Post-combustion Capture Applications Research Articles

3D-printing of adsorbents for increased productivity in carbon capture applications (3D-CAPS)

An important driver in the development of adsorption-based CO2 capture technologies is the reduction of cost through increasing the productivity. The 3D-CAPS project aims to increase the productivity (kg CO2/m3hr) of such technologies through structuring, enabled by 3D-printing. This productivity increase would allow for a reduction of the size of the adsorbers and the associated CAPEX and/or energy requirements. Pre-combustion, as well as post-combustion technologies, are investigated using potassium-promoted hydrotalcite (K-HTC) for sorption-enhanced water-gas shift (SEWGS) and amine-functionalized silica (ImmoAmmo) as sorbents, respectively. This contribution presents a technical overview highlighting several aspects of the project ranging from CFD modelling to assess the shape of the sorbents, 3D-printing of the sorbent materials as well as testing of the ImmoAmmo sorbent for post-combustion capture applications. It is discussed how several essential elements of the productivity improvement have been separately proven in the 3D-CAPS project, both by modelling and experimentally: maintained adsorption capacity upon 3D-printing, reduced pressure drop, and improved mass transfer.

Biomass-derived carbon/MgO-Al2O3 composite with superior dynamic CO2 uptake for post combustion capture application

In this work, the biomass-derived activated carbon (AC)/MgO-Al2O3 composite with high-efficiency dynamic carbon dioxide (CO2) capture performance was prepared. The effects of MgO loading ratio, calcination temperature, calcination time, and magnesium source on the CO2 uptake of AC-based composites were studied. Moreover, the CO2 uptake of AC-based composites loaded with single metal MgO and loaded with bimetal MgO-Al2O3 were compared, and the cyclic stability of AC-based composites under different desorption temperatures was compared. In addition, the pseudo-first-order (PFO) and pseudo-second-order (PSO) kinetic fitting analysis of the CO2 uptake at different adsorption temperatures were carried out. Finally, the AC-based composites were thoroughly characterized by BET, SEM, EDX, FT-IR and XRD. The most optimal AC-based composite with bimetal MgO-Al2O3 shows the maximum dynamic CO2 uptake of 4.50 mmol g-1, which is comparable to the static CO2 capture performance in the previous report. It suggested that biomass-derived carbon/MgO-Al2O3 composite has high potential application value in the development of CO2 adsorption materials.

3d-Printing of Adsorbents for Increased Productivity in Carbon Capture Applications (3d-Caps)

The 3D-CAPS project aims to increase the productivity (kg CO2/m3hr) of adsorbent based carbon capture technologies by an order of magnitude through structuring, enabled with 3D-printing. This productivity increase would allow for a reduction of the size of the adsorbers and the associated CAPEX and/or energy requirements. pre-combustion, as well as post-combustion technologies, are investigated using potassium-promoted hydrotalcite (K-HTC) for sorption-enhanced water-gas shift (SEWGS) and aminefunctionalized silica (ImmoAmmo) as sorbent, respectively. This contribution presents a technical overview highlighting several aspects of the project ranging from CFD modelling to assess the shape of the sorbents, 3D-printing of the sorbent materials as well as testing of the ImmoAmmo sorbent for post-combustion capture applications. It is discussed how several essential elements of the productivity improvement have been separately proven in the 3D-CAPS project, both by modelling and experimentally: maintained adsorption capacity upon 3D-printing, reduced drop reduction, and improved mass transfer .

Salen-Based Metal Complexes and the Physical Properties of their Porous Organic Polymers

Porous organic polymers (POPs) represent interesting candidate materials for carbon dioxide (CO2) adsorption applications owing to the permanently porous nature of the structures and the ability to vary metalloligand centres that can be incorporated as a potential means of property tuning. This work reports the synthesis and characterisation of four transition metal complexes (using M=Mn, Ni, Fe, and Pd) of the bis-bromo salen ligand, and the incorporation of these complexes into POPs with tris-(p-ethynyl)-triphenylamine to yield metallated polymers (POPMn, POPNi, POPFe, and POPPd). The POPs were shown to possess Brunauer–Emmett–Teller (BET) surface areas of up to 650m2g−1. Overall, this work provides further insight into the potential of permanently porous polymeric materials in post-combustion capture applications.

Chemical reaction kinetics measurements for single and blended amines for CO2 postcombustion capture applications

AbstractThe present study has established the direct pseudo–first‐order reaction kinetics of different aqueous‐based single and blended amines over the temperature range of 298.15‐313.15 K using stopped‐flow techniques. The single amines include one primary amine (monoethanolamine, MEA), two secondary amines (diethanolamine, DEA and 2‐ethyl(amino)ethanol, 2EAE), four tertiary amines (N‐methyldiethanolamine, MDEA, 1‐dimethylamino‐2‐propanol, 1DMA2P, 3‐dimethylamino‐1‐propanol, 3DMA1P, and 2‐dimethylaminoethanol, 2DMAE), one sterically hindered amine (2‐amino‐2‐methyl‐1‐propanol, AMP), and one cyclic diamine (piperazine, PZ). The blend systems used are MEA/PZ, DEA/PZ, MDEA/PZ, AMP/PZ, MEA/AMP, MDEA/2EAE, 1DMA2P/2EAE, 3DMA1P/2EAE, and 2DMAE/2EAE.Different reaction mechanisms for the reaction of CO2 with aqueous solutions of amines, such as base‐catalysis, zwitterion, termolecular, hybrid of zwitterion, hybrid of base‐catalysis‐zwitterion, and hybrid of base‐catalysis‐termolecular reaction mechanisms, are used to correlate the experimental data. For the single amines, the zwitterion mechanism is well suited to fit the experimental data of primary, secondary, sterically hindered and cyclic amines with an absolute average deviation (AAD%) less than 5%. The base‐catalysis mechanism fits the experimental data of all the tertiary amines well with an AAD less than 5%. For the blends, the hybrid of zwitterion mechanism fits the experimental data of MEA/PZ, DEA/PZ, AMP/PZ, and MEA/AMP well with an AAD less than 5%, whereas the hybrid of base‐catalysis‐zwitterion mechanism fits the experimental data of MDEA/PZ, MDEA/2EAE, 1DMA2P/2EAE, 3DMA1P/2EAE, and 2DMAE/2EAE well with an AAD less than 5%.

A Compararitive Review of Next-generation Carbon Capture Technologies for Coal-fired Power Plant

Despite the demonstration of large-scale carbon capture and storage (CCS) at a small number of coal power plants in North America, development of the technology remains slow in Europe, where several large projects have been cancelled in the last five years. Established CO2 capture technologies such as amine scrubbing consume significant amounts of energy, reducing power plant efficiency by around 10%pts and contributing to increases in the cost of electricity production by up to 80%. Within these economic constraints, CCS demonstrations have been limited to regions where CO2 has a value for enhanced oil recovery, a low cost coal supply is available, and effective CO2 emissions caps or pricing are in place. For CCS to be competitive as a low carbon energy source in a broader context, there is clearly a need for new technologies which can achieve dramatic reductions in the cost of capture, primarily through a reduction in the process energy consumption.Concerted research efforts worldwide are therefore developing a wide range of innovative solutions to the fundamental gas separation step at the heart of nearly all forms of carbon capture, whether post-combustion, pre-combustion or oxyfuel combustion. Dedicated research programmes in the US and Europe in particular have set ambitious targets for new technologies to achieve a CO2 capture cost approaching $20/t. Novel solvents aim to achieve lower regeneration energy requirements than conventional amines, with phase change systems, ionic liquids and other non-aqueous solvents, and enzyme-activation all representing promising approaches. Alternatively, techniques used in other commercial gas separations, including solid sorbents, membranes, and cryogenic separation, have also been widely investigated. Whilst challenging for post-combustion capture applications, these techniques may be of particular benefit to pre-combustion capture systems where much higher partial pressures of CO2 are available, and integration of the CO2 capture step and water gas shift reaction can be achieved using sorbents or membranes. In oxyfuel combustion, pressurised systems have demonstrated the most potential for efficiency improvements, with novel power cycles such as the supercritical CO2 cycle well-suited to exploiting the unique combustion conditions. Developments in ceramic membranes for oxygen production may also provide a lower cost alternative to cryogenic air separation. Finally, chemical looping combustion is a unique approach to carbon capture which can achieve dramatic energy savings through its inherent avoidance of any gas separation step. This technology has recently begun to see significant scale up by a number of companies and research institutes, with a focus on low-cost oxygen carriers.This paper will review these developments in novel capture technologies and compare them on the basis of efficiency penalty, cost of electricity, cost of CO2 capture, and their current developmental status. Processes which inherently incorporate CO2 capture with the power generation process, such as chemical looping combustion or the oxyfuel-based Allam Cycle appear to offer the greatest potential to meet the economic targets. For retrofit applications, high performances are associated with capture plant which is able to compensate for energetic losses by acting as an additional source of power, with calcium looping and fuel-cell based processes as notable examples.

Toward sustainable hydrogen storage and carbon dioxide capture in post-combustion conditions

This work addresses two environmental issues of major concern: hydrogen storage for hydrogen economy implementation and CO2 capture to reduce greenhouse gas emissions. For these purposes, two granular activated carbons were synthesized through chemical activation of olive stones by means of potassium salts (KOH and K2CO3). The porosity characterizations reveal typical ultramicroporous carbons with average pore sizes of about 0.53 and 0.69nm for K2CO3 and KOH-activated carbons, respectively. The volumetric measurements of cryogenic hydrogen adsorption show monolayer process. At sub-atmospheric pressures the narrower micropores show stronger binding energy to hydrogen molecules. However, at higher pressures this porosity range saturates and KOH-activated carbon exhibits a H2 storage capacity of 3wt%, 70% of which is achievable at only 1bar. CO2 shows a similar behavior than H2 when it was adsorbed purely at 0°C, and AC_KOH retains its excellence with a capacity of 5.6mmolg−1at 1bar. Finally, the two carbons were tested as CO2 adsorbents in conditions representative of post combustion capture applications (10% CO2 at atmospheric pressure and at 50°C). Both carbons show fast adsorption-desorption kinetics, perfectly described by pseudo-first order model. At these conditions, it was proven that only narrow micropores are essential for CO2 adsorption.

Biomass-derived activated carbon with simultaneously enhanced CO2 uptake for both pre and post combustion capture applications

Activated carbons from biomass (grass and Camellia japonica) exhibit enhanced CO2 uptake at 25 °C; up to 1.5 mmol g−1 at 0.15 bar, 5.0 mmol g−1 at 1 bar and 21.1 mmol g−1 at 20 bar, and depending on level of activation, have excellent uptake at both low (≤1 bar) and high (20 bar) pressure.

Chitin-acetate/DMSO as a supramolecular green CO2-phile

The supramolecular chemisorption of CO2 by the oligosaccharide chitin-acetate (CA) in DMSO as a green, binary sorbent-based system offers a potential, novel and eco-friendly approach for post combustion capture applications.

A study of bovine and human carbonic anhydrases as a model enzyme system for CO2 hydration in post combustion capture

The Post Combustion Capture (PCC) process is currently the most applicable and effective approach to reduce emissions of CO2 from fossil fuel electricity generation. If the rate of CO2 hydration can be accelerated, the size of the absorber column can be reduced accordingly. Carbonic anhydrase type II (CAII), being one of the most active enzymes known for the reaction of CO2 with H2O, is a promising catalyst for CO2 absorption in aqueous solution for PCC application. In this study, the catalytic efficiencies of human (hCAII), wild type bovine (wtbCAII), and a series of wtbCAIIs (bCAM1–bCAM9) structurally modified in an attempt to improve thermal and salt stability were determined by stopped-flow spectrophotometry at 25°C. wtbCAII and hCAII were found to have the highest activity for the hydration of CO2 while bCAM9 was the least efficient catalyst (catalytic rate constants of 1.198(6)×108, 1.14(1)×108 and 0.77(2)×108M−1s−1, respectively). The remaining mutants have similar catalytic efficiencies for CO2 hydration and fall in the range of 8.63(6)×107–1.072(2)×108M−1s−1. In addition to these results, this study also verifies the analytical method developed for the study of enzymatic systems.

CO 2 adsorbent pellets produced from pine sawdust: Effect of coal tar pitch addition

The main drawbacks of developing carbon adsorbents from pine sawdust, an abundant biomass feedstock, are the low carbon yield of the process and the poor mechanical properties of the resulting carbons. In an attempt to overcome these limitations, the effect of the addition of coal tar pitch was assessed. Adsorbent pellets were produced from pine sawdust and coal tar pitch by activation with CO2. The preparation process was optimized by using as decision variables the carbon yield and the adsorption performance of the adsorbents in conditions representative of post-combustion capture applications (10% CO2 at atmospheric pressure and at 50 °C). Subjecting the composite pellets to a pre-oxidation treatment with air increased the carbon yield of the production process, and also improved the adsorption kinetics and capacity of the final adsorbents. The prepared adsorbents present a high carbon yield, a superior mechanical resistance and a competitive adsorption performance.

Electrochemical investigation of corrosion in CO2 capture plants—Influence of amines

Post Combustion Capture (PCC) and storage of CO2 with amines is arguably the best available technology for mitigation of rising atmospheric concentrations of CO2. However, a number of serious operational issues threaten its utility. Among these is corrosion of PCC plant in which degradation of amines, particularly in the presence of oxygen, can lead to a range of corrosive products.This study uses electrochemical methods to quantify the corrosiveness of well-known capture agents, such as monoethanolamine (MEA), and compare them with novel solvent blends that have been developed at CSIRO. The amines used in our novel solvents also satisfy the standard PCC criteria of high rates of reaction with CO2, low energy requirements (for regeneration), low volatility and low toxicity.The results of the corrosion tests on carbon steel show that reductions in corrosion rate, compared with those for MEA, are possible with the novel solvents. Under laboratory conditions, the electrochemical data also indicate that the presence of oxygen causes a significant decrease in the corrosion rate in all systems studied. Whether an increase in oxygen concentration can be used in practical PCC applications depends on the long term stability of new amine formulations under these more strongly oxidizing conditions. Longer term testing is required to determine whether novel blends, such as CSIRO-1, possess the required chemical stability in the presence of typical variations in oxygen and CO2 concentration as well as temperature.

The evaluation of monoethanolamine-based CO2 post-combustion capture process waste handling approaches considering the regulations in UAE

Monoethanolamine (MEA) is one of the solvents that has shown a good performance in CO2 post-combustion capture application. Nonetheless, the waste that consists of heat stable salts and MEA degradation products is unavoidable although it has been reclaimed thermally. In this study, reclaimer waste from the CO2 capture process is characterized and its compatibility for reuse application and biological handling is explored. Particularly, waste components and their properties are analyzed from a reference case of Fluor's Econamine FGSM technology incorporating the other proven findings. MEA process waste can be deployed in NOx-SNCR scrubbing process directly. In addition, the installment of crystallization unit and KOH addition in reclaiming MEA can produce potassium sulfate that is useful for the other applications. This investigation incorporates the regulations in UAE, which suggest the need of treatment for MEA reclaimer waste by means of wastewater treatment technology (i.e. biological process). The treated wastewater can furthermore be reused for landscape irrigation, construction, and district cooling thus it can promote ecologically-sound CO2 capture application in UAE.

Evaluation of amine-blend solvent systems for CO2 post-combustion capture applications

This work evaluates amine-blend solvent systems for CO2 post-combustion capture applications for a 600 MWe conventional coal-fired power plant. The equilibrium-based Aspen Plus® absorption/desorption simulation tool was used for this evaluation. The total amine blends concentration was kept at the value of 30wt% for all different systems. Monoethanolamine (MEA) and diethanolamine (DEA) of weight variation of 3, 5, 10 and 15% are blended with 2-amino-2-methylpropanol (AMP), and methyldiethanolamine (MDEA). Fixed cross heat exchanger approach temperature of 10°C and stripper bottom temperature of 120°C are used as design specifications. These design specifications are used to screen each blend without CO2 loading through sensitivity analysis. The AMP with 3, 5, 10 and 15wt% blended DEA (the activator) was found to require lesser reboiler duty in comparison with 30wt% MEA, with lowest value of 3.17GJth/tonCO2 for 5wt% DEA activation. The promising four blends are further optimized using varying CO2 loadings. The blend of 5wt% DEA and 25wt% AMP with lean loading of 0.07 molCO2/molblend requires the lowest reboiler duty of 3.03GJth/ton-CO2 and lowest recirculation rate of 14.882m3/ton. Absorber temperature profiles indicate temperature changes depend significantly on the lean loading. Stripper temperature profile shows that temperature swing is pronounced at the bottom, suggesting that CO2 desorption takes place more at the lower stages.

Valorisation of spent coffee grounds as CO2 adsorbents for postcombustion capture applications

In this work spent coffee grounds from single-use capsules were used as the starting material for producing low-cost activated carbons. The activation conditions were selected and optimised to produce microporous carbons with high CO2 adsorption capacity and selectivity, thus with potential to be used as adsorbents in postcombustion CO2 capture applications. Two activation methods are compared: physical activation with CO2 and chemical activation with KOH. The first method is considered less contaminant; however, leads to carbons with lower textural development and thus lower CO2 adsorption capacity than those obtained by activation with KOH. On the other hand, multicomponent adsorption cyclic experiments pointed out that the CO2/N2 selectivity of physically activated carbons is higher than that of chemically activated carbons.

Comparison of Current and Advanced Post-Combustion CO2 Capture Technologies for Power Plant Applications

Most energy scenarios suggest carbon capture and storage (CCS) from power generation might contribute to reduce the carbon emissions necessary to stabilize the long-term global average atmospheric temperature. GE is actively investigating and developing novel technologies for both capturing and compressing CO2 from power plants with potential lower energy requirements and environmental impact than state-of-the-art processes. One technology that is currently the focus of significant research effort is phase-changing absorbents for post-combustion capture applications. This investigation compared the performance of phase-changing absorbents to state-of-the-art monoethanolamine (MEA) capture for three different flue gas conditions with CO2 concentrations ranging from 4 mole% to 13 mole%. Results indicate that depending on the flue gas conditions, the specific equivalent work necessary for operating phase-changing absorbents is expected to be up to 40% lower than for MEA capture. However, as the level of maturity of phase-changing absorbents is certainly lower than MEA capture, higher uncertainty in performance is expected. Besides lower energy requirements, a reduction of up to 6% in specific water cooling load is expected from the phase-changing absorbents compared to MEA capture, in particular for cases with high CO2 concentrations in the flue gas.

The effect of operating conditions on the performance of hollow fiber membrane modules for CO 2/N 2 separation

A commercialized polysulfone (PSf) hollow-fiber membrane module was tested for CO 2/N 2 separation performance for application in post-combustion capture. Cost efficiency, easy module manufacturing, and efficiency in gas separation are the main advantages of using PSf hollow-fiber modules for CO 2 separation. The effects of operating conditions such as temperature, pressure, and feed composition on separation performance were examined at various stage cuts. A 2-stage system including concentration of feed composition at stage 1 and production of high-purity CO 2 at stage 2 was constructed to improve separation efficiency. Higher operating temperature and pressure increased CO 2 permeance, but the loss of selectivity and higher energy consumption are a concern. Modules with various membrane areas were also used to test the effect of area on CO 2 separation.

Comparison of the rate of CO 2 absorption into aqueous ammonia and monoethanolamine

Aqueous ammonia has been proposed as an absorbent for use in CO 2 post combustion capture applications. It has a number of advantages over MEA such as high absorption capacity, low energy requirements for CO 2 regeneration and resistance to oxidative and thermal degradation. However, due to its small molecular weight and large vapour pressure absorption must be carried at low temperature to minimise ammonia loss. In this work the rate of CO 2 absorption into a falling thin film has been measured using a wetted-wall column for aqueous ammonia between 0.6 and 6 mol L −1, 278–293 K and 0–0.8 liquid CO 2 loading. The results were compared to 5 mol L −1 MEA at 303 and 313 K. It was found that the overall mass transfer coefficient for aqueous ammonia was at least 1.5–2 times smaller than MEA at the measured temperatures. From determination of the second-order reaction rate constant k 2 (915 L mol −1 s −1 at 283 K) and activation energy E a (61 kJ mol −1) it was shown that the difference in mass transfer rate is likely due to both the reduced temperature and differences in reactivity between ammonia and MEA with CO 2.