CO2 Capture Technology Research Articles

Study on Carbon Emission Characteristics and Emission Reduction Measures of Lime Production—A Case of Enterprise in the Yangtze River Basin

A scientific carbon accounting system can help enterprises reduce carbon emissions. This study took an enterprise in the Yangtze River basin as a case study. The accounting classification of carbon emissions in the life cycle of lime production was assessed, and the composition of the sources of carbon emission was analyzed, covering mining explosives, fuel (diesel, coal), electricity and high-temperature limestone decomposition. Using the IPCC emission factor method, a carbon life cycle emission accounting model for lime production was established. We determined that the carbon dioxide equivalent from producing one ton of quicklime ranged from 1096.68 kg CO2 equiv. to 1176.96 kg CO2 equiv. from 2019 to 2021 in the studied case. The decomposition of limestone at a high temperature was the largest carbon emission source, accounting for 64% of the total carbon emission. Coal combustion was the second major source of carbon emissions, accounting for 31% of total carbon emissions. Based upon the main sources of carbon emission for lime production, carbon emission reduction should focus on CO2 capture technology and fuel optimization. Based on the error transfer method, we calculated that the overall uncertainty of the life cycle carbon emissions of quicklime from 2019 to 2021 are 2.13%, 2.07% and 2.09%, respectively. Using our analysis of carbon emissions, the carbon emission factor of producing one unit of quicklime in the lime enterprise in the Yangtze River basin was determined. Furthermore, this research into carbon emission reduction for lime production can provide a point of reference for the promotion of carbon neutrality in the same industry.

The development path of direct coal liquefaction system under carbon neutrality target: Coupling green hydrogen or CCUS technology

Direct coal liquefaction can directly transform solid coal into high-end oil products with a conversion efficiency of nearly 60 %, but still emit a certain amount of CO2 during the oil production process. The carbon neutrality target places an urgent demand on its low/zero-carbon emissions and technology transformation. In this work, based on the analysis of the main carbon emissions in a traditional oil production system, carbon neutral technology-based direct coal liquefaction systems coupled with green hydrogen, green electricity, or CCUS technologies are proposed. The technical–economic characteristics, environmental impact, and influences of key parameters (e.g., coal/oil/photovoltaic electricity prices, carbon tax) for industrial-scale low/zero-carbon oil production systems are analyzed. Compared with the traditional system, the proposed systems coupled with CCUS technology for high and full concentration CO2 capture could have competitive advantages when the carbon tax prices are higher than 159.1 and 234.7 yuan/t CO2, respectively. When coupled with green hydrogen or green electricity, the cost of hydrogen or electricity storage will have an important impact on oil production profits and scheme selection. To achieve ∼zero carbon emissions, when the photovoltaic green electricity price is > 0.28, 0.07–0.28 and < 0.087 yuan/kWh (or energy storage breakthrough), the appropriate technical options are CCUS full carbon capture, CCUS capture of high concentration carbon with photovoltaic power generation, and photovoltaic green hydrogen with the photovoltaic electric boiler replacing coal-fired boiler, respectively. The research results could provide an important reference for the net-zero carbon emissions of the coal chemical industry under the carbon neutrality target.

Highly-Controlled Soft-Templating Synthesis of Hollow ZIF-8 Nanospheres for Selective CO2 Separation and Storage.

Global warming is an ever-rising environmental concern, and carbon dioxide (CO2) is among its major causes. Different technologies, including adsorption, cryogenic separation, and sequestration, have been developed for CO2 separation and storage/utilization. Among these, carbon capture using nano-adsorbents has the advantages of excellent CO2 separation and storage performance as well as superior heat- and mass-transfer characteristics due to their large surface area and pore volume. In this work, an environmentally friendly, facile, bottom-up synthesis of ZIF-8 hollow nanospheres (with reduced chemical consumption) was developed for selective CO2 separation and storage. During this soft-templating synthesis, a combined effect of ultra-sonication and low-temperature hydrothermal synthesis showed better control over an oil-in-water microemulsion formation and the subsequent growth of large-surface-area hollow ZIF-8 nanospheres having excellent particle size distribution. Systematic studies on the synthesis parameters were also performed to achieve fine-tuning of the ZIF-8 crystallinity, hollow structures, and sphere size. The optimized hollow ZIF-8 nanosphere sample having uniform size distribution exhibited remarkable CO2 adsorption capability (∼2.24 mmol g-1 at 0 °C and 1.75 bar), a CO2/N2 separation selectivity of 12.15, a good CO2 storage capacity (1.5-1.75 wt %), and an excellent cyclic adsorption/desorption performance (up to four CO2 adsorption/desorption cycles) at 25 °C. In addition, the samples showed exceptional structural stability with only ∼15% of overall weight loss up to 600 °C under a nitrogen environment. Therefore, the hollow ZIF-8 nanospheres as well as their highly controlled soft-templating synthesis method reported in this work are useful in the course of the development of nanomaterials with optimized properties for future CO2 capture technologies.

Optimal integration of hydrogen production process with carbon dioxide capture, utilisation and storage

Hydrogen (H2) has been identified as one of the potential energy carriers for the future. Currently, most H2 is produced via steam methane reforming (SMR) from non-renewable natural gas. This process produces a large amount of carbon dioxide (CO2) emissions as a by-product. Therefore, CO2 capture, utilisation, and storage (CCUS) technologies are typically integrated with conventional H2 plants to produce cleaner H2, known as blue H2. However, such systems face many challenges, such as high process cost, complex transportation and storage of captured CO2. This work presents an optimisation-based model to optimise the integration of H2 processes with CCUS systems to produce blue H2. The developed model considered different grey H2 production paths, CO2 capture technologies, CO2 transportation, utilisation, and storage, as well as H2 storage. The model also factors in technology efficiency, cost and overall energy consumption. A case study of scenarios such as minimum annualised cost, minimum energy consumption, and minimum CO2 production/emissions is solved to illustrate the proposed model. Three optimum blue H2 production routes were obtained with total annualised cost: Case A1 – Minimum annualised production cost (88,953 MMUSD), Case B1 – Minimum energy consumption (96,632 MMUSD) and Case D – Minimum annualised production cost – CO2 storage (89,950 MMUSD).

Process simulation and techno-economic analysis on novel CO2 capture technologies for fluid catalytic cracking units

To reduce CO2 emissions in the FCC process, the post-combustion carbon capture and storage (CCS) technology has been first applied in the FCC process due to its ease of retrofit. However, the required chemicals and high energy consumption turn it into a high-cost method. Oxy-fuel combustion, with the use of different advanced air separation units (ASU), has the potential to be a cost-effective technology for carbon capture in the FCC system. This study first develops steady state models of a 1.4 Mt./a resid FCC unit operated in two carbon capture conditions, namely post-combustion and oxy-fuel combustion, by using Aspen Plus. Second, it compares the economic performances of three different ASUs in oxy-fuel combustion, which are cryogenic ASU, pressure swing adsorption (PSA) ASU, and vacuum pressure swing adsorption (VPSA) ASU. A comparative study on the performances of the industrial-scale CCS FCCUs is conducted for a comprehensive analysis. The analysis shows that the power consumption of the whole system reduces by 30–50 MW when adopting the oxy-firing method, as compared to the post-combustion technology. The air-firing FCC unit with a VPSA air separation unit has the highest NPV and IRR (511.76 M$ and 23.45%) among these technologies. It presents the best performance in all aspects including CO2 recovery rate, energy consumption, and economics, which promises to become strongly competitive in CCS technologies of FCCUs.

A review of ionic liquids and deep eutectic solvents design for CO2 capture with machine learning

Ionic liquids (ILs) and deep eutectic solvents (DESs) are regarded as the next generation solvents for carbon capture which consist of cations and anions. Thousands of combinations of cations and anions can lead to varied properties of ILs/DESs, which makes it difficult to screen such ILs/DESs for CO2 in experiments. Computer-aided molecular design (CAMD) saves time and cost by reversing the search for the structure of ILs that are suitable for carbon capture. Compared with other thermodynamic models, machine learning (ML) models have the advantages of efficiency and accuracy in CAMD; hence, the number of studies on the application of ML models in the field of CAMD is growing each year. In this paper, a concise review of the application of ML to ILs/DESs-based CO2 capture technology is provided. The development process of ML models in (1) the prediction of the properties of ILs/DESs using their structure; and (2) the prediction of the carbon capture effect using process parameters is discussed. Perspectives on future research directions are proposed and key challenges are identified for screening suitable ILs/DESs using the capture effectiveness of a specific carbon capture process as an evaluation criterion.

Enhanced CO2 desorption rate for rich amine solution regeneration over hierarchical HZSM-5 catalyst

High energy consumption during the carbon dioxide (CO2) desorption process in amine-based CO2 capture technology is a crucial hindrance to achieving carbon neutrality. HZSM-5 is one of the most widely reported solid acid catalysts used in primary amine regeneration. This work compared a series of HZSM-5 zeolites with different Si/Al ratios in terms of CO2 desorption performance. To further enhance catalytic activity, hierarchical HZSM-5 was synthesized by the dealumination and desilication re-assembly method with different acid and alkali concentrations. The experimental results suggested that desilication by modification in sodium hydroxide resulted in a significant improvement of mesoporous surface area. The NaOH-0.4 catalyst could improve the amount of desorbed CO2 by 40.3% and decrease the relative heat duty by 28.5%. And the cyclic tests revealed that catalytic activity was well preserved in the recycling process. Moreover, the structure and acidity of modification samples were characterized by X-Ray diffraction (XRD), Fourier transforms infrared (FT-IR), Nitrogen adsorption–desorption experiment, temperature programmed desorption of ammonia (NH3-TPD), Pyridine-adsorption infrared spectroscopy (Py-IR), and scanning electron microscopy (SEM). The characterization results suggested that the synergistic effect of larger mesoporous surface area and total acid sites was important to enhance catalytic CO2 desorption performance. These results showed a new understanding of catalyst design for CO2 capture technology by modifying the structure of the catalyst support.

Economic and scale prediction of CO2 capture, utilization and storage technologies in China

In response to the lack of global quantitative research on the potential and scale prediction of CO2 capture, utilization and storage (CCUS) in China under the background of carbon peak and carbon neutrality goals, this study predicts the future economic costs of different links of CCUS technologies and the carbon capture needs of different industries in the scenario of fossil energy continuation. Based on the CO2 utilization and storage potential and spatial distribution in China, a cost-scale calculation model for different regions in China in 2060 is constructed to predict the whole-process economic cost and its corresponding scale potential of CCUS. The results show that a local + remote storage mode is preferred, together with a local utilization mode, to meet China's 27×108 t/a CO2 emission reduction demand under the scenario of fossil energy continuation. Specifically, about 5×108 t CO2 emission is reduced by capture utilization, and the whole-process cost is about −1400–200 RMB/t; about 22×108 t CO2 emission is reduced by capture storage, and the whole-process cost is about 200–450 RMB/t. According to the model results, it is recommended to develop the chemical utilization industry based on P2X (Power to X, where X is raw material) technology, construct the CCUS industrial cluster, and explore a multi-party win-win cooperation mode. A scheme of national trunk pipeline network connecting areas connecting intensive emission reduction demand areas and target storage areas is suggested. The emission reduction cost of thermal power based on CCUS is calculated to be 0.16 RMB/(kW·h).

Desorption performance of commercial zeolites for temperature-swing CO2 capture

CO2 capture is an inevitable option for carbon reduction, and adsorption-based CO2 capture technology offers a promising way to lowering the energy cost of the most mature amine-scrubbing method. Most of the recent studies focused on pursuing materials with high adsorption capacities, but desorption performance as well as recovery of high purity CO2 are long been overlooked. In this study, four commercial zeolites were screened for CO2 capture from simulated flue gas, among which, 5 A zeolite was selected to systematically investigate the desorption behavior. A more practically available temperature-swing procedure was proposed for desorption and regeneration of the material, and a CO2 stream of over 70% purity with 90% recovery can be achieved by only one-stage adsorption.

Simulation and analysis of a peak regulation gas power plant with advanced energy storage and cryogenic CO2 capture

Flexible gas power plants are subject to energy storage, peak regulations, and greenhouse gas emissions. This study proposes an integrated power generation system that combines liquid air energy storage (LAES), liquefied natural gas (LNG) cold energy utilization, gas power systems, and CO2 capture and storage (CCS) technologies, named the LAES-LNG-CCS system. The off-peak electricity can be stored in liquid air. During the peak period, air and gas turbines generate supplementary electricity. Both LNG chemical energy and cold energy were considered: the former was used for gas power plants, and the latter was used for LAES regasification and CCS processes. Based on the thermodynamic analysis, we evaluated the effects of the recovery pressure, CCS pressure, and combustion temperature on the system power consumption and efficiency. The results demonstrated that the system recovery pressure, CCS pressure, and combustion temperature had the greatest effects on system power generation. Round-trip efficiency (RTE) was significantly affected by combustion temperature. The largest exergy loss occurred in the gas power plant. The optimal system operating ranges of the system recovery pressure, CCS pressure, and combustion temperature were 6−10 MPa, 0.53−0.8 MPa, and 1,503−1,773 K, where the RTEs and ηEx,RS reached 55%−58.98% and 74.6%−76%, respectively. The proposed system can simultaneously achieve the synergistic functions of large-scale energy storage, multilevel energy utilization, peak regulation, and carbon emission reduction. It can also be widely used in advanced distributed energy storage applications in the future.

A mini-review on cryogenic carbon capture technology by desublimation: theoretical and modeling aspects

Carbon capture, utilization, and storage (CCUS) technologies are the most effective methods to reduce CO2 emissions from fossil fuel power plants. Of the different CCUS technologies, cryogenic carbon capture (CCC) methods are the most mature technology as they can obtain remarkably high CO2 recovery and purity (99.99%). The significant advantage of the CCC process is that it can be easily retrofitted to existing systems and can handle the gas stream’s impurities. Different desublimation-based CCC technologies like Cryogenic packed bed, Anti sublimation, External cooling loop, CryoCell process and Novel low-cost CO2 capture technology (NLCCT) are reported in the literature. The significant limitations of these processes are the continuous removal of the dry ice into storage tanks. For the efficient design of CCC systems, accurate prediction of the phase equilibria data and modeling of the frost formation is called for. This paper reviews the recently reported cryogenic desublimation technologies and analyses the various challenges in making them economically viable. The article also examines the different heat and mass transfer models employed to model CO2 frost formation.

Simulating and Comparing CO2/CH4 Separation Performance of Membrane-Zeolite Contactors by Cascade Neural Networks.

Separating carbon dioxide (CO2) from gaseous streams released into the atmosphere is becoming critical due to its greenhouse effect. Membrane technology is one of the promising technologies for CO2 capture. SAPO-34 filler was incorporated in polymeric media to synthesize mixed matrix membrane (MMM) and enhance the CO2 separation performance of this process. Despite relatively extensive experimental studies, there are limited studies that cover the modeling aspects of CO2 capture by MMMs. This research applies a special type of machine learning modeling scenario, namely, cascade neural networks (CNN), to simulate as well as compare the CO2/CH4 selectivity of a wide range of MMMs containing SAPO-34 zeolite. A combination of trial-and-error analysis and statistical accuracy monitoring has been applied to fine-tune the CNN topology. It was found that the CNN with a 4-11-1 topology has the highest accuracy for the modeling of the considered task. The designed CNN model is able to precisely predict the CO2/CH4 selectivity of seven different MMMs in a broad range of filler concentrations, pressures, and temperatures. The model predicts 118 actual measurements of CO2/CH4 selectivity with an outstanding accuracy (i.e., AARD = 2.92%, MSE = 1.55, R = 0.9964).

Solid base LDH-catalyzed ultrafast and efficient CO2 absorption into a tertiary amine solution

Due to its high capacity, low energy consumption, and low corrosiveness, chemical absorption using aqueous tertiary amine solutions is a potential approach for CO2 capture. The fundamental limitation of this technology is its low CO2 absorption kinetics (rate), which impedes its large-scale use. Here, five typical solid-base catalysts, MgAl-layered double hydroxide (LDH) and its corresponding layered double oxide (LDO), BaCO3, MgCO3, and CaCO3, were adopted to improve the rate of CO2 absorption in an aqueous methyldiethanolamine solution (MDEA). The results indicated that LDH and LDO promoted CO2 absorption, with LDH exhibiting significantly superior catalytic activity. In particular, compared to the non-catalytic absorption, using LDH considerably improved the CO2 absorption rate by 92.7%. The catalytic effects of LDH on CO2 absorption were demonstrated by 13C NMR and FT-IR techniques, and theoretical calculation. A possible catalytic CO2 absorption mechanism over LDH was suggested. Additionally, the stability of LDH was certified with 10 cyclic CO2 absorption–desorption experiments. The excellent catalytic CO2 absorption performance of LDH may be primarily owing to the chemical absorption improvement mechanism of basic sites. Therefore, the LDH-catalyzed CO2 absorption process is a promising option for increasing the CO2 absorption rate in tertiary amine solution. This work may open up a new approach to developing plentiful and affordable solid-base catalysts for CO2 capture technologies with faster absorption kinetics and lower energy requirement.

An Overview of Conventional Techniques and Recent Advancements in CO2 Capture Technologies

Aspects in Mining & Mineral Science An Overview of Conventional Techniques and Recent Advancements in CO2 Capture Technologies Waqad Ul Mulk* Department of Mechanical Engineering, Universiti Teknologi PETRONAS, Malaysia *Corresponding author:Waqad Ul Mulk, Department of Mechanical Engineering, Universiti Teknologi PETRONAS, 32610 Bandar Seri Iskandar, Perak Darul Ridzuan, Malaysia Submission: April 28, 2023; Published: May 17, 2023 DOI: 10.31031/AMMS.2023.11.000761 ISSN 2578-0255Volume11 Issue3

A novel technique for quantifying the fate of CO2 injected in oil reservoir for geological utilization and storage

CO2-enhanced oil recovery (CO2-EOR) is a potential CO2 capture, utilization, and storage technology. In particular, CO2 can break the hydrochemical balance of water–rock and converts into carbonate minerals which are the most stable sequestration phase. The water–rock reactions are complex kinetic processes because the rate of dissolution/precipitation of minerals are vary with the pH of the formation water. However, studies on the effect of geochemical reactions on CO2-EOR processes are lacking, and the fate of CO2 cannot be accurately quantified. In this study, we combine the characteristics of the oil phase into the thermal–hydraulic–chemical TOUGHREACT simulator to consider various water–rock geochemical kinetic reactions in CO2-EOR. Therefore, the distribution phase of CO2 can be determined completely in the reservoir. Our analyses use the realistic fluid property (pressure–volume–temperature) of multicomponent oil phase–CO2 mixtures. The model considers the possible geochemical reactions and the resulting changes in porosity and permeability. The results indicate that in gas–water cycle of 9% hydrocarbon pore volume CO2 slug, the largest distributed phase of CO2 is the gas phase, accounting for 52.2% during the CO2 injection period. After water injection, the solubility of CO2 in the oil phase increases, and CO2 is mostly dissolved in the oil phase, accounting for 53.0%. Without considering the water–rock geochemical reactions will result in an underestimation of the dissolved aqueous phase and correspondingly the others were overestimated. The maximum error of the distributed quantity is up to 6.4% of the total injection. In addition, the omission of water–rock reactions result in an underestimation of the oil recovery. Comparing with the CO2 storage in a saline aquifer, dissolution of CO2 in oil phase in CO2-EOR scenario dampens the effect of buoyancy, which leads to higher sequestration capacity for the same footprint of storage reservoir.

The effect of pressure on the concentration of methane and carbon dioxide absorption in biogas

Biogas is playing a vital role in the emerging market for renewable energy. Biogas is an alternative energy that can be used as a substitute for fossil energy. The main composition of biogas is methane gas (CH4) and carbon dioxide gas (CO2) with a small amount of hydrogen sulfide (H2S). Therefore, it is necessary to do treatment to enrich gas methane and reduce CO2 and H2S content in optimizing the use of biogas. Absorption is a CO2 capture technology often used in the chemical industry. A chemical absorption technique using a solvent solution is one of the most widely used techniques to capture CO2. This research uses MDEA (Nmethyldiethanolamine) solvent as an alkanolamine solution dissolved in water. The unit operation usually used to carry out the absorption process is an absorber, and the type of absorber used is a spray column absorber. Simulating variations in pressure on the absorber was conducted in this research. The result of this research is that the increase in pressure will increase the composition percent of CH4 in sweet gas and increase the amount of CO2 absorption in biogas. The best result of absorber pressure is obtained at a pressure of 48 bar. The purity of CH4 and %removal of CO2 in biogas can be solved simply by using the evaluation parameters of the various absorber pressures presented, which we expect to contribute to the biogas industry in the future.

Understanding the role of imidazolium-based ionic liquids in the electrochemical CO2 reduction reaction

The development of efficient CO2 capture and utilization technologies driven by renewable energy sources is mandatory to reduce the impact of climate change. Herein, seven imidazolium-based ionic liquids (ILs) with different anions and cations were tested as catholytes for the CO2 electrocatalytic reduction to CO over Ag electrode. Relevant activity and stability, but different selectivities for CO2 reduction or the side H2 evolution were observed. Density functional theory results show that depending on the IL anions the CO2 is captured or converted. Acetate anions (being strong Lewis bases) enhance CO2 capture and H2 evolution, while fluorinated anions (being weaker Lewis bases) favour the CO2 electroreduction. Differently from the hydrolytically unstable 1-butyl-3-methylimidazolium tetrafluoroborate, 1-Butyl-3-Methylimidazolium Triflate was the most promising IL, showing the highest Faradaic efficiency to CO (>95%), and up to 8 h of stable operation at high current rates (−20 mA & −60 mA), which opens the way for a prospective process scale-up.

Valorizing saline biomass from horticultural waste via pyrolysis

Large emissions of greenhouse gases (GHGs) are severely affecting the planet. Thus, considerable effort has been undertaken to deploy technologies for CO2 capture and long-term storage. Biochar is a carbon-rich material that can have a two-fold contribution toward mitigating climate change: (a) it enhances soil fertility, thus reducing the requirement for fertilizers and (b) it can persist in soil for thousands of years, serving as a carbon sink material. Herein, we evaluate the operating conditions required to produce biochar using saline biomass obtained from horticultural waste in a university campus on the coast of the Red Sea in Saudi Arabia. The biomass has >10 wt% of Ca, Na, and Mg, which allows for the production of microporous biochar with a surface area of ∼150 m2/g without any additional chemical or physical activation treatment. The bio-oil obtained as an associated product has ∼25 %–50 % of terpenoids and 9 %–42 % of phenols, and its composition varies based on the pyrolysis conditions. These high-value compounds can enhance the economic feasibility of a process that can contribute to environmental remediation.

Imines supported on silica as CO2 capture selective adsorbents

CO2 capture technologies must be developed to reduce Green House Gas emissions in order to fulfill the Paris Agreement. Adsorption is considered one of the available technologies due to the mild conditions used in the process. Selective sorbents with high CO2 adsorption capacities are needed. In this work, several types of branched polyethylenimines (PEI), with different average molecular weight, are used agglomerated with silica at different amounts by weight. The adsorption has been measured and the kinetic parameters are estimated from breakthrough experiments in a fixed bed. The results showed that the materials produced were selective to CO2 and can be used in adsorption processes, the sample lowest average molecular weight had the higher adsorption capacity.

Investigating the solution behavior of CO2 in ester based on a hybrid of ANN technology and PS method

ABSTRACT Artificial neural networks (ANNs) are artificial intelligence tools, and pattern search (PS) is a method for solving optimization problems. Although these two technologies have been extensively used in the chemical and engineering fields, they have limitations. This study proposes a methodology based on a hybrid of ANN technology and PS method to investigate the solution behavior of carbon dioxide (CO2). Five CO2-ester binary systems are selected as the model systems to demonstrate the point of interest. The results reveal that this methodology can overcome the defects of the two technologies and develop their advantages, thereby providing a satisfactory description of the solubility data of CO2 in these esters. The proposed methodology can be applied to a series of CO2 binary systems and is helpful in selecting a suitable absorbent for CO2 capture technology.