Pressure Temperature Swing Adsorption Research Articles

High Hydrogen Storage in Trigonal Prismatic Monomer-based Highly Porous Aromatic Frameworks.

Hydrogen storage is crucial in the shift toward a carbon-neutral society, where hydrogen serves as a pivotal renewable energy source. Utilizing porous materials can provide an efficient hydrogen storage solution, reducing tank pressures to manageable levels and circumventing the energy-intensive and costly current technological infrastructure. Herein, we report two highly porous aromatic frameworks (PAFs), C-PAF and Si-PAF, prepared through a Yamamoto C-C coupling reaction between trigonal prismatic monomers. These PAFs exhibited large pore volumes and BET areas, 3.93 cm3 g-1 and 4857 m2 g-1 for C-PAF, and 3.80 cm3 g-1 and 6099 m2 g-1 for Si-PAF, respectively. Si-PAF exhibited a record-high gravimetric hydrogen delivery capacity of 17.01 wt% and a superior volumetric capacity of 46.5g L-1 under pressure-temperature swing adsorption conditions (77 K, 100bar → 160 K, 5bar), outperforming benchmark hydrogens storage materials. By virtue of the robust C-C covalent bond, both PAFs showed impressive structural stabilities in harsh environments and unprecedented long-term durability. Computational modeling methods were employed to simulate and investigate the structural and adsorption properties of the PAFs. These results demonstrate that C-PAF and Si-PAF are promising materials for efficient hydrogen storage. This article is protected by copyright. All rights reserved.

Rapid and Accurate Screening of the COF Space for Natural Gas Purification: COFInformatics.

In this work, we introduced COFInformatics, a computational approach merging molecular simulations and machine learning (ML) algorithms, to evaluate all synthesized and hypothetical covalent organic frameworks (COFs) for the CO2/CH4 mixture separation under four different adsorption-based processes: pressure swing adsorption (PSA), vacuum swing adsorption (VSA), temperature swing adsorption (TSA), and pressure-temperature swing adsorption (PTSA). We first extracted structural, chemical, energy-based, and graph-based molecular fingerprint features of every single COF structure in the very large COF space, consisting of nearly 70,000 materials, and then performed grand canonical Monte Carlo simulations to calculate the CO2/CH4 mixture adsorption properties of 7540 COFs. These features and simulation results were used to develop ML models that accurately and rapidly predict CO2/CH4 mixture adsorption and separation properties of all 68,614 COFs. The most efficient separation process and the best adsorbent candidates among the entire COF spectrum were identified and analyzed in detail to reveal the most important molecular features that lead to high-performance adsorbents. Our results showed that (i) many hypoCOFs outperform synthesized COFs by achieving higher CO2/CH4 selectivities; (ii) the top COF adsorbents consist of narrow pores and linkers comprising aromatic, triazine, and halogen groups; and (iii) PTSA is the most efficient process to use COF adsorbents for natural gas purification. We believe that COFInformatics promises to expedite the evaluation of COF adsorbents for CO2/CH4 separation, thereby circumventing the extensive, time- and resource-intensive molecular simulations.

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.

Process-performance of solid sorbents for Direct Air Capture (DAC) of CO2 in optimized temperature-vacuum swing adsorption (TVSA) cycles

The process performance of three amine-functionalized chemisorbents (TRI-PE-MCM-41, SI-AEATPMS, APDES-NFC-FD-S) and two physisorbents (SIFSIX-18-Ni-β and NbOFFIVE-1-Ni) was evaluated for direct air capture (DAC) of CO2 in temperature-vacuum swing adsorption (TVSA) and steam-assisted temperature-vacuum swing adsorption (s-TVSA) cycles. Rigorous process optimizations were performed to evaluate the trade-off between energy consumption and productivity. Thermal energy consumption, with main contributions arising from desorption of CO2 and H2O, sensible heat of solids, is higher than electrical energy. While steam purge generally improves productivity at the cost of energy, an exception was noticed where it was also found to reduce energy. For the sorbents studied, minimum energy and maximum productivity ranged between 6.25–30.4 MJth/kgCO2, and 0.01–0.15 TPD of CO2/m3 of sorbent, respectively. For all the sorbents, while target CO2 purity (≥95%) can be achieved with moderate vacuum pressure (≈0.30 bar), low regeneration pressures (≈0.050 bar) can lower energy demand and increase productivity. A new ambient pressure temperature swing adsorption cycle is introduced. This cycle achieves target purities, albeit at higher energy consumption compared to those that use vacuum. The study showed that physisorbents, generally not studied for DAC, can be promising. Parametric studies revealed that the lack of multi-component thermodynamic and kinetic data impedes the objective evaluation of DAC processes.

Experimental validation of bed depth service time model using vapor adsorption bed for coolant purification system of fusion research

A breeding blanket system breeds tritium for fuel, and the system heat is removed by a helium cooling system in the fusion reactor. A Coolant Purification System (CPS) is an ancillary system that removes tritium and impurities from the coolant so that the levels of tritium and impurity in a helium cooling system remain within design requirements. The CPS consists of an oxidation bed that oxidizes Q2 (H, D, T) to Q2O, respectively, an Ambient Molecular Sieve Bed (AMSB) that adsorbs oxidized Q2O, a reduction bed that reduces Q2O back to Q2, and a heated getter bed that removes other impurities. An AMSB filled with zeolite has excellent vapor adsorption at room temperature, and is used semi-permanently by repeating adsorption and regeneration through a pressure–temperature swing adsorption process. In this work, an experimental study on the vapor adsorption and desorption of AMSB was conducted with research apparatus for vapor adsorption and desorption. The purpose of this study was to identify the adsorption and desorption characteristics of an AMSB with various geometries and operation conditions of vapor concentration and flow rate, and to verify its performance. The experimental results were analyzed by applying the bed depth service time model. Through such analysis, real-scale operating conditions could be predicted from the scaled-down test results, and this could be used for code validation of CPS in the future.

Temperature Effects in Flexible Adsorption Processes for Amorphous Microporous Polymers.

A collection of atomistic molecular simulations is reported that illustrate the impact of adsorption temperature on species uptake and adsorbate-induced structural rearrangement for amorphous polymers of intrinsic microporosity. Temperature-sensitive structural rearrangement is evaluated by contrasting two methods: standard grand canonical Monte Carlo simulations using a rigid framework approximation and a combined Monte Carlo/molecular dynamics approach that fully incorporates framework flexibility. We report single-component gas phase adsorption isotherms for CH4, C2H4, C2H6, C3H6, C3H8, and CO2 across a temperature range of 250-400 K for models of an archetypal polymer of intrinsic microporosity, PIM-1. A quadratic model is presented that captures two main mechanisms of temperature-dependent adsorption-induced deformation of PIM-1 up to a relative swelling of 1.15: thermal expansion and an increased propensity to swell as a function of species uptake. Two case studies are reported that highlight the critical role of operating temperature in industrial storage and separation applications. The first study focuses on methane storage and delivery applications using a pressure-temperature swing adsorption application (PTSA). We demonstrate that larger working capacities are accompanied by increased volumetric strain between adsorption-desorption steps. The second case study considers PIM-1 as an adsorbent to separate an exemplar ternary syngas mixture at operating temperatures ranging 300-550 K. A temperature threshold of ∼400 K is identified, beyond which adsorption-induced PIM-1 swelling is negligible and the solubility selectivity-loading curve transitions to exhibiting a nearly linear relationship.

Effects of MgCl2 loading on ammonia capacity of activated carbon for application in temperature swing adsorption, pressure swing adsorption, and pressure-temperature swing adsorption process

Effects of MgCl2 loading on ammonia capacity of activated carbon for application in temperature swing adsorption, pressure swing adsorption, and pressure-temperature swing adsorption process

Carbon Capture and Storage Using Renewable Energy Sources: A Review

The world is undergoing a population explosion; urbanization has also taken giant leaps with higher standards of people. It is noted that the supply and the demand for energy have not been in correlation with one another, as around. When the supply of energy is scaled up, there will large amounts of emissions released from the power plants. Therefore, it is important to focus on capturing and storage of harmful greenhouse gas emissions, using renewable energy resources, so that emission mitigation can be made in an efficient and economically feasible way. The pragmatic analysis of solar-assisted post-combustion carbon capture (SPCC) has been reviewed upon, where the energy compensation of a coal-fired plant due to regeneration of absorbent has been scrutinized. It is also been compared with the integration of geothermal energy (GTCC) for carbon capture. In the adsorption process, various techno-economic analysis of Carbon Capture and Storage (CCS) integrating solar-assisted temperature swing adsorption has been reported along with the effect of absorbent material in pressure-temperature swing adsorption for CO2 capture. Assessment of solar-assisted CCS are also been accomplished by adopting pliable thinking on the energy system. Finally, the integration with solar thermal power plant using novel Sodium Carbonate as a solvent is discussed. Thus, several parts of the CCS system have been construed with renewable energy towards the goal of zero-emission power generation, which seems highly impossible, can be harnessed by 2050

Computational Selection of High-Performing Covalent Organic Frameworks for Adsorption and Membrane-Based CO2/H2 Separation.

Covalent organic frameworks (COFs) have high potential in gas separation technologies because of their porous structures, large surface areas, and good stabilities. The number of synthesized COFs already reached several hundreds, but only a handful of materials were tested as adsorbents and/or membranes. We used a high-throughput computational screening approach to uncover adsorption-based and membrane-based CO2/H2 separation potentials of 288 COFs, representing the highest number of experimentally synthesized COFs studied to date for precombustion CO2 capture. Grand canonical Monte Carlo (GCMC) simulations were performed to assess CO2/H2 mixture separation performances of COFs for five different cyclic adsorption processes: pressure swing adsorption, vacuum swing adsorption, temperature swing adsorption (TSA), pressure−temperature swing adsorption (PTSA), and vacuum−temperature swing adsorption (VTSA). The results showed that many COFs outperform traditional zeolites in terms of CO2 selectivities and working capacities and PTSA is the best process leading to the highest adsorbent performance scores. Combining GCMC and molecular dynamics (MD) simulations, CO2 and H2 permeabilities and selectivities of COF membranes were calculated. The majority of COF membranes surpass Robeson’s upper bound because of their higher H2 permeabilities compared to polymers, indicating that the usage of COFs has enormous potential to replace current materials in membrane-based H2/CO2 separation processes. Performance analysis based on the structural properties showed that COFs with narrow pores [the largest cavity diameter (LCD) < 15 Å] and low porosities (ϕ < 0.75) are the top adsorbents for selective separation of CO2 from H2, whereas materials with large pores (LCD > 20 Å) and high porosities (ϕ > 0.85) are generally the best COF membranes for selective separation of H2 from CO2. These results will help to speed up the engineering of new COFs with desired structural properties to achieve high-performance CO2/H2 separations.

Water vapor harvesting by a (P)TSA process with MIL-125(Ti)_NH2 as adsorbent

The potential of the MIL-125(Ti)_NH2 for water (H2O) capture from air is assessed in the present study. To achieve this goal, the adsorption affinity of the material towards different adsorbates, and its subsequent regeneration in adsorption/desorption cycles, were evaluated. Adsorption equilibrium isotherms were measured in a temperature range between 283 and 323 K and pressure between 0 and 7 bar. Water vapor presented isotherms of Type V and were fitted by applying the Cooperative Multimolecular Sorption (CMMS) model and Polanyi’s theory model. Breakthrough experiments of water vapor corroborated that the adsorption equilibrium isotherm is of Type V. Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) analysis revealed a high capability of regeneration during the adsorption/desorption cycles. The pressure-temperature swing adsorption (P)TSA proposed process shows a maximum productivity of 320 L·day−1·ton−1, considering a regeneration temperature of 373 K, and condensate the outlet stream during the regeneration step at 283 K.

Parametric study of pressure–temperature swing adsorption for gas dehumidification on two-layered bed of porous desiccants

A two-layer cyclic pressure–temperature swing adsorption system was designed for effective water vapor removal from air or helium. The system consists of two fixed bed adsorption columns, each containing two layers of adsorbents consisting of silica gel and zeolite molecular sieves 13×. To gain in-depth insights about the process, a descriptive model considering mass, energy and momentum balances, along with kinetic and equilibrium equations has been developed. The results of computer simulation showed that the layered bed, containing silica gel and molecular sieves 13×, offers both a longer water breakthrough time and significantly enhanced two-layered bed desorption performance compared with those for the one-layered bed. The influence of total gas pressure during the adsorption step, and height of the adsorbent layers on the process efficiency were studied. The cyclic steady state cycles were obtained under various conditions by a cyclic iteration method. Condensation of desorbed water in the adsorbent bed during regeneration has been considered. Theoretical study indicated no water vapor condensation.

Evaluating Regeneration Options for Production of High Purity CO2 from Air Using Solid Amine Sorbents

The production of high purity CO2 from air using solid amine sorbents is studied. It is shown that high purity CO2 can be produced by a pressure temperature swing adsorption. The sorbent can be fully regenerated using a steam purge. An energy evaluation showed that the use of a steam purge can lower energy requirements although the amount of steam should be minimized.

Production of high purity CO2 from air using solid amine sorbents

For CO2 capture from air on a supported amine sorbent, the effects of water co-adsorption and steam purge on the CO2 working capacity and energy requirement for CO2 desorption are studied. Working capacities are studied by fixed bed operation for changing temperature, pressure and amount of steam purge. Results show that for pressure-temperature swing adsorption a temperature above 100 °C and a pressure below 200 mbar as desorption conditions are required to maximize CO2 working capacity and reduce energy requirement for desorption. Co-adsorption of water reduces energy requirement due to an increased CO2 working capacity. Application of a steam purge increases the CO2 working capacity and hence reduces sorbent inventory required. However, the net energy requirement per kilogram CO2 does not decrease due to the latent heat of water. Concluding, steam purge regeneration for air capture does not reduce opex but might reduce capex.

Techno-economic analysis of carbon capture from a coal-fired power plant integrating solar-assisted pressure-temperature swing adsorption (PTSA)

This paper presents a techno-economic study to seek the feasibility about the proposed system that integrating solar-assisted pressure-temperature swing adsorption (PTSA) into an 800MWe coal-fired power plant. Solar energy has the potential to supply thermal energy demand for carbon capture, which can avoid the energy consumption of the traditional method such as the steam extraction. The performance of the proposed system is largely affected by the climatic conditions and solar collector's types. The assessment criteria include carbon emission intensity (CEI), levelized cost of electricity (LCOE) and cost of CO2 avoidance (COA). By the parametric analysis, the results show that CEI of the novel system with solar thermal collectors is approximately 2g/kWh lower than that of the referenced power plant with CO2 adsorption capture. In addition, CEI of the novel system can be further decrease with the decline of desorption temperature, adsorption pressure and desorption pressure. For the sake of lower LCOE and COA, the prices of the power plant capacity, adsorbents and solar collectors should be reduced. Specifically, LCOE of the system with evacuated tube collector will be lower than that of the reference system with CO2 capture as the price of solar field is lower than 46.08 USD/m2.

Solar-assisted pressure-temperature swing adsorption for CO2 capture: Effect of adsorbent materials

Because of the ability to utilize the low-grade solar thermal energy for regeneration, a CO2 capture system characterized by solar-assisted pressure temperature swing adsorption (SOL-PTSA) is studied on the effects of adsorbent materials. A detailed cycle description is firstly presented within the diagram of adsorption isotherm for the energy-efficiency analysis. Typical adsorbent materials, including zeolites and chemical adsorbent, are assessed in terms of sensible heat and latent heat, etc. Then, the energy consumption and the second-law efficiency, which can be considered as lumped indicators from such material parameters, are chosen as performance indicators as well. The influence of separation temperature, desorption temperature, CO2 concentration and CO2 adsorption pressure on system performance are finally obtained. For the chosen three adsorbent materials, the energy consumption of SOL-PTSA system is at the range of 25.96–87.76 kJ/mol, and the corresponding second-law efficiencies are at the range of 9.18–26.89%. The effect of adsorbent materials on the energy-efficiency of SOL-PTSA system mainly depends on specific heat, CO2 working capacity and cycle design. In addition, the integration options of solar energy into PTSA technology are also discussed from the standpoint of the utilization of solar grade heat due to two energy loads required for PTSA's operation.

Multi-objective optimization of a multi-layer PTSA for LNG production

In this work, a novel multi-layer pressure-temperature swing adsorption (PTSA) process was designed for efficient simultaneous water and mercaptans removal from natural gas (NG) to less than 0.1 ppmv and 3 ppmv in a mini liquefied NG unit. The proposed multi-layer PTSA consists of a three-layer fixed bed including activated alumina, molecular sieves 4A and 13X. To gain in-depth insights about the process, a descriptive model considering mass, energy and momentum balances, along with the kinetic and equilibrium equations was developed. After validating the model with the experimental and operational data from the literature, the total energy requirement and long-term operational requirements (e.g. maximum water and mercaptan removal during regeneration process) were optimized. Results of the multi-objective optimization revealed that substitution of present series of dehydration and mercaptan removal columns with an integrated multi-layer PTSA for NG purification can decrease 5.1% of energy consumption, which is approximately equivalent to 137 GJ each year. The outcomes of this study can be used as an innovative design strategy for NG purification (i.e. the combination of dehydration and mercaptan removal columns in a single multi-layer PTSA bed) and can also provide process engineers with a cost-effective tool for the optimization of regeneration parameters in the present PTSA systems.

Modeling and simulation of a pressure–temperature swing adsorption process for dehydration of natural gas

Water vapor in a natural gas stream can result in line plugging due to hydrate formation, reduction of line capacity due to collection of free water in the line, and increased risk of damage to the pipeline due to the corrosive effects of water. Therefore, water vapor must be removed from natural gas to prevent hydrate formation and corrosion from condensed water. Molecular sieves are considered as one of the most important materials that are used as desiccant materials in industrial natural gas dehydration. This paper focuses on modeling of pressure–temperature swing adsorption (PTSA) process in a commercial two-layer adsorption system during sequential steps of cyclic operation to remove water from natural gas. The dynamic model equations were constructed from 4 mol balances; model molecule of water vapor in natural gas, a total mass balance, a pressure drop equation and two energy balances of solid and gas phases in the adiabatic column. Results reveal that about 1 m of the bed was overdesigned by vendor and it doesn’t work in optimum condition. The influential parameters of the process were investigated through a parametric analysis of the process efficiency. For the sake of energy saving some suggestions were proposed for upgrading the design conditions with no significant effect on the purification performance. Results show that optimum conditions will be obtained using adsorption time 22 h and regeneration time 9 h with maximum temperature of 240 °C.

A comparative study on CO2 capture performance of vacuum-pressure swing adsorption and pressure-temperature swing adsorption based on carbon pump cycle

Currently, the significant energy penalty and performance limitation of energy consumption are the main technical barriers to the large-scale applications of CO2 capture. Carbon pump, which realizes an enrichment of CO2 from carbon source to carbon sink, is applied in a modeling for energy-efficiency analysis of CO2 capture technologies. In this study, two adsorption technologies, including vacuum-pressure swing adsorption (VPSA) and pressure-temperature swing adsorption (PTSA), are compared in terms of the minimum separation work and the second-law efficiency. Based on carbon pump, two adsorption cycles can be presented through the process expression in the adsorption isotherm diagram, which is an easy pathway to show CO2 adsorbed amounts for each step. The influence of process parameters for VPSA and PTSA were studied as well.Results show that the maximum values of the second-law efficiency are 24.30% and 19.09%, respectively for VPSA and PTSA with the change of CO2 concentration from 5% to 25%. However, the second-law efficiency for VPSA and PTSA decreases with the increase of the other three factors, including desorption temperature, pressure of the feed and percent of unused bed. Parameters of component in cycle should also receive more attention for energy-efficiency analysis.

Cryogenic pressure temperature swing adsorption process for natural gas upgrade

Abstract Removal of carbon dioxide from natural gas for LNG production, can be carried out by cryogenic distillation using a multicolumn sequence to obtain a product stream with less than 50 ppm of CO 2 . Cryogenic adsorption-based processes, particularly pressure thermal swing adsorption, arise as a reliable and innovative alternative to replace the distillation columns, in particular the last one. In this work, the implementation of a new methodology to design and simulate an industrial scale pressure and temperature swing adsorption process at low temperature (Cryo-PTSA) is presented, in order to produce an almost pure methane stream, with a maximum of 50 ppm of CO 2 , maximizing the methane recovery. Binderless 13X zeolite was selected as adsorbent and adsorption equilibrium isotherms of methane and carbon dioxide were determined experimentally, in the temperature range 183–473 K, up to 80 bar. The GERG2008 equation of state (EoS) was used during the dynamic simulations to account for deviation from ideal gas law, through the use of REFPROP (REFerence fluid PROPerties) software package. Since this method leads to high simulation time consumption, Surface Equations (SE) were used as alternative calculation method to determine the compressibility factor and the heat capacities at constant pressure and volume. A methane recovery of 90.7% and a product stream with 41.8 ppm of CO 2 in CH 4 is achieved after cyclic steady state is reached. Cryo-PTSA simulation results were then compared with an existing cryogenic distillation process. The results obtained by process simulation showed that it is possible to replace the 3 rd column of the cryogenic distillation process by a Cryo-PTSA achieving higher CH 4 recovery and lower power consumption (2.2 MW).

Reducing energy consumption of advanced PTSA CO2 capture process―Experimental and numerical study

Climate change caused by the emission of greenhouse gases (GHGs), in particular carbon dioxide, has become a critical challenge. However, high energy penalty of CO2 capture processes is still a critical bottleneck that restricts its commercial application. In this study, an advanced pressure–temperature swing adsorption (PTSA) CO2 capture process by integrating chemical heat transformer and pressure recovery is investigated to reduce energy requirement. To evaluate the energy consumption of the proposed adsorption process, experimental and numerical study were both carried out. Initially, the adsorption kinetics (i.e. adsorption isotherm, breakthrough curve and isosteric heat) of the sorbent (zeolium®F9-HA) were tested using a fixed-bed setup. Based on the obtained experimental data, the energy consumption of the advanced PTSA process was evaluated by a commercial process-simulation software (PRO/II ver. 9.1, Invensys). The simulation results indicate that the energy consumption of the proposed PTSA process decreased to 1.18 MJ/kg CO2 (approximately 40% that of the conventional PTSA process).