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Global warming and associated global climate change have led to serious efforts towards reducing CO2 emissions through the CO2 capture from the major emission sources. CO2 capture using the amine functionalized adsorbents is regard as a direct and effective way to reducing CO2 emissions due to their large CO2 adsorption amount, excellent CO2 adsorption selectivity and lower energy requirements for adsorbent regeneration. Moreover, large number of achievements on the amine functionalized solid adsorbent have been recorded for the enhanced CO2 capture in the past few years. In view of this, we review and analyze the recent advances in amine functionalized solid adsorbents prepared with different supporting materials including mesoporous silica, zeolite, porous carbon materials, metal organic frameworks(MOF) and other composite porous materials. In addition, amine functionalized solid adsorbents derived from waste resources are also reviewed because of the large number demand for cost-effective carbon dioxide adsorbents and the processing needs of waste resources. Considering the importance of the stability of the adsorbent in practical applications, advanced research in the capture cycle stability has also been summarized and analyzed. Finally, we summarize the review and offer the recommendations for the development of amine-based solid adsorbents for carbon dioxide capture.

The NOx emission of conventional circulating fluidized bed (CFB) boilers could hardly meet the increasing strict standards in China, so the initial NOx emission and control of Shenmu coal and char were investigated in a 0.5 MWth high temperature CFB test platform with a main combustion zone (MCZ) and a post-combustion zone (PCZ), the reducing atmosphere in MCZ suppressed the formation of NOx, high temperature in PCZ made the residual carbon and CO burnout, the technology of high temperature CFB with post-combustion had the advantage of decreasing the initial NOx emission while maintaining the combustion efficiency of fuel. The experimental results showed that as the injection position of post-combustion air (PCA) moving backward, the reducing zone in PCZ was enlarged so more NOx could be converted to N2. When PCA was injected from PCA1 and PCA3, NOx and CO emission were both relatively lower than other injection positions, the temperature in PCZ of Shenmu char was more uniform and its NOx emission was lower compared to Shenmu coal, the peak temperatures of MCZ and PCC were 968 °C and 936 °C respectively, the initial NOx emission of Shenmu coal was 46 mg/m3 (at 6% O2), meanwhile, the CO emission was 139 ppm. The initial NOx emission of Shenmu char could reach 41 mg/m3 when the temperatures of MCZ and PCZ were 931 °C and 913 °C respectively, the new ultra-low emission requirement (≤50 mg/m3) was successfully achieved without additional denitration equipment, so the technology of high temperature CFB with post-combustion is an effective ultra-low nitrogen combustion technology.

Li4SiO4-based adsorbent is considered as a promising choice for the CO2 removal from power plants’ flue gases. However, the relatively high raw materials cost still limits its industrial applications. In this work, aiming to reduce the cost of Si-source, three novel natural occurring minerals including the pumicestone, the montmorillonite and the attapulgite were employed as Si-sources for the production of Li4SiO4-based adsorbents. The phase composition, surface morphology as well as the cyclic CO2 ad-desorption performance of obtained adsorbents were experimentally and kinetically investigated. It is found that the Si content of minerals directly determines the adsorption capacity of adsorbents, resulting in a relatively high and stable capacity of nearly 0.1 g/g within 22 cycles for the pumicestone derived adsorbent compared with other adsorbents obtained from minerals. Moreover, the excess Ca inside the minerals is found forming CaO, which is harmful to the desorption performance of adsorbent owing to the occurrence of Li–Ca–CO2 interactions. As a consequence, Si-source with high Ca content was proven inadaptable for the synthesis of Li4SiO4-based adsorbent, which provides guidance for the future selection of mineral Si-sources in this field.

Carbon dioxide (CO2) capture by gas-separation membranes has become increasingly attractive due to its high energy efficiency, relatively low cost, and environmental impact. Polyvinylamine (PVAm)-based facilitated transport (FT) membranes were developed in the last decade for CO2 capture. This work discusses the challenges of applying PVAm-based FT membranes from materials to processes for post-combustion CO2 capture in power plants and cement factories. Experiences learned from a pilot demonstration system can be used to guide the design of other membranes for CO2 capture. The importance of module and process design is emphasized in the achievement of a high-performance membrane system. Moreover, the results from process simulation and cost estimation indicate that a three-stage membrane system is feasible for achieving a high CO2 purity of 95 vol%. The specific CO2 capture cost was found to significantly depend on the required CO2 capture ratio, and a moderate CO2 capture ratio of 50% presented a cost of 63.7 USD per tonne CO2 captured. Thus, FT membrane systems were found to be more competitive for partial CO2 capture.

A framework to perform real-time optimization (RTO) and nonlinear model predictive control (NMPC) is presented for a post-combustion carbon capture absorber unit. The NMPC is applied as a set point regulator with and without an accompanying RTO scheme. Moreover, a Kalman filter (KF) is used to perform state estimation for the scheme. The absorber RTO formulation considers solvent degradation cost, carbon tax, and electrical pumping costs. The two scenarios (with and without RTO) are assessed in situations with a fixed carbon tax, and a time-varying carbon tax. The results show that the RTO/NMPC scheme provides substantial economic benefit over the NMPC-only scheme, even for a short simulation time (~130 minutes). Furthermore, the RTO also aids in guaranteeing reachable set points for the NMPC, which may not occur otherwise.

A detailed model of a post-combustion CO2 capture plant (pcc-plant) is developed in the Modelica® language which allows the simulation of start-up and shutdown processes. The model of the pcc-plant is coupled to a simplified model of a coal fired power plant to investigate the coupled process. To guarantee a stable and automatic operation, a sequential control for start-up and shutdown procedures is implemented in both plants. Two case studies, focussing on the pcc-plant, are subsequently performed in this contribution. In the first case study, the influence of different parameters and input variables on the start-up time is investigated in order to analyze the start-up process of the pcc-plant. The varied variables are the steam flow rate to the reboiler, the solvent flow rate and the total amount of solvent in the pcc-plant. In the second case study two different start-up control structures for the carbon capture plant are proposed and their performances are presented and compared.

The development of new amine solvents without the major drawbacks of conventional amines is crucial to industrial applications of CO2 capture. This paper presents a water-lean CO2 capture solvent having a low regeneration energy and low degradation. The water-lean solvent, K2Sol, is a sterically hindered diamine; because of the hindered amine site, K2Sol easily forms bicarbonate, resulting in a high absorption capacity. The minimum solvent regeneration energy is obtained using Gaussian process Bayesian optimization (GPBO) and bench-scale pilot plant experiments. GPBO finds the optimal solution using the input and output relationship of experiments; thus, expensive first-principle model construction can be avoided. According to the pilot plant experiment, the optimal regeneration energies of monoethanolamine (MEA) and K2Sol are 4.3 and 2.8 GJ/t CO2, respectively, indicating that K2Sol requires only 65% of the regeneration energy of MEA. Fewer than 30 experiments are required to find the optimal pilot plant operation for both the MEA and K2Sol experiments. We also describe the superior properties of K2Sol in terms of the CO2 loading, cyclic capacity, regeneration temperature, and degradation.

This article presents a study on the optimal design and operation of a pilot-scale absorber column in post-combustion CO2 capture in the presence of uncertainty. A mechanistic model describing the behaviour of a post-combustion CO2 absorber column is explicitly considered in the present robust optimization formulation. This formulation takes into account process uncertainty, which will impact the absorber column operation due to seasonal or unexpected changes in the operating policies of a fossil-fired power plant, e.g. changes in the flue gas stream. Different scenarios were assessed in order to evaluate the impact of uncertainty on the optimal process design and operation. The results show that environmental constraints determine the impact of process uncertainty in the operation of the absorber column. Similarly, the operation of the absorber unit may become infeasible even when process design specifications are estimated under limited information on process uncertainty.

Accurate knowledge of hydrate phase equilibria is of fundament in terms of the hydrate-based gas separation process (HBGS) for post-combustion CO2 capture. In this work, we experimentally investigated the phase equilibria of flue gas during hydrate-based CO2 capture. Additionally, new experimental data for dissociation pressure of flue gases with different CO2 concentration were reported. Subsequently, a more accurate thermodynamic model combining Cubic-Plus-Association Equation of State (CPA-EoS) and Chen-Guo model was employed to predict the dissociation pressure of flue gases. To better perform the hydrate equilibria, a temperature dependent binary interaction parameter kij and new parameters for Chen-Guo model were developed. The results showed that the general tender of the new experimental data was in line with previous results. In addition, an improved accuracy was noticed for the mixtures with an Average Absolution Deviation (AAD) approximately to 4.07%, through comparing the predicted results with the experimental data. Especially, in terms of the gases with a CO2 concentration less than 85.32%, the improvement was significant. Lastly, this work also utilized the thermodynamic model and the Clausius-Clapeyron equation to predict the dissociation enthalpies of CO2 hydrate. The results showed that the prediction results were located in the margin of experimental data, which demonstrated the thermodynamic model proposed in our work was capable of describing the gas hydrate behavior with high accuracy.

Five different diamine-appended metal-organic frameworks (MOFs) that show a S-shaped CO2 isotherm are evaluated for post-combustion CO2 capture from dry flue gas using a vacuum swing adsorption process. A comprehensive simulation and optimization study using a multi-objective genetic algorithm is performed. The optimization to maximize CO2 purity and recovery showed a key link between the feed temperature, evacuation pressure and process performance. The MOFs that achieve a target CO2 purity ⩾95% and recovery ⩾90%, namely, mmen-Mn2(dobpdc) and mmen-Mg2(dobpdc) were optimized to reduce parasitic energy and increase productivity. The adsorbents, mmen-Mn2(dobpdc), mmen-Mg2(dobpdc) and Zeolite 13X showed minimum parasitic energies of 142, 152 and 167 kWh e / tonne CO 2 cap , respectively and maximum productivities of 0.4, 0.45 and 0.65 mol CO 2 m - 3 ads s - 1 , respectively while achieving CO2 purity ⩾ 95 % and recovery ⩾ 90 % . The possible low N2 affinity and the unique shape of the CO2 isotherm were found to be key reasons for a lower energy consumption.

The purpose of rotating packed bed is to intensify process conditions by using centrifugal forces. The effective interfacial area is a critical design factor and has a direct relationship with operational condition and mass transfer rate. Process intensification by the rotating packed bed is an emerging technology to improve the mass transfer rate in a high gravity system. Since there are limited modeling studies in order to control rotating packed bed parameters, in the present study, the multilayer perceptron artificial neural network (MLP) framework was successfully used to investigate the gas-liquid effective interfacial area in a rotating packed bed. In this regard, a number of 265 experimental data for the gas-liquid effective interfacial area was utilized by considering three groups including operational factors, physical dimension, and gas-liquid properties as the network’ inputs. The mean relative error and R-square as analogy factors for verification of the model accuracy obtained to be 8.2% and 0.97, respectively. Accordingly, the present model can be a huge value in the CO2-liquid system and it is introduced as a novel strategy to determine the gas-liquid effective interfacial area in a rotating packed bed.

For environmental protection, solvent-based post-combustion carbon capture (PCC) process has been applied to the coal-fired power plant as an end-of-pipe approach. Power plant needs to provide steam for PCC process and this will significantly influence the net power output. In this regard, this paper aims to: 1) provide an integrated model of small-scale PCC process with small-scale coal-fired power plant; 2) propose feed-back control structures for the integrated system and 3) develop a feed-forward controller to manipulate the steam draw-off flowrate in order to satisfy the rapid response to grid demand. Case studies were presented to investigate the system performance in the face of setpoints tracking and response to load change. The simulations were carried out in gCCS toolkit. Results demonstrate that the feed-forward controller can satisfactorily lower the time needed for power output target tracking.

The most important challenge in the post-combustion CO2 capture process is energy consumption. Using intercooled absorption columns increases absorption rate and decreases the energy needed for solvent regeneration. In this study, the optimum conditions for the usage of intercoolers (height and duty) have been investigated. First of all, the accuracy of rate-base model was validated to predict industrial unit in four different situations. The results showed that CO2 absorption percentage and temperature along the height of the absorption column were predicted precisely with average error of 1.38% and 3.85%, respectively. The second part of this article is dedicated to the optimization to maximize CO2 absorption and minimize total cooling duty by applying response surface methodology (RSM). The statistical analysis showed that the optimum heights for intercoolers I and II were found to be 2 and 5 m, respectively. The energy consumption of intercoolers I and II in optimum conditions were -496 and -809.28 kW respectively. By applying intercoolers’ optimum conditions in the model, the CO2 absorption percentage and energy consumption were obtained at 87.29 and −3890 kW, respectively. Hence, by decreasing the intercoolers’ height in the absorption column and using intercoolers in the optimum heat duty, with constant packing height, the CO2 absorption increased by 3.3%.

Post-combustion Carbon dioxide (CO2) capture (PCC) via amine absorption-stripping is an evolving technology towards mitigation of CO2 emissions. One of the major challenges in the technology development is the suitability of the solvent. Under the process operating conditions, irreversible reactions occur, thereby degrading the amine. The consequences of amine degradation are inevitable. The degradation products are harmful to the environment, increase the corrosion in the process equipment, cause fouling and ultimately make the process inefficient, hazardous and expensive. Monoethanolamine (MEA) is the benchmark solvent used and tested at industrial level for CO2 capture because of its high absorption rate and capacity to capture CO2 as well as medium to high resistance against oxidative and thermal degradation. This review reports degradation of MEA under process operating conditions, which includes up-to-dated list of degradation products, degradation kinetics and degradation pathways. Furthermore, degradation inhibition, computational studies, corrosivity as well as environmental concerns regarding the emissions of amine degradation products are critically reviewed. The objective of study is to provide researchers with a comprehensive knowledge on degradation of MEA, ways to reduce degradation, corrosion inhibition and understanding of environmental concerns for development of models for better understanding of behaviour of MEA and knowledge gaps.

Aqueous ammonia (NH3) is a promising alternative solvent for the capture of industrial CO2 emissions, given its high chemical stability and CO2 removal capacity, and low material costs and regeneration energy. NH3 also has potential for capturing multiple flue gas components, including NOx, SOx and CO2, and producing value-added chemicals. However, its high volatility and low reactivity towards CO2 limit its economic viability. Considerable efforts have been made to advance aqueous NH3-based post-combustion capture technologies in the last few years: in particular, General Electric's chilled NH3 process, CSIRO's mild-temperature aqueous NH3 process and SRI International's mixed-salts (NH3 and potassium carbonate) technology. Here, we review these research activities and other developments in the field, and outline future research needed to further improve aqueous NH3-based CO2 capture technologies.

Bechtel National (Reston, VA) have undertaken a FEED study for retrofitting a 2x2x1 natural gas-fired gas turbine combined cycle power plant with post-combustion carbon capture (PCC) for CO2 storage/utilization. The comprehensive programme of work covers the integration of the retrofitted carbon capture and compression plant to the combined cycle power plant, together with the detailed design of an amine-based conventional absorber-stripper scrubbing system with a non-proprietary solvent, 35% w/w MEA. Supporting studies have analysed options for single- and two-stage thermal reclaiming and also examined discrepancies between process modelling packages and the possible scope for alternative trade-offs between capital and operating costs. Given that modelling alone cannot predict commercially-important factors such as solvent management costs a long-term pilot test programme is strongly recommended, with outline details supplied for pilot size and the testing period.

Since most of real-world operations of post combustion capture of CO2 are burdened with issues on oxidative and thermal degradation of amine solutions, it is advantageous to find operational means to maintain process performance even while solution degradation proceeds. Although the chemical composition of degraded amine solutions is complex and variable, the relationship between solution properties, operating conditions, and process performance is reasonably explainable. As a strategy to deal with a plethora of amine compounds and degradation products, we propose a holistic approach which connects amine degradation to process performance via the alteration of solution properties. This approach includes altering the operating condition in response to the change in solution properties caused by amine degradation. This study is based on the comparison with fresh monoethanolamine aqueous solution and its degraded solution produced by continuous operation of a 10 kg-CO2/day bench-scale CO2 capture system. The solution properties and process performance were obtained experimentally as degradation progressed. From the analysis of obtained data, it was elucidated that the decrease in the CO2 loading capacity due to the amine degradation lead to deterioration of process performance. Moreover, it was indicated that the appropriate liquid flow rate for the degraded solution tends to be higher than that for the fresh solution because of decrease in the CO2 loading capacity.

The maritime industry has set clear objectives towards reducing greenhouse gas emissions in the coming decades. Ship based carbon capture (SBCC) could play a large role in reducing these emissions on the short term. This study gives an update on the work that has been conducted towards carbon capture and storage on LNG fuelled vessels. This is done by discussing the results of the DerisCO2 project where CO2 capture on the LNG fuelled Sleipnir vessel from Heerema Marine Contractors is analysed. One of the main advantages of SBCC is the heat integration of the vessel and the capture plant, which drastically decreases the heat and electricity demand of the capture plant and the total capture costs become fully CAPEX dominated. Taking into account the operational profile of the Sleipnir vessel, a conceptual design is proposed which consists of four absorbers and a single desorber, which is able to capture 72.5% of the CO2 emissions over the whole sailing profile. The total cost of CO2 capture, liquefaction and on-board storage for the Sleipnir vessel is estimated at 115 €/ton CO2, where the variable OPEX is estimated at 5.7% of the total costs. Lastly, the results of the tilting table experiments in the DerisCO2 project are discussed, where the effect of vessel tilting at sea on CO2 absorption is analysed. It is shown that static tilting causes a reduction in the overall mass transfer rate of CO2 absorption, but upon continuous tilting, the mass transfer rate is similar compared to static tests, which sets the expectation that vessel tilting at sea will have no negative effect on CO2 absorption.

This paper gives an overview of all the most significant results obtained during the CO2 capture pilot plants operation with Shell CANSOLV’s amine-based solvent DC-103. The pilot plant campaign at a full-scale waste to energy (WtE) plant in Oslo, Norway achieved its primary purpose of demonstrating low amine related emission levels during a test campaign of many months during 2019. This assures that the planned full-scale CO2 capture plant will meet the expected emissions specifications. It also allowed to gather important data on absorbent degradation in actual operation on WtE plant flue gas and confirm other performance parameters of the technology such as capture efficiency, energy requirements and product (CO2) purity.

With almost a decade of operational experience from an amine-based post combustion carbon capture plant in Norway, Technology Centre Mongstad has under multiple occasions and operating scenarios monitored the work environment exposure risk for such facilities. Primary focus has been on concentrations of Nitrosodimethylamine in the work environmental atmosphere. This paper presents some findings from work environmental gas sapling collected between 2012 and 2020, where Thermosorb-N filters, impingers and PTR-MS were used for sampling. The main objective has been to investigate work environment exposure risk in a CO2 capture plant. The findings show that the median outdoor background concentration during the different test campaigns have been 0.2 ng/m3(Arithmetic Mean 5.8 ng/m3, range

This first-of-its-kind, large-scale pilot is vital to the carbon capture knowledge base and experience. It will also serve as a reference for future commercial projects and provide critical design and operations information needed to scale-up the technology for commercial implementation, while minimizing costs and risks. The pilot is a 10 MWe slipstream taken from Dallman #4 at City Water, Light, and Power (CWLP) in Springfield, Illinois. The post-combustion capture technology being demonstrated is the Linde/BASF advanced capture system, which has been previously demonstrated at the National Carbon Capture Center at a 1.5 MWe level. The successful construction and operation of this plant will provide a means to demonstrate an economically attractive and transformational capture technology that can be used to retrofit existing plants and be deployed at new plants. The regional economic benefit and the ability to repurpose some exiting workforce at CWLP will also demonstrate how carbon capture can aid regional economies when it is deployed. If the technology performs as planned, the capture plant will remain in place and be utilized for future testing of capture and utilization technologies.

A water-lean solvent for post-combustion CO2 capture was techno-economically assessed and compared with its parent water-based solvent. At a first glance, the use of nonaqueous solvents, appears to offer lower energy requirements and reduced solvent degradation. However, it is necessary to look at the full picture to avoid rushing to develop a concept that may not deliver all that it promises. A nonaqueous solvent technology requires less regeneration energy compared with using standard aqueous amine solvents, especially if combined with a flash vessel instead of a regeneration column, and has a lower amine degradation rate compared with the aqueous solvent. However, using a nonaqueous formulation offers important technical challenges in terms of operability (increased solvent viscosity) and health, safety and environmental risks (higher amine emissions). The economic evaluation shows a hypothetical reduction of 15% in unit total cost based on savings in energy consumption and solvent refill. However, implementing measures to mitigate viscosity changes and amine emissions nullifies these gains. Therefore, no economic improvement over the benchmark is likely from using the nonaqueous version of a solvent. It is expected that the same risks apply for other nonaqueous technologies, so it is very unlikely that a magic bullet will be found to make nonaqueous solvents an attractive option for CO2 capture.

In this study, the high-concentrated CO2 has been recovered in the CFB-type dry sorbent CO2 capture process using 85 kg PEI-based sorbents, which were developed by KAIST. The CO2 uptake was measured by TGA was 0.067 kg-CO2/kg-solid. The process consists of a fast fluidized bed type sorption reactor, a bubbling fluidized bed type regenerator and sorbent cooler. The 85 kg of sorbent was charged to the process and the solid circulation rate, which was quantitatively controlled by manipulating the rpm of the rotary valve, was 145 kg/h so that it took about 35 minutes for the sorbents to cycle through the process. The CO2 removal efficiency at absorber and CO2 purity at regenerator were measured or calculated with an on-line IR gas analyser. The dynamic sorption capacity was calculated using the amount of CO2 absorbed in the absorber and the solid circulation rate. The performances were as follows: about 60% of the CO2 removal efficiency, 100 kg/day of the CO2 removal rate, 91% of the CO2 purity, and 2.9 wt.% of the dynamic sorption capacity. As a result, the dynamic sorption capacity was rather low, about 43% of the sorbent performance measured by TGA, because the solid residence time in the sorption reactor was insufficient. If the height of the sorption reactor would be increased to ensure the solid residence time enough to increase the dynamic sorption capacity to 0.04 kg-CO2/kg-solid, then 85% CO2 removal efficiency and 138 kg/day CO2 removal rate would be possible.

Retro-fitting of post-combustion CO2 capture units to coal fired power plants is key to the transition to a net-zero CO2 emission reality. Different separation technologies have been found suitable for CO2 capture, but a more comprehensive approach is required to identify the most viable option among those commercially available. In this study we analyze the three most established technologies, namely absorption, adsorption and membrane separation, comparing both their exergetic efficiency and their total cost. This assessment provides an overview of the technical differences among the three capture routes and a realistic estimate of the expenditures associated with post-combustion CO2 capture, as of today.

The Solid Sorbent Technology (SST) is a breakthrough technology which separates CO2 from flue gas in a continuous Temperature Swing Adsorption (TSA) fluidized bed process using solid adsorbent. The technology simultaneously delivers > 90% CO2 capture efficiency and > 95% CO2 purity with low to no process related emissions and at lower capture costs compared to state-of-the-art liquid amines technology. This paper will discuss results of a 900 h piloting campaign using Lewatit VP OC 1065 adsorbent and its impact on the cost comparison with liquid amines technology. The successful operation of the pilot plant and finalization of the test campaign marked the progression of the technology readiness level from TRL4 to TRL6.

This front-end engineering and design (FEED) study is for a carbon dioxide (CO2) capture system for Unit #2 (816 MW) at the Prairie State Generating Company’s (PSGC) Energy Campus in Marissa, IL. The capture technology used is the Advanced KM CDR Process™ from Mitsubishi Heavy Industries (MHI). The project will be the largest post-combustion capture plant in the world. In addition, it will incorporate advancements in the technology including lessons learned from past projects and a new proprietary solvent. The overall business model being developed by PSGC focuses on the generation of 45Q tax credits as a result of sequestering the captured CO2. Because the Prairie Research Institute (PRI) within the University of Illinois at Urbana-Champaign (UIUC) leads both this capture effort and the storage effort, there is close coordination and integration between the capture and storage efforts. This integration is vital to achieving the desired business targets for the project.

Mitigation of climate change by reducing the anthropogenic CO2 emissions has recently gained huge momentum. A prime pathway to achieve it in the short-medium term lies within capturing CO2 from industries’ flue gases. Post-combustion CO2 capture (PCC) is the most mature methodology for large-scale CO2 capture and closest to market. However, the conventional chemical absorption-based PCC process implies high regeneration energy requirements, constituting the majority of the energy load when adding PCC to the plant from which the CO2 is going to be captured. As such, reducing the overall parasitic load of the conventional process is of interest. Changing the solvent or improving the process flowsheet are two main methodologies to achieve higher energetic efficiency and lower exergy losses. As there are several reviews dealing with novel solvents, this review critically evaluates the progress in improving the conventional PCC process through modifications of process configurations and shadowed by solvent replacements as drop-in solutions. The process configurations were grouped into absorption and stripping enhancement categories. A comparative analysis was conducted between the different available schemes in the literature and interactions between solvents and process configurations were showcased, highlighting the advantages and shortcomings of some of them. The review reveals the need for standardized framework and optimization algorithms using exergo-economic performance indicators for integrated solvent and process synthesis.

CO2 capture performance of 50 wt.% K2CO3/alumina was investigated using various types of alumina supports such as γ-Alumina, Boehmite and Aerogel. Physical mixing and incipient wetness impregnation were used for preparing sorbents. Physically mixed K2CO3/γ-Alumina was the most efficient sorbent, with a maximum CO2 capture capacity of 5.5 mmol CO2/g K2CO3. γ-Alumina displayed the lowest, and Aerogel the highest, hydrophilicity and surface area. Increasing hydrophilicity and surface area also increased water adsorption capacity, which adversely affected the CO2 capture capacity of the physically mixed sorbents. The excess water adsorption capacity converted K2CO3 to an almost inactive precursor of K2CO3·1·5H2O. BET and SEM results showed that recrystallization of K2CO3 from water had an adverse impact on the physical structure of the impregnated sorbents which affected their CO2 capture performance. The kinetic behavior of the samples was analyzed using the Avrami kinetic model. K2CO3/γ-Alumina prepared by physical mixing and impregnation methods showed the highest carbonation rates with K-values of 0.1168 and 0.2260, and n-values of 1.1257 and 1.2004, respectively. K2CO3/Aerogel and K2CO3/Boehmite prepared by the physical mixing method exhibited higher performance than the respective impregnated sorbents in terms of carbonation rate and CO2 capture capacity.

This study investigated the absorption heat, equilibrium CO2 solubility, absorption and desorption rates, cyclic capacities, heat duty, and absorption kinetic modeling of amine blends containing AMP and DETA. The AMP and DETA concentrations were varied (1–2.5 kmol/m3 and 0.5–2 kmol/m3, respectively) while the total amine concentration was constant at 3 kmol/m3. The absorption experiment was conducted at 15 %v/v CO2 and 313 K while the desorption temperature was at 363 K. Experimental results revealed that the absorption rates, cyclic capacities and desorption rates of some AMP–DETA blends were higher than those of 5 kmol/m3 MEA. The absorption heat of the blends is comparable to that of MEA while the heat duty of some AMP–DETA blends are much lower than that of 5 kmol/m3 MEA. The optimal amine blend was confirmed to be 2 kmol/m3 AMP – 1 kmol/m3 DETA. A model similar to the power law kinetic model showed that CO2 composition in the feed gas affected the initial absorption rates as compared to AMP/DETA molar concentration ratio. The model predicted the initial absorption rate with a %AAD of 0.52%. These results provide good prospects for AMP–DETA blends towards CO2 capture.

It is typical to assume that the capture system operates at the full working load of the power plant. This study aims to develop systematic design framework which can provide a cost-effective strategy for operating CO 2 capture plant under different operating load. The part-load performance of CO 2 capture process together with power plant is modeled and evaluated with a process simulator UniSim ® . This study considers both natural gas-fired combined cycle (NGCC) and coal-fired plants, in which optimization is carried out for finding an economic operating strategy to minimize regeneration energy without compromising process efficiency of the capture system. The multi-period modeling approach is applied to accommodate discontinuous nature of part-load performance, with which techno-economic impacts of part-load operation is investigated in a holistic manner. The case study is presented to demonstrate the usefulness of proposed design and optimization framework and to provide practical guidelines and conceptual insights for part-load operation in practice. From the case study, the specific reboiler duty is reduced through the superstructure optimization at full-load operation, which is about 3% lower than one without structural modifications. Also, the operational optimization for part-load achieves energy savings by 2–3% in NGCC and 3–5% in coal-fired power plant.

This work presents a mathematical modeling framework for the simulation and optimization of pressure/vacuum swing adsorption (P/VSA) processes for post-combustion CO 2 capture. A single-stage P/VSA process for CO 2 capture from dry flue gas is considered using new zeolite 13X-based adsorbents resulting from perturbation on the 13X zeolite isotherm. A two-bed six-step P/VSA cycle configuration with light product pressurization is employed in systematic simulation and optimization studies. First a zeolite 13X, the current benchmark commercial adsorbent for CO 2 capture, is considered. Accordingly, the model is used to study and evaluate new zeolite 13X-based adsorbents for more efficient CO 2 capture. The results from systematic comparative simulation studies demonstrate that a modified zeolite 13X-based adsorbent appears to have better process performance compared with the original zeolite 13X. Furthermore, process optimization studies employing the above potential adsorbents are performed to minimize energy consumption for specified minimum requirements in CO 2 purity and recovery. The optimization results indicate that the minimum target of 95% in CO 2 purity and 90% in CO 2 recovery is easily met for the P/VSA process under consideration for both potential adsorbents under different operating conditions resulting in different energy requirements and CO 2 productivity.

Amine-based post-combustion CO 2 capture (PCCC) technology is regarded as one of the most viable solutions for the mitigation of CO 2 emissions. It has been mature enough to be implemented on commercial scales. However, N- nitrosamines and N- nitramines can be formed as by-products of amine degradation during PCCC processes. They are suspected carcinogens and strictly regulated. With the development of PCCC technology across the global, PCCC facility may become a main source of N- nitrosamines and N- nitramines to the environment. Due to the possible adverse effects of N- nitrosamines and N- nitramines on the environment and human health, the interests in the occurrence, fate and mitigation of PCCC-derived N- nitrosamines and N- nitramines have been shared by a growing number of researchers recently. Therefore, this article provides a comprehensive review on the most recent efforts in this emerging field. In detail, this review focuses on (a) the formation, emission and degradation of N- nitrosamines and N- nitramines from amine-based PCCC processes, (b) the toxicology and environmental impact of PCCC-derived N- nitrosamines and N- nitramines, (c) the methods to destruct and remove N- nitrosamines and N- nitramines from PCCC waste, and (d) the future research perspectives.

The reduction of CO2 emissions has become a challenge due to rapid economic growth all over the world. Growing concerns on this issue have led the researcher to develop and implement several strategies including one very promising strategy involving CO2 capture from power plants. This paper presents a Computer Aided Molecular Design (CAMD) technique to design new alternative solvents as replacements for commonly used solvents during the post combustion carbon capture process in power plants, which is often costly and energy intensive. The CAMD technique can quickly identify the most suitable solvents and avoid spending resources on infeasible solvent replacements. In this study, the reverse design approach is used where, first, the criteria of the targeted solvents are identified and then the desired solvent candidates generated. The methods for this work consists of five steps: 1) Problem formulation, 2) Generation of single reactive solvent candidate using ProCAMD tools in ICAS software, 3) Prediction of the reaction mechanism between the potential amine solvent candidate and CO2 using the zwitterion mechanism and base-catalysed hydration mechanism, 4) Evaluation of process performance by calculating the heat required for the solvent regeneration process, and 5) Selection of the best solvent candidate based on its desired process performance. The result of this study reveals that 25 amine-based solvents for the chemical absorption process were successfully generated from the amine and alcohol functional groups. By using the proposed solvent, significant savings on regeneration energy, up to 31.4%, could be achieved compared to the conventional solvent, MEA. The percentage average absolute deviation (AAD) of the property prediction model that this study used to estimate the value of heat of formation is 4.67%. This finding is important to further reduce the regeneration energy, which makes the CO2 capture process costly, and achieve a more sustainable and cleaner environment.

Amino-MIL-101(Fe) was synthesized and assessed for post-combustion CO2 capture. A hybrid model has been applied which resulted in better agreement with the experimental data. The achieved adsorption values for the pure CO2 and N2 gases at 1 bar and 298 K were equal to 0.41 and 0.33 mmol.g−1. The kinetic modeling of adsorption data indicated that the adsorption of CO2 and N2 at low pressure was not kinetically controlled. The adsorption selectivity of CO2 over N2 was estimated using IAST, which was achieved equal to 1.6.

A superstructure-based optimisation model for the CO2 capture process using an N2-selective and CO2-selective membranes is presented. The model automatically selects either of the membranes for each membrane stage to have a hybrid membrane CO2 capture process. The superstructure embeds numerous process routes and allows the collection of product streams and residue streams from either the retentate side or permeate side of the multi-membrane stages. This results in novel process flowsheets for post-combustion CO2 capture using membrane technology. In the study, the optimisation of carbon capture by an all N2-selective membrane process is also carried out. At 90% recovery and 95% product purity, the multi-stage optimisation of the N2–CO2 hybrid membrane process reduces the total membrane area by 46% and the cost of capture by 14% compared to the optimised CO2-selective membrane process.

Large-scale CO2 abatement is key to avoid the detrimental environmental impacts of increased CO2 emissions worldwide. Solvent-based absorption is a mature post-combustion capture technology for short- to medium-term implementation. However, high energetic requirements, capture costs and technical challenges have been prohibiting its wide industrial deployment. Extensive research efforts have enabled significant improvements that resulted in scaling-up of pilot plants to industrial-level systems and commercial installations. This work provides a detailed review of these activities for plants of different capacities in 37 locations worldwide. The presented information pertains to: a) baseline, packed bed, absorption/desorption flowsheets, originally developed for alkanolamines, b) flowsheets with significant structural modifications that increase the operating driving forces, c) flowsheets including modifications for phase-change solvents and d) flowsheets that incorporate rotating packed beds (RPB). Technical details are presented regarding tested solvents, energetic performance, operating conditions, types and capacity of equipment, emissions, degradation and corrosion. It is observed that energy recovery in the stripper enables significant regeneration energy reduction, as proven in a commercial-scale plant. Equivalent performance has also been achieved with the chilled ammonia process in large-scale pilots. Liquid-liquid phase-change solvents and RPBs exhibit high potential for operating and capital expenditure reductions, but require significant scaling-up effort. Research in RPBs includes mainly lab-scale, mass transfer investigations. Several large-scale plants are being developed in China.

Membrane technology is a promising strategy in flue gas CO2 capture. Recently, many high-performance multilayer composite membranes for CO2/N2 separation were successfully developed in the laboratory. However, the detailed scaling-up processes were rarely discussed due to the lack of mature technology and equipment that specially designed for the proven advanced membrane materials. This study investigated the large-scale production of the defect-free thin multilayer composite membrane for flue gas CO2 capture. A novel coating machine with double blades and surface cross-linking unit was designed, and the industrial scale multilayer composite membranes were prepared by running the coating machine twice. The coating solution stability of intermediate layer solution was prolonged to more than 72 h. The key technologic parameters including web speed and the concentration of cross-linking unit were analyzed. The continuously prepared multilayer composite membrane shows high and stable CO2/N2 performance and great potential in the application of flue gas CO2 capture.

As a promising alternative, polyethyleneimine-functionalized silica (PEI/SiO2) is investigated extensively for post-combustion CO2 capture from flue gas to alleviate the global fossil-related CO2 emissions, with the superiority of prominent adsorption capacity, selectivity, and regeneration performance. However, significant concerns of the trace acid impurities (SO2 and NOx) coexisted in flue gas have arisen, due to the potential interference on the stability of PEI/SiO2 in the long-term operation. To identify the effects of different acid impurities on CO2 capture performance, herein, we explored the behavior of PEI/SiO2 on exposure to various simulated flue gases containing single or multiple acid impurities, and the poisoning effects of SO2 and NO2 were revealed, which would result in the drastic losses of capacity. Similarly, in the continuous adsorption-regeneration cycles, the working capacities were linearly decreased by 39.8% and 19.2% in the presence of SO2 and NO2, respectively, ascribed to their strong affinity toward amines. In contrast, the adsorbent treated by NO could still maintain a stable performance, and the synergetic effects proved to be not significant, considering co-existence of multiple impurities. Additionally, the interference was demonstrated in detail to be associated with the irreversible binding of SO2 and NO2 with amines, and the formation of some induced species, which gradually occupied the available amine sites, would lead to the degradation of PEI/SiO2 upon exposure to acid impurities in the flue gas.

Solvent-based post-combustion carbon capture (PCC) process is widely viewed as the most viable option for reducing CO2 emission. This technology has been deployed globally and many researches have been conducted in this area. In this paper, current status of dynamic modelling, system identification and control scheme of solvent-based PCC process is reviewed. Different research directions of these areas are discussed to conclude the existing challenges. Based on this, this paper is also trying to provide potential solutions as possible pathways for flexible and economical operation.

Amine-functionalized solid adsorbents have significant application potential in post-combustion CO2 capture due to the advantages of high capacity, low regeneration cost and long-term stability. Although the powdery adsorbents exhibit higher CO2 uptake capacity, the poor strength and large pressure drop limit their practicability. Monolithic adsorbent is considered as a good choice to solve these problems, but still facing the bottle-neck of insufficient CO2 capacity. In this work, a facile and feasible gel-casting method was proposed to fabricate monolithic adsorbents with high CO2 capacity, excellent mechanical strength, and good cycling stability. MCM-41 with rich mesoporous structure was immobilized by polymerization of organic polymer to construct monolithic adsorbents supports with high specific surface area (~1088 m2 g−1) and mechanical strength. The 70T-MM-550 monolithic adsorbent impregnated with TEPA achieved high adsorption capacity of 151.1 mg g−1 at 75 ℃ under 1 atm pure CO2. The monolithic adsorbents also showed good reversibility of CO2 adsorption under mild conditions, where the adsorption capacity decreased only by 2.8% after five regeneration cycles. In addition, the radial and axial compressive strength of 70T-MM-550 is over 200 N cm−1 and 4.5 MPa, respectively. In consideration of the high CO2 capture performance and mechanical properties of the monolithic adsorbents, the findings here open a new avenue for designing efficient monolithic CO2 adsorbents with industrially potential.

The research conducted in the last five years can potentially paint a picture of the next generation’s research related to solvent development for post-combustion carbon dioxide capture. This paper presents a comprehensive summary of the research work in this field conducted in the period from 2015 to 2020. The work includes research efforts in the areas of: (i) solvent chemistry, which refers to the work conducted on solubility, reaction kinetics, nuclear magnetic resonance or NMR analysis for ion speciation, and alternative solvents, (ii) development of amine solvents, which includes development of catalyst and enhancement of current solvents with the aid of catalysts, (iii) a novel regeneration process called Electrochemically Mediated Amine Regeneration, and (iv) applications of artificial intelligence technologies to the carbon dioxide capture process. The paper can be considered an update discussion and summary of the research work conducted in diverse areas related to solvent development for post-combustion carbon dioxide capture since our review of the research area published in 2015.

This paper deals with the effect of solvent vapor liquid equilibrium (VLE) properties on the heat duty in a post-combustion CO2 capture process. The conceptual solvent properties include the absorption heat, absorption performance and cyclic capacity, modeled by a three-parameter VLE equation. There are four processes considered. A conventional process serves as a reference case. An ideal process is used to study the energy saving potential. As typical process improvements, an intercooling and a rich split process are used to analyze the heat duty reduction effect. The optimal solvent in each process is obtained by minimizing the total heat duty. By the sensitive analysis, the solvent with less favorable VLE properties owns a larger energy saving potential and energy saving effect. Results show that the rich split is a more energy-efficient process improvement method than the intercooling configuration for the typical amine solvents.

High cycle-to-cycle variations (CCV) in the spark ignition (SI) engine will not only lead to incomplete combustion and even misfire, but also affect the fuel economy and even influence the drivability and conformability of a vehicle, particularly at the lean-burn condition. However, the detail information about the root causes of CCV are still relatively limited, particularly the natural gas SI engine. In this paper, the impacts of the key operating and design parameters were investigated on the CCV of the high compression ratio SI natural gas engine under lean mixture condition. The results indicated that the in-cylinder pressure distribution tended to be concentrated, the number of partial burning or incomplete combustion cycles also reduced with increasing the engine speed. With increasing the load, the in-cylinder pressure distribution, peak combustion pressure and its location were tended to be concentrated. Furthermore, the number of the partial combustion or post combustion cycles declined from low-load to medium- and high-load zones. Moreover, the relationship between the peak combustion pressure and its location was almost linear with increasing the engine load. Unfortunately, with further increasing engine load, in-cylinder pressure traces started to disperse slightly. Under the low-load condition, in-cylinder pressure traces were tended to be concentrated with increasing compression ratio (CR). As CR continually increased, its influence on the in-cylinder pressure distribution decreased. In addition, the number of the partial combustion or post combustion cycles decreased with increasing CR. However, under the high-load condition, increasing the CR has slightly effects on the in-cylinder pressure distribution.

Mesoporous magnesium oxides with a high surface area (672–686 m 2 /g) were synthesized by an aerogel method and subsequently evaluated for CO 2 capture efficiency under ambient-temperature sorption and intermediate-temperature regeneration. The effects of one-step (MgO-1) and four-step (MgO-4) calcination methods on the as-prepared MgO samples were evaluated with respect to textual properties and CO 2 sorption capacity at various temperatures (30–350 °C). The as-prepared MgOs showed greater than 10 wt% of CO 2 sorption at 30 °C, showing very fast sorption of more than 7 wt% CO 2 within 5 min. The cyclic stability of the sorbents was tested by using CO 2 sorption at 30 °C and N 2 regeneration at 450 °C. The sorption performance of MgO-1 was more stable and higher than that of MgO-4, but the surface area and pore volume were still reduced. The cyclic sorption capacity became 6.1 wt% at the condition of mixture gas sorption (CO 2 /N 2 : 15/85 vol%) and CO 2 regeneration. Since inter-crystallites coupling plays an important role in pore formation as well as stability, calcination condition can contribute to preventing the degradation level of performance and textural properties of sorbents.

The energy consumption associated with absorbent regeneration remains the most critical challenge for the industrial implementation of chemisorption based CO 2 capture processes. Aimed at reducing the energy consumption, this paper proposes a promising process modification of the ammonia (NH 3 ) based CO 2 capture process that involves an advanced flash stripper with a cold rich split. We investigated the techno-economic performance of the advanced NH 3 process integrated with a 650 MW coal-fired power plant, and evaluated it technical and energy performance using a rigorous, rate-based model in Aspen Plus. A sensitivity study was also performed to optimise the modelling parameters, i.e. the stripper pressure and the absorbent NH 3 concentration, and minimize the regeneration duty. A very competitive regeneration duty of 1.86 MJ/kg CO 2 was achieved for an optimised stripper pressure of 12 bar and an NH 3 concentration of 10.2 wt%, with a total equivalent work of 0.164 MW h/t CO 2 for absorbent pumping, NH 3 regeneration and CO 2 compression. We also used a validated economic model to estimate the capital investment of the advanced NH 3 process and its corresponding economic performance. With its significant reduction in energy consumption, the proposed process was economically competitive with CO 2 avoided cost was as low as US$40.7/t CO 2 . This was 34% and 44% less than the reference NH 3 and monoethanolamine (MEA) processes, respectively. The advanced NH 3 based flash stripper also had technical and economic advantages over other amine absorbents, such as MEA and piperazine (PZ), as well as other advanced stripper modifications, such as inter-heating process, revealing its process viability in commercial application.

This paper provides a short review of the multitude of processes proposed for solvent-based and sorbent-based post-combustion CO 2 capture. (Membrane-based systems, another important technology for CO 2 capture is outside the scope of this review.) The majority of process configurations discussed in the open literature focus on reducing the energy penalty with little consideration of capital cost or operability — key factors for industrial implementation. This paper highlights advances in all three areas and identifies opportunities for future research.

Gas-fired industrial furnaces are used for heat-treatment of semi-finished steel products. The required energy is provided by gas-fired burners, which are supplied by fuel and air. The combustion is often realized fuel rich to avoid scale formation at the product surface. Thus, the flue gas contains unburnt products, which are oxidized in a post combustion chamber by adding fresh air. The control of the volume flow of air to the post combustion chamber is a crucial task because the flue gas leaving the furnace must not contain unburnt products. For this control task, a two-degrees-of-freedom control strategy based on differential flatness in combination with a MIMO-PI controller is proposed. The basis for the control design is a first-principles mathematical model of the air supply circuit and the combustion of flammable products. The model is validated by means of measurement data from a real plant.

IHI has been developing Post Combustion Capture (PCC) technology using a chemical absorption process which is applied to coal-fired power plants. To reduce the costs of CO 2 capture, we have been investigating advanced amine solvents, packings, and process. The 2 nd IHI packing and new process were evaluated at a 20 ton-CO 2 /d pilot plant. The absorption performance of the 2 nd IHI packing was 1.8 times higher than a conventional packing with almost the same pressure loss per unit height. As a result of process performance tests, the regeneration energy of new IHI process achieved less than 2.4 GJ/t-CO 2 exluding the radiation heat.

A new synthetic polyamine was found as a suitable compound for amine-impregnated solid sorbent through screening of amine compounds with the aid of density functional theory calculations. CO 2 capture performance of the sorbent was evaluated on a lab-scale CO 2 capture system. The solid sorbent was excellently regenerable even at low temperature condition. Then, Bench-scale demonstration will be started on current project, using the sorbent developed by Research Institute of Innovative Technology for the Earth (RITE) and moving bed system of Kawasaki Heavy Industries, Ltd (KHI).