Maximum CO2 Research Articles

Ladder type covalent organic frameworks constructed with natural units for the oxygen and carbon dioxide reduction reactions

Covalent organic frameworks (COFs) constructed with metallocyclophane units and organic linkers have found application as electrocatalytic systems. Nevertheless, the majority of linkers within COFs necessitate intricate design and synthesis. Conversely, the potential utilization of natural building blocks in COF construction remains largely unexplored. In this study, we constructed a natural COF (CoPc-EA-COF) by employing a natural phenolic molecule (ellagic acid (EA)) as the linker and Co-hexadecafluorophthalocyanine (CoPc) as blocks. This framework serves as an electrocatalyst for both the oxygen reduction reaction (ORR) and carbon dioxide reduction reaction (CO2RR). The incorporation of EA units imparts the CoPc-EA-COF with elevated electronic conductivity, enhanced CO2 binding affinity, and superior reductive capacity compared to the controlled COF lacking EA units. The CoPc-EA-COF demonstrated enhanced performance in the ORR, as evidenced by a half-wave potential of 0.80 V. Moreover, it showcased elevated activity and selectivity in the CO2RR, achieving a maximum CO faradic efficiency of 97.32 % at − 0.8 V, along with turnover frequency (TOF) values reaching 2092 h−1. Theoretical calculations revealed that the presence of EA units facilitated the generation of OOH* and COOH* species, which are pivotal in the rate-determining stages of both ORR and CO2RR processes. The contribution of EA units significantly bolstered the overall catalytic activity.

Mathematical modeling of dispersed CO2 dissolution in ionic liquids: Application to carbon capture

We develope a 2D computational fluid dynamic (CFD) model in COMSOL Multiphysics® to investigate CO2 absorption in an ionic liquid ([Bmim][TCM]). Factors such as pressure (1–20 bar), temperature (278–330 K), inlet gas velocity (0.0001–1 ▪), sparger radius to column diameter ratio (0.1–0.5), and column height to diameter ratio (1–3) are investigated. A quadratic model for absorption behavior (p-value < 0.0001 and R2 > 0.98) is developed. Four sparger geometries are considered, and the optimal values for column height to diameter and sparger radius to column diameter are estimated. The maximum CO2 concentration is obtained at a pressure of 18.26 bar, temperature of 309.5 K, velocity of 0.825 ▪, the sparger radius to column diameter of 0.414, and column height to diameter of 2.5.

Energy, exergy and environmental analysis of concentrated parabolic trough collector using alumina-water nanofluid and twisted tape insert

Concentrating parabolic trough collector (CPTC) is used to convert energy of solar radiation into useful heat energy utilized in different thermal applications. The present article discusses the use of nanofluids and inserts in CPTC to improve its performance parameters such as collector efficiency, exergy efficiency, Nusselt number, friction factor, and performance augmentation factor (PAF). Al2O3-water nanofluid with different volume concentrations of 0.25%, 0.5%, 0.75%, and 1% was used as working fluid. The effect of simple twisted-tape insert (STI) and overlapped twisted-tape insert (OTI) were studied with the nanofluid to evaluate performance of CPTC. Nanofluid, with highest volume fraction (φ = 1%), demonstrated maximum enhancement as 5.3%, 17.4%, 70%, 230%, and 140% in collector efficiency, exergy efficiency, Nusselt number, friction factor, and PAF as compared to water as working fluid flowing through plain absorber tube. Employing STI and OTI with nanofluid (φ = 1%) represented maximum enhancement of 14.5% and 15.9% in collector efficiency, 19.9% and 20.8% in exergy efficiency, 282% and 367% in Nusselt number, 1800% and 1900% in friction factor, and 231% and 475% in PAF as compared to water flowing through bare absorber tube at a minimum flow rate. OTI with nanofluid (φ = 1%) demonstrated maximum CO2 reduction of 1.61 tons/year and maximum enviro-economical gain of 23.41 $/year.

Co-grafting of polyethyleneimine on facilely synthesized mesoporous P(DVB-D) for highly effective CO2 adsorption and enhanced oxidation resistance

Solid amine adsorbents are showing promise as effective adsorbents for the capture of CO2 from various gas mixtures, including biogas and flue exhaust gas. In this study, we introduced a co-grafting strategy using 1,4-butanediol diglycidyl ether (BDDE) on the surface of P(DVB-D). This approach aimed to exploit the reaction involving the opening of epoxy groups with amine groups, forming covalent bonds between polyethyleneimine (PEI) and mesoporous organic polymers, along with the introduction of hydroxy groups to enhance adsorbent long-term stability and antioxidation ability. After an extensive assessment, P(DVB-D)@B-41.2 %PEI exhibited a maximum CO2 capture capacity of 4.53 mmol/g at 50 °C and 50 % RH. Notably, its remarkable CO2 adsorption performance persisted across a diverse temperature spectrum (30–90 °C) and an extensive concentration span (5–30 % vol.). In contrast to conventional adsorbents prepared solely through impregnation methods, P(DVB-D)@B-41.2 %PEI exhibited impressive long-term stability throughout 50 successive cycles and excellent resistance to oxidative degradation. These findings underscore the considerable potential of P(DVB-D)@B-41.2 %PEI in the realm of carbon capture and sequestration (CCS) technology.

Gram-scale synthesis of Ni-Zn diatomic sites catalyst for efficient electrochemical CO2 reduction

Diatomic catalysts inherit the advantages of single atom catalysts and use the adjacent metal-N sites for functional complementary and synergistic effects in electrochemical CO2 reduction (ECR). However, preparation of diatomic catalysts with high yield, Faradaic efficiency and stability together with low overpotential still remains challenging. In this work, we develop a nitrogen-doped carbon supported Ni-Zn diatomic catalyst, whose CO Faradaic efficiency of is higher than 92.0 % in the wide potential range of −0.57 ∼ −1.07 V vs RHE, and the maximum CO Faradaic efficiency is 97.5 % at −0.77 V vs RHE. And also, CN-NiZn performs an extraordinary stability for 30 h in the long-time durability test. More importantly, large-quantities (around 1.66 g) of Ni-Zn diatomic catalysts with remarkable catalytic performance can be prepared by this method. Synchrotron radiation X-ray absorption spectroscopy was tested to reflect the coordination environment and valence states around Ni and Zn atoms. Theoretical calculations further reveal that the synergistic effect between Ni and Zn binary metal sites largely reduces the energy barrier of the reaction to produce the intermediate *COOH, thus effectively increasing the selectivity of ECR. This work indicates that the introduction of another coordination metal can significantly affect the electronic structure of monatomic catalysts, thus improving the electrocatalytic activity and selectivity of ECR.

Adsorption and Diffusion Properties of Functionalized MOFs for CO2 Capture: A Combination of Molecular Dynamics Simulation and Density Functional Theory Calculation.

The capture of carbon dioxide (CO2) from fuel gases is a significant method to solve the global warming problem. Metal-organic frameworks (MOFs) are considered to be promising porous materials and have shown great potential for CO2 adsorption and separation applications. However, the adsorption and diffusion mechanisms of CO2 in functionalized MOFs from the perspective of binding energies are still not clear. Actually, the adsorption and diffusion mechanisms can be revealed more intuitively by the binding energies of CO2 with the functionalized MOFs. In this work, a combination of molecular dynamics simulation and density functional theory calculation was performed to study CO2 adsorption and diffusion mechanisms in five different functionalized isoreticular MOFs (IRMOF-1 through -5), considering the influence of functionalized linkers on the adsorption capacity of functionalized MOFs. The results show that the CO2 uptake is determined by two elements: the binding energy and porosity of MOFs. The porosity of the MOFs plays a dominant role in IRMOF-5, resulting in the lowest level of CO2 uptake. The potential of mean force (PMF) of CO2 is strongest at the CO2/functionalized MOFs interface, which is consistent with the maximum CO2 density distribution at the interface. IRMOF-3 with the functionalized linker -NH2 shows the highest CO2 uptake due to the higher porosity and binding energy. Although IRMOF-5 with the functionalized linker -OC5H11 exhibits the lowest diffusivity of CO2 and the highest binding energy, it shows the lowest CO2 uptake. Accordingly, among the five simulated functionalized MOFs, IRMOF-3 is an excellent CO2 adsorbent and IRMOF-5 can be used to separate CO2 from other gases, which will be helpful for the designing of CO2 capture devices. This work will contribute to the design and screening of materials for CO2 adsorption and separation in practical applications.

Effect of syngas recirculation in the pyrolysis zone on the rice husk gasification process using the downdraft reactor

As one of the world's largest rice producers, Indonesia has an abundance of rice husk as a byproduct of rice milling. Rice husks were utilized to examine downdraft gasification with syngas recirculation system. This study attempts to produce better syngas than conventional downdraft gasifier. With an equivalency ratio of 0.20, syngas was recirculated into the reactor in the pyrolysis zone with valve openings at 25%, 50%, and 75%. This study determined the syngas recycling ratio that maximizes H2 and CO gas and decreases tar. Increasing the syngas recirculation valve (25%, 50%, and 75%) accelerates flame propagation and pyrolysis zone temperature. Syngas study showed no recirculation condition produces the maximum CO2 and CH4. Different recirculation valve openings little affect CO and CH4 gas composition. The H2 gas composition demonstrates that valve openings significantly change H2 gas generation and that the peak was at 50% syngas recirculation. Tar content decreased to 30% and 35% at 50% and 75% valve openings. Based on H2/CO comparison and tar concentration, 50% opening syngas recirculation became the optimum case.

Net-zero, resilience, and agile closed-loop supply chain network design considering robustness and renewable energy.

The Net-zero, Resilience, and Agile Closed-Loop Supply Chain Network (NZRACLSCND) concept integrates net-zero, resiliency, and agility in a circular economy. Regarding net-zero, this research embeds renewable energy like solar energy and hybrid trucks to supply energy for facilities and transportation of goods and products between components. Applying redundancy, multi-source, and flexible capacity as resiliency strategies is suggested to cope with the demand disruption. Satisfaction demand level is utilized for the agile approach. This research proposes Robust Stochastic Optimization (RSO), including the weighted expected value and maximum CO2 for NZRACLSCND. This study locates and determines the flow of CLSC in the home appliance industry by considering NZRA, robustness, and risk against demand disruption. CO2 emission using the NZRA concept is 233.33% less than without considering NZRA concepts. In addition, the conservative coefficient, agile coefficient, decreased CO2 coefficient, and the model scale are analyzed. The results show that when the conservative coefficient increases, the risks of CO2 emission increase. In addition, when the agile coefficient increases, as a result, CO2 emission increases. Finally, when the decreased CO2 coefficient and the model scale increase, we can see that CO2 emission and cost are increased.

Functionalization of Ordered Mesoporous Silica (MCM-48) with Task-Specific Ionic Liquid for Enhanced Carbon Capture.

This work presents new composites of AAILs@MCM-48 obtained by functionalizing ordered mesoporous silica MCM-48 with two amino acid-based ionic liquids (AAILs) ([Emim][Gly] and [Emim][Ala]) to improve carbon capture and the selectivity of CO2 over nitrogen. Thermogravimetric and XRD analyses of the composites showed that the MCM-48 support's thermal and structural integrity was preserved after the AAILs were encapsulated. An N2 adsorption-desorption study at 77 K confirmed AAIL encapsulation in the porous support. Under post-combustion flue gas conditions, both [Emim][Gly]@MCM-48 and [Emim][Ala]@MCM-48 demonstrated improved CO2 adsorption in comparison to the unmodified MCM-48, with a CO2 partial pressure of around 0.15 bar. Regarding the maximal CO2 uptake, the 40 wt.%-[Emim][Gly] composite outperformed the others at 303 K, with values of 0.74 and 0.82 mmol g-1, respectively, at 0.1 and 0.2 bar. These numbers show a 10× and 5× increase, respectively, compared to the pure MCM-48 under identical conditions. In addition, the selectivity of the composites was improved significantly at 0.1 bar: the selectivity of composites containing 40 wt.% [Emim][Ala] increased to 17, compared to 2 for pristine MCM-48. These composites outperform other silica-based studies reported in the literature, even those using amines as solvents. The presented composites offer therefore promising prospects for advancing carbon capture technology.

Optimizing particle morphology: Atomic iron–nitrogen centers with graphitic‐N for highly efficient CO2 electroreduction

AbstractTransition metal‐coordinated nitrogen sites on carbon catalysts (M‐N‐C) hold potential for CO2 electroreduction (CO2ER), but optimal morphology and active sites are unclear. We introduce a novel approach, developing zeolitic imidazolate framework‐8 (ZIF‐8)‐derived carbon catalysts with Fe‐N and graphitic‐N sites (Fe2‐NC) via molecular confinement and thermal activation. Fine‐tuning ZIF‐8 size and activation temperature yielded 44.98% active N sites. The 300 nm Fe2‐NC catalyst displayed outstanding CO2‐to‐CO conversion, with a 170 mV overpotential and 94.3% Faradaic efficiency at −0.5 V, outperforming state‐of‐the‐art materials. Enhanced CO2ER kinetics and conductivity contributed to this superiority. Results highlight the correlation between maximum CO Faradaic efficiency and cumulative Fe‐N/graphitic‐N sites, dependent on size and activation. The 300 nm Fe2‐NC in a gas diffusion electrode‐loaded flow cell achieved a 15.3‐fold CO partial current density increase. In a Zn‐CO2 battery, the 300 nm Fe2‐NC demonstrated a peak power density of 0.618 mW cm−2, showcasing energy storage potential.

Numerical investigation of premixed combustion of producer gas with hydrogen injection in a cyclonical chamber

ABSTRACT This paper employs computational fluid dynamics (CFD) simulations with an eddy dissipation concept model (EDC) and a skeletal reaction mechanism (SK17) to analyze the impact of hydrogen addition on the premixed combustion mode of producer gas (PG) fuel in a cyclonic flow combustion chamber. The results, validated against measured wall temperature data, demonstrate a minor discrepancy between simulation and experiment. The studied result showed that injection of hydrogen into PG fuel combustion elevates the temperature of the combustion process, which can be indicated by the average temperature across the combustion chamber, outlet temperature of exhaust gas, and reactive radical species. However, increasing H2 injection over 20% results in strongly increasing CO formations. Compared to a fixed thermal input case, hydrogen injection with a variable input power resulted in a higher combustion temperature and increased emissions of both CO and NO. The maximum CO emission reached approximately 1246 ppm, while NO peaked at around 75 ppm, both observed at a 30% hydrogen injection rate. The key finding of this study revealed that direct injection of hydrogen to the combustion under the condition of a given equivalence ratio is unfavorable due to insufficient oxygen for the reaction, leading to an increase in CO emissions. The optimal condition would be a hydrogen injection below 20%, which produces low CO and NO emissions.

Optimal economic and environmental arbitrage of grid-scale batteries with a degradation-aware model

Energy arbitrage is a potential revenue stream for battery operators with access to variable electricity prices. However, the power shifted by grid-scale energy storage has the potential to influence the production mix in real time, impacting the carbon emissions of the electricity system. Little research is available on the CO2 emissions induced by arbitrage operations, and studies that consider arbitrage-related CO2 emissions often neglect battery degradation. To address this gap, this study proposes a novel modeling and assessment framework based on mixed-integer linear programming to analyze the trade-offs between profit and CO2 emissions of battery arbitrage operations as well as the impact of degradation on arbitrage profit and emissions. We present the results in terms of Pareto-optimal solutions that identify maximum profit and minimum CO2 emissions. We illustrate our model through a case study in Germany and we show that performing maximum-profit arbitrage increases the system emissions by up to 7.5 tCO2 per MWh of storage capacity (or about 12% of battery life cycle emissions per year). 60% of the added emissions can be avoided by sacrificing only 1.5% to 2.7% of the net arbitrage profit, and CO2-neutral operation can be achieved by sacrificing about 7% of the profit. Our findings also highlight the importance of modeling battery degradation, as degradation-unaware arbitrage models may lead to a substantial profit loss (potentially to negative profits) and higher CO2 emissions (up to +260%) with respect to degradation-aware models.

Improving the ventilation of a classroom to achieve heating energy savings and better indoor air quality

Indoor air quality and heating energy consumption are closely linked, especially in densely occupied spaces, as classrooms. In a classroom of Rennes University, a transient thermal simulation highlights the impact of ventilation on heating consumptions for different cases: (1) without controlled mechanical ventilation (CMV), (2) with a single flow CMV (SF CMV) of a regulatory flow of 18 m3.h−1. person−1 during periods of occupancy, and (3) a double flow CMV (DF CMV) whose flow is during periods of occupancy either equal to 18 m3.h−1. person−1 or (4) to 35 m3.h−1.person−1. The infiltration flowrate was evaluated experimentally using CO2 concentration measurements in the first case, which corresponds to the actual situation. In the normal use of the classroom with 30 persons inside, CO2 concentration exceeds 5000 ppm and the heating energy consumption is equal to 52 kWh.m−2.year−1. In case (2) and (3), CO2 concentration has a maximum level of 1350 ppm and the energy consumption is equal to 65 and 53 kWh.m−2.year−1, respectively. In case (4), the maximum CO2 concentration stays in the range 800-900 ppm without excessive heating consumption (58 kWh.m−2.year−1). Finally, by limiting the fresh air flowrate to 18 m3.h−1.person−1 in DF CMV and coupling it to a façade insulation (extra Case 5), the heating consumption is reduced to 32 kWh.m−2.year−1. These results are valuable within the context of the upcoming energy renovation strategy of the campus. Practical application In most schools, in France and elsewhere, insufficient ventilation flowrates are often observed compared to regulatory requirements. If compliance with ventilation standards and the subsequent revision of CMV installations are necessary to ensure the health of users, it is important to evaluate the energy cost of these renovations, and to identify the best choice to reduce heating consumptions. Our contribution is to compare different renovation choices in terms of two indicators: energy consumption and indoor air quality evaluated using CO2 concentration.

Assessing the geological storage potential of CO2 in Baltic Basin: A case study of Lithuanian hydrocarbon and deep saline reservoirs

The need to reduce carbon emissions, via exploring the CO2 storage potential in the depleted subsurface hydrocarbon and the deep saline aquifers in the Baltic Basin region of Lithuania, is discussed. The paper presents a unique methodology, using multi-deterministic numerical models, for evaluating the CO2 storage potential of the deep saline aquifers and the depleted hydrocarbon fields of Lithuania. Such an approach has never been presented before for evaluation of Lithuanian subsurface reservoirs for CO2 storage potential. The paper also explains the limitations of previous estimates of CO2 storage potential computed for deep saline aquifers in Lithuania and introduces a new study that uses uncertainty quantification principle and numerical modelling to estimate the maximum CO2 injection and storage potential in the region. Three deep saline aquifers D11 (offshore), Syderiai and Vaskai (on shore) are evaluated along with depleted hydrocarbon reservoirs of Gargzdai residual oil zone. Evaluation estimates presented in this paper suggest a maximum theoretical storage potential in range of 96 –407 Mt. of CO2 for the three deep saline aquifers and in range of 64–267 Mt. of CO2 for Gargzdai residual oil zone. Although the primary focus of this paper is on the storage capacity estimation, a high-level analysis of the risks associated with CO2 injection and storage are also presented.

Microclimatic study under wheat, mustard and chickpea crops in western plain zone of Uttar Pradesh

The present study to quantify the variations in microclimate under wheat, mustard and chickpea crops was conducted at ICAR-Indian Institute of Farming Systems Research, Modipuram, Meerut (U.P.), India. Air temperature, relative humidity, CO2 concentration below and above the canopies of wheat, mustard and chickpea were recorded at hourly interval from 07:30 to 17:30 hours at different heights (0.5 m, 1.0 m and 2.0 m) from the ground. CO2 probes like GMP-343, (Diffusion aspiration) was used to record data of CO2 concentration and HPM-75 probes was used to capture the observation of air temperature and relative humidity. Results revealed that diurnal air temperature was continuously increasing from morning to afternoon hrs and highest air temperature was recorded at 13:30 hrs (afternoon). Thereafter, air temperature decreased and reached to the lowest at 17:30 hrs irrespective of crops and height from the ground. Analysis of diurnal air temperature variations at different height clearly showed that tall statured crop such as wheat and mustard reached higher air temperature regime early (13.30 hrs) compared to short statured crop like chickpea at 15.30 hrs. Highest relative humidity was observed at 07.30 hrs and lowest relative humidity was recorded either at 13:30 hrs or at 15:30 hrs. As per study maximum CO2 concentration was found at 07:30 hrs morning and minimum at 15:30 hrs. The lowest concentration of CO2 (624 ppm) was recorded from the chickpea field and highest from the mustard field (630 ppm) at the same point of observation during vegetative phase of crops.

Circular usage of waste cooking oil towards green electrical discharge machining process with lower carbon emissions

A global manufacturing community is dedicatedly striving to implement the concept of NetZero in precision cutting of difficult-to-machine materials, specifically, Inconel 617 (IN617) with due consideration to environmental protocols. The fast strain hardening issue of the said alloy during conventional processing rationalizes the application of electric discharge machining (EDM). However, EDM has been criticized for its high energy consumption and limited cutting efficiency. Moreover, conventional dielectric (kerosene) employed in EDM has drastic environmental and operator health concerns. To address the abovementioned issues, waste cooking oil (WCO) has been employed in this study which enhances the reusability of resources and minimizes the cost of the dielectric. Making the process sustainable is imperative along with continuously escalating scarcity of engineering resources. Therefore, the potential of shallow and deep cryogenically treated electrodes (SCT and DCT) has been comprehensively examined against nanofilled WCO to achieve the aforementioned objective. Three different concentrations of powder (Cp) and surfactant (Cs) to uplift the machining responses are investigated through a detailed parametric experimental design. Core machining factors such as material removal rate (MRR), surface roughness (SR), and specific energy consumption (SEC) are examined through optical and electron microscopy studies and 3D surface profilometry. Hereafter, machining factors are modelled using the artificial neural network (ANN) technique. An exceptional improvement of 80%, 25.3%, and 75.16% has been achieved in MRR, SR, and SEC respectively using nanopowder-mixed WCO against SCT brass compared to the responses’ values obtained against conventionally used kerosene. Furthermore, compared to kerosene, the maximum CO2 reduction of 79.97 ± 11.2% is achieved with WCO.

The Lagrangian Atmospheric Radionuclide Transport Model (ARTM) – sensitivity studies and evaluation using airborne measurements of power plant emissions

Abstract. The Atmospheric Radionuclide Transport Model (ARTM) operates at the meso-γ scale and simulates the dispersion of radionuclides originating from nuclear facilities under routine operation within the planetary boundary layer. This study presents the extension and validation of this Lagrangian particle dispersion model and consists of three parts: (i) a sensitivity study that aims to assess the impact of key input parameters on the simulation results, (ii) the evaluation of the mixing properties of five different turbulence models using the well-mixed criterion, and (iii) a comparison of model results to airborne observations of carbon dioxide (CO2) emissions from a power plant and the evaluation of related uncertainties. In the sensitivity study, we analyse the effects of the stability class, roughness length, zero-plane displacement factor, and source height on the three-dimensional plume extent as well as the distance between the source and maximum concentration at the ground. The results show that the stability class is the most sensitive input parameter as expected. The five turbulence models are the default turbulence models of ARTM 2.8.0 and ARTM 3.0.0, one alternative built-in turbulence model of ARTM, and two further turbulence models implemented for this study. The well-mixed condition tests showed that all five turbulence models are able to preserve an initially well-mixed atmospheric boundary layer reasonably well. The models deviate only 6 % from the expected uniform concentration below 80 % of the mixing layer height, except for the default turbulence model of ARTM 3.0.0 with deviations of up to 18 %. CO2 observations along a flight path in the vicinity of the lignite power plant Bełchatów, Poland, measured by the Deutsches Zentrum für Luft- und Raumfahrt (DLR) Cessna aircraft during the Carbon Dioxide and Methane Mission (CoMet) campaign in 2018 allowed for evaluation of model performance for the different turbulence models under unstable boundary layer conditions. All simulated mixing ratios are of the same order of magnitude as the airborne in situ data. An extensive uncertainty analysis using probability distribution functions, statistical tests, and direct spatio-temporal comparisons of measurements and model results help to quantify the model uncertainties. With the default turbulence setups of ARTM versions 2.8.0 and 3.0.0, the plume widths are underestimated by up to 50 %, resulting in a strong overestimation of the maximum plume CO2 mixing ratios. The comparison of the three alternative turbulence models shows good agreement of the peak plume CO2 concentrations, the CO2 distribution within the plumes, and the plume width, with a 30 % deviation in the peak CO2 concentration and a less than 25 % deviation in the measured CO2 plume width. Uncertainties in the simulations may arise from the different spatial and temporal resolutions of simulations and measurements in addition to the turbulence parametrisation and boundary conditions. The results of this work may help to improve the accurate representation of real plumes in very unstable atmospheric conditions through the selection of distinct turbulence models. Further comparisons at different stability regimes are required for a final assessment of model uncertainties.

Carbon dioxide adsorption capacity of porous carbon after polyamine impregnation under different pore structures and temperatures

Composites of polyethyleneimine (PEI) and porous carbon (PC) are effective and reversible CO2 adsorbents. Within these composite materials, the morphologies of PEI in different pore structures significantly influence CO2 capture behaviors, yet little is known about the movement of PEI molecules in PC. In this work, the CO2 adsorption capacity of PEI loaded on PC with different pore structures was investigated. The result shows that the average pore size of 3.63 nm loaded PEI has the maximum CO2 adsorption capacity at 50 ℃. Based on it, we establish a model that the loading of PEI in different pore size PCs for the first time and explain the morphology of PEI in the pore channel. This model displayed the changes in PEI chains and PEI agglomerated cores at different temperatures and pore sizes. In particular, the uptake amount of CO2 in PEI is attributed to the number of amine sites accessible. The PEI agglomerated core formed in smaller pore sizes is smaller and is more susceptible to temperature, thus the PEI agglomerated core exposes more amine sites for CO2 adsorption with increasing temperature. As the PC pore size increases, the PEI agglomerate core also enlarges, leading to greater spatial resistance and therefore exposing fewer amine-based sites when the temperature increases. The investigation of PEI/PC structure–property correlations and adsorption properties provides unique insights that could inform the rational design of better adsorbents.

CO2 adsorption by KOH-activated hydrochar derived from banana peel waste

Hydrothermal carbonization is one of the effective methods of converting wet lignocellulosic biomass into carbon-rich hydrochar. Due to its characteristic application on CO2 capture and storage, many researchers have studied the CO2 uptake on activated hydrochar. The present work studies the CO2 uptake from banana-peel-derived activated hydrochar which is not presented in the literature. Hydrochar is obtained at three different temperatures (180, 200, and 220 °C) and activated using KOH. Characterization studies including SEM, XRD and FTIR were performed to examine the structure and chemistry of the derived activated hydrochar. The hydrochar sample (BP-180) when activated with a KOH/hydrochar ratio of 3 and an activation temperature of 700 °C has a well-developed microstructure with a surface area and pore volume of 243.4 m2/g and 0.0931 cm3/g, respectively. Samples obtained at higher process temperatures (BP-200 and BP-220) showed much lower porosity. Similarly, the maximum CO2 adsorption is recorded for BP-180 (3.8 mmol/g), followed by BP-200 and BP-220 with maximum adsorption capacities of 3.71 and 3.18 mmol/g, respectively, at 1 bar and 25 °C.

Development of an Ir/TiO2 catalytic coating for plasma assisted hydrogenation of CO2 to CH4

The hydrogenation of CO2 to methane over a 20 wt% Ir/TiO2 catalytic coating has been investigated in a tubular dielectric barrier discharge (DBD) reactor. The 1.2 µm Ir/TiO2 coating was deposited onto the inner wall of a quartz tube by a combustion-evaporation method from a mixture containing a Ti precursor and a colloidal suspension of Ir nanoparticles (2 nm). The catalyst was characterised by XRD, SEM, TEM/EDS and CO chemisorption. The Ir(0) state in the as-synthesised film was confirmed by XPS. The CH4 conversion increased by 1.5 times, as compared to an empty tube. A maximum CO2 conversion rate of 2.1 μmol s−1 was achieved at a fuel production efficiency of 3.5%. Surface reactions onto the catalyst surface are responsible for enhancement of reaction rate. The results presented in this work open up new possibilities in plasma-catalysis, whereby efficient reactions can be carried out over small volumes of catalyst.