Natural Gas Processing Research Articles

Monitoring of group-structured high-dimensional processes via sparse group LASSO

In a general high-dimensional process, a large number of process parameters or quality characteristics is found to be featured through their dependencies and relevance. The features that have similar characteristics or behaviors in the process operation can be categorized into multiple groups. Thus, when a few quality characteristics in the process change, it is highly probable that the process shift would have occurred in a few relevant groups. Recently, several advanced statistical process control techniques are developed to monitor the changes in high-dimensional processes under sparsity. However, monitoring schemes that utilize the grouped pattern of the quality characteristics are sparse. This paper proposes a new method to monitor the high-dimensional process when the grouped structure of the process data is observed. The proposed method identifies the potentially changed groups and individual variables within the groups based on a modified sparse group LASSO (MSGL) model. Then, a monitoring statistic is obtained using MSGL-based likelihood function to test abnormality of the process. Extensive numerical studies are conducted to demonstrate the effectiveness and efficiency of the proposed method. In addition, a real-life application of a liquefied natural gas process is presented to illustrate the proposed method.

Prediction of variables involved in TEG Dehydration using hybrid models based on boosting algorithms

The extraction of gas from fields often involves impurities, necessitating natural gas processing to separate these impurities. This process typically entails the removal of acid gases (such as carbon dioxide and hydrogen sulfide) and dehydration, commonly achieved through absorption using triethylene glycol (TEG). Efforts to minimize BTEX emissions and maintain optimal dry gas water content are pivotal for enhancing the economic and environmental sustainability of natural gas processing. In this study, the accurate prediction of BTEX and dry gas water contents is aimed by boosting-based methods and hybridization techniques. Four hybrid models, including XGBoost, CatBoost, HGBR, and LightGBoost, were developed in conjunction with the Arithmetic Optimization Algorithm (AOA) meta-heuristic algorithm to optimize and fine-tune hyperparameters. Through a comprehensive case study and comparison of various evaluation indices, the XGBoost-AOA hybrid model emerged as the most accurate in predicting both outputs. Hence, we recommend the XGBoost algorithm optimized with the AOA algorithm as the preferred approach for predicting BTEX and dry gas water contents in natural gas processing.

Application of four intelligent models for the estimation of formation pressure of natural gas hydrate

Natural gas hydrate is a clean and efficient resource that contains lots of heat energy. The production, processing and transportation of natural gas can be influenced dramatically by natural gas hydrate. Natural gas hydrate will accumulate at the bottom of the pipeline, even block the pipeline and reduce the flow rate of the natural gas. This article presents four intelligent models named GWO-SVM (Grey Wolf Optimizer connected with Support Vector Machine), GWO-LSSVM (Grey Wolf Optimizer connected with Least Squares Support Vector Machine), GA-LSSVM (Genetic Algorithm connected with Least Squares Support Vector Machine), and GWO-RBF (Grey Wolf Optimizer connected with Radial Basis Function) to predict the formation pressure of natural gas hydrate in different systems. In order to determine the degree of influence of each input variable on the formation pressure of natural gas hydrate, this paper uses Spearman correlation analysis method to calculate the correlation coefficients between the formation pressure of natural gas hydrate and various influencing factors. The contradistinction among different intelligent models shows that the GWO-LSSVM model has the exceptional performance of the smallest average absolute relative deviation (AARD=2.89%), the minimum standard deviation (SD=0.05) with all 244 data of natural gas hydrate formation pressure in different systems. When compared to six commonly used empirical models for predicting formation pressure in common natural gas hydrate, the GWO-LSSVM model has the highest prediction accuracy, with an AARD of only 1.82%. Furthermore, when compared to three thermodynamic models employed for predicting formation pressure in sour natural gas hydrate, the GWO-LSSVM model has the highest prediction accuracy, with an AARD of 2.38%. The leverage method demonstrates that four intelligent models have excellent robustness in reflecting the inner relationships among natural gas hydrate formation pressure and influential factors. The four intelligent models for predicting hydrate formation pressure will be helpful to find hydrate formation pressure in different systems.

Enhancing liquefied petroleum gas production through debutanizer column optimization

Debutanizer columns are important in natural gas processing as they are crucial in generating Liquefied Petroleum Gas (LPG). LPG is well recognised for its environmentally benign combustion properties, making it a desirable fuel option for cooking, heating, and transportation. The optimisation of debutanizer units has significant relevance in improving the efficiency of LPG separation. This study aims to enhance the separation efficiency of a butane removal tower by modelling and optimising its operation using HYSYS software. The research aims to introduce innovation in this field. A series of comprehensive simulations were carried out to achieve this goal, resulting in outcomes that nearly corresponded to the findings obtained from natural gas units. Moreover, a thorough examination was conducted to examine the impact of temperature, pressure, feed flow rate, and reflux ratio on the production yield of n-butane. The study reached this conclusion by optimising tower conditions, with a particular emphasis on improving the performance of the condenser during the hot summer season. In ideal circumstances, the distillate demonstrated a butane concentration ranging from 70% to 74%, while all overhead gas is condensed in all instances. This study highlights the importance of optimising the debutanizer column in enhancing the quality and efficiency of LPG production in the natural gas processing sector.

Experimental demonstration of a sorption-enhanced methanation (SEM) cyclic process on a lab-scale TRL-3 fixed bed reactor

In this work, the scaling-up of the sorption-enhanced methanation (SEM) process to a TRL-3 fixed bed reactor has been demonstrated. The SEM process for synthetic natural gas (SNG) production consists mainly of two stages: in the first stage, the zeolite facilitates the removal of a product from the methanation reaction, thereby enhancing CO/CO2 conversion; in the second stage, zeolite regeneration takes place. The functional materials chosen were a zeolite 4A and a Nickel-based catalyst, selected for their high H2O adsorption capacity and high catalytic activity, respectively. Various operational variables, including temperature and pressure, were optimized during both SEM and regeneration stages to enhance the performance of the process. Optimum regeneration conditions consisted of pressure swing operation—from 10 bar during the SEM reaction to atmospheric pressure—while maintaining a constant temperature at 230°C. These operating conditions were tested for more than 20 SEM/regeneration cycles using a feed gas containing H2/CO/CO2. Stable performance throughout the cycles was fulfilled, reaching a CH4 purity of 100 % during 25 min during SEM for the operating conditions chosen. Finally, the number of reactors needed to obtain a continuous stream of CH4 was calculated resulting in a process productivity of 8.00×10-4 molCH4/kgcat·s.

Bench and pilot scale assessment of 5A molecular sieves for tail gas treatment applications

The modified Claus Process stands out as the predominant method for sulfur recovery within natural gas and crude oil processing facilities. Over the past five decades, in a bid to mitigate the environmental consequences of SO2 emissions, the efficiencies of sulfur recovery units have been enhanced through the integration of tail gas treating units (TGTU). Globally, it is imperative that this sulfur recovery efficiency attains a minimum of 99.95%. This paper delves into both bench- and pilot-scale evaluations of utilizing commercial 5 A molecular sieves to extract H2S from specific tail gas streams, as part of scrutinizing the efficacy of a novel tail gas treatment process, delineated in Patent No. US 10662061 B1 (May 26, 2020). The evaluation revealed that employing a 5 A molecular sieve to remove H2S from dry tail gas treating presents distinct advantages. Notably, the CO2 adsorption capacity on 5 A molecular sieves, being several times that of H2S, did not substantially impair the physical stability and removal capacity of 99.95+% tail gas treating, even after 99 adsorption/desorption cycles. Furthermore, the evaluation demonstrated that extended regeneration at 300°C (as opposed to 250°C) following the 50th and 90th cycles could effectively reinstate the original removal capacity of the 5 A molecular sieves. Additionally, the gas emanating from the 5 A molecular sieve bed could be reused as regeneration gas for the second stage of the patented process. The H2S removal capacity of 5 A molecular sieves from dry tail gas, approximately 1.3 mmol/g, aligns with the reported capacities of other adsorbents, which range from 0.37 to 1.53 mmol/g. Given the cost-effectiveness of 5 A molecular sieves compared to AgY molecular sieves, and based on the evaluation outcomes, it is judicious to conclude that the use of 5 A molecular sieves will be a compelling option for future tail gas treating within sulfur recovery units.

Обеспечение энергетической безопасности на основе развития внутреннего производства продуктов переработки природного газа

The article presents the results of a study of energy security processes based on the development of domestic production of natural gas processing products. The structure of the global ammonia market has been studied. The possibilities of the Russian Federation for the development of domestic processing of natural gas through the use of volumes previously exported to Europe have been identified.

Rigid-flexible coupled organosilica membranes toward high-efficiency molecules separation

Membrane-based technology has garnered significant interest in the separation and purification of molecules due to its inherent advantages, such as high efficiency, low energy consumption, and ease of operation. In this study, rigid-flexible coupled organosilica membranes were fabricated through co-polymerization using 1,2-bis(triethoxysilyl)acetylene (BTESA) containing rigid acetylene bridges and 1,2-bis(triethoxysilyl)propane (BTESP) containing flexible propane bridges. The incorporation of flexible propane bridges into BTESA networks allowed for precise adjustment of the network structures, resulting in composite BTESA-P membranes with improved molecular sieving properties. BTESA-P membrane demonstrated significant promise for applications in both CO2 capture and pervaporation (PV) dehydration due to its high potential. BTESA-P30 membrane, fabricated using the rigid-flexible coupled strategy, demonstrated a CO2 permeance of 3807 GPU and a CO2/N2 selectivity of approximately 40. These results surpassed those of numerous previously reported membranes, indicating significant potential for CO2 capture applications. BTESA-P30 membrane exhibited significant competitiveness in the decarbonization process of natural gas. More significantly, analogous occurrences are evident in gas permeation and PV separation process, where the permeation mechanism of gas and PV separation is primarily governed by molecular sieving. The utilization of diverse organosilica precursors in the rigid-flexible coupled strategy proposed in this study offers increased potential for membrane structure design and energy-efficient separation of molecules.

Techno-economic analysis of vacuum pressure swing adsorption process for a sustainable upgrading of biogas

Vacuum pressure swing adsorption (VPSA) has demonstrated promising features for the upgrading of biogas to biomethane. In this study, a biogas upgrading plant, comprised of a hybrid of an N-column VPSA unit (2 ≤N ≤ 6) with a combined heat and power (CHP) engine, was developed and its techno-economic characteristics were assessed via a mathematical approach. Moreover, the techno economic analysis was used for the state-of-the-art VPSA configuration (a sophisticated configuration) and compared with the developed hybrid process. The prominent parameters including feedstock transport, biogas production, desulfurization, drying, upgrading, combustion, and grid injection were considered in the analyses of the plant for the upgrading capacity in the range of 100–6500 Nm3/h. Sensitivity analysis of the most influencing parameters, i.e., electricity price, gas price, and feed processing revenues, was conducted for the developed models. Beside comparing upgrading cost of the sophisticated VPSA with other upgrading technologies, a detailed comparison with the best available membrane unit for biogas upgrading was conducted. The limitations of adsorption process and VPSA in reducing the upgrading cost were also investigated. The results showed that in the absence of subsidies and requirements for CO2 capture, the hybrid plant outperforms the sophisticated VPSA units. Also, higher market price of natural gas or feedstock processing revenues were necessary in order to render the plant profitable. The results showed that, at flowrates larger than 175 Nm3/h, the sophisticated VPSA unit required a lower investment cost than the membrane unit for identical outputs. The results also show that even at the most idealistic conditions in the adsorption process, the upgrading is not economically favorable without subsidies. The findings of this study shed light on the importance of process design for biogas upgrading.

Economic analysis of hydrogen production and refueling station via molten-medium-catalyzed pyrolysis of natural gas process

The urgent need for sustainable energy solutions has been underscored by escalating greenhouse gas emissions and the global commitment to net-zero emissions. Clean hydrogen energy, despite its potential for the global low-carbon transition, faces challenges such as high production and transport costs and significant carbon emissions. Herein, we investigate the molten-medium-catalyzed pyrolysis of natural gas (MPN) for hydrogen production and refueling. We highlight the urgent environmental and economic motivations for cleaner energy, specifically addressing the existing challenges faced by traditional hydrogen production methods. Our research introduces an innovative integrated system for onsite hydrogen production, showcasing its economic advantages, carbon emission reduction potential, and compatibility with current infrastructures. The study meticulously evaluates the MPN technology's economic feasibility, including a detailed analysis of cost drivers and the market value of by-product carbon materials. Furthermore, we stress the importance of further research to optimize the technology and promote its adoption for a low-carbon future. This investigation presents MPN as a promising alternative, potentially revolutionizing the hydrogen supply chain and contributing significantly to global decarbonization efforts.

Novel ethane recovery process from natural gas using ZIF-8/water–glycol slurry: Techno-economic and energy consumption evaluation

Ethane recovery is a vital step in natural gas processing and can provide raw material for ethylene production. The widely used cryogenic separation process is energy intensive, and the absorption-adsorption coupling process based on porous ZIF-8 slurry (SorbPro I) has been proven to be more energy-efficient. To further reduce energy consumption, this paper proposes a novel process with two absorption-adsorption columns (SorbPro II) and establishes its mathematical model by equilibrium stage method. Taking the natural gas with an ethane content of 6.19 mol% at 300,000 Nm3/d as a case study, the operating parameters of SorbPro I and SorbPro II are optimized by sensitivity analysis, and ethane recovery ratio of both processes can reach 90 %. The techno-economic/energy consumption evaluations of the two processes are conducted. Results show that the total annualized cost and the energy consumption per Nm3 feed gas of SorbPro II are 41.7 % and 47.7 % lower than those of SorbPro I, respectively. It indicates that SorbPro II has the same separation performance as SorbPro I, but is more economical.

Contamination control in the oil and gas industries using industrial separation technologies: A sustainability and safety-oriented DSS under Pythagorean fuzzy environment

ABSTRACT The challenges related to the sustainability and safety policies to use the technologies for separating industrial contaminants in the oil and gas industry necessitate an investigation based on these policies. The criteria are in four economic, technical, social, and environmental aspects (as sustainability principles), and three applicability, functionality, and integrity aspects (as safety principles). The research aims at extending a novel decision support system (DSS) by integrating MEREC (method based on the removal effects of criteria) and MABAC (multi-attributive border approximation area comparison) methods under the Pythagorean fuzzy set. Its notable advantages are that renders a stronger expression of uncertainty and the decision-making process is more closely managed. Also, it allows the decision-maker (DM) to evaluate in a wider area and avoid data and conflict among the decision-making team. The industrial separation technologies prioritization is implemented with the DSS. These technologies have been taken into account for contamination control in the sector of Iran’s natural gas processing. The results of the prioritization are: High-efficiency liquid–gas coalescer technology, mesh pad technology, filter separator technology, cyclonic separator technology, vane pack technology, two-phase separator technology, and supersonic separator technology. The high-efficiency liquid–gas coalescer technology is selected as the preferable alternative.

Piston rod fracture in natural gas process compressors for underground gas storage: A comprehensive case study

The reliable operation of process gas compressors is critical in the operation of underground gas storage (UGS). The piston rod is a critical moving part of the compressor, whose fracture can lead to serious consequences, including gas leakage or explosion. In this study, simulation and experimental investigations are carried out to analyse the factors contributing to the fracture failure of the piston rod in an actual engineering case in a UGS. Firstly, a three-dimensional computational fluid dynamics model is developed to elucidate the mechanism by which liquid-carry compression imposes significant piston rod overload. It is also established to capture the dynamic pressure changes in the compression cylinder during gas–liquid two-phase compression. A finite element model is then constructed, allowing analysis of the stress distribution of the piston rod in conjunction with the liquid-carry load patterns. Next, the crack propagation of the piston rod is analysed to unveil its effect on the service life during liquid-carry overload conditions. Finally, fracture analysis is performed on the actual fractured components to conclusively determine the root cause of this accident. The objective of this investigation was to enhance the comprehension of potential risks and causative factors leading to the fracture of compressor piston rods, which hope to contribute valuable insights and theoretical fundamentals towards the safety and maintenance of UGS.

Supercritical Direct-Methane-to-Methanol Coupled with Gas-to-Wire for Low-Emission Offshore Processing of CO2-Rich Natural Gas: Techno-Economic and Thermodynamic Analyses

A greater H/C ratio and energy demand are factors that boost natural gas conversion into electricity. The Brazilian offshore pre-salt basin has large reserves of CO2-rich associated gas. Selling this gas requires high-depth long-distance subsea pipelines, making gas-to-pipe costly; in particular, gas-to-wire instead of gas-to-pipe is more practical since it is easier to transmit electricity via long subsea distances. This research proposes and investigates an innovative low-emission gas-to-wire alternative consisting of installing supercritical direct-methane-to-methanol upstream to gas-to-wire, which is embedded in an exhaust-gas recycle loop that reduces the subsequent carbon capture costs. The process exports methanol and electricity from remote offshore oil-and-gas fields with available CO2-rich natural gas, while capturing CO2. Techno-economic, thermodynamic and lost work analyses assess the alternative. Supercritical direct-methane-to-methanol is conducted in supercritical water with air. This route is chosen because supercritical water readily dissolves methanol and CO2, helping to preserve methanol via stabilization against further oxidation by gaseous air. Besides being novel, this process has intensification since it implements exhaust-gas recycle for –flue-gas reduction, CO2 abatement via post-combustion capture with aqueous monoethanolamine, CO2 dehydration with triethylene glycol and CO2 densification for enhanced oil recovery. The process is fed with 6.5 MMS m3/d of CO2-rich natural gas (CO2 > 40%mol) exporting methanol (2.2 t/h), electricity (457.1 MW) and dense CO2 for enhanced oil recovery, with an investment of 1544 MMUSD, 452 MMUSD/y in manufacturing costs and 820 MMUSD/y in revenues, reaching 1021 MMUSD net present value (50 years) and a 10 year payback time. The Second Law analysis reveals overall thermodynamic efficiency of 28%. The lost work analysis unveils the gas-combined-cycle sub-system as the major lost work sink (76% lost work share), followed by the post-combustion capture plant (14% lost work share), being the units that prominently require improvements for better economic and environmental performance. This work demonstrates that the newly proposed process is techno-economically feasible, environmentally friendly, thermodynamically efficient and competitive with the gas-to-wire processes in the literature.

Hydrate-based technique for natural gas processing: Experimental study of pressure-dropping and continuous modes

Gas hydrate crystallization is perspective and energy-efficient technology for gas mixtures processing, including natural gas. There were compared pressure-dropping and continuous gas hydrate crystallization methods for separation of gas mixture closed to natural gas. The studied mixture has been chosen similar to the natural gas composition: CH4 (75.68 mol.%) - С2H6 (7.41 mol.%) - C3H8 (4.53 mol.%) - н-C4H10 (2.47 mol.%) - CO2 (5.40 mol.%) - H2S (1.39 mol.%) - N2 (3.01 mol.%) - Xe (0.11 mol.%). Experiments were provided in the 4 L high pressure reactor, using water solution of SDS (0.20 wt.%). The experiment conditions were 280.15 K and pressure of 4.25 MPa. The components separation factors and recovery for two modes have been researched and compared for choosing more effective options. After comparing these characteristics, it was concluded that continuous process is more productive than pressure-dropping mode. At the stage cut (θ) of 0.9, the gas components total recovery (R) for the continuous mode have exceeded the total recovery for the pressure-dropping mode by 8.15 %, and at θ = 0.8, exceeded by 6.11 %. The recovery and separation factors have the highest values for H2S, C3H8, Xe in the continuous mode: 97.62 %, 94.90 %, 84.98 % and 8.7, 10.53, 6.36, respectively. Thus, the choosing of the more effective stage cut depends on the aim of the process: the highest purity or the largest recovery.

A comprehensive study on applications of nanomaterials in petroleum upstream and downstream industry.

Nanotechnology has emerged as a revolutionary technology that has been applied in the oil and gas industry for over a decade, spanning the upstream, midstream, and downstream sectors. Nanotechnology has made significant contributions to the exploration of crude oil and natural gas, both in underground and deep-water environments. It has also played a crucial role in improving the drilling process, enabling the extraction of oil and gas resources from beneath the Earth's surface. Nanoparticles, with their unique physical and chemical properties, such as high specific surface area, high pore volume, and small size, have demonstrated considerable potential in the oil industry. Extensive research has been conducted to explore various types of nanoparticles for advanced applications, including oil exploration, drilling, production, and enhanced oil recovery (EOR). Moreover, nanomaterials have found applications in downstream and intermediate sectors, such as crude oil refining, natural gas processing, and transportation and storage of petroleum products. Ongoing advancements in nanomaterial synthesis methods, the exploration of new nanomaterial uses, and understanding the remarkable properties of nanomaterials will continue to make them increasingly valuable in the oil and gas sector. The oil and gas industry recognises the potential of nanotechnology and nanoparticles and is investing significantly in research and development in this area. This comprehensive review aims to summarise successful applications of nanotechnology while addressing associated challenges. It serves as a valuable resource for future research and application endeavours in the field, highlighting the potential of nanotechnology in the oil and gas industry.

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.

Assessment of chemical enhancement and energy consumption of natural gas dehydration processes

Water vapors are found in high concentrations during natural gas production and processing. Energy consumption is known to be a drawback of the glycol dehydration process. Toxic and greenhouse gas emissions are another drawback from the environmental point of view. This paper served to propose a solution to the two problems together by using an emissions stream from the regenerator distillation tower to serve as a striping gas which solved the environmental problem of emissions and helped to reduce energy consumption. Aspen HYSYS was used to model glycol dehydrating as the most widely used and economically viable technique for drying off natural gas streams. This method uses the solvent tri ethylene glycol (TEG) as the absorbent. The focus of this research is to analyze sensitivity to the modeling outcomes. Furthermore, the results suggest that the process might be enhanced and save energy consumption. The simulation used three different tri-ethylene glycol flows, stripping gas flows, and different reboiler temperatures were used in the simulation. The modeling technique was effective in decreasing the water content in the regeneration column from 75lb/MMSCF to 2.5lb/MMSCF and saving energy consumption during the dehydration of natural gas. However, the results showed that in the fourth case when the amount of triethylene glycol is equal to 665.3 kg/h, and reboiler energy is equal to 247300 kJ/h, therefore the energy consumed per kilogram of the TEG is equal to 371.7 kJ/kg which represents the lowest amount of energy consumed during solvent regeneration. However, the results suggest that using emissions as a stripping gas can increase TEG purity and boost the efficiency of the dehydration plant, which appears to be a better option in the long run. The results suggest that the demonstrated approach may help towards decarbonization and zero emission of the dehydration process.

Improving separation of CH4 and N2 by adsorption on zeolite Y Ion–Exchanged with ammonium Cations: An experimental and Grand–Canonical Monte Carlo (GCMC) simulation investigation

The separation of methane (CH4) from industrially–important nitrogen (N2)-rich vent streams such as those in liquefied natural gas processing plants is challenging. Pressure swing adsorption (PSA) is a promising, cost–effective solution in gas separation, especially for small–scale units. Further development and commercialisation of PSA–based technologies require access to low–cost, selective adsorbent materials. The current work investigates the improved separation of CH4 from N2 by TMA–Y zeolite which is obtained from the ion exchange treatment of Na–Y zeolite with the ammonium salt tetramethylammonium chloride (TMACl). TMA–Y is commercially called Ionic Liquidic Zeolite (ILZ), patented at The University of Western Australia, and has now been demonstrated on tonne–scale. In particular, we use a combination of experimental and molecular simulation techniques to provide insights into the high CH4–over–N2 selectivity of TMA–Y. For this, we obtain equilibrium isotherms of CH4 and N2 on Na–Y at different temperatures and pressures before and after ion exchange. The true selectivities of the zeolite samples are determined using the Ideal Adsorbed Solution Theory (IAST) and binary–gas grand–canonical Monte Carlo (GCMC) molecular simulations. From experiments and IAST calculations, we report an increase of >110% in the CH4/N2 selectivity of Na–Y after treatment with TMACl (from 2.2 to 4.7 at 5.0 MPa and 303.15 K for a mixture of 0.1 CH4+0.9 N2 mol.mol−1). GCMC molecular simulations provide a detailed picture of the molecular origins of this effect. Specifically, the introduction of TMA+ ions into the structure of Na–Y zeolite leads to a reduction of the available adsorption volume by more than 40% (from 0.30 to 0.17 cm3.g−1 with N2 as the probe molecule) for both adsorbing gas species (i.e. CH4 and N2). However, at the same time, this leads to stronger CH4–cation interactions due to the much higher affinity of TMA+ cations (5 kJ.mol−1) than extra–framework Na+ cations (1 kJ.mol−1) towards CH4. The overall effect of these two trends combined is the higher selectivity of the resulting TMA–Y zeolite for CH4. These molecular insights are useful in the systematic engineering of new materials with improved separation performance.

Brazil’s New Gas Law: Analysis, Implications, and Remuneration of Gas Processing Plants with Non-Discriminatory Access to Customers

Brazil will increasingly rely on the availability of natural gas as new discoveries in the Pre-Salt portion are explored. Currently, a substantial amount of the gas produced associated with oil is reinjected (60,84 million m³/day in 2021, according to the Ministry of Mines and Energy), with the lack of structure being one of the factors for this non-energy purpose. The New Gas Law proposes to fill this gap by stimulating investments in infrastructure. In this sense, market opening has the potential to promote the rupture of natural monopolies by providing access to infrastructure, including Natural Gas Processing Plants (NGPP). This units, in addition to conditioning the gas for sale, allow the recovery of higher molecular weight fractions, or (Natural Gas Liquid). However, the instructions for this access required by the government are insufficient for issues related to the NGL recovery efficiency of these units, as well the method of remuneration arising from the NGL production capacity. It is proposed in this paper to include a processing tariff, based on static simulation of available technological routes. Comparison of energy spent and NGL recovery efficiency will allow to formulate the gas price, unfolding from the price of the molecule.