Amine-based CO2 Capture Process Research Articles

Catalytic behavior of aluminum-modified SAPO-34 catalysts for reducing the energy penalty of CO2-rich amine solutions regeneration

The goal of this research is to develop a potential strategy to significantly decrease the heat duty for the amine-based CO2 capture process. Here, a variety of Al2O3-modified SAPO-34 composite catalysts with varying Al2O3 contents are synthesized and utilized to catalytically facilitate the CO2 desorption process. The catalytic CO2 desorption characteristics of various catalysts, Al-SAPO-34, SAPO-34, and γ-Al2O3 are investigated in a CO2-loaded 5 M monoethanolamine (MEA) solution. The results indicate that all catalysts accelerate CO2 desorption, while the Al-SAPO-34 catalysts work better than the parent Al2O3 and SAPO-34 catalysts. Especially, the 15 % Al-SAPO-34 increases the CO2 desorption rate by 78.4 % and reduces the relative energy requirement by 37 % at a desorption time of 1440 s. The catalysts are characterized by different methods and their structure–activity relationship is analyzed. The increased acid sites and mesoporous surface area of the Al-SAPO-34 catalyst may be responsible for its greater catalytic activity. The intermediates of the catalytic CO2 desorption process are identified by FT-IR and NMR, and then a possible catalytic regeneration mechanism is put forward. Additionally, the cyclic stability of the Al-SAPO-34 catalyst for cyclic CO2 absorption–desorption is evaluated. This work demonstrates that the Al-SAPO-34 exhibits greater catalytic CO2 desorption performance, and outstanding stability, and has the opportunity to become an attractive industrial catalyst for the amine-based CO2 capture process.

Impact of thermodynamics and kinetics on the carbon capture performance of the amine-based CO2 capture system

Solvent-based CO2 capture is a commonly employed post-combustion technique in processes involving absorber-stripper columns. This study focused on computer simulations with equilibrium- and rate-based modeling of CO2 capture using the amine solvents 2-amino-2-methyl-1-propanol (AMP), diethanolamine (DEA), and methyl diethanolamine (MDEA) and thermodynamic methods involving electrolyte NRTL models. The objective of this study was to understand the impacts of rate-based modeling, the type of amine, and thermodynamic methods on carbon capture. Within this study, the amine-based CO2 capture process from coal-power plant flue gas was studied using Aspen Plus modeling. Simulations were also conducted to determine the impact of thermodynamics and kinetics on the CO2 capture performance of the system. The results were analyzed on the basis of captured CO2 according to the solvents and models. The equilibrium approach was mostly invalid because of the oversimplified ideal stage assumptions through the column. The lowest carbon capture capacity was obtained with MDEA, while DEA yielded the best results. A sensitivity analysis with rate-based modeling showed the significant impact of the inlet CO2 composition. The amine-based CO2 capture process simulation included solution chemistry, electrolyte thermodynamics, rigorous transport property modeling, reaction kinetics, and rate-based multistage simulation, which could be applicable to different solvent systems.

Design and simulate an amine-based CO2 capture process for a steam methane reforming hydrogen production plant

Steam methane reforming (SMR) is a common technique for hydrogen production, however CO2, which is created as a by-product, needs to be captured. Chemical absorption utilizing amine solvents is the most economically practical method of CO2 capturing. Amines are a class of organic compounds that are commonly used as chemical solvents for carbon capture. The effectiveness of a particular amine as a carbon capture solvent depends on its chemical structure and properties. Some commonly used amines for carbon capture include monoethanolamine (MEA), diethanolamine (DEA), and methyldiethanolamine (MDEA). This study aims to simulate SMR hydrogen production plant utilizing amine-based carbon dioxide capture system using Aspen HYSYS V11 software and figure out the efficiency of different chemical solvents in capturing carbon dioxide. The results of this study show that MEA has high efficiency to capture CO2 due to its high reactivity and ability to form a strong chemical bond with CO2. However, it is also highly corrosive and can be costly to regenerate.

New improvement of amine-based CO2 capture processes using heat integration and optimization

The post-combustion capture process (PCCP) using amine-based solvent was the most mature and adequately researched carbon capture and storage (CCS) technology. Monoethanolamine (MEA) solvent regeneration in the stripper (desorption process) usually takes high energy consumption and a MEA make-up is required before re-entering the absorber (absorption process). To improve the CO2 capture efficiency and reduce the overall energy consumption of PCCP, four configurations (Design-1, Design-2, Design-3, Design-4) are presented, where Design-1 is denoted as the base case design. Design-2 is an extension of Design-1 by adding the side intercooler in the absorber. Design-3 is an extension of Design-2 by using internal heat integration in the stripper. Design-4 is an extension of Design-3 by adding the side interheater in the absorber. By using response surface methodology (RSM) in conjunction with central composite design (CCD), operating parameters (MEA solvent flowrate, MEA concentration, pressure) including side intercooler/side interheater locations of Design-2 to Design-4 are optimized. It is successfully validated that the side intercooler absorber could increase the CO2 capture ability by MEA solvent and the side interheater stripper with internal heat integration could effectively reduce energy consumption about 36% to 62%.

Enhancing energy efficiency of chemical absorption-based CO2 capture process with advanced waste-heat recovery modules at a high capture rate

A commercial-ready amine-based CO2 capture process (CCP) restricts its potential for industrial deployment at a high capture rate to achieve a net-zero carbon target due to its energy-intensive nature. This study aims to enhance the energy efficiency of a monoethanolamine (MEA)-based CCP, operating at a 95% capture rate, by developing advanced process modules that utilize low-grade waste heat. To establish a foundation for designing cascade modules that can recover energy from all available waste heat, the waste heat characteristics were analyzed, and the feasibility of four single modules was explored to recover the latent heat in a stripped gas. Subsequently, this study comparatively investigated the equivalent electrical works of the two designed cascade modules combined with lean vapor compression (LVC). A techno-analysis indicated that cascade modules provided outstanding energy-saving performance ranging from 12.27% to 24.55%, with an average improvement of 50% over single modules. Although the cascade modules combined with LVC showed similar energy-saving performances, higher robustness for equivalence factor (EF) and more energy-savings were discovered in the electricity generation and direct heat supply strategies, respectively. Economic analysis indicated that advanced process modules were economically feasible, with a savings-to-investment ratio (SIR) exceeding 1. The SIR and payback period (PBP) depended on EF and electricity prices. Significantly, the cascade module for direct heat supply emerged as the most appropriate in terms of both economic viability and energy-saving efficiency in amine-based CCPs, particularly at a higher EF.

Comprehensive technical analysis of CO2 absorption into a promising blended amine of DEEA-HMDA

Comprehensive technical analysis is vital for the large-scale industrialization of a certain potential amine solvent. This paper proposes a technical evaluation method to assess amine-based CO2 capture processes thoroughly. The method's validity was also verified by using the DEEA-HMDA as an example, compared with various conventional amine solutions in terms of the above three technical properties. Based on the technical properties analysis, a new rapid screening assessment method for amines based on technical indicators proposed. In addition, eight conventional amine solvents selected to calculate the technical indicators (including packed column design, solvent consumption, and regeneration energy consumption) reflected by these three technical properties. The packed column volume (44.5 m3), solvent consumption (2.28 kg/tCO2), and regeneration energy consumption (18.64 KW·h/tCO2) of using DEEA-HMDA as a CO2 absorbent were lower than the most commonly used MEA. In conclusion, the blended amine DEEA-HMDA is a potential carbon capture alternative solvent.

Design and economic evaluation of a novel amine-based CO2 capture process for SMR-based hydrogen production plants

Chemical absorption using amine solvents is the most commercially recognized technology to capture CO2 from the SMR-based hydrogen production plant. Most studies focused on the use of PSA inlet or tail gas streams to remove CO2 using MDEA solvent which is limited to about 60% of total plant CO2 emitted. Whilst the capture of a flue gas stream has been reported via the MEA solvent to remove 90% CO2 yet at relatively higher costs. A systematic investigation is required to identify the cost-effective use of the absorption processes when multiple positions are available for CO2 capture. In this study, multiple cases of the CO2 absorption process have been evaluated using MEA or MDEA solvents. Especially, a novel design for the simultaneous removal of CO2 from the flue gas of a reformer and the PSA inlet gas stream is proposed and its techno-economic benefits are examined. For this purpose, the rate-based model has been implemented in the MATLAB environment to simulate the absorption process, whereas the solvent regeneration energy and the capital and operating costs of the main equipment have been estimated using the correlations taken from the literature. The new system based on the sequential reuse of MEA solvent for two streams is found to be the most economic process to remove 99% of total plant CO2. The annualized cost of the proposed system is found 17.9% less in comparison to the best relevant conventional studied system of simultaneously removing CO2 from the PSA inlet and reformer flue gas streams using MEA and MDEA solvents.

Activated Carbon Produced from the Hydrothermal Treatment of Glucose with KOH Activation for Catalytic Absorption of CO2 in a BEA-AMP Bi-Solvent Blend.

The amine-based postcombustion CO2 capture (PCC) process involves absorption of CO2 into a solvent and then regenerating the solvent to produce CO2. In this study, the effect of an activated carbon (AC) catalyst, synthesized through hydrothermal treatment and furnace activation on CO2 absorption in a 4M BEA/AMP amine blend, was evaluated and compared with that of a KMgO/CNTs (1:4) catalyst. The physical and chemical properties of AC were investigated with a scanning electron microscope (SEM), CO2 temperature-programmed desorption (CO2-TPD), Brunauer-Emmett-Teller (BET), powder X-ray diffraction (XRD), and thermogravimetric analyzer (TGA) and compared with the KMgO/CNTs (1:4) catalyst. The results showed that when compared against noncatalytic CO2 absorption, AC enhanced the linear rate of CO2 absorption by 33.3%, while for KMgO/CNTs, it was reported as 25.5%. The relatively higher surface area, combined with the higher number and strength of basic sites of AC relative to the KMgO/CNTs (1:4) catalyst, provided effective basic reaction sites for CO2 absorption, thereby enhancing the rate of CO2 absorption into the amine. AC was also relatively easier to synthesize which would provide a good replacement for the CNT-based catalyst which has carcinogenic tendencies.

Development of a Diagnostic Approach for Early Detection and Control of Amine Degradation During an Amine-Based Co2 Capture Process

Development of a Diagnostic Approach for Early Detection and Control of Amine Degradation During an Amine-Based Co2 Capture Process

Novel CO2-negative design of palm oil-based polygeneration systems

A palm oil-based polygeneration system (POPS), which is a combination of a fixed bed hydrotreating reactor (FBHTR), a three-phase separator, and a series of cryogenic separators, is co-production process of green diesel and liquefied petroleum gas (LPG) named Design 1. The FBHTR model is validated by experiment data and its optimal operating parameters are determined by solving the response surface methodology-based optimization algorithm. Two CO2-negative designs for the POPS named Designs 2 and 3 adopt approaches of (i) the evacuated tube solar collector (ETSC) for reducing 35% flue gas from the furnace, (ii) the amine-based CO2 capture process coupling with pre- or post-separation system for producing the high-purity CO2 product, and (iii) the heat integration design for reducing the energy duties of hot/cold utilities. Design 2 is validated to achieve the maximum negative net CO2 emissions. Design 3 not only ensures the negative net CO2 emissions, but also it produces three high-purity products (98.3% green diesel, 100% LPG, and 99.9% CO2) simultaneously.

SnO2/ATP catalyst enabling energy-efficient and green amine-based CO2 capture

CO2 capture using aqueous amine solutions necessitates intensive heat duty because the temperature of solvent regeneration required to decompose the carbamate is>120 °C. In this work, we reported a SnO2 modified attapulgite (SnO2/ATP) solid acid catalyst to accelerate CO2 desorption in a rich 5 M monoethanolamine (MEA) solution at 88 °C. The SnO2/ATP catalyst with improved Brønsted acid sites and strong acid sites worked better than SnO2 and ATP. Particularly, utilizing 1/2-SnO2/ATP increased the CO2 desorption rate and desorbed CO2 by 265 and 222 %, respectively, as compared to CO2 desorption without a catalyst. The relative heat duty could be reduced by about 52 % by using 1/2-SnO2/ATP to regenerate the rich MEA solution, and its catalytic performance was superior to most reported solid catalysts for this purpose. FT-IR technique was employed to confirm the catalytic effect and a possible catalytic CO2 desorption mechanism was suggested. Additionally, 12 CO2 absorption–desorption cyclic tests were conducted to certificate the recyclability of 1/2-SnO2/ATP. These findings demonstrated that SnO2/ATP catalyst had significant potential for industrial use in low-energy and green amine-based CO2 capture processes. This study provides a practical strategy for utilizing efficient, affordable and environmentally benign solid acid catalysts for CO2 desorption, thereby advancing energy-efficient CO2 capture technology.

Attapulgite as a cost-effective catalyst for low-energy consumption amine-based CO2 capture

The extensive heat duty of solvent regeneration has significantly hampered the industrial application of amine-based CO2 capture technology. Catalytic CO2 desorption with solid acid catalysts has recently emerged as a promising and competitive strategy for improving solvent regeneration performance. The reported catalysts have exhibited poor activities and are relatively expensive, which has slowed the large-scale implementation of this technique. In this work, three low-cost and environmentally friendly clay catalysts, namely, attapulgite (ATP), activated bentonite (K-10), and sepiolite (SEP), were used to catalyze the CO2 desorption in the CO2-loaded 5 M monoethanolamine (MEA) solution at 88 °C. The findings revealed that ATP, K-10, and SEP catalysts accelerated CO2 desorption, and the ATP demonstrated better catalytic activity in the early stage of the desorption process. In particular, the introduction of ATP significantly increased the CO2 desorption rate by 54–57% and reduced the relative heat duty by about 32%, compared to the blank test. The superior catalytic performance of ATP might be attributed to its favorable surface area and medium acid sites. The catalytic effect of ATP was confirmed using FT-IR and Raman techniques, and a potential catalytic desorption mechanism was proposed. Furthermore, the stability of activated ATP was demonstrated using 15 CO2 absorption-desorption cycles. These results demonstrated that ATP significantly contributes to the advancement of the amine-based CO2 capture process and has significant potential for large-scale deployment. This work may pave the avenue for developing abundant and inexpensive clay-based solid acid catalysts for low-energy consuming CO2 capture technology.

Monitoring and mitigation of foaming in amine-based CO2 capture processes

Monitoring and mitigation of foaming in amine-based CO2 capture processes

Evaluating Energy-Efficient Solutions of CO2 Capture within Tri-solvent MEA+BEA+AMP within 0.1+2+2–0.5+2+2 mol/L Combining Heterogeneous Acid–Base Catalysts

To reduce the extensive energy penalty of CO₂ desorption process of amine-based CO₂ capture technology, the combination of “coordinative effect” with “heterogeneous catalysis” was adopted into “MEA+BEA+AMP” tri-solvents at special concentrations (0.1–0.5+2+2 mol/L) with solid base catalysts “CaCO₃” and various solid acid catalysts “γ-Al₂O₃, H-ZSM-5, and blended γ-Al₂O₃/H-ZSM-5”. Experiments were performed to evaluate if there were synergetic effects within the optimization of amine blend concentrations and catalyst selections. Reaction schemes were investigated within the tri-solvents to understand the absorption and desorption mechanisms of coordinative effect. CO₂ absorption was performed at 40 °C, and CO₂ desorption was performed at 90 °C. Five tri-solvent compositions with various catalysts were investigated in terms of initial absorption rate (Iₐbₛ), initial desorption rate (Idₑₛ), heat duty (H), and cyclic capacities, which were categorized into absorption–desorption parameters systematically. The results indicated that tri-solvents with catalysts were highly energy-efficient. The optimized tri-blend was 0.3+2+2 mol/L MEA+BEA+AMP, which performed better than the 2+2 mol/L BEA+AMP benchmark on both absorption and desorption. The optimized regeneration performance of tri-blends was 0.3+2+2 mol/L, and its relative heat duty was 32.9% of that of 5 M MEA and 66.5% of that of 2+2 M BEA+AMP. Results manifested that the combination of solid acid–base catalysts with tri-solvents containing “coordinative effects” was a promising solution to further optimize the energy efficiency of CO₂ absorption–desorption within industrial amine-based CO₂ capture processes.

Seawater Desalination with an Amine-based CO2-Capture Process

A new concept for seawater desalination integrated into an amine-based CO2-capture process is presented. It is based on the use of forward osmosis to transfer water from seawater into the absorption solution via a membrane. Desalted water can subsequently be recovered as the condensate from the desorber outlet or through membrane distillation from the absorber. Suitable membranes have been identified and the most promising one was selected for laboratory evaluation using representative amine solutions. The process performance parameters, membrane water flux and reverse amine flux were determined. The process performance was best for amino-acid salt solutions. Further work will focus on demonstration of the technology using a post-combustion CO2 capture pilot plant operating on real flue gas.

Effects of Plant Scale on Flexible Operation of Amine-based CO2 Capture Processes

The transition of energy systems to meet net-zero targets for CO2 emissions will require increased integration of intermittent renewable energy. Thermal power plants with carbon capture and storage (CCS) will have the important role of providing affordable dispatchable low carbon capacity, maintaining security of supply and enabling the expansion of other low-carbon sources. Whilst the flexibility of power plants is relatively well characterised, the flexibility of the CO2 capture plant is not well understood, particularly in terms of the overall CO2 emissions, process dynamics, operatbility and the energy requirements. Pilot plant and demonstration studies provide valuable insight on the key characteristics and factors that impact process flexibility. This study investigates the impact of plant scale and key process factors on the performance of amine-based CO2 capture during flexible operation. These insights will be applied to a case study that investigates dynamic performance during the start-up and shut down of CO2 capture plants.

Techno-Economic Assessment of Different Heat Exchangers for CO2 Capture

We examined the cost implications of selecting six different types of heat exchangers as the lean/rich heat exchanger in an amine-based CO2 capture process. The difference in total capital cost between different capture plant scenarios due to the different costs of the heat exchangers used as the lean/rich heat exchanger, in each case, is in millions of Euros. The gasketed-plate heat exchanger (G-PHE) saves significant space, and it saves considerable costs. Selecting the G-PHE instead of the shell and tube heat exchangers (STHXs) will save €33 million–€39 million in total capital cost (CAPEX), depending on the type of STHX. About €43 million and €2 million in total installed costs (CAPEX) can be saved if the G-PHE is selected instead of the finned double-pipe heat exchanger (FDP-HX) or welded-plate heat exchanger, respectively. The savings in total annual cost is also in millions of Euros/year. Capture costs of €5/tCO2–€6/tCO2 can be saved by replacing conventional STHXs with the G-PHE, and over €6/tCO2 in the case of the FDP-HX. This is significant, and it indicates the importance of clearly stating the exact type and not just the broad classification of heat exchanger used as lean/rich heat exchanger. This is required for cost estimates to be as accurate as possible and allow for appropriate comparisons with other studies. Therefore, the gasketed-plate heat exchanger is recommended to save substantial costs. The CO2 capture costs of all scenarios are most sensitive to the steam cost. The plate and frame heat exchangers (PHEs) scenario’s capture cost can decline from about €77/tCO2 to €59/tCO2 or rise to €95/tCO2.

Quantitative risk assessment of an amine-based CO2 capture process

This study presents a risk assessment study on an amine-based CO2 capture process. Based on the critical risks identified by a hazard and operability study (HAZOP) conducted in our previous work, we performed detailed quantitative risk assessment, including frequency estimation using fault tree analysis (FTA) and consequence estimation using the process hazard analysis software tool (PHAST). As a result of our FTA study on explosion accidents in the absorber column as a top event, we identified 25 basic events and eight intermediate events that lead to the top event. The probability of a T-102 explosion was estimated to approximately 3.55E-03 per year, which satisfies international safety regulations. Additionally, we performed consequence estimation for three types of accidents in an absorber, namely toxic substance leakage, explosions, and fireballs, under two different weather conditions, namely modest and worst conditions. It was determined that in the event of a toxic substance leakage accident, the effect zone of acid gas with high toxic substance content is approximately four-times larger than that of raw gas.

Dynamic analysis and linear model predictive control for operational flexibility of post-combustion CO2 capture processes

A key feature of amine-based post-combustion CO2 capture process is a wide operating range induced by periodic load changes in power plants, which necessitates flexible operation. One possible approach to enhance the operational flexibility is to design a reliable controller that can effectively regulate the process over the operating range. To this end, in this study, a robust model predictive controller is designed by analyzing the dynamic characteristics of a post-combustion CO2 capture process. Specifically, gap metric analysis is performed to analyze the sensitivity of the process. From this analysis, optimal operating conditions are identified by evaluating similarity among the dynamics around different operating conditions. Then, a single linear model predictive controller is designed on the basis of the linear approximation of the original nonlinear model at the chosen conditions. Finally, the effectiveness of the controller is illustrated through a case study on an example CO2 capture process.

Artificial Neural Networks (ANNs) for Density and Viscosity Predictions of CO2 Loaded Alkanolamine + H2O Mixtures

The physical properties, like density and viscosity, of alkanolamine + H2O (water) + CO2 (carbon dioxide) mixtures receive a significant amount of attention as they are essential in equipment sizing, mathematical modelling and simulations of amine-based post-combustion CO2 capture processes. Non-linear models based on artificial neural networks (ANNs) were trained to correlate measured densities and viscosities of monoethanol amine (MEA) + H2O, MEA + H2O + CO2, and 2-amino-2-methyl-1-propanol (AMP) + MEA + H2O + CO2 mixtures and results were compared with conventional correlations found in literature. For CO2-loaded aqueous amine mixtures, results from the ANN models are in good agreement with measured properties with less than 1% average absolute relative deviation (AARD). The ANN-based methodology shows much better agreement (R2 > 0.99) between calculated and measured values than conventional correlations.