High CO2 Capture Research Articles

Efficient CO2 Capture by Nitrogen-Doped Biocarbons Derived from Rotten Strawberries

In this study, rotten strawberry was used as carbon precursor to prepare nitrogen-doped porous bio-carbons for CO2 capture. The sorbents were synthesized by hydrothermal treatment of rotten strawberry, followed by KOH activation. The nitrogen in the resulting sorbents is inherited from the rotten strawberry precursor. This series of samples demonstrates high CO2 uptake at 1 bar, up to 4.49 mmol g-1 at 25 °C, and 6.35 mmol g-1 at 0 °C. In addition to narrow micropore volume and nitrogen content, the pore size of narrow micropores also plays a key role in determining the CO2 capture capacity under ambient condition. Furthermore, these sorbents possess stable reusability, moderate heat of CO2 adsorption, quick CO2 adsorption kinetics, reasonable CO2/N2 selectivity, and high dynamic CO2 capture capacity under simulated flue gas conditions. All these merits along with the zero-cost and wide availability of rotten strawberry precursor make this type of sorbents highly promising in CO2 capture form combustion fl...

High-Performance Self-Cross-Linked PGP–POEM Comb Copolymer Membranes for CO2 Capture

We report a high performance CO2 capture membrane based on the copolymerization and self-cross-linking of poly(glycidyl methacrylate-g-poly(propylene glycol))-co-poly(oxyethylene methacrylate) (PGP–POEM) comb copolymer. The epoxide–amine reaction is responsible for the self-cross-linking reaction, which takes place under mild conditions without any additional cross-linkers or catalysts. The effects of self-cross-linking on the membrane properties are investigated by comparing the copolymers with those containing a low PPG grafting density (l-PGP–POEM). Furthermore, the gas separation performance of the membranes is systematically investigated as a function of POEM content in the comb copolymer. Both the permeance and selectivity of the PGP–POEM membranes are enhanced simultaneously with increase in the POEM content up to 51.2 wt % (PGP–POEM13), at which the best performance was achieved among the membranes. The high performance results from the reduced diffusion of N2 due to the self-cross-linked structur...

Coal combustion with a spray granulated Cu-Mn mixed oxide for the Chemical Looping with Oxygen Uncoupling (CLOU) process

The Chemical Looping with Oxygen Uncoupling (CLOU) process is a form of Chemical Looping Combustion (CLC) technology that enables the combustion of solid fuels by means of oxygen carriers that release gaseous oxygen in the fuel reactor, i.e. with oxygen uncoupling capability. In recent years, tests have found several Cu-based, Mn-based and mixed oxide oxygen carriers with suitable properties for the CLOU process. Among them, Cu-Mn mixed oxides show high reactivity and high O2 equilibrium concentration at temperatures of interest for coal combustion. In this work, proof of concept was demonstrated by burning coal with Cu-Mn mixed oxides in a 1.5kWth CLOU unit for the first time. The effect of fuel reactor temperature, solids circulation flow, fluidization agent in the fuel reactor (inert N2 or steam as gasifying agent), and excess air in the air reactor on combustion efficiency and CO2 capture rate was analysed. The results showed that high combustion efficiency and CO2 capture are feasible using this material at relatively low fuel reactor operating temperatures. Therefore, the developed Cu-Mn mixed oxide was a suitable material for use as an oxygen carrier for the CLOU combustion of solid fuels. Optimum operating conditions were determined for this oxygen carrier with regard to the oxygen circulation rate and air reactor conditions for the regeneration of the oxygen carrier.

Biomass-facilitated production of activated magnesium oxide nanoparticles with extraordinary CO2 capture capacity

Discovering sustainable materials that can efficiently capture and store CO2 is a crucial step towards mitigating anthropogenic greenhouse gas emissions. The current materials used in post-combustion scenarios have significant drawbacks, including high cost and resulting hazardous byproducts. This study developed a simple and cost-effective method of producing activated MgO nanoparticles that have high CO2 capture efficiency. To optimize CO2 capture, we incorporate biomass during the production to ensure complete and dispersed MgO nanoparticle formation from the decomposition of MgCl2 hydrate. Materials are characterized by SEM, XRD, BET/DFT, ICP, and TGA analysis. Resulting carbon-supported activated MgO nanoparticles efficiently captured CO2 at low temperature, by physisorption and magnesium carbonate formation. Without the incorporation of biomass, MgCl2 hydrate decomposed via low temperature pyrolysis, is still capable of CO2 capture; however, the efficiency is enhanced with the addition of biomass, as this helps support the formation and distribution of MgO nanoparticles. The carbon-supported MgO nanoparticles produced with a 5:2.5 (w/w MgCl2:biomass) ratio was capable of greatest CO2 capture capacity on both a g−1 material (up to 235 mg g−1) and g−1 magnesium (733 mg g−1) basis after 3 h. The carbon-supported MgO nanoparticles have potential to be applied in inexpensive large-scale CO2 capture, as the production can be adjusted based on capacity, resource, or energy constraints.

Populus wood biomass-derived graphene for high CO2 capture at atmospheric pressure and estimated cost of production

Abstract In the present study, populus wood biomass (PWB), as a precursor, was first carbonized under a nitrogen atmosphere and the obtained carbon was used to prepare graphene via chemical activation using KOH. The graphene samples were used to study as adsorbents for CO2 capture. The effect of different parameters, such as various KOH/C weight ratios (2:1–4:1 g/g), different heating temperatures (750–950 °C) and heating time (30–90 min), on the surface characteristics and CO2 uptake capacity of the as-synthesized graphene was investigated. Various characterization techniques including elemental, TGA, BET, TEM, FT-IR and Raman were used. Under the experimental conditions of KOH/C impregnation ratio of 3:1, heating temperature of 850 °C and heating time of 60 min, the graphene sample showed a BET surface area of 1317.1 m2/g, total pore volume of 0.604 m3/g, up to 94% microporocity, and an average micropore diameter size of 1.84 nm. The measured uptake capacity of 7.2 mmol/g at a pressure of 1 bar and 293 K by sample G-3-850-60 was among the highest reported values in the literature data for carbon base materials. The isosteric heat of CO2 adsorption onto the graphene samples were computed from the Clausius–Clapeyron equation, which was consistent with the physical nature of adsorption. Furthermore, these nano-adsorbents exhibited a high CO2 adsorption capacity, thus proving to be good candidates for cost-effective CO2 capture and storage for the downstream application on an industrial scale. In addition, the results of our laboratory investigations explore a process for scaling-up a complete flow diagram of graphene production from populous wood biomass and an economic evaluation of graphene production is estimated at a cost of about $25 per kg.

Parametric study and effect of calcination and carbonation conditions on the CO2 capture performance of lithium orthosilicate sorbent

The world is currently facing the challenges of global warming and climate change. Numerous efforts have been taken to mitigate CO2 emission, among which is the use of solid sorbents for CO2 capture. In this work, Li4SiO4 was synthesised via a sol–gel method using lithium nitrate (LiNO3) and tetraethylorthosilicate (SiC8H20O4) as precursors. A parametric study of Li:Si molar ratio (1-5), calcination temperature (600–800 °C) and calcination time (1–8 h) were conducted during sorbent synthesis. Calcination temperature (700–800 °C) and carbonation temperature (500–700 °C) during CO2 sorption activity were also varied to confirm the optimum operating temperature. Sorbent with the highest CO2 sorption capacity was finally introduced to several cyclic tests to study the durability of the sorbent through 10 cycles of CO2 sorption–desorption test. The results showed that the calcination temperature of 800 °C and carbonation temperature of 700 °C were the best operating temperatures, with CO2 sorption capacity of 7.95 mmol CO2∙(g sorbent)− 1 (93% of the theoretical yield). Throughout the ten cyclic processes, CO2 sorption capacity of the sorbent had dropped approximately 16.2% from the first to the tenth cycle, which was a reasonable decline. Thus, it was concluded that Li4SiO4 is a potential CO2 solid sorbent for high temperature CO2 capture activity.

CO2 Adsorption of Nitrogen-Doped Carbons Prepared from Nitric Acid Preoxidized Petroleum Coke

Petroleum coke was pretreated by HNO3 before urea modification and KOH activation to synthesize N-doped porous carbons. The as-synthesized samples were carefully characterized by various techniques. This series of samples demonstrate high CO2 uptake at 1 bar up to 4.13 mmol/g at 25 °C and 6.24 mmol/g at 0 °C, respectively. In addition, these sorbents possess high CO2/N2 selectivity, stable reusability, moderate heat of CO2 adsorption, and high dynamic CO2 capture capacity under simulated flue gas conditions. Further comparison shows that sorbents synthesized by HNO3 pretreatment possess higher nitrogen content and narrow microporosity than the control sample without HNO3 pretreatment but a lower CO2 uptake. Additional investigations show that in addition to nitrogen content and narrow micropores, the size of narrow micropores, the narrow micropore size distributions, surface acidity, and the content of specific N and O species on the surface of the N-doped porous carbons also play major roles in determini...

Fluorine-rich carbon nanoscrolls for CO2/CO (C2H2) adsorptive separation

Carbon nanoscrolls have shown great potential in gas adsorption and storage. In this paper, a feasible method for synthesizing one-sided fluorine doped carbon nanoscroll (F-CNS) is proposed, and the adsorption behavior of CO2, CO and C2H2 on one-sided F-CNS has been firstly investigated via Grand Canonical Monte Carlo calculations. It is demonstrated that the one-sided F-CNS possesses outstanding CO2 uptake with good CO2/CO and CO2/C2H2 selectivity compared with pristine CNS. Specially, at 300K and 1bar, one-sided F-CNS shows a CO2 uptake of 68.87mmol/mol and CO uptake of 12.09mmol/mol, which is much higher than those of CO2 (16.6mmol/mol) and CO (6.02mmol/mol) for pristine CNS. Furthermore, our results demonstrate that the excellent selective CO2 adsorption capacity of one-sided F-CNS is owing to its stronger interactions with CO2 molecules than CO and C2H2 molecules. Our research suggests that one-sided F-CNS is a promising candidate for high selective CO2 capture.

CO2 capture by carbide slag calcined under high-concentration steam and energy requirement in calcium looping conditions

In this work, calcination under high-concentration steam that can be implemented by O2/H2O combustion was proposed to replace high-concentration CO2 that usually was implemented by O2/CO2 combustion in calcium looping. CO2 capture performance of the carbide slag, an industrial solid waste from chlor-alkali plants, was investigated in a dual fixed-bed reactor under high-concentration steam calcination condition during the calcium looping cycles. Calcined under high-concentration steam (95%) atmosphere, the carbide slag can be completely and quickly decomposed at 800°C, which is 150°C lower than the calcination temperature under high-concentration CO2 (100%) atmosphere. The carbonation conversions of the carbide slag calcined under high-concentration steam condition after 1 and 10 cycles are about 42% and 36% higher than those calcined under high-concentration CO2 condition, respectively. This is because when the carbide slag is calcined under high-concentration steam, the relatively smaller CaO grains and more porous structure are generated, which are beneficial for CO2 capture by carbide slag. Due to the low calcination temperature and the high CO2 capture capacity of the carbide slag, the energy requirement in the calciner to capture per mole CO2 under high-concentration steam condition is lower than that under high-concentration CO2 condition. High-concentration steam calcination in place of high-concentration CO2 calcination improves the CO2 capture efficiency from 0.68 to 0.88 and saves a quarter of the energy consumption in the calciner for capturing per mole CO2 in the calcium looping system, when the ratio of recycled carbide slag flow rate to CO2 flow rate is 2 and the sorbent make-up ratio is 0.09. Thus, it is reasonable to consider O2/H2O combustion as an alternative energy-supply way of O2/CO2 combustion for the calcium looping of carbide slag.

CO2 adsorption at nitrogen-doped carbons prepared by K2CO3 activation of urea-modified coconut shell

This article reports on the synthesis and characterization of porous nitrogen-doped carbons synthesized by carbonization of coconut shell followed by urea modification and K2CO3 activation. The as-synthesized samples were carefully characterized by various techniques. This series of samples demonstrate high CO2 uptake at 1bar, up to 3.71mmol/g at 25°C in addition to 5.12mmol/g at 0°C. Furthermore, these sorbents possess fast CO2 adsorption kinetics, stable reusability, moderate heat of CO2 adsorption, reasonable CO2/N2 selectivity, and high dynamic CO2 capture capacity under simulated flue gas conditions. It is found that, in addition to nitrogen content and narrow micropore volume, the pore size distribution of narrow micropore also plays a major role in determining the CO2 capture capacity under ambient condition. This work is intended to provide useful information and to inspire ways to develop new carbonaceous sorbents for removing CO2 from combustion flue gas.

Resorcinol–formaldehyde resin-based porous carbon spheres with high CO2 capture capacities

Porous carbon spheres are prepared by direct carbonization of potassium salt of resorcinol–formaldehyde resin spheres, and are investigated as CO2 adsorbents. It is found that the prepared carbon materials still maintain the typical spherical shapes after the activation, and have highly developed ultra-microporosity with uniform pore size, indicating that almost the activation takes place in the interior of the polymer spheres. The narrow-distributed ultra-micropores are attributed to the “in-situ homogeneous activation” effect produced by the mono-dispersed potassium ions as a form of –OK groups in the bulk of polymer spheres. The CS-1 sample prepared under a KOH/resins weight ratio of 1 shows a very high CO2 capture capacity of 4.83 mmol/g and good CO2/N2 selectivity of ∼17–45. We believe that the presence of a well-developed ultra-microporosity is responsible for excellent CO2 sorption performance at room temperature and ambient pressure.

Development of Potassium- and Sodium-Promoted CaO Adsorbents for CO2 Capture at High Temperatures

Development of highly efficient adsorbents for the high temperature CO2 capture process is crucial for large scale implementation of this technology. In this work, development of novel potassium- and sodium-promoted CaO adsorbents (K–Ca and Na–Ca) is discussed, and their CO2 capture performance at high temperatures is presented. A series of K–Ca and Na–Ca adsorbents with various K/Ca or Na/Ca molar ratios were developed and tested for CO2 capture at high temperatures ranging from 300 to 400 °C. The structural, chemical, and morphological characteristics of the double salts were systematically evaluated before and after exposure to CO2. Our results indicated that CO2 capacity is largely influenced by both K or Na concentration and adsorption temperature. Maximum capacities of 3.8 and 3.2 mmol/g were obtained for K–Ca and Na–Ca double salts, respectively, at 375 °C and 1 bar. Further investigation of the effect of temperature revealed that the window temperature for operation ranges from 300 to 650 °C, whil...

Enhanced Cyclic Stability and CO2 Capture Performance of MgO-Al2O3 Sorbent Decorated with Eutectic Mixture

Recently, alkali nitrate activated MgO has been proposed as an alternative solid sorbent for high temperature CO2 capture due to the facile solvation of MgO in the activation step. However, it tends to be unstable under multi-cyclic sorption-regeneration process due to continuous deformation. In this work, it is demonstrated that MgO-Al2O3 composite sorbent decorated with eutectic mixture (KNO3-LiNO3) can be a feasible candidate for high temperature CO2 capture without losing cyclic performance. It is noteworthy that the eutectic mixture could activate both MgO and MgO-Al2O3 composite, while NaNO3 can only activate MgO. Also, the inactive MgO-Al2O3 is activated at high temperature sorption with the help of the eutectic mixture. Further, it is demonstrated that the EM-MgO-Al2O3 could overcome aggregation and shows stable CO2 sorption performance for 10 cycles corresponding to ∼8.7 wt.%.

Total Integrated Operation of Gasifier, Hot Gas Desulfurizer, and SEWGS Process for Pre-combustion CO2 Capture Using Real Syngas from Coal

SEWGS (Sorption Enhanced Water Gas Shift) process is one of options for pre-combustion CO2 capture using dry absorbent and water gas shift catalyst. In this process, the thermodynamic equilibrium in the shift reaction can be enhanced to give more hydrogen yield by adding a CO2 absorbent into the shift reactor. Total integrated system consists of coal gasifier, hot gas clean-up process (two interconnected fluidized bed desulfurizer), and one loop SEWGS process. In this presentation, continuous operation results of the hot gas clean-up process and one loop SEWGS process using dry absorbents at high temperature and pressure conditions were discussed. Dry absorbents (for desulfurization, CO2 absorption) were produced by KEPCO RI (Korea Electric Power Corporation Research Institute) by means of spray-drying method. Continuous operation was performed at high pressure (21bar for gasifier, 20bar for hot gas clean-up process, and 18bar for SEWGS process) and reaction temperature was 550oC for desulfurizer and 236oC for SEWGS reactor. Totally integrated operation was maintained up to 50hours. We could get high sulfur capture efficiency (99.6%) in the desulfurizer, high CO conversion (98.9%) and CO2 capture efficiency (98.0%) in the SEWGS reactor.

Comparative Evaluation of the Performance of Coal Combustion in 0.5 and 50 kWth Chemical Looping Combustion Units with Ilmenite, Redmud or Iron Ore as Oxygen Carrier

Chemical Looping Combustion (CLC) is one of the most promising technologies to achieve the CO2 capture at a low economic and energetic penalty. In CLC the combustion is split in two steps: fuel combustion assisted by an oxygen carrier in the fuel reactor, and oxygen carrier regeneration in the air reactor by oxygen in air. Usually, the air and fuel reactors are interconnected fluidized beds, with the oxygen carrier circulating between them. Thus, the CO2 capture is inherent to the CLC process. The use of solid fuels in CLC is attracting great attention due to coal is the most abundant fuel, and burning biomass with CO2 capture would allow to reduce the atmospheric CO2 concentration. The in situ Gasification CLC (iG-CLC) allows the conversion of the solid fuel by performing both gasification and combustion of gasification products in the fuel reactor. In iG-CLC complete combustion is not reached, and an oxygen polishing step is required downstream by using a small fraction of pure oxygen.In this work, an overview of the operational experience in ICB-CSIC is presented. Results obtained in 0.5 kWth and 50 kWth CLC units burning different coals with ilmenite, redmud or iron ore are compiled and critically compared. Insights were obtained in order to achieve high CO2 capture and combustion efficiency values. Eventually, the use of ring-type internals in the fuel reactor of the 50 kWth CLC unit was accomplished to promote the gas-solid contact, thus increasing the combustion efficiency.

Screening CO2 Capture Test for Cement Plants Using a Lab Scale Calcium Looping Pilot Facility

This poster presents the first experimental results obtained from a 30 kWth Calcium Looping test facility upgraded to work at conditions closer to those expected in a calcium looping system retrofitted to a cement plant. The main modification in the facility is the use of a second recycle of fine solids (<40 micron) collected in the secondary cylones located after the main calcium loop for CO2 capture. This allowed the operation of the main calcium loop using finer particle size distributions (dp50 around 60-75 micron), which should generate solid purges more suitable to be processed in clinker ovens. High CO2 capture efficiencies have been achieved in preliminary experiments with high make-up flow of limestone and high CO2 concentrations. Further experimental work and modeling activities for an adequate interpretation of results are ongoing within the CEMCAP H2020 project.

Application of the DMXTM CO2 Capture Process in Steel Industry

The VALORCO project coordinated by ArcelorMittal and funded by ADEME aims at reducing and valorizing CO2 emissions from steel industry. This paper presents the main results of task 1.1A of the VALORCO project dedicated to CO2 capture on blast furnace gases by means of amine scrubbing technologies. Blast furnace gases are characterized by high CO2 and CO partial pressures and the absence of oxygen. Since few literature data are available on the effect of CO on solvent degradation and CO2 absorption, experimental work was needed. In this context, three IFP Energies nouvelles (IFPEN) processes initially developed for CO2 capture on coal power stations were evaluated for blast furnace applications: HicaptTM process (MEA 30wt.%), Hicapt+TM process (MEA 40wt.%) and DMXTM process (Demixing solvent).For the three processes, it was shown that CO absorption is slow and mainly physical even though kinetic studies highlighted a chemical absorption of CO in CO2-free amine solutions, especially for MEA solvents. This chemical absorption is however largely inhibited in presence of CO2 which limits this phenomenon to occur in real process conditions. Degradation studies in batch reactors showed a low impact of CO on MEA solutions and no quantitative effect on DMX solvent. Compared to flue gases containing oxygen, amine degradation observed with blast furnace gases is globally negligible for all tested solvents. Above conclusions were confirmed with two long-run tests (∼1500h) on a CO2 capture mini-pilot at IFPEN. These tests also underlined a high CO2/CO selectivity with very few CO in CO2 produced, the possibility of reaching high CO2 capture rate (>99.5%) and the good operability for all studied processes. Moreover, DMX solvent allows using carbon steel as process metallurgy and producing CO2 at 6 bara which turn into subsequent economical savings. Considering an available steam at 21 €/t, it would be possible to produce CO2 from blast furnace gases at around 40 €/t by using the DMXTM process.

Amine-impregnated Alumina Solid Sorbents for CO2 Capture. Lessons Learned

The application of Amine-impregnated Alumina Solid Sorbent Carbon Capture is a suitable option to increase CO2 capture efficiency and to reduce by several percentage points the efficiency penalty of CCS in power plants. These sorbents require less regeneration energy due to the reduction in water content and the higher heat capacity of solids. The objective is to demonstrate that the use of amine-impregnated alumina solid sorbents is a suitable option to increase CO2 capture efficiency and to reduce several percentage points the efficiency penalty caused by the capture system in the power plant. The proposed innovative sorbent consists in amines supported on high surface area and high porosity solid materials, such as alumina and silica-alumina.Good results have been achieved. Important high porosity support makes possible to obtain high CO2 capture capacities over 50 mg CO2/g of sorbent. As a consequence, the combination of this CCS option with a coal power plant may reduce the efficiency penalty down to 7 efficiency points. This figure could make feasible the impregnated amine solid sorbent as a future and promising option for CO2 capture.

Fabrication of Lithium Silicates As Highly Efficient High-Temperature CO2 Sorbents from SBA-15 Precursor.

A series of lithium silicates with improved CO2 sorption capacity were successfully synthesized using SBA-15 as the silicon precursor. The influence of Li/Si ratio, calcination temperature, and calcination duration on the chemical composition and CO2 capture capacity of obtained lithium silicates was systematically investigated. The correlation between CO2 sorption performance and crystalline phase abundance was determined using X-ray diffraction and a normalized reference intensity ratio method. Under the optimized condition, Li-SBA15-4 prepared using Li/Si = 4 that contains mainly Li4SiO4 achieved an extremely high CO2 capture capacity of 36.3 wt % (corresponding to 99% of the theoretical value of 36.7 wt % for Li4SiO4), which is much higher than the Li4SiO4 synthesized from conventional SiO2 sources. It also showed very high cycling stability with only 1.0 wt % capacity loss after 15 cycles. Li-SBA15-10 (Li/Si = 10) that mainly contains Li8SiO6 displayed an extremely high CO2 uptake of 62.0 wt %, but its regeneration capacity was poor, with only 10.5 wt % of reversible CO2 capture capacity. The influence of CO2 concentration on the CO2 capture performance of Li-SBA15-4 and Li-SBA15-10 samples was also studied. With the decrease in CO2 concentration, relatively lower temperatures are needed for its maximum CO2 capture capacity. The CO2 sorption kinetics and mechanism for Li-SBA15-4 and Li-SBA15-10 samples were explored. Overall, we have shown that the lithium silicates synthesized from SBA-15 possessed much improved CO2 sorption performance than that attained from conventional SiO2.

Phase-Change Aminopyridines as Carbon Dioxide Capture Solvents

Carbon dioxide is the main atmospheric greenhouse gas released from industrial point sources. In order to mitigate adverse environmental effects of these emissions, carbon capture, storage, and utilization are required. To this end, several CO2 capture technologies are being developed for application in carbon capture, including aqueous amines and water-lean solvents. Herein we report new aminopyridine solvents with the potential for CO2 capture from coal-fired power plants. These four solvents, 2-picolylamine, 3-picolylamine, 4-picolylamine, and N′-(pyridin-4-ylmethyl)ethane-1,2-diamine, are liquids that rapidly bind CO2 to form crystalline solids at standard room temperature and pressure. These solvents have displayed high CO2 capture capacity (11–20 wt %) and can be regenerated at temperatures in the range of 120–150 °C. The advantage of these primary aminopyridine solvents is that a crystalline salt product can be separated, making it possible to regenerate only the CO2-rich solid and ultimately reduc...