Search Results (38)

This study systematically investigates the catalytic effect of histidine (HIS) on CO₂ desorption in amine-based solvents, with a primary focus on 30 wt% N-(2-aminoethylamino)ethanol (AEEA) and its blends with N-methyldiethanolamine (MDEA). Experimental results show that the addition of 0.22 wt% HIS significantly enhances both the equilibrium desorption amount and the maximum desorption rate of CO₂, particularly at elevated temperatures (e.g., 100 °C). Under optimal conditions, HIS increased the maximum desorption rate by 22.1% and reduced the heat duty to 71.7% compared to the non-catalytic benchmark. The catalytic performance was further confirmed in AEEA-MDEA mixed solvents, with the most pronounced effect observed in the 3:2 molar ratio system, where HIS enhanced both the equilibrium desorption amount and the maximum desorption rate by 15.3% and 20.8%, respectively. Through ¹³C NMR analysis and pH-dependent speciation monitoring, we revealed that HIS alters the reaction pathway by suppressing the formation of stable carbamate species (AEEA_(a)COO⁻). The protonated (HIS⁺) and neutral (HIS^±) forms were identified as the active species that promote more direct CO₂ release from carbamate, while the deprotonated (HIS⁻) form facilitates proton transfer and amine regeneration. HIS also exhibited excellent catalytic stability over 10 absorption–desorption cycles. These findings highlight HIS as an efficient and stable organocatalyst for energy-efficient CO₂ desorption processes. Full article

A rigorous rate-based absorption model integrated with an improved thermodynamic framework was developed to simulate natural gas desulfurization using TMS–MDEA (Tetramethylene Sulfone–Methyldiethanolamine) aqueous solutions. The model was validated against 50 sets of industrial and experimental data, achieving R² values above 0.98 and average deviations within 5%. The model was formulated for steady-state operation of a trayed absorber integrated with flash and packed-bed regeneration and applicable over industrially relevant ranges (absorber pressure 3–6.4 MPa; gas–liquid ratio 350–720; flash pressure 0.3–0.6 MPa; packing height ≥ 3 m). The results indicate that H₂S can be removed almost completely (>99.9%); CO₂ and COS achieve 70–85% and 75–83% removal, respectively; and CH₃SH removal exceeds 90% under typical conditions. Parametric analysis revealed that higher tray numbers, weir heights, and pressures enhance absorption efficiency, whereas hydrocarbon solubility increases with carbon number and is strongly affected by pressure and the gas–liquid ratio. In the desorption section, flash regeneration efficiently strips light hydrocarbons, with decreasing desorption efficiency from CH₄ to C₆H₁₄. This study provides quantitative insights into the coupled absorption–desorption process and offers practical guidance for process design, solvent selection, and energy-efficient operation in natural gas purification. Full article

The urgent global issue of climate change caused by rising carbon dioxide (CO₂) levels has led to the widespread use of gas separation processes. Among the available processes, chemical absorption has received more attention due to its maturity and higher efficiency compared to others. However, the high energy consumption during the desorption step poses several technical challenges, limiting its industrial applications. To overcome those challenges, several research studies have been conducted to improve the performance of the desorption process. In particular, various types of catalysts have been tested to improve the performance of the CO₂ desorption process. Among the available catalysts, Titanium Oxyhydrate (TiO(OH)₂) has shown remarkable characteristics for replacing conventional catalysts, mainly due to its stability and the potential for increasing the CO₂ desorption rate. However, limited studies have been conducted to evaluate the performance of the CO₂ desorption process, especially by utilizing commercial solvents such as piperazine (PZ) promoted methyldiethanolamine (MDEA). Hence, this study aims to evaluate the stability of TiO(OH)₂ as a catalyst during the CO₂ desorption process using various characterization techniques. The CO₂ desorption performance is also assessed under different operating conditions. Moreover, the regeneration energy is determined and reported as the sensible heat duty per released CO₂. The results show no significant difference between fresh and cycled TiO(OH)₂, indicating its substantial thermal stability. Furthermore, a notable rise of 19.58% is observed in desorption rate while utilizing TiO(OH)₂ with a mass concentration of 5 wt%, reflecting less energy consumption. These findings suggest that TiO(OH)₂ could serve as a transformative catalyst in industrial-scale CO₂ desorption processes, potentially paving the way for more sustainable CO₂ capture technologies. Full article

This study utilizes aqueous solutions of organic amines as extractants to remove phenolic compounds from coal tar. It elucidates the extraction mechanism between phenolic compounds and organic amines, and conducts a comprehensive investigation into the extraction performance of various monomeric organic amine aqueous solutions and their composite solutions for phenolic compounds in model oils or light coal tar. The experimental results showed that monoethanolamine (MEA), characterized by a higher reaction equilibrium constant, exhibits superior extraction performance for phenolic compounds in light coal tar compared to diethanolamine (DEA), triethanolamine (TEA), methyldiethanolamine (MDEA), and diethylaminoethanol (DEAE) when used at the same mass concentration of extractant. The addition of a specific concentration of DEA or TEA to a 20 wt%–25 wt% MEA solution significantly reduces the entrainment of neutral oil impurities during the extraction process and enhances the precipitation of phenolic compounds during the acidification phase. Under the optimal process parameters, the composite aqueous solution, comprising 25 wt% MEA, 5 wt% DEA, and 5 wt% TEA, demonstrated a 35.1 wt% increase in the acidification yield of phenolic compounds, Y_a,P, a 20.8 wt% increase in the total yield of phenolic compounds, Y_P, and a 46.0% significant decrease in neutral oil entrainment compared to the solution with a 30% MEA aqueous solution. Full article

Carbon dioxide (CO₂) is the primary component contributing to anthropogenic greenhouse gas emissions, necessitating the adoption of effective mitigation strategies to promote environmental sustainability. Among the various carbon capture methodologies, chemical absorption is acknowledged as the most scalable solution for post-combustion applications. This investigation presents a thorough, comparative, and scenario-based evaluation of both singular and blended amine solvents for CO₂ capture within packed absorption–desorption columns. A validated rate-based model employing monoethanolamine (MEA) functions as the benchmark for executing process simulations. Three sequential scenarios are meticulously examined to switch the solvents and see the results. In the preliminary scenario, baseline performance is assessed by applying MEA to achieve the designated 73% removal target. Then the implementation of alternative solvents is examined—piperazine (PZ), a combination of methyldiethanolamine (MDEA) and PZ, and a blend of MEA and PZ—under uniform design parameters to ascertain their relative effectiveness and performance. In the second scenario, the design of the system is changed to reach a CO₂ removal efficiency for MEA of 90%, and then MEA is switched to other solvents. In the final scenario, critical design parameters, including column height and diameter, are adjusted for each solvent system that did not meet the 90% capture efficiency in Scenario 2 to achieve 90% CO₂ capture. A comprehensive sensitivity analysis is subsequently conducted on the adjusted systems to evaluate the influence of critical operational variables such as temperature, flue gas and solvent flow rates, and concentrations. Importantly, the MEA + PZ blend also demonstrated the lowest specific reboiler duty, as low as 4.28 MJ/kg CO₂, highlighting its superior energy efficiency compared to other solvents in the condition that the system in this study is pilot-scale, not commercial-scale, and due to this reason, the energy consumption of the system is slightly higher than the reported value for the commercial-scale systems. The results yield invaluable insights into the performance trade-offs between singular and blended amines, thereby facilitating the development of more efficient CO₂ capture systems that function within practical constraints. Full article

The synthesis of high performance catalysts for the catalytic wet oxidation (CWO) of N-methyldiethanolamine (MDEA) in water remains a challenge, and is a topic of considerable importance in relation to sustainability. In this paper, a Ru-CN_x/CeO₂ catalyst was synthesized through a modified impregnation process for the CWO of MDEA, exhibiting a high activity of 80% COD removal at 180 °C and 2.5 MPa. EPR, Raman, and XPS characterizations revealed that the CN_x species facilitated the reduction in Ru⁴⁺ to Ru⁰ species and enhanced the Ru–Ce interaction to form a high-density Ru-O-Ce structure with Ce³⁺ sites, which strongly correlate to the generation of oxygen vacancies. The oxygen vacancies enabled the adsorption and activation of the oxygen, generating active species (h⁺, ·O₂⁻, and ·OH) that effectively oxidized the MDEA during the catalytic reaction. Full article

In chemical absorption for carbon capture, the regeneration heat is a key factor determining solvent regeneration energy consumption, and the sterically hindered amine 2-amino-2-methyl-1-propanol (AMP) has great potential for application. In this paper, a CO₂ reaction heat measurement system designed and constructed by our team was used to perform a comparative study on AMP and monoethanolamine (MEA). Moreover, five additives—MEA, diglycolamine (DGA), diethanolamine (DEA), methyldiethanolamine (MDEA), and piperazine (PZ)—were introduced into AMP-based solutions to investigate the promotion performance of these blended solvents. The results revealed that although AMP exhibited a slower absorption rate compared to MEA, it demonstrated a higher CO₂ loading capacity and cyclic capacity, as well as a lower reaction heat, making it advantageous in terms of regeneration energy consumption. At the same total concentration, the absorption capacity of blended solutions (excluding AMP-MEA solutions) was generally lower than that of single-component AMP solutions. Among these additives, MEA and PZ could enhance the absorption rate clearly yet increase the reaction heat at the same time; DGA and DEA could decrease the overall absorption performance. Generally, AMP-MDEA solutions showed the best desorption performance, with the 15 wt% AMP + 5 wt% MDEA mixture demonstrating the lowest regeneration heat and good cyclic capacity. Full article

The increase in atmospheric CO₂ caused by human activities has driven the development of technologies to capture this gas before it reaches the atmosphere. This study analyzed CO₂ sorption using amine-based solvents, such as methyldiethanolamine (MDEA), diethylenetriamine (DETA), triethanolamine (TEA), and monoethanolamine (MEA) in 40 wt.% aqueous solutions, under high-pressure conditions (initial pressure: 500 psia) and room temperature (30 °C), in both non-stirred and stirred systems. Piperazine (PZ), a heterocyclic compound, was tested as an additive to improve the kinetics of the CO₂ sorption process. Kinetic and thermodynamic analyses were conducted to evaluate the efficiency of each amine-based solution in terms of reaction rate and CO₂ loading capacity. MEA and TEA exhibited higher reaction rates, while DETA and MDEA were the most thermodynamically efficient due to the highest CO₂ loading capacity. The PZ kinetic behavior depended on the equipment used; in the non-stirred system, no kinetic effect was observed, while in the stirred system, this effect was appreciable. Additionally, a corrosivity study revealed that MEA, a primary amine, was the most corrosive, whereas TEA, a tertiary amine, was the least corrosive. Full article

Traditional alkanolamine absorption methods for CO₂ capture suffer from significant absorbent loss and high regeneration energy consumption. To address this issue, novel blended alkanolamine formulations based on monoethanolamine (MEA), methyldiethanolamine (MDEA) and 2–amino–2–methyl–1–propanol (AMP) were investigated. Based on the optimization of CO₂ absorption conditions, a low–temperature and high–efficiency microwave heating desorption method for CO₂ was proposed, and the microwave heating desorption process of a CO₂ alkanolamine absorption solution was optimized. The results show that when the mass ratio of monoethanolamine (MEA), methyldiethanolamine (MDEA) and 2–amino–2-methyl–1–propanol (AMP) was 4:5:1, the composite alkanolamine solution with a concentration of 20% had the best absorption effect at an absorption temperature of 30 °C. The desorption efficiency of this group of formulations at 95 °C reached 89% in 4 min. Compared with the traditional heating desorption method, the CO₂ desorption rate of the microwave heating method at 95 °C increased by 62%, the desorption time was significantly shortened, and the energy consumption was significantly reduced. This study provides a new research direction for the efficient and low-energy desorption of CO₂ by blended alkanolamine. Full article

This study employs Density Functional Theory (DFT) calculations and traditional all-atom Molecular Dynamics (MD) simulations to reveal atomistic insights into a task-specific Deep Eutectic Solvent (DES) supported by graphene oxide with the aim of mimicking its application in the natural gas desulfurization process. The DES, composed of N,N,N′,N′-tetramthyl-1,6-hexane diamine acetate (TMHDAAc) and methyldiethanolamine (MDEA) supported by graphene oxide, demonstrates improved efficiency in removing hydrogen sulfide from methane. Optimized structure and HOMO-LUMO orbital analyses reveal the distinct spatial arrangements and interactions between hydrogen sulfide, methane, and DES components, highlighting the efficacy of the DES in facilitating the separation of hydrogen sulfide from methane through DFT calculations. The radial distribution function (RDF) and interaction energies, as determined by traditional all-atom MD simulations, provide insights into the specificity and strength of the interactions between the DES components supported by graphene oxide and hydrogen sulfide. Importantly, the stability of the DES structure supported by graphene oxide is maintained after mixing with the fuel, ensuring its robustness and suitability for prolonged desulfurization processes, as evidenced by traditional all-atom MD simulation results. These findings offer crucial insights into the molecular-level mechanisms underlying the desulfurization of natural gas, guiding the design and optimization of task-specific DESs supported by graphene oxide for sustainable and efficient natural gas purification. Full article

Hydrogen is an industrial raw material both for the production of chemicals and for oil refining with hydrotreating. It is the subject of increasing attention for its possible use as an energy carrier and as a flexible energy storage medium. Its production is generally accomplished in Steam Methane Reforming (SMR) plants, where a gaseous mixture of CO and H₂, with a limited number of other species, is obtained. The process of production and purification generates relevant amounts of carbon dioxide, which needs to be removed due to downstream process requirements or to limit its emissions to the atmosphere. A work by IEAGHG focused on the study of a state-of-the-art Steam Methane Reforming plant producing 100 kNm³/h of H₂ and considered chemical absorption with MethylDiEthanolAmine (MDEA) solvent for removing carbon dioxide from the PSA tail gas in a baseline scheme composed of the absorber, one flash vessel and the regeneration column. This type of process is characterized by high energy consumption, in particular at the reboiler of the regeneration column, usually operated by employing steam, and modifications to the baseline scheme can allow for a reduction of the operating costs, though with an increase in the complexity of the plant. This work analyses three configurations of the treatment section of the off gas obtained after the purification of the hydrogen stream in the Pressure Swing Adsorption unit with the aim of selecting the one which minimizes the overall costs so as to further enhance Carbon Capture and Storage in non-power industries as well. Full article

This study explores the stability of electrodeposited copper catalysts utilized in electrochemical CO₂ reduction (ECR) across various amine media. The focus is on understanding the influence of different amine types, corrosion ramifications, and the efficacy of pulse ECR methodologies. Employing a suite of electrochemical techniques including potentiodynamic polarization, linear resistance polarization, cyclic voltammetry, and chronopotentiometry, the investigation reveals useful insights. The findings show that among the tested amines, CO₂-rich monoethanolamine (MEA) exhibits the highest corrosion rate. However, in most cases, the rates remain within tolerable limits for ECR operations. Primary amines, notably monoethanolamine (MEA), show enhanced compatibility with ECR processes, attributable to their resistance against carbonate salt precipitation and sustained stability over extended durations. Conversely, tertiary amines such as methyldiethanolamine (MDEA) present challenges due to the formation of carbonate salts during ECR, impeding their effective utilization. This study highlights the effectiveness of pulse ECR strategies in stabilizing ECR. A noticeable shift in cathodic potential and reduced deposit formation on the catalyst surface through periodic oxidation underscores the efficacy of such strategies. These findings offer insights for optimizing ECR in amine media, thereby providing promising pathways for advancements in CO₂ emission reduction technologies. Full article

A series of cationic waterborne polyurethane (CWPU) emulsions was synthesized with isophorone diisocyanate (IPDI) and hexamethylene diisocyanate (HDI) as hard segments; polyol (N210) and polyethylene glycol (PEG-2000) as soft segments; N-methyldiethanolamine (MDEA) as a hydrophilic chain extender; and trimethylolpropane (TMP) as a crosslinker. Then, the effects of the R-value, MDEA content, and TMP content on the properties of the CWPU emulsion, film, and fabric treatment were investigated. The results indicated that when the R-value was 3.0, the MEDA content accounted for 4.0% of the solid and the TMP content accounted for 1.0% of the solid. CWPU has excellent storage stability. Applying it to the fixing treatment of the viscose fiber fabrics can effectively improve the color fastness to rubbing, elasticity, surface smoothness, and anti-static properties. Full article

Vinyl-capped cationic waterborne polyurethane (CWPU) was prepared using isophorone diisocyanate (IPDI), polycarbonate diol (PCDL), N-methyldiethanolamine (MDEA), and trimethylolpropane (TMP) as raw materials and hydroxyethyl methacrylate (HEMA) as a capping agent. Then, a crosslinked FPUA composite emulsion with polyurethane (PU) as the shell and fluorinated acrylate (PA) as the core was prepared by core-shell emulsion polymerization with CWPU as the seed emulsion, together with dodecafluoroheptyl methacrylate (DFMA), diacetone acrylamide (DAAM), and methyl methacrylate (MMA). The effects of the core-shell ratio of PA/PU on the surface properties, mechanical properties, and heat resistance of FPUA emulsions and films were investigated. The results showed that when w(PA) = 30~50%, the stability of FPUA emulsion was the highest, and the particles showed a core-shell structure with bright and dark intersections under TEM. When w(PA) = 30%, the tensile strength reached 23.35 ± 0.08 MPa. When w(PA) = 50%, the fluorine content on the surface of the coating film was 14.75% and the contact angle was as high as 98.5°, which showed good hydrophobicity; the surface flatness of the film was observed under AFM. It is found that the tensile strength of the film increases and then decreases with the increase in the core-shell ratio and the heat resistance of the FPUA film is gradually increased. The FPUA film has excellent properties such as good impact resistance, high flexibility, high adhesion, and corrosion resistance. Full article

As the most mature natural gas sweetening process, absorption has always been improved to meet the separation requirement. Recently, ultrasonic irradiation has been proposed as a technique that can intensify CO₂ absorption. However, further studies are still required, particularly focusing on the sonochemical effect. Since the influence of the sonochemical effect on the reaction pathway is still debatable, attention must be given to verifying the influence of ultrasonic irradiation on the chemical reactions of CO₂ absorption. Hence, this work aims to evaluate the influence of $\dot{\mathrm{O}\mathrm{H}}$ radicals generated by the sonochemical effect on the chemical reactions involved during CO₂ absorption using promoter-free methyldiethanolamine (MDEA). For the evaluation, various samples under irradiated and non-irradiated conditions are analyzed using the HPLC characterization technique. The results show that the hypothesis of changing the reaction pathway due to the presence of the sonochemical effect is invalid. However, it can accelerate the generation of hydroxyl radicals ($\dot{\mathrm{O}\mathrm{H}}$) via water sonolysis. Thus, the origin of sonochemistry in aqueous solutions is defined as water sonolysis. The analysis of the CO₂ absorption rate also demonstrates the presence of accelerated chemical reactions (contributed by the $\dot{\mathrm{O}\mathrm{H}}$ radicals), which could potentially make the slow kinetic MDEA more practical for industrial application. Full article