of synthesis parameters on the CCR activity are also described by combination of ex-situ characterisation of the materials and catalytic testing.

Thermodynamic analysis of a post-combustion carbon dioxide capture process in a pilot plant equipped with a heat integrated stripper

This paper presents a thermodynamic analysis of a carbon dioxide absorption process from flue gases, focusing on the Heat Integrated Stripper (HIS) as a promising modification to the conventional process. The primary objective is to compare the performance of the HIS-modified process with that of the standard process. Experimental research was conducted on a mobile pilot plant using aqueous solutions of MEA 30% for treating 200 m3/h of the flue gas.An advanced data validation and reconciliation method was used to reconcile measurements in the mass balancing of the carbon dioxide absorption process. The results demonstrate that heat integration has a positive impact on the temperature profile of the stripper, leading to an increase in carbon dioxide capture without requiring additional heat consumption. Specifically, the reboiler heat duty in the process was reduced from 3.22 to 3.00 MJ/kgCO2, indicating the effectiveness of the HIS-modified process in reducing energy consumption. The use of the advanced data validation and reconciliation method also increases the reliability of the obtained results, which can be beneficial for process modeling and design. These findings contribute to the development of more efficient carbon capture technologies.

Investigations on biomass gasification of compact-fast dual fluidized bed calcium looping

In this study, a 10 kWth hot rig of dual fluidized bed is developed to investigate the performance of the calcium looping process for biomass hydrogen-rich gasification and carbon dioxide capture. The system consists of a compact fluidized bed and a fast fluidized bed riser. The compact fluidized bed, which is comprised of a lower bubbling fluidized bed and an upper riser, is used as the gasifier, and the fast fluidized bed riser is used as the regenerator. The solid from the regenerator goes upward from the bottom of the upper riser gasifier, and then downward to the lower bubble fluidized bed gasifier, bringing heat from the generator to the gasifier, and is finally circulated to the regenerator form the bottom of the bubble fluidized bed, taking carbon dioxide from the gasifier to the regenerator. Dolomite and quartz sand are used as bed materials. The effects of variables such as temperature, bed material, and solid circulating flux on product gas compositions, yield, calorific value, tar content, and cold gas efficiency were investigated. The dolomite bed material has a more obvious improvement in hydrogen production as compared with quartz sand as bed material. The maximum H2 production is 0.46 Nm3/kgFuel, the purity reaches 70.88%, the cold gas efficiency is 45.93%, and the low calorific value is 13.26 MJ/Nm3. The high temperature of the upper riser favors tar conversion. When the riser temperature was 800 °C, the tar content decreased by 4.46 g/Nm3, and the total gas production increased by 0.03 Nm3/kgFuel. In addition, the increase of solid circulating flux can improve the concentration and the yield of hydrogen, and decrease the content of tar.

Metal Oxides Enhance the Absorption Performance of N-Methyldiethanolamine Solution during the Carbon Dioxide Capture Process.

Fly ash from coal-fired power plants can enter chemical absorbents along with flue gas. Silica and metal oxides are the main components of fly ash. To explore the effect of the metal oxides on absorbents, we analyzed the integrated CO2 absorption-desorption process using N-methyldiethanolamine (MDEA) as the standard and an amine absorbent after adding different metal oxides. The effects of each metal oxide on CO2 capture by the MDEA solution, including CO2 reaction heat, absorption rate, cyclic loading, and carbonation rate, were assessed. It was found that supplementation with appropriate calcium oxide and magnesium oxide proportions accelerates the CO2 absorption rate and shortens the saturation time of the MDEA solution by 9%-17%. Magnesium oxide and calcium oxide were precipitated as carbonates during absorption. The CO2 reaction heat of the MDEA solution increased by 95% after adding magnesium oxide, thereby significantly increasing the energy consumption of the desorption process. On the basis of the experimental studies, the increase in CO2 absorption rate by MDEA after adding MgO and CaO may be mediated through two different mechanisms.

Simulation Analysis of Novel Integrated LNG Regasification-Organic Rankine Cycle and Anti-Sublimation Process to Generate Clean Energy

Recently, the depletion of fossil fuel reserves and the harmful environmental effects caused by burning fossil fuels have signified the supreme importance of utilizing sustainable energy reserves such as geothermal and solar energies. The advancement of the Organic Rankine Cycle as a clean energy generation path by researchers has gained momentous demand for its commercialization. The sole Organic Rankine Cycle can produce a large amount of energy in contrast to other power production cycles. To make this clean energy recovery sustainable, liquefied natural gas cold energy can be utilized through regasification to integrate the Organic Rankine Cycle with the anti-sublimation carbon dioxide capture process, merging the biogas setup. Liquefied natural gas cold energy recovery has paramount importance with aspects of energy economy and environment preservation. Liquefied natural gas regasification in shell and tube heat exchangers poses a minimal freezing risk and is high duty. Anti-sublimation of biogas is an energy-intensive process. It can be materialized from liquefied natural gas cold energy implementation through the Organic Rankine Cycle by maintaining cryogenic temperatures there. In this situation, greenhouse gas emissions can be minimized. The simulation analysis is performed based on thermodynamic and techno-economic assessments of the poly-generation energy systems. It is proved to be useful in conducting by regulating different working fluids. The optimum electric power generated is 2492 MW. While the optimum net present value, energy efficiency, and exergy efficiency of this proposed energy system are 19.5, 57.13%, and 76.20%, respectively. The governmental authorities and environmental protection can benefit from this scientific research work to create an environmentally friendly atmosphere and energy for contemporary society.

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.

Process Optimization and CO2 Emission Analysis of Coal/Biomass Gasification Integrated with a Chemical Looping Process

Biomass gasification is an attractive technology and one of the pathways for producing hydrogen. Due to the variable seasons and low calorific value of biomass, the addition of coal in the gasifier is suggested because coal has a high calorific value and carbon-to-hydrogen ratio. In general, the gaseous product obtained in gasification always contains a high amount of carbon dioxide, therefore, the co-gasification of biomass and coal should integrate with the calcium looping carbon dioxide capture process to provide purified hydrogen. In this work, the model of the co-gasification of biomass and coal integrated with the calcium looping carbon dioxide capture process was developed through an Aspen Plus simulator. The developed model was used to analyze the performance of this process. The sensitivity analysis demonstrated that increasing the gasification temperature, steam-to-feed (S/F) ratio, calcium oxide-to-feed (CaO/F) ratio, and regenerator temperature could improve hydrogen production. Next, further optimization was performed to identify the optimal operating condition that maximizes hydrogen production. The results showed that the optimal operating temperature of the gasifier is 700 °C with an S/F mass ratio of 2 and coal to biomass (C/B) mass ratio of 0.75:0.25. However, the carbonator and regenerator temperatures should be 450 °C and 950 °C, respectively, with a CaO/F mass ratio of 3. Under these operating conditions, the maximum H2 content and H2 yield can be provided as 99.59%vol. (dry basis) and 92.38 g hydrogen/kg biomass feeding. The other results revealed that the energy efficiency and carbon capture efficiency of this process are 42.86% and 99.99%, respectively, and that the specific emission of released CO2 is 80.77 g CO2/MJ.

Maximization of CO2 Capture Capacity Using Recent RUNge Kutta Optimizer and Fuzzy Model

This study aims to identify the optimal operating parameters for the carbon dioxide (CO2) capture process using a combination of artificial intelligence and metaheuristics techniques. The main objective of the study is to maximize CO2 capture capacity. The proposed method integrates fuzzy modeling with the RUNge Kutta optimizer (RUN) to analyze the impact of three operational factors: carbonation temperature, carbonation duration, and H2O-to-CO2 flow rate ratio. These factors are considered to maximize the CO2 capture. A fuzzy model was developed based on the measured data points to simulate the CO2 capture process in terms of the stated parameters. The model was then used to identify the optimal values of carbonation temperature, carbonation duration, and H2O-to-CO2 flow rate ratio using RUN. The results of the proposed method are then compared with an optimized performance using the response surface methodology (RSM) and measured data to demonstrate the superiority of the proposed strategy. The results of the study showed that the suggested technique increased the CO2 capture capacity from 6.39 to 6.99 by 10.08% and 9.39%, respectively, compared to the measured and RSM methods. This implies that the proposed method is an effective approach to maximize the CO2 capture capacity. The results of this study can be used to improve the performance of the CO2 capture process in various industrial applications.

Dynamic Modeling and Sensitivity Analysis for an MEA-Based CO2 Capture Absorber

The absorber is the key unit in the post-combustion monoethanolamine (MEA)-based carbon dioxide (CO₂) capture process. A rate-based dynamic model for the absorber is developed and validated using steady-state experimental data reported in open literature. Sensitivity analysis is performed with respect to important model parameters associated with the reaction, mass transport and physical property relationships. Then, a singular value decomposition (SVD)-based subspace parameter estimation method is proposed to improve the model accuracy. Finally, dynamic simulations are carried out to investigate the effects of the feed rate of lean MEA solution and the flue inlet conditions. Simulation results indicate that the established dynamic model can reasonably reflect the physical behavior of the absorber. Some new insights are gained from the simulation results.

Novel cryogenic carbon dioxide capture and storage process using LNG cold energy in a natural gas combined cycle power plant

This study proposes a novel cryogenic CO2 capture and storage (CCS) process using liquefied natural gas (LNG) cold energy in a natural gas combined cycle (NGCC) power plant. This study makes two major contributions to the literature. First, the cryogenic solid-phase CCS process using LNG cold energy can effectively reduce the efficiency penalty in NGCC power plants by solving the fundamental problems associated with the conventional CCS process: energy-intensive thermal treatment of the monoethanolamine-based absorption process and significant power consumption for compressing CO2 to 150 bar. Second, the cryogenic CCS process requires minimal equipment installation in the NGCC power plant by integrating LNG cold energy utilization and CO2 capture processes. The proposed cryogenic CCS process reduces the efficiency penalty from 14.34 % to 3.51 %, with a 99.93 % CO2 capture rate. We believe this study will provide a novel guideline for reducing the efficiency penalty by overcoming the challenges of the conventional CCS process.