High CO2 Capture Research Articles

Water Enables Efficient CO2 Capture from Natural Gas Flue Emissions in an Oxidation-Resistant Diamine-Appended Metal-Organic Framework.

Supported by increasingly available reserves, natural gas is achieving greater adoption as a cleaner-burning alternative to coal in the power sector. As a result, carbon capture and sequestration from natural gas-fired power plants is an attractive strategy to mitigate global anthropogenic CO2 emissions. However, the separation of CO2 from other components in the flue streams of gas-fired power plants is particularly challenging due to the low CO2 partial pressure (∼40 mbar), which necessitates that candidate separation materials bind CO2 strongly at low partial pressures (≤4 mbar) to capture ≥90% of the emitted CO2. High partial pressures of O2 (120 mbar) and water (80 mbar) in these flue streams have also presented significant barriers to the deployment of new technologies for CO2 capture from gas-fired power plants. Here, we demonstrate that functionalization of the metal-organic framework Mg2(dobpdc) (dobpdc4- = 4,4'-dioxidobiphenyl-3,3'-dicarboxylate) with the cyclic diamine 2-(aminomethyl)piperidine (2-ampd) produces an adsorbent that is capable of ≥90% CO2 capture from a humid natural gas flue emission stream, as confirmed by breakthrough measurements. This material captures CO2 by a cooperative mechanism that enables access to a large CO2 cycling capacity with a small temperature swing (2.4 mmol CO2/g with ΔT = 100 °C). Significantly, multicomponent adsorption experiments, infrared spectroscopy, magic angle spinning solid-state NMR spectroscopy, and van der Waals-corrected density functional theory studies suggest that water enhances CO2 capture in 2-ampd-Mg2(dobpdc) through hydrogen-bonding interactions with the carbamate groups of the ammonium carbamate chains formed upon CO2 adsorption, thereby increasing the thermodynamic driving force for CO2 binding. In light of the exceptional thermal and oxidative stability of 2-ampd-Mg2(dobpdc), its high CO2 adsorption capacity, and its high CO2 capture rate from a simulated natural gas flue emission stream, this material is one of the most promising adsorbents to date for this important separation.

Carbon Dioxide Capture from Flue Gas Using Tri-Sodium Phosphate as an Effective Sorbent

Fossil fuels are dominant as an energy source, typically producing carbon dioxide (CO2) and enhancing global climate change. The present work reports the application of low-cost tri-sodium phosphate (TSP) to capture CO2 from model flue gas (CO2 + N2) mixture, in a batch mode and fixed-bed setup. It is observed that TSP has a high CO2 capture capacity as well as high CO2 selectivity. At ambient temperature, TSP shows a maximum CO2 capture capacity of 198 mg CO2/g of TSP. Furthermore, the CO2 capture efficiency of TSP over a flue gas mixture was found to be more than 90%. Fresh and spent materials were characterized using powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), and Fourier transformed infrared spectroscopy (FTIR). Preliminary experiments were also conducted to evaluate the performance of regenerated TSP. The spent TSP was regenerated using sodium hydroxide (NaOH) and its recyclability was tested for three consecutive cycles. A conceptual prototype for post-combustion CO2 capture based on TSP material has also been discussed.

Sensitivity analysis of CO2 capture process in cyclic fluidized-bed with regeneration of solid sorbent

In cyclic CO2 capture processes using dry sorbents, the regeneration of sorbents is a key factor that determines the overall performance and energy efficiency. In this study, the sensitivity of capture performance and energy consumption was determined using a dynamic model for a cyclic fluidized-bed system circulating a K2CO3-based sorbent. The sensitivity study focused on the sorbent properties, operating conditions, and regenerating conditions. The performance was more sensitive to the operating conditions than the physical properties of sorbent. For the carbonator, the inlet velocity of feed gas was the most critical parameter for assessing the capture efficiency, and the CO2 content in feed gas was crucial for determining the energy efficiency. A slight increase in the regeneration temperature led to a steep increase in CO2 removal performance as well as energy consumption. To achieve CO2 removal of over 78.5%, high energy consumption in the regenerator was expected. Additionally, a high capital cost would be required to procure a large-sized regenerator or compressor. Thus, at the designing stage, the target of CO2 removal should be carefully decided for the given sorbent. By varying the sorbent properties, improved CO2 removal performance was accompanied with reduced energy consumption in the regenerator. Meanwhile, the adjustment of operating conditions led to an increase in both CO2 removal and energy consumption. Therefore, a delicate control of operating conditions was required to achieve high CO2 capture performance with reasonable energy efficiency.

Conceptual Design for Integrating Lithium-Based Carbon Capture Looping Systems into Natural Gas Combined Cycle Power Plants

Lithium orthosilicate (Li4SiO4) based sorbents have been reported to show relatively high CO2 capture capacity and high stability and require lower regeneration temperatures than other high-temperature sorbents. Based on these properties, a capture plant concept could be envisaged, aiming for achieving as low as possible CO2 capture penalties. Accordingly, this work presents a conceptual AspenPlus process simulation study that evaluates the thermal integration of Li4SiO4-based looping systems into a natural gas combined cycle (NGCC) power plant with the addition of a secondary oxyfuel combustion system and a secondary steam cycle. Based on previously obtained experiment results, absorption and desorption temperatures of 525 and 700 °C, respectively, a sorbent fractional conversion of 0.2 in the absorber, and a sorbent make up ratio of 0.01 were used in the model. The results show that implementation of a Li4SiO4-based high-temperature carbon capture (HTCC) system into a NGCC power plant reduces the plant ...

Chemical-looping combustion in a 100 kW unit using a mixture of synthetic and natural oxygen carriers – Operational results and fate of biomass fuel alkali

Biomass fuel use in chemical looping combustion enables negative CO2 emissions through BECCS (Bio-Energy Carbon Capture and Storage). Effective biomass utilization in CLC requires an economical and effective oxygen carrier to achieve high fuel conversion, effective CO2 capture, and management of the harmful effects of biomass alkali release (bed agglomeration, oxygen carrier deactivation, fouling and corrosion). These issues were addressed in 100 kW CLC pilot experiments.Building on previous work, a mixture of a synthetic calcium manganite perovskite and natural ilmenite was used as the oxygen carrier. Four biomass fuels of varied alkali content were tested: black pellets of steam-exploded stem wood (BP), BP impregnated with K2CO3, a mixture of 50% BP with 50% straw pellets, and wood char. Experiments showed high fuel conversion and very high CO2 capture, with overall performance exceeding that of ilmenite and manganese ore. More than 95% gas conversion was achieved with black pellets at around 950 °C.The fate of biomass alkali, previously virtually unknown in CLC research, was explored by implementing online surface-ionization-based measurement of alkali released in the flue gases of the fuel reactor (FR) and air reactor (AR). Release levels were found to correlate with the fuel alkali content. The flue gas measurements and bed material elemental analyses suggest that most of the fuel alkali are accumulated in the oxygen carrier. Unexpectedly, it was found that flue gas alkali release occurs in both the FR and AR, with AR exhibiting an equal or higher rate of release vs. the FR.

CO2 capture by modified porous carbon adsorbents: Effect of various activating agents

Abstract Activated carbons with highly porous structure have been successfully synthesized via carbonization of the polyacrylonitrile followed by the chemical activation with various activating agents (NaNH2, NaOH, and K2CO3) and the different mass ratios (1–4). Total pore volume and surface area of the adsorbents lie in between the range of 0.14–0.64 cm3 g−1 and 263–1250 m2 g−1, respectively. XPS analysis confirms the presence of the various functional groups on the carbon surface which increases the total basicity of the adsorbents. Both of the properties of microporosity and functional groups explicate the high CO2 capture performance of the activated carbons under dynamic conditions. In particular, K2CO3 activated carbons exhibited maximum dynamic adsorption capacities (2.05–2.44 mmol g−1) in comparison to NaOH (1.90–2.20 mmol g−1) and NaNH2 (1.10–1.75 mmol g−1) activated carbons at 30 °C respectively. The synthesized carbons can be regenerate and reuse by multiple times without loss in the adsorption performance. Furthermore, the Temkin isotherm model shows the best description for the adsorption data at different temperatures, confirms the heterogeneous surface of the adsorbents.

5 Ultramicropore-rich renewable porous carbon from biomass tar with excellent adsorption capacity and selectivity for CO2 capture

Biomass tar was a conspicuous hazardous byproduct from biomass gasification, and it has become a great challenge in the development of biomass energy technology. Here, we proposed the facile one-step synthesis of highly porous carbon using biomass tar as feedstock, porous CaO as a template, and KOH as an activation agent. Following a simultaneous activation-template-carbonization process, the product displayed tunable porosity and high specific surface area (up to 2424 m2 g−1). When applied to CO2 capture, the ultramicropores of this carbon material played a significant role in enhancing the CO2 affinity. In particular, the adsorbent synthesized with biomass tar:CaO:KOH in 1:2:3 wt ratio exhibited the high CO2 capture capacity of 5.03 and 3.13 mmol g−1 at 273 K and 298 K (1.20 mmol g−1 at 0.15 bar), respectively, perfect cyclic regeneration property (95% retention) and excellent initial isosteric heat of adsorption (48.55 kJ mol−1). The CO2/N2 selectivity from Henry’s Law and ideal solution adsorption theory reached 26.3 and 15.4 at 273 K, and 32.4 and 19.7 at 298 K, respectively.

Reforming of coal volatiles over ilmenite ore

Chemical-looping combustion is one of the most promising technologies for generating electricity from coal with high CO2 capture. This process burns the fuel with the oxygen from metal oxide particles in the fuel reactor while the depleted oxygen in the metal oxides is compensated for in the air reactor.This study investigated the performance of ilmenite as an oxygen carrier during the steam reforming when actual coal volatiles are used as fuel. Steam reforming experiments on coal volatiles with ilmenite were carried out in a two-stage fixed-bed reactor under various steam conditions. The effect of pre-oxidation and of steam ratios on the conversion reactivity of ilmenite was investigated at 1173 K. The conversion reactivity of ilmenite was greatly enhanced after pre-oxidation, and there was no tar formation when pre-oxidized ilmenite was used. The internal and external porosity of ilmenite also increased after steam reforming of coal volatiles.Ilmenite showed good performance under the various steam conditions. Carbon formation decreased considerably as steam ratios increased. Moreover, the reduced phase FeTiO3 of ilmenite was maintained with the addition of steam, and its reactivity was relatively stable compared with a synthetic iron-based carrier, Fe2O3/Al2O3.

Evaluation of the performance and economic viability of a novel low temperature carbon capture process

A novel Advanced Cryogenic Carbon Capture (A3C) process is being developed using low cost but high intensity heat transfer to achieve high CO2 capture efficiencies with a much reduced energy consumption and process equipment size. These characteristics, along with the purity of CO2 product and absence of process chemicals, offer the potential for application across a range of sectors. This work presents a techno-economic evaluation for applications ranging from 3% to 35%vol. CO2 content. The A3C process is evaluated against an amine-based CO2 capture process for three applications; an oil-fired boiler, a combined cycle gas turbine (CCGT) and a biogas upgrading plant. The A3C process has shown a modest life cost advantage over the mature MEA technology for the larger selected applications, and substantially lower costs in the smaller biogas application. Enhanced energy recovery and optimization offer significant opportunities for further reductions in cost.

Synthesis of Novel Organic-Inorganic Hybrid Materials for High Temperature CO2 Capture from Industrial Sources

Synthesis of Novel Organic-Inorganic Hybrid Materials for High Temperature CO2 Capture from Industrial Sources

Advancing CO2 Capture from Natural Gas Combined Cycle Power Plants with Piperazine Scrubbing

Carbon dioxide capture and storage is widely recognized as an essential technology for limiting the global temperature rise to 2 °C by the end of the century. Technology development efforts so far focus on coal-fired power plants and other industrial sources with relatively high CO2 partial pressures. However, natural gas is increasingly used in power generation because of its abundance and low greenhouse gas impacts among the fossil fuels. For deep decarbonization that is required in the future, fossil fuels with CCS continue to play a relevant role in scenarios that balance cost of energy with climate impacts. Carbon capture from natural gas sources has been an ongoing interest to CO2 Capture Project (CCP) and its members from the oil and gas industry. This paper describes the work related to solvent-based natural gas carbon capture sponsored by CCP and pilot studies performed in collaboration with University of Texas at Austin researchers. The collaboration with University of Texas at Austin (UT) is aimed at demonstrating the application of an aqueous piperazine solution-a second-generation solvent-in a pilot plant. The goal is to test CO2 separation from synthetic flue gas representative of the exhausts from natural gas-fired combined cycle power plant (i.e. ~4 mol% CO2). The low CO2 concentration in NGCC flue gas is considered to be a challenge for many capture technologies. This work tested the performance of 5m piperazine in the UT pilot plant at a range of operating conditions, including solvent loadings, gas and liquid flow rates, assessing two different absorber configurations. High CO2 capture rates above 90% were confirmed. The pilot test results were used to verify and extend the range of applicability of the thermodynamic model developed by UT. This work increases the confidence for the application of the process models to design CCS processes for low CO2 concentrations. The model’s predictions of the pilot plant tests at low concentrations are now as accurate and reliable as those for higher CO2 concentrations where much of the data have been collected until now. Further pilot tests at NCCC are being designed to supplement the model evaluation data set for NGCC flue gas as well as to address questions related to oxidation/corrosion and cooling scheme optimization for NGCC applications.

Improving the efficiency of Chemical Looping Combustion with coal by using ring-type internals in the fuel reactor

Chemical Looping Combustion (CLC) with solid fuels has been widely developed by using two interconnected fluidized beds, the fuel reactor and the air reactor, with an oxygen carrier continuously circulating between them. Experience gained in this process shows that high CO2 capture values can be reached. However, complete combustion of the fuel is not achieved, with some H2, CO and CH4 as the main unconverted compounds in the combustion products from the fuel reactor. It is believed that the combustion efficiency can be increased by improving the gas-solid contact in the fuel reactor. In this work, the solids distribution in the fuel reactor was modified by using ring-type internals with the objective of enhancing the gas-solid contact. Two experimental campaigns were carried out in a 50 kWth CLC unit burning a bituminous coal with ilmenite particles in the temperature interval of 900–1000 °C. The first campaign was conducted with the original riser of the fuel reactor, which was characterized by a smooth section from bottom to top. For the second campaign, three ring-type internals were implemented in the riser in order to modify the solids distribution in the fuel reactor. The presence of the internals had a beneficial effect on the coal combustion. The major benefit was an improved oxidation of volatile matter in the form of CH4 and the full conversion of H2. As a result, the total oxygen demand decreased by 20%, from 12.2% to 9.8%, with the implementation of the internals.

CO2 adsorption and conversion into cyclic carbonates over a porous ZnBr2-grafted N-heterocyclic carbene-based aromatic polymer

A new nanoporous N-heterocyclic carbene-based cross-linked aromatic polymer (NHC-CAP-1) incorporated with highly nucleophilic bromide anions and with a large surface area was synthesized by a simple Friedel-Crafts reaction of imidazolium salt, triphenylbenzene, and formaldehyde dimethyl acetal. Subsequently, ZnBr2 was grafted onto the NHC-CAP-1 to obtain NHC-CAP-1(Zn2+) with enhanced Lewis acidity. After systematic evaluation of the structural and chemical properties using different analytical techniques, these were explored for CO2 adsorption and CO2 chemical fixation to cyclic carbonates. Whilst NHC-CAP-1 showed a high CO2 capture capacity (188.2 mg g−1 at 273 K/1 bar) with a moderate CO2/N2 selectivity, NHC-CAP-1(Zn2+) displayed significantly enhanced CO2/N2 selectivity (100/80 at 273/298 K) at the expense of diminished CO2 capture (123.0 mg g−1 at 273 K/1 bar). These values are among the highest reported so far for porous cross-linked organic polymers. As a catalyst, NHC-CAP-1(Zn2+) showed high catalytic activities for CO2 cycloaddition to a series of epoxides to form cyclic carbonates in the absence of co-catalyst and solvent, producing a high turnover frequency (TOF) of 2202 h−1 at 100 °C. The effect of reaction parameters including temperature, reaction time, and catalyst loading was examined. NHC-CAP-1(Zn2+) could be separated readily and reuse for a minimum of 10 runs while maintaining high activity and stability owing to the strong covalent bonding of Lewis acidic Zn2+ to the NHC-CAP-1 backbones. This work demonstrated that NHC-CAP-1 and NHC-CAP-1(Zn2+) are viable porous materials that are highly efficient for both CO2 capture and catalytic conversion of CO2 to cyclic carbonates.

DFT study of CO2 adsorption across a CaO/Ca12Al14O33 sorbent in the presence of H2O under calcium looping conditions

The synthetic CaO/Ca12Al14O33 sorbent has been regarded as an efficient CO2 sorbent during the calcium looping cycles. In this work, the CO2 adsorption performance of the synthetic CaO/Ca12Al14O33 sorbent in the presence of H2O was investigated by density functional theory (DFT) calculations. DFT was used to analyze the adsorption of CO2 and H2O on the synthetic sorbent. Both structural parameters (atomic layout and electronic configuration) and the adsorption parameters (energy, bond lengths, angles, bond population and charge transfer) of CO2 and H2O on the synthetic sorbent were determined. To confirm the feasibility of DFT analysis, the CO2 capture performance of the synthetic sorbent in the presence of steam was examined in a dual fixed bed reactor. The results indicate strong interactions between the C atom and the O atom in CaO and interactions between the H atom and the O atom in CaO. The higher adsorption energy of CO2 than H2O on pristine CaO and Ca12Al14O33-supported CaO suggests that the adsorptions of CO2 and H2O are competitive and that the adsorption of CO2 is stronger than that of H2O. The adsorption of H2O leads to the activation of adjacent O atoms of CaO and thus stronger CO2 adsorption on the O atom with H2O adsorbed. The electrons in the p orbital of the O atom near the Fermi level play important roles in CO2 adsorption by CaO. The presence of Ca12Al14O33 hinders CO2 adsorption by CaO. A low Ca12Al14O33 content in synthetic sorbents should be maintained to ensure high CO2 capture capacity and sintering resistance of synthetic sorbents. DFT calculations can predict the CO2 adsorption performance of CaO-based sorbents with additives under different reaction atmospheres.

Recyclability of Encapsulated Ionic Liquids for Post-Combustion CO2 Capture

Ionic liquids (ILs) with aprotic heterocyclic anions (AHAs) are promising candidates for post-combustion carbon capture technologies since they react with CO2 stoichiometrically and reversibly. CO2 solubilities in two AHA-ILs, triethyl(octyl)phosphonium 2-cyanopyrrolide ([P2228][2CNPyr]) and triethyl(octyl)phosphonium benzimidazolide ([P2228][BnIm]), are reported for multiple temperatures and a third, triethyl(octyl)phosphonium 6-bromobenzimidazolide ([P2228][6-BrBnIm]), at one temperature. Ionic liquid [P2228][2CNPyr] and phase-change ionic liquid (PCIL) tetraethylphosphonium benzimidazolide ([P2222][BnIm]) were encapsulated in a chemically compatible and CO2-permeable polydimethylsiloxane (PDMS) polymer shell in order to enhance absorption and desorption kinetics. Both the free and encapsulated [P2228][2CNPyr] and [P2222][BnIm] were subjected to thermodynamic testing. The CO2 solubilities in the encapsulated IL and PCIL were in good agreement with the free IL and PCIL, meaning that the encapsulation of IL and PCIL greatly enhanced the kinetics of CO2 absorption while maintaining the high CO2 capture capacity. Recyclability testing was also performed on both the free and encapsulated [P2228][2CNPyr] and [P2222][BnIm]. The IL and PCIL materials, as well as the capsules, were stable upon cycling, with the CO2 capacities for each cycle remaining unchanged. The IL and the PCIL showed no sign of degradation after cycling, which demonstrated excellent performance.

CO2 capture over amine-functionalized MCM-41 and SBA-15: Exploratory analysis and decision tree classification of past data

This study aims to extract knowledge for CO2 capture by amine-functionalized mesoporous silica (MCM-41 and SBA-15) through exploratory analysis and decision tree classification of the data reported in over 100 papers published between the years 2002 and 2017. A database containing 1039 data points showing the effects of 15 input variables (grouped in four as support properties, preparation method, amine properties and operational variables) over two performance variables as CO2 adsorption capacity and amine efficiency (CO2 captured/amino groups involved) was constructed. Box and whisker plots were applied (as a part of exploratory data analysis) to determine how various input variables influence the performance variables. Moreover, decision tree classification was used to determine the relative significance of the input variables and the possible combinations of these variables leading to high performance (to deduce heuristics for high CO2 uptake). It was found from the exploratory data analysis that amine density was the most significant variable affecting the adsorption capacity whereas remaining pore volume and adsorption temperature were the most influential variables in case of amine efficiency. Furthermore, various combinations of input variables leading to high CO2 capture performance were revealed through the decision tree analysis, all of which may be used as guidelines for future studies in this area.

Nitrogen-doped nanoporous carbons derived from lignin for high CO2 capacity

In this paper, nitrogen (N)-doped ultra-porous carbon derived from lignin is synthesized through hydrothermal carbonization, KOH activation, and post-doping process for CO2 adsorption. The specific surface areas of obtained N-doped porous carbons range from 247 to 3064 m2/g due to a successful KOH activation. N-containing groups of 0.62–1.17 wt% including pyridinic N, pyridone N, pyridine-N-oxide are found on the surface of porous carbon. N-doped porous carbon achieves the maximum CO2 adsorption capacity of 13.6 mmol/g at 25 °C up to 10 atm and high stability over 10 adsorption/desorption cycles. As confirmed by enthalpy calculation with the Clausius–Clapeyron equation, an adsorption heat of N-doped porous carbon is higher than non-doped porous carbon, indicating a role of N functionalities for enhanced CO2 adsorption capability. The overall results suggest that this carbon has high CO2 capture capacity and can be easily regenerated and reused without any clear loss of CO2 adsorption capacity.

Drawing a Pencil‐Trace Cathode for a High‐Performance Polymer‐Based Li–CO2 Battery with Redox Mediator

AbstractLithium–carbon dioxide (Li–CO2) batteries have received wide attention due to their high theoretical energy density and CO2 capture capability. However, this system still faces poor cycling performance and huge overpotential, which stems from the leakage/volatilization of liquid electrolyte and instability of the cathode. A gel polymer electrolyte (GPE)‐based Li–CO2 battery by using a novel pencil‐trace cathode and 0.0025 mol L−1 (M) binuclear cobalt phthalocyanine (Bi‐CoPc)‐containing GPE (Bi‐CoPc‐GPE) is developed here. The cathode, which is prepared by pencil drawing on carbon paper, is stable because of its typical limited‐layered graphitic structure without any binder. In addition, Bi‐CoPc‐GPE, which consists of polymer matrix filled with liquid electrolyte, exhibits excellent ion conductivity (0.86 mS cm−1), effective protection for Li anode, and superior leakproof property. Moreover, Bi‐CoPc acts as a redox mediator to promote the decomposition of discharge products at low charge potential. Interestingly, different from polymer‐shaped discharge products formed in liquid electrolyte–based Li–CO2 batteries, the morphology of products in Li–CO2 batteries using Bi‐CoPc‐GPE is film‐like. Hence, this polymer‐based Li–CO2 battery shows super‐high discharge capacity, low overpotential, and even steadily runs for 120 cycles. This study may pave a new way to develop high‐performance Li–CO2 batteries.

Chemical looping with oxygen uncoupling: an advanced biomass combustion technology to avoid CO2 emissions

Bioenergy with carbon dioxide (CO2) capture and storage (BECCS) technologies represent an interesting option to reach negative carbon emissions, which implies the removal of CO2 already emitted to the atmosphere. Chemical looping combustion (CLC) with biomass can be considered as a promising BECCS technology since CLC has low cost and energy penalty. In CLC, the oxygen needed for combustion is supplied by a solid oxygen carrier circulating between the fuel and air reactors. In the fuel reactor, the fuel is oxidized producing a CO2-concentrated stream while the oxygen carrier is reduced. In the air reactor, the oxygen carrier is regenerated with air. Chemical looping with oxygen uncoupling (CLOU) is a CLC technology that allows the combustion of solid fuels as in common combustion with air by means of an oxygen carrier that release gaseous oxygen in the fuel reactor. In the last years, several Cu-based, Mn-based, and mixed oxide oxygen (O2) carriers have been tested showing good CLOU properties. Among them, copper (Cu)-based and Cu-Manganese (Mn) mixed oxides showed high reactivity, O2 release rate, and high O2 equilibrium concentration. The aim of this work is to study the viability of biomass combustion by CLOU process. The combustion of three types of biomass (pine sawdust, olive stone, and almond shell) were studied in a continuous 1.5 kWth CLC unit. Two O2 carriers were tested: a Cu-based oxygen carrier with Magnesium, Aluminum, Oxgen (MgAl2O4) as an inert prepared by spray drying (Cu60MgAl) and a mixed Cu-Mn oxide prepared by spray granulation (Cu34Mn66). These materials are capable of releasing gaseous oxygen when they are reduced in a different range of temperatures. CO2 capture and combustion efficiency were evaluated. Two fuel reactor operation temperatures were used: 775–850 °C for Cu34Mn66 and 900–935 °C for Cu60MgAl. High CO2 capture efficiencies and 100% combustion efficiency were reached with both oxygen carriers and with all the biomasses tested. Therefore, the CLOU technology with the Cu- and Cu-Mn-based oxygen carriers allowed avoiding CO2 emissions maintaining high combustion efficiencies. Results obtained demonstrate that this innovative biomass combustion technology combined with carbon storage lets an efficient BECCS process implementation.

Investigation of Pore-Formers to Modify Extrusion-Spheronized CaO-Based Pellets for CO2 Capture

The application of circulating fluidized bed technology in calcium looping (CaL) requires that CaO-based sorbents should be manufactured in the form of spherical pellets. However, the pelletization of powdered sorbents is always hampered by the problem that the mechanical strength of sorbents is improved at the cost of loss in CO2 sorption performance. To promote both the CO2 sorption and anti-attrition performance, in this work, four kinds of pore-forming materials were screened and utilized to prepare sorbent pellets via the extrusion-spheronization process. In addition, impacts of the additional content of pore-forming material and their particle sizes were also investigated comprehensively. It was found that the addition of 5 wt.% polyethylene possesses the highest CO2 capture capacity (0.155 g-CO2/g-sorbent in the 25th cycle) and mechanical performance of 4.0 N after high-temperature calcination, which were about 14% higher and 25% improved, compared to pure calcium hydrate pellets. The smaller particle size of pore-forming material was observed to lead to a better performance in CO2 sorption, while for mechanical performance, there was an optimal size for the pore-former used.