Gas Sweetening Research Articles

Direct CO2 mineralization using seawater reverse osmosis brine facilitated by hollow fiber membrane contactor

The urgent demand for sustainable water management has given rise to widespread seawater desalination, leading to significant brine waste and a substantial carbon footprint resulting from extensive energy consumption. To address this challenge, we propose the utilization of hollow fiber membrane contactors (HFMCs) for direct CO2 mineralization. By mimicking lotus leaf surfaces, HFMs are successfully modified to possess superhydrophobic and antifouling properties, resulting in enhanced operational stability, as evidenced by a marginal 3.5 % flux decline after 10 days. Moreover, HFMCs incorporating these modified membranes achieve remarkable CO2 removal (up to 94 %) and selective mineral carbonation of Ca2+ and Mg2+ through staged pH swing. A techno-economic analysis highlights the superiority of our system compared to traditional amine scrubbing, with a 35 % reduction in CO2 capture costs and the generation of valuable products. This innovative application of HFMCs presents a promising solution for CO2 management, transforming seawater reverse osmosis brine into a valuable resource.

Blended-amine CO2 capture process without stripper for high-pressure syngas

With the emergence of the hydrogen economy, advanced CO2 capture technologies are essential for cost-effective H2 production until renewable-energy based H2 production technologies gains competitiveness. A novel stripper-free pre-combustion CO2 capture process, in which the stripper was replaced with a low-pressure (LP) flash column, was developed for cost-effective pre-combustion CO2 capture from H2-rich syngas at high pressure. The developed process could regenerate the blended N-methyldiethanolamine/piperazine (MDEA/PZ) solvent at relatively low temperature (<373.15 K). After the sensitivity analysis using key operating parameters, process optimization was performed by the deep learning-based surrogate models using non-dominated sorting genetic algorithm-II (NSGA-Ⅱ). The heat duty of 1.881GJ/tonCO2 was required at the optimal condition, but the required energy could be supplied through the utilization of a waste heat recovery (WHR) system because the regeneration was possible at low temperatures. Compared with advanced stripper-incorporated amine processes, the equivalent work of the developed process with WHR system using a heat source at 370 K was lowered by 50 % and more cost-effective (32.89$/tonCO2 at the discount rate of 10 %) from the economic analysis considering carbon emission price. The performance assessment of the stripper-free CO2 capture process provided design guidelines for effective CO2 capture from H2-rich syngas and emphasized the importance of CO2 capture unit in net-zero scenario.

Integrated experimental and theoretical studies for unravelling CO2 capture of dual function CeO2-CaO bio-based sorbents

Solid CaO-based sorbents for CO2 capture represent a promising alternative technology compared to traditional amine scrubbing methods. However, CaO-based sorbents are rapidly sinter and easily decrease CO2 uptake capacity with regenerated carbonation–calcination cycle. Thus, in this study, doping CaO with CeO2 make it an excellent candidate for improving stability and facilitating CO2 capture efficiency. The dual function of CaO bio-based sorbents with varying ratios of cerium (Ce) were derived from naturally occurring blood clam using the gel-combustion method. Their nanostructures and physicochemical properties were characterized through the specific methods, including in situ XAS, CO2 chemisorption and physisorption, XPS, XRD, and SEM. An in-depth understanding of CO2 adsorption mechanism was further emphasized using a density functional theory (DFT) simulation. The results demonstrate that nanosized CeO2-CaO, with a mole ratio of 1:9, exhibited the highest performance for CO2 capture (6.44 mmol CO2/g sorbent). It is postulated that Ce serves as a physical barrier, effectively partitioning adjacent CaO grains and thereby diminishing the sintering rate. CaO is identified as the primary adsorption site, in contrast to CeO2. Mixing the Ce-Ca dual oxide initiates the electron-rich O at the O’ site. The electron localization at the O’ active site improves the activity of O’, making the performance CeCa(200) for capturing CO2 capture dominant. This discovery suggests that CeO2-CaO holds promise as a sustainable alternative sorbent for future CO2 capture applications.

Sulfur Migration Enhanced Proton-Coupled Electron Transfer for Efficient CO2 Desorption with Core-Shelled C@Mn3O4.

Transforming hazardous species into active sites by ingenious material design was a promising and positive strategy to improve catalytic reactions in industrial applications. To synergistically address the issue of sluggish CO2 desorption kinetics and SO2-poisoning solvent of amine scrubbing, we propose a novel method for preparing a high-performance core-shell C@Mn3O4 catalyst for heterogeneous sulfur migration and in situ reconstruction to active -SO3H groups, and thus inducing an enhanced proton-coupled electron transfer (PCET) effect for CO2 desorption. As anticipated, the rate of CO2 desorption increases significantly, by 255%, when SO2 is introduced. On a bench scale, dynamic CO2 capture experiments reveal that the catalytic regeneration heat duty of SO2-poisoned solvent experiences a 32% reduction compared to the blank case, while the durability of the catalyst is confirmed. Thus, the enhanced PCET of C@Mn3O4, facilitated by sulfur migration and simultaneous transformation, effectively improves the SO2 resistance and regeneration efficiency of amine solvents, providing a novel route for pursuing cost-effective CO2 capture with an amine solvent.

Optimal operation of a natural gas sweetening plant

The most common method of removing acid gases from natural gas is through the use of solvent-based gas sweetening plants, which are energy-intensive. The present study aims to establish a plant-wide structure to operate natural gas sweetening plants optimally. Thus, a steady-state simulation of the Khangiran plant was carried out, and a 17% reduction in energy usage was achieved as a result of the optimization by the application of surrogate models. The self-optimizing method was applied to find the best set of controlled variables (CVs). There was found one unconstrained degree of freedom (DOF). The best CV for the remaining DOF was found to be the top stage temperature of the regenerator. Aspen Plus Dynamics was used to examine the performance of the proposed control structure utilizing simple traditional PIDs and compare it to modern feedback and feedforward MPCs.

Sp3 -Rich Heterocycle Synthesis on DNA: Application to DNA-Encoded Library Production.

DNA encoded library (DEL) synthesis represents a convenient means to produce, annotate and store large collections of compounds in a small volume. While DELs are well suited for drug discovery campaigns, the chemistry used in their production must be compatible with the DNA tag, which can limit compound class accessibility. As a result, most DELs are heavily populated with peptidomimetic and sp2 -rich molecules. Herein, we show that sp3 -rich mono- and bicyclic heterocycles can be made on DNA from ketochlorohydrin aldol products through a reductive amination and cyclization process. The resulting hydroxypyrrolidines possess structural features that are desirable for DELs and target a distinct region of pharmaceutically relevant chemical space.

Sp3‐Rich Heterocycle Synthesis on DNA: Application to DNA‐Encoded Library Production

AbstractDNA encoded library (DEL) synthesis represents a convenient means to produce, annotate and store large collections of compounds in a small volume. While DELs are well suited for drug discovery campaigns, the chemistry used in their production must be compatible with the DNA tag, which can limit compound class accessibility. As a result, most DELs are heavily populated with peptidomimetic and sp2‐rich molecules. Herein, we show that sp3‐rich mono‐ and bicyclic heterocycles can be made on DNA from ketochlorohydrin aldol products through a reductive amination and cyclization process. The resulting hydroxypyrrolidines possess structural features that are desirable for DELs and target a distinct region of pharmaceutically relevant chemical space.

Amino-λ3 -iodane-Enabled Electrophilic Amination of Arylboronic Acid Derivatives.

In this report, we describe the use of amino-λ3 -iodanes in the electrophilic amination of arylboronic acids and boronates. Iodine(III) reagents with transferable amino groups, including one with an NH2 group, were synthesized and used in the amination, allowing the synthesis of a wide range of primary and secondary (hetero)arylamines. Mechanistic studies by DFT calculations indicate that the reaction proceeds through an electrophilic amination process from a tetravalent borate complex with a B-N dative bond.

Amino‐λ3‐iodane‐Enabled Electrophilic Amination of Arylboronic Acid Derivatives

AbstractIn this report, we describe the use of amino‐λ3‐iodanes in the electrophilic amination of arylboronic acids and boronates. Iodine(III) reagents with transferable amino groups, including one with an NH2 group, were synthesized and used in the amination, allowing the synthesis of a wide range of primary and secondary (hetero)arylamines. Mechanistic studies by DFT calculations indicate that the reaction proceeds through an electrophilic amination process from a tetravalent borate complex with a B−N dative bond.

Conjugated Microporous Polymers for Catalytic CO2 Conversion.

Rising carbon dioxide (CO2) levels in the atmosphere are recognized as a threat to atmospheric stability and life. Although this greenhouse gas is being produced on a large scale, there are solutions to reduction and indeed utilization of the gas. Many of these solutions involve costly or unstable technologies, such as air-sensitive metal-organic frameworks (MOFs) for CO2 capture or "non-green" systems such as amine scrubbing. Conjugated microporous polymers (CMPs) represent a simpler, cheaper, and greener solution to CO2 capture and utilization. They are often easy to synthesize at scale (a one pot reaction in many cases), chemically and thermally stable (especially in comparison with their MOF and covalent organic framework (COF) counterparts, owing to their amorphous nature), and, as a result, cheap to manufacture. Furthermore, their large surface areas, tunable porous frameworks and chemical structures mean they are reported as highly efficient CO2 capture motifs. In addition, they provide a dual pathway to utilize captured CO2 via chemical conversion or electrochemical reduction into industrially valuable products. Recent studies show that all these attractive properties can be realized in metal-free CMPs, presenting a truly green option. The promising results in these two fields of CMP applications are reviewed and explored here.

A comparison between Claus and THIOPAQ sulfur recovery techniques in natural gas plants

A sulfur recovery process is one of the most important processes in the oil and gas industry to get rid of hydrogen sulfide (H2S) which is produced from the acid gas removal process of sour natural gas to convert it into sweet natural gas. Actual data from a gas field is used to obtain a realistic comparison between two sulfur recovery techniques, through which researchers and/or manufacturers can obtain information that will help them choose the most appropriate and cheapest method. A total feed acid gas flow rate of 5.1844 MMSCFD with an H2S concentration of 24.62% by mole percent was produced from amine acid gas removal units. Claus sulfur recovery technique is a traditional chemical process that uses thermal and catalytic reactors. Therefore, an acid gas enrichment unit is applied to increase the H2S concentration to approximately 50% mole to provide reliable and flexible operation in the thermal and catalytic reactors. Moreover, a tail gas treatment unit is applied to increase the overall conversion efficiency to 99.90% with the Claus technique instead of 95.08% without it to achieve high sulfur recovery and reliable operation through the conversion of carbonyl sulfide (COS) and mercaptans. Studies on the safety and simplicity of the Claus technique revealed many important hazards and a large number of transmitters (379) and control loops (128) in one Claus train. THIOPAQ sulfur recovery as a new technology is a biological desulfurization process that uses a natural mixture of sulfide-oxidizing bacteria. It is also a unique H2S removal process with an efficiency of 99.999%. In addition, studies on the safety and simplicity of the THIOPAQ technique have shown that the hazards, the number of transmitters (74), and the number of control loops (29) of a one THIOPAQ train are lower. The THIOPAQ technique showed higher efficiency, was safer, simpler, and had lower CAPEX and OPEX. This study was conducted using Aspen HYSYS V11 and actual data.

Membranes and membrane processes for CO2 separation: MEMFO's long-term effort in reducing carbon emissions

Urgent actions are needed to reduce CO2 emissions and mitigate the increasingly severe impacts of climate change. Since the 1990s, the membrane research group (MEMFO) at the Norwegian University of Science and Technology has been committed to developing effective membranes and membrane processes for CO2 separation. MEMFO's research can be categorized into five main themes: facilitated transport membranes, hybrid membranes, carbon membranes, membrane contactors, and related modeling and process simulation. These themes are tied to industrial applications in CO2 capture from flue gas, biogas upgrading, natural gas sweetening, and hydrogen purification. Promising membranes, identified based on their laboratory-scale performances, have been selected for onsite testing in industrial processes to validate their performances as well as stability and durability. Verified membranes are upscaled for pilot tests. This account paper summarizes MEMFO's research and development outcomes over the past decade and discusses our research strategies and perspectives for future work.

Demonstration of water-lean 30 wt% MEA + 15 wt% MEG with rich solvent recycle for biogas upgrading

This study investigates the potential of a water-lean 30 wt% monoethanolamine (MEA) solvent for biogas upgrading. The solvent consists of 30 wt% MEA, 15 wt% monoethyleneglycol (MEG), and 55 wt% water at zero loading. The solvent is investigated using a mobile pilot scale amine scrubbing unit, with a capacity of 1 ton CO2 per day, with the option to utilize a rich solvent recycle (RSR) configuration. Without the RSR configuration, the water-lean solvent obtains a low rich loading of 0.46 mol/mol resulting in a specific reboiler duty (SRD) of 3.92 MJ per kg CO2, which is 6 % higher compared to aqueous 30 wt% MEA. Combining the RSR configuration with cooling enables a higher rich loading of 0.49 mol/mol and decreases the SRD to 3.48 MJ per kg CO2, which is 6% lower than for aqueous 30 wt% MEA. It is found that 30 wt% MEA + 15 wt% MEG only achieves lower SRD than aqueous 30 wt% MEA if similar rich loading can be achieved. By measuring emissions from the absorber and stripper columns, it was found that MEG and MEA form 2-methyl-dioxolane resulting in increased emissions when utilizing this water-lean solvent.

Air pollution impacts of amine scrubbing for CO2 capture

The current political discussion in the United States around carbon capture and storage includes statements that suggest a need for a technical review to clarify the expected air pollution impacts of amine scrubbing. The Center for International Law and 50 other organizations published an open letter claiming that “CCS is not consistent with the principles of environmental justice… CCS makes dirty energy even more dangerous for frontline communities. Facilities equipped with carbon capture technology have to burn more fossil fuel to get the same energy output, resulting in increased emissions of toxic and hazardous pollutants, like fine particulates (PM2.5).”This paper reviews air pollutants produced by the use of amine scrubbing on coal- and gas-fired power plants in the U.S. and the process features and mitigation strategies that will minimize their impact on air quality. Even with atmospheric reactions, emissions of amine, nitrosamine, and other air toxics are likely to have insignificant environmental and health impacts. Stacks will disperse emissions with a dilution factor greater than 8000. Water wash with or without acid will reduce emissions of amine and nitrosamine that is produced from atmospheric reactions. Nitrosamine emissions will be managed with selective catalytic reduction (SCR) to reduce the NO/NO2 and/or selection of primary or non-volatile amines. With coal-fired power plants, amine aerosols, Hg, SO3, and fine particulate emissions will probably be managed by a fabric filter with alkali addition. Carbon capture by amine scrubbing will reduce significantly the effect of the power plant emissions on ambient levels of PM2.5. With coal-fired power plants, the application of amine scrubbing will significantly reduce SO2 emissions. NOx emissions will usually be minimized by selective catalytic reduction (SCR) in both gas- and coal-fired plants. Ammonia emissions will be minimized by managing amine oxidation, and if necessary, by adding an acid wash or other controls.

Iterative real-time optimization of a reductive amination process in a thermomorphic multiphase system

In this paper, we discuss the optimization of the operation of a reductive amination (RA) reaction process in a miniplant without an accurate process model using iterative real-time optimization (RTO). The rhodium-catalyzed RA of undecanal with diethylamine produces a tertiary amine from a long-chain aldehyde and is performed in a thermomorphic multiphase system (TMS) to recover and reuse the expensive catalyst efficiently. An iterative RTO method called modifier adaptation with quadratic approximation (MAWQA) is used in combination with guaranteed model adequacy (GMA) to drive the RA process to its optimum iteratively. MAWQA utilizes online measurements to overcome model deficiencies. GMA ensures that the model used in MAWQA satisfies the model adequacy conditions. The optimal operating conditions of the RA process in the miniplant were identified during an experimental run of the plant, thereby validating the applicability and efficiency of MAWQA with GMA. The results illustrate the benefits of process optimization using iterative RTO methods without accurate process models.

Observing C-N bond formation in plasma: a case study of benzene and dinitrogen coupling via an arylnitrenium ion intermediate.

Directly fixing dinitrogen into value-added organics is one of the core issues, and yet a long-standing challenge, in chemical synthesis. In earlier discrete studies, direct amination of benzene with N2 has been achieved via non-thermal plasma-liquid reaction. Nonetheless, the reaction mechanism thereof remains elusive and the amination product was non-selective primarily including aniline and diphenylamine. Herein, non-thermal plasma reaction in combination with on-line mass spectrometry was employed to probe the reaction pathway by on-line detection of the transient intermediate and the stable amination product. The long-lived atomic nitrogen ions N+(3P) as well as the arylnitrenium ions' intermediacy were shown to play a pivotal role in the amination process, and the product distribution was affected by an external hydrogen source and likely dependent on the competing hydrogen abstraction reaction and intersystem crossing of the initially generated triplet state arylnitrenium ions. The mechanistic investigation in this work has implications for plasma-based nitrogen conversion into organics, but also has broader relevance for understanding the C-N coupling by other means directly with N2.

Minimalization of Dissolved Heavy Hydrocarbon on Lean Solvent with Absorption Optimization

Pertamina EP DonggiMatindok Field has an Acid Gas Removal Unit (AGRU)which is an acid gas (H2S) separator unit that flows from the LP Separator. An increase of pressure differential occurred in the AGRU indicates a foaming tendency and impacting on decrease in sales gas. The well switch method was carried out to overcome foaming event by opening the manual valve in stages from 25%, 50%, 75% and 100% with waiting time of 30 minutes each stage. Besides, solvent flow adjustment is carried out using HYSYS simulation to find optimal solvent flow requirements through ratio of flow balance between feed gas and lean solvent. This method aims to minimize heavy hydrocarbons dissolved in the solvent by optimizing absorption process. After implementing this method, a decrease occurred in the average solvent flow of 2,308 BPD at 10 MMSCFD feed gas, the pressure differential relatively stable at 3-4 psig which indicate no foaming event. Laboratory result shows that Heavy Hydrocarbon Content parameter were 60 mg/L and Particulate Matter Content (&gt;0.45µm) was 22 mg/L. This method also extends the lifecycle of the solvent and has an impact on reducing the solvent packaging waste which categorized as toxic and hazardous waste.

Insights into the role of the H-abstraction reaction kinetics of amines in understanding their degeneration fates under atmospheric and combustion conditions.

Amines, a class of prototypical volatile organic compounds, have garnered considerable interest within the context of atmospheric and combustion chemistry due to their substantial contributions to the formation of hazardous pollutants in the atmosphere. In the current energy landscape, the implementation of carbon-neutral energy and strategic initiatives leads to generation of new amine sources that cannot be overlooked in terms of the emission scale. To reduce the emission level of amines from their sources and mitigate their impact on the formation of harmful substances, a comprehensive understanding of the fundamental reaction kinetics during the degeneration process of amines is imperative. This perspective article first presents an overview of both traditional amine sources and emerging amine sources within the context of carbon peaking and carbon neutrality and then highlights the importance of H-abstraction reactions in understanding the atmospheric and combustion chemistry of amines from the perspective of reaction kinetics. Subsequently, the current experimental and theoretical techniques for investigating the H-abstraction reactions of amines are introduced, and a concise summary of research endeavors made in this field over the past few decades is provided. In order to provide accurate kinetic parameters of the H-abstraction reactions of amines, advanced kinetic calculations are performed using the multi-path canonical variational theory combined with the small-curvature tunneling and specific-reaction parameter methods. By comparing with the literature data, current kinetic calculations are comprehensively evaluated, and these validated data are valuable for the development of the reaction mechanism of amines.

Simulation and Optimization of Gas Sweetening Plant of Iraq Majnoon Refinery

Simulation and Optimization of Gas Sweetening Plant of Iraq Majnoon Refinery

Modular synthesis of α-branched secondary alkylamines via visible-light-mediated carbonyl alkylative amination.

The development of methods for the assembly of secondary α-alkyl amines remains a central challenge to chemical synthesis because of their critical importance in modulating the physical properties of biologically active molecules. Despite decades of intensive research, chemists still rely on selective N-alkylation and carbonyl reductive amination to make most amine products. Here we report the further evolution of a carbonyl alkylative amination process that, for the first time, brings together primary amines, aldehydes and alkyl iodides in a visible-light-mediated multicomponent coupling reaction for the synthesis of a wide range of α-branched secondary alkylamines. In addition to exploring the tolerance and limitations in each reaction component, we also report preliminary applications to the telescoped synthesis of α-branched N-heterocycles and an N-alkylation protocol that is selective for primary over cyclic secondary amines. Our data support a mechanism involving addition of an alkyl radical to an uncharged alkyl imine which, to the best of our knowledge, has not previously been described. We believe that this method will enable practitioners of synthetic chemistry in academic and industrial settings to approach the synthesis of these important molecules in a manner that is streamlined compared to established approaches.