Pressure Swing Adsorption Research Articles

Optimization of hydrogen purification from biomass‐derived syngas via water gas shift reaction integrated with vacuum pressure swing adsorption for energy storage

AbstractBiomass is one of the promising sources to produce green H2, which can be considered an energy storage medium. To produce high‐purity H2 from biomass‐derived syngas, this study implemented a two‐stage H2 purification process. In the first stage, a water gas shift reaction (WGSR) was performed to enhance the H2 concentration in the syngas. The Taguchi method was employed to analyze the influence of the operating conditions and maximize the H2 concentration in the water gas shift reaction product. The results suggested that reaction temperature is a more dominant factor for enhancing the H2 concentration than the molar steam/carbon monoxide (S/CO) ratio. In the second stage, vacuum pressure swing adsorption was employed to obtain the high‐concentration H2 using the product from the water gas shift reaction having the optimum H2 concentration. Using the adsorption pressure as the primary parameter, it was found that high H2 purity and recovery could be obtained from vacuum pressure swing adsorption operated at low adsorption pressures. Based on this study's results, the vacuum pressure swing adsorption unit's best outcome occurs during an adsorption pressure of 2 kg·cm−2 and a flow rate of 17 L·min−1. Under these conditions, 93.61% H2 purity, 31.63% H2 recovery, 4.86 mol H2·(kgads·h)−1 productivity, and 448.14 kJ·(kg H2)−1 energy consumption are obtained.

Production of hydrogen using plastic waste via Aspen Hysys simulation

Plastic waste is being manufactured for the production of hydrogen. The amount of plastic waste collected annually is 189,953 tonnes from adjacent nations like Indonesia and Malaysia. Polyethylene (PE), Polypropylene (PP), Polyethylene Terephthalate (PET), Polyvinyl chloride (PVC), and Polystyrene (PS) are the five most prevalent forms of plastic found in most waste. Pyrolysis, water gas shift and steam reforming reaction, and pressure swing adsorption are the three main phases utilized and studied. In this research, authors examines the energy consumption on every stage. The plastic waste can be utilized to manufacture many hydrocarbons using the pyrolysis reaction. For this process, fast pyrolysis is being used at a temperature of 500 °C. A neutralization process is also needed due to the presence of Hydrochloric acid from the pyrolysis reaction, with the addition of sodium hydroxide. This is being carried to prevent any damage to the reactor during the process. Secondly, the steam reforming process continues after the water gas shift reaction has produced steam and carbon monoxide, followed by carbon dioxide and hydrogen formation. Lastly, pressure swing adsorption is designed to extract H2S and CO2 from the water gas shift and steam reforming reaction for greater purity of hydrogen. From the simulation study, it is observed that using various types of plastic waste procured (total input of 20,000 kg per hour of plastics) from, Brunei Darussalam, Malaysia and Indonesia, can produce about 340,000 tons of Hydrogen per year. Additionally, the annual profit of the Hydrogen production is estimated to be between $ 271,158,100 and $ 358,480,200. As per the economic analysis, it can be said that its a good to start hydrogen production plant in these regions.

High-throughput computational screening of MOF adsorbents for efficient propane capture from air and natural gas mixtures.

In this study, we used a high-throughput computational screening approach to examine the potential of metal-organic frameworks (MOFs) for capturing propane (C3H8) from different gas mixtures. We focused on Quantum MOF (QMOF) database composed of both synthesized and hypothetical MOFs and performed Grand Canonical Monte Carlo (GCMC) simulations to compute C3H8/N2/O2/Ar and C3H8/C2H6/CH4 mixture adsorption properties of MOFs. The separation of C3H8 from air mixture and the simultaneous separation of C3H8 and C2H6 from CH4 were studied for six different adsorption-based processes at various temperatures and pressures, including vacuum-swing adsorption (VSA), pressure-swing adsorption (PSA), vacuum-temperature swing adsorption (VTSA), and pressure-temperature swing adsorption (PTSA). The results of molecular simulations were used to evaluate the MOF adsorbents and the type of separation processes based on selectivity, working capacity, adsorbent performance score, and regenerability. Our results showed that VTSA is the most effective process since many MOFs offer high regenerability (>90%) combined with high C3H8 selectivity (>7 × 103) and high C2H6 + C3H8 selectivity (>100) for C3H8 capture from air and natural gas mixtures, respectively. Analysis of the top MOFs revealed that materials with narrow pores (<10Å) and low porosities (<0.7), having aromatic ring linkers, alumina or zinc metal nodes, typically exhibit a superior C3H8 separation performance. The top MOFs were shown to outperform commercial zeolite, MFI for C3H8 capture from air, and several well-known MOFs for C3H8 capture from natural gas stream. These results will direct the experimental efforts to the most efficient C3H8 capture processes by providing key molecular insights into selecting the most useful adsorbents.

CO2 Capture and Enhanced Hydrogen Production Enabled by Low-Temperature Separation of PSA Tail Gas: A Detailed Exergy Analysis

Hydrogen from natural gas reforming can be produced efficiently with a high CO2 capture rate. This can be achieved through oxygen-blown autothermal reforming as the core technology, combined with pressure-swing adsorption for hydrogen purification and refrigeration-based tail gas separation for CO2 capture and recirculation of residual hydrogen, carbon monoxide, and methane. The low-temperature tail gas separation section is presented in detail. The main objective of the paper is to study and quantify the exergy efficiency of this separation process in detail. To achieve this, a detailed exergy analysis is conducted. The irreversibilities in 42 different process components are quantified. In order to provide transparent verification of the consistency of exergy calculations, the total irreversibility rate is calculated by two independent approaches: Through the bottom-up approach, all individual irreversibilities are added to obtain the total irreversibility rate. Through the top-down approach, the total irreversibility rate is calculated solely by the exergy flows crossing the control volume boundaries. The consistency is verified as the comparison of results obtained by the two methods shows a relative deviation of 4·10−7. The exergy efficiency of the CO2 capture process is calculated, based on two different definitions. Both methods give a baseline exergy efficiency of 58.38%, which indicates a high degree of exergy utilisation in the process.

Quantitative analysis on chemical influence of modified activated carbon in TSA/PSA for methanol via alterable phosphorus functional groups and stable structure

Volatile organic compounds (VOCs) emissions cause serious health problems and environmental pollution, and modified activated carbon is widely used in the treatment of VOCs pollution. Methanol was selected as adsorbate and activated carbon with alterable phosphorus functional groups was synthesized as adsorbent. In the absence of the influence of the physical properties, the chemical functional groups influence coefficient (AC) was proposed, which can be used to analysis and predict the influence of chemical functional groups specially. The results show that the performances including adsorption capacity and enrichment ratio are positively related to the AC whether in temperature swing adsorption (TSA) or pressure swing adsorption (PSA). By comparison, the adsorption capacity of PSA is greater than that of TSA because of the higher efficiency caused by faster cycle. Further research on process showed that the curve character of TSA, including breakthrough time and equilibrium time, is highly related with AC, but the curve character of PSA is mainly depended on the state of activated carbon. Therefore, the attenuation of TSA is mainly caused by the change of chemical functional groups, while the attenuation of PSA is mainly caused by the failure of activated carbon.

Optimizing [formula omitted] capture in pressure swing adsorption units: A deep neural network approach with optimality evaluation and operating maps for decision-making

This study presents a methodology for surrogate optimization of cyclic adsorption processes, focusing on enhancing pressure swing adsorption units for carbon dioxide (CO2) capture. We developed and implemented a multiple-input, single-output (MISO) framework comprising two deep neural network (DNN) models, predicting key process performance indicators. These models were then integrated into an optimization framework, leveraging particle swarm optimization (PSO) and statistical analysis to generate a comprehensive Pareto front representation. This approach delineated feasible operational regions (FORs) and highlighted the spectrum of optimal decision-making scenarios. A key aspect of our methodology was the evaluation of optimization effectiveness. This was accomplished by testing decision variables derived from the Pareto front against a phenomenological model, affirming the surrogate model’s reliability. Subsequently, the study delved into analyzing the feasible operational domains of these decision variables. A detailed correlation map was constructed to elucidate the interplay between these variables, thereby uncovering the most impactful factors influencing process behavior. The study offers a practical, insightful operational map that aids operators in pinpointing the optimal process location and prioritizing specific operational goals.

Hydrogen safety effect calculation (dispersion and thermal radiation effects) for determination of siting and safe distance

AbstractThe main aim of this study was to evaluate the potential effect of dispersion, thermal radiation, and explosion from a poly‐bed pressure swing adsorption (PSA) unit with its surrounding facility to determine its safety distance. Thus, the Shell FRED (fire, release, explosion, and dispersion) consequence modeling was used to predict the impact of a release scenario and assist in designing, developing, and maintaining safe operation. This study was intended to calculate dispersion contours to 50% lower flammable limit (LFL) and 100% LFL, thermal impacts of radiation flux levels of 4, 5, 12.5, and 37.5 kW/m2 at a distance, and including explosive effects of 0.1, 0.2, and 0.35 bar to the chosen target. Based on the findings, it was found that, to avoid exposure to heat radiation of 12.5 kW/m2 from the PSA unit, equipment should be located at a minimum distance of 20.84 m. Meanwhile, process modules and buildings must be located at a minimum distance of 13.8 m. The explosive nature of hydrogen makes on‐site handling and storage more challenging than fossil fuels. The findings of this study will have important implications for the future handling and storage of hydrogen as a potential fuel.

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.

Ethylene Purification by Pressure Swing Adsorption with the Paraffin Selective Metal–Organic Framework─DUT-8

Ethylene Purification by Pressure Swing Adsorption with the Paraffin Selective Metal–Organic Framework─DUT-8

Life cycle cost and life cycle environmental analysis of the different waste-to-renewable natural gas pathways: An effort to identify an optimal pathway under different Multi-criteria decision-based scenarios

Currently, due to the insufficient resources of renewable natural gas, the development of renewable pathways to integrate into the natural gas-industry portfolio can reduce many concerns about the reserves depletion and the environmental crises. In the present article a structure-oriented framework for gas networks is developed to compare and prioritize different investment scenarios for renewable natural gas production projects. In this regard, different pathways to produce renewable natural gas through the waste-to-natural gas process were discussed and compared based on different waste feedstocks. To discuss and compare different pathways, a decision-making structure and framework under life cycle cost analysis (LCCA) and life cycle environmental analysis (LCEA) is employed to choose the appropriate pathway for the waste-to-natural gas process. The optimal pathway is identified through different multi-variable decision-making scenarios (under different geographical conditions, access to different feedstocks, and different interests of stakeholders). From the outcomes, under the neutral and Pro-economic scenarios, the renewable natural gas production pathway driven by landfill gas integrated with the pressure swing adsorption- biogas upgrading unit is the optimal and desirable option. While under an Eco-friendly scenario, the pathway driven by animal manure integrated with the pressure swing adsorption-upgrading unit is an optimal and desirable pathway.

Life cycle analysis (cost and environmental) of different renewable natural gas from waste procedures based on a multivariate decision-making approach: a comprehensive comparative analysis

Abstract This article presents a framework that focuses on structural considerations within gas networks to evaluate and rank various feasibility options for renewable natural gas (RNG) cases. Specifically, the analysis examines and compares a range of methods for producing RNG using natural gas from waste (NGFW), considering different types of waste as feedstock. To analyze and evaluate the different methodologies, the article uses a decision architecture based on life cycle analysis (cost and environmental). These tools are used to determine the most favorable path for the NGFW process. The preferred pathway is identified by considering a range of decision scenarios that take into account variables such as geographical conditions, the availability of various feedstocks and the different stakeholders’ priorities. The results show that according to the economically neutral scenarios and those that favor economic considerations, the pathway involving RNG generation from landfill gas coupled with a pressure swing adsorption (PSA) upgrading technology emerges as the optimum choice. Conversely, in a scenario where environmental sustainability is a priority, the process that emerges as most advantageous is the use of animal manure with the addition of a PSA upgrading unit. The designed structure can be adapted to different regions, each with its own unique geographical features and feedstock resources, and can be customized to meet the varying interests of stakeholders. Based on both parametric assessments and analytical interpretations, this article not only identifies optimal pathways but also provides a set of recommendations and strategies aimed at improving economic behavior.

Evaluating the efficiency of a proton exchange membrane green hydrogen generation system using balance of plant modeling

A system model of a proton exchange membrane green hydrogen generation system is developed with the intent of demonstrating the dynamic interactions of the system with varying inputs such as electrolyzer current density and hydrogen pressure. The model includes physics-based modules that are validated with available experimental data for the power electronics, electrolyzer stack, pressure swing adsorption dryer, hydrogen compressor, and cooling circuit components of the system. A single electrolyzer system and multi-electrolyzer system are evaluated with varying operating conditions and multi-stack system operating strategies. Increasing electrolyzer cathode pressure results in an overall increase in specific energy consumption but may allow the use of low-pressure storage without the need for a hydrogen compressor. For a theoretical case study of excess renewable energy generation in Texas, the system achieves an overall efficiency of 46.5 % defined as the efficiency of converting electricity into an equivalent energy content of the produced hydrogen.

Techno-economic analysis of carbon molecular sieve membranes to produce oxygen enrichment air

Oxygen Enriched Air (OEA) is essential for medical applications, metal production, chemical production, the petrochemical industry, and energy processes. In this work, carbon molecular sieve membranes (CMSM) and membrane systems are analyzed concerning their technical and economic feasibility to produce OEA for medical, post-combustion, and oxy-combustion applications. Process parameters, such as stage-cut, feed-to-permeate pressure ratio, membrane area, and the number of stages, were studied to assess the technical and economic feasibility of this technology. In this work, it was observed that for each membrane, there is a permeating oxygen concentration that minimizes the specific oxygen cost. The production of 56 tonO2·day−1 for a combustion enhancement process with a concentration of 72 % was obtained in a single-stage with a specific cost of 61.0 €·tonO2−1. A single-stage is also effective for producing OEA for medical applications (required concentration of 82 %) at a minimum separation cost of 45.8 €·tonO2−1. However, a two-stage system is required to produce OEA with a concentration higher than 95 % for oxy-combustion with an OEA production cost of 83.8 €·tonO2−1. These production costs are lower than those obtained with two different commercial membranes and are competitive with medium-scale cryogenic distillation and pressure swing adsorption processes.

Simulation of Pressure Swing Adsorption for Oxygen Concentrator Using LiX Zeolite

The existence of oxygen is needed in various fields such as health, industry, aerospace, and energy. Pressure swing adsorption method using zeolite A and X is commonly used in the oxygen separation process. Zeolite LiX is widely used especially in oxygen purification systems from air for medical needs until the purity reach &gt;90%. In the present work the simulation studies of oxygen separation from air using zeolite LiX were investigated by pressure swing adsorption method. This simulation uses 2 beds/4 steps Skarstrom cycle which generally consists of bed pressurization, adsorption, depressurization and desorption. Several variables were studied such as the effect of pressure, cycle time, and temperature to determine the level of product purity. The simulation shows that the increase in oxygen concentration is caused by an increase in operating pressure and total cycle time to obtain maximum results. Meanwhile, large pressures can reduce the efficiency of the adsorbent. The maximum oxygen concentration that can be obtained up to 99%. However, the temperature variation has no significant change. In general, pressure plays the most significant role in oxygen purification.

An innovative gas management methodology based on PSA for efficient gas allocation and utilization in hybrid hydrogen network: Integrating process simulation, modeling, and machine learning

Pressure swing adsorption(PSA) based gas separation technology is widely applied in chemical industries, especially in hydrogen purification. Its complex mechanism and non-steady state feature restrict the separation performance adjustment and application on efficient gas utilization. Process simulation, machine learning and modelling combined innovating gas management methodology is proposed in this paper to perform accurate gas separation for natural gas based syngas mixture. VB script program is employed to drive Aspen adsorption simulation, and then classical and regression tree(CART), polynomial regression(PNR) and surrogate model are comprehensively used to perform machine learning. Consequently, the coefficient matrix is obtained to quantify the separation performance. This method holds the potential for broader application in refineries and SPCs hybrid hydrogen network, facilitating the comprehensive utilization of hydrogen containing gases. Case study results show this methodology can conserve natural gas and gas productivity by 21.3 %, as well as carbon emission by 8211.6 Nm3/h. This work highlights the promising application of digital twin technology within the chemical industry, showcasing how process simulation, machine learning, and modeling can collectively revolutionize gas management and resource conservation.

Multidisciplinary high-throughput screening of metal–organic framework for ammonia-based green hydrogen production

This study presents a comprehensive, multidisciplinary approach to high-throughput screening (HTS) of metal–organic frameworks (MOFs) for efficient ammonia-based green hydrogen production. Previous HTS methods, relying on molecular simulations, often estimate adsorption uptakes under constant conditions, leading to inadequate evaluation of MOFs for practical applications where competitive adsorption and varying operating conditions are critical. To address this limitation, we propose a multidisciplinary HTS method employing an efficient computational algorithm that minimizes the number of molecular simulations while generating isotherm models across a wide pressure range. Our algorithm strategically selects simulations for further analysis based on initial results. Using this innovative approach, we screened 12,020 MOFs. Furthermore, as the next step of the multidisciplinary approach, we performed pressure swing adsorption (PSA) process simulations to assess MOFs’ potential for purifying green hydrogen derived from decomposed ammonia, which can be produced by sustainable energy sources and transported intercontinentally. The top-performing MOFs were evaluated for stability based on literature data and MOFSimplify, a neural network model estimating thermal stability. By considering adsorption process operation and MOF stability, the proposed HTS methodology identified 10 high-performing materials, with RAVXIX ranking as the top adsorbent. This comprehensive evaluation advances the search for efficient MOFs in green hydrogen production, contributing to the development of a more sustainable hydrogen-based economy.

Oxygen absorption/desorption behaviors of Sr0.72Ca0.28Fe1-xAlxO3-δ perovskite oxygen sorbents for air separation

Perovskite-type oxides are extensively studied as oxygen sorbents in pressure swing adsorption (PSA) for air separation at elevated temperatures. However, quantitative analysis of desorption kinetics and the basis of material optimization are rarely reached on a fixed bed. In this study, the effects of Al doping on the oxygen absorption/desorption behaviors of Sr0.72Ca0.28Fe1-xAlxO3-δ (SCFA, x = 0, 0.03, 0.05, 0.07, 0.1) were investigated by temperature programmed desorption (TPD) and fixed bed absorption/desorption experiments. The desorption kinetics were analyzed by a Geometrical contraction model. O2-TPD results show that Al doping reduces the total absorption amount of Sr0.72Ca0.28FeO3-δ (SCF). Through the peak-differentiation-imitating analysis, it was found that the SCFA series materials have three different oxygen desorption sites, and the desorption peak area and temperature corresponding to each site are different. CO2-TPD results reveal that Al doping improves the CO2 resistance of the perovskite oxides. Compared with SCF, Al doped materials show enhanced equilibrium oxygen absorption capacity at temperature higher than 550 °C. The oxygen desorption rates of SCFA series were calculated by fitting the desorption curves with Geometrical contraction model (R2). Both initial oxygen desorption concentration and oxygen desorption rate constants increase with temperature but decrease with the Al doping amount. The similar apparent activation energies of the desorption rate constant of the SCFA series reveal that the desorption mechanism not changes with Al doping. Ideal oxygen production rate, equaling to the multiplication of equilibrium oxygen absorption capacity and the desorption rate constant, is suggested to evaluate the performance of an oxygen sorbent. The x = 0.03 sample shows the highest ideal oxygen production rate among the SCFA series.

Electrostatically tunable interaction of CO2 with MgO surfaces and chemical switching: first-principles theory.

Electric field-assisted CO2 capture using solid adsorbents based on basic oxides can immensely reduce the required energy consumption compared to the conventional processes of temperature or pressure swing adsorption. In this work, we present first-principles density functional theoretical calculations to investigate the effects of an applied external electric field (AEEF) within the range from -1 to 1 V Å-1 on the CO2 adsorption behavior on various high and low-index facets of MgO. When CO2 is strongly adsorbed on MgO surfaces to form carbonate species, the coupling of electric fields with the resulting intrinsic dipole moment induces a 'switch' from a strongly chemisorbed state to a weakly chemisorbed or physisorbed state at a critical value of AEEF. We demonstrate that such 'switching' enables access to different metastable states with variations in the AEEF. On polar MgO(111) surfaces, we find a distinct feature of the adsorptive dissociation of CO2 towards the formation of CO in contrast to that on the non-polar MgO(100) and MgO(110) surfaces. In some cases, we observe broken inversion symmetry because of the AEEF that results in induced polarity at the interaction site of CO2 on MgO surfaces. Our results provide fundamental insights into the possibility of using AEEFs in novel solid adsorbent systems for CO2 capture and reduction.

High throughput screening of pure silica zeolites for CF4 capture from electronics industry gas.

The capture and separation of CF4 from CF4/N2 mixture gas is a crucial issue in the electronics industry, as CF4 is a commonly used etching gas and the ratio of CF4 to N2 directly affects process efficiency. Utilizing high-throughput computational screening techniques and grand canonical Monte Carlo (GCMC) simulations, we comprehensively screened and assessed 247 types of pure silicon zeolite materials to determine their adsorption and separation performance for CF4/N2 mixtures. Based on screening, the relationships between the structural parameters and adsorption and separation properties were meticulously investigated. Four indicators including adsorption selectivity, working capacity, adsorbent performance score (APS), and regenerability (R%) were used to evaluate the performance of adsorbents. Based on the evaluation, we selected the top three best-performing zeolite structures for vacuum swing adsorption (LEV, AWW and ESV) and pressure swing adsorption (AVL, ZON, and ERI) processes respectively. Also, we studied the preferable adsorption sites of CF4 and N2 in the selected zeolite structures through centroid density distributions at the molecule level. We expect the study may provide some valuable guidance for subsequent experimental investigations on adsorption and separation of CF4/N2.

Progress of research on purification of CH4 from a CH4/CO2/N2 mixture by pressure swing adsorption

This review primarily addresses the types of adsorbents, molecular simulation, and process optimization involved in the purification of CH4 by variable pressure adsorption.