Zeolite Y Research Articles

Dechlorination of a real plastic waste pyrolysis oil by adsorption with zeolites

The adsorptive dechlorination of a pyrolysis oil coming from real plastic waste was investigated using different Na-zeolites (4A, 13X, and Y) as adsorbents. The dechlorination experiments were performed in a fixed bed trap under inert atmosphere operating at moderate temperatures (< 180 °C). The dechlorination efficiency of the adsorbents was significantly improved by performing a dehydration pre-treatment due to the removal of water molecules physisorbed on the zeolite surface. Among the zeolitic materials tested, 13X zeolite showed the best dechlorination efficiency, which was related to its high content of Lewis acid sites (attributed to the presence of Na+ cations ionically interacting with the zeolite framework), acting as chemisorption sites, as well as the high accessibility of the FAU-zeolitic topology to the Cl-containing compounds. For that sample, a detailed study of the adsorption temperature (from 30 to 180 °C) and time on stream (1–6 h) was further carried out. The maximum chlorine removal efficiency was achieved, reducing the chlorine content of the pyrolysis oil from 421 to 45 ppm, at temperatures of about 150 – 180 °C. Interestingly, under these conditions, thermal or catalytic cracking effects of the zeolite on the feedstock were not observed. However, the study of the time on stream showed that, after 3 h, the chlorine removal efficiency of the zeolite started to decrease. Thus, different regeneration treatments were evaluated proving that, after a combustion at 600 °C, the zeolite recovered its initial dechlorination efficiency. This research reveals the potential of the adsorptive dechlorination process with Na-zeolites to reduce the chlorine content in plastic pyrolysis oils under mild operating conditions.

High capacity laminate adsorbers: Enhancing separation performance beyond packed beds

In response to the growing demand for more efficient adsorption processes, structured adsorbents have emerged as a promising solution as they offer improved mass transfer and pressure drop characteristics. However, they are often hampered by a lower volumetric capacity due the presence of support structures or a large bed void fraction. This research focuses on the manufacturing and evaluation of self-standing zeolitic laminates of various thickness and spacing, comparing their performance to a traditional packed bed. A shaping method to obtain laminates with a 84 wt% zeolite 13X content is described. Furthermore, a method for precise assembly and spacing of the laminates is detailed. Three such laminar adsorbers with different geometries were evaluated in breakthrough experiments and compared to a packed bed to assess their efficiency in the bulk separation of carbon dioxide. Superior performance of the laminar adsorbers was found, with one configuration employing 1.2 mm laminates and 0.4 mm spacing showing a significant 19 % increase in volumetric capacity compared to a packed bed of pellets. This enhanced capacity is achieved while maintaining efficient heat and mass transfer, resulting in sharp breakthrough profiles. Furthermore, using thinner (0.5 mm) laminates, the length of unused bed was further reduced. Additionally, pressure drop calculations were performed and experimentally validated. The pressure drop over the laminar adsorbers was shown to be significantly lower than over a packed bed. These findings underscore the potential of laminar adsorbers to intensify adsorptive separation processes, reduce energy consumption, and address the demand for more effective adsorption technologies.

Experimental Testing System for Adsorption Space Heating

Approximately 40 % of the final energy is used for heating and cooling of buildings. Of this, as much as 75 % is used in residential buildings. The proportion of energy needed in buildings is relatively high, so it is necessary to start using technologies that have low energy consumption, use it efficiently or provide it from renewable sources. One such technology is thermal energy storage, which allows us to store excess energy for later when we need extra energy. The paper presents two experiments in the field of adsorption space heating. In the first experiment, measurements were carried out on the adsorbents - zeolite 13X and zeolite NaYBFK, which were placed into a duct, through which humid air was transported by means of a centrifugal fan. In the second experiment, water vapour as the working medium was used. With the first experiment we achieved better water uptake on NaYBF, while the second experiment shows the increase of water uptake of zeolite 13X.

Concentration of stigmasterol, β-sitosterol and squalene from passion fruit (Passiflora edulis Sims.) by-products by supercritical CO2 adsorption in zeolite 13-X

Phytosterols and squalene, widely applied in pharmaceutical and food industries, were extracted and concentrated from passion fruit by-products (PFBP). A supercritical extraction using CO2 (SFE) was performed for PFBP, and the obtained extract underwent supercritical fractionation (SFA) (inlet at 35 MPa, 50–70 ℃) in a column packed with zeolite 13-X (5–15 g). The extraction and fractionation yields were measured, whereas the composition of the PFBP extract and their fractions was assessed by gas chromatography-mass spectrometry (GC-MS). Fractionated extract recovered presented different trends depending on temperature and zeolite mass combinations, and the highest recovery (approximately 95%) was achieved at 50 ºC with 15 g of adsorbent. At the same SFA conditions, the concentration of squalene, β-sitosterol and stigmasterol was twice that obtained in PFBP extract. Finally, SFA proved to be a clean and effective technique to concentrate squalene and phytosterols from PFBP, which should be extended to other food residues.

Impact of varied zeolite materials on nickel catalysts in CO2 methanation

Ni catalysts supported on 4A, 5A, 13X, ZSM-5, and BEA zeolites were prepared using the vacuum-heating method for CO2 methanation. These support materials play a pivotal role in shaping the catalysts' properties and their catalytic performance. High-resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and energy-dispersive X-ray spectroscopy (EDS) mappings suggest a significant concentration of Ni nanoparticles situated on the external surfaces of catalysts with low Si/Al ratios zeolites (Ni-4A, Ni-5A, and Ni-13X). These Ni nanoparticles exhibit characteristics of weaker metal-support interaction, lower metal reduction temperatures, and moderate H2 adsorption activity. Moreover, these low Si/Al ratio zeolites demonstrate robust CO2 adsorption activity. These properties endow Ni-5A and Ni-13X catalysts with heightened CO2 conversion (70.4–70.9%) and methane selectivity (92.4–96.4%). In contrast, high Si/Al ratio zeolite-based catalysts (Ni-ZSM-5 and Ni-BEA) exhibit smaller Ni particles, strong metal-support interaction and weaker CO2 adsorption activity, resulting in reduced CO2 methanation activity and decreased methane selectivity (71.2–73.4%). The normalized CO2 conversion rate presents a correlation with the average Ni particle size.

Experimental microwave assisted CO2 desorption of a solid sorbent in a fluidized bed reactor

In this study, a novel method has been applied to regenerate CO2 from a solid sorbent (Zeolite 13X) using a mono-mode microwave unit under fluidization conditions. Several parameters have been varied to investigate their effect on the desorption characteristics as well as on the energy consumption. While flow rate varied between 200 Nml/min to 1,000 Nml/min, regeneration temperature changed from 40 °C to 100 °C. Microwave initial forward power also varied from 15 W to 30 W.Volumetric heating of microwave led to desorption of CO2 from the sorbent effectively while fluidization enhanced the heat transfer within the sorbent by providing homogeneous heat transfer with lower desorption time and absorbed energy. The most dominant parameters on the desorption time and energy consumptions were found to be flow rate and regeneration temperature, respectively. Under different conditions, the energy consumptions to regenerate a kg CO2 varied between 2.84 MJ and 27.17 MJ. Even though the lowest energy consumption was obtained when the flow rate was 200 Nml/min at 40 °C; the time for a complete desorption found to be quite high with this flow rate. Therefore, a minimum energy consumption of 3.87 MJ/kg CO2 within a short period of regeneration time can be achieved under the fluidization regime with the flow rate of 1,000 Nml/min at 40 °C. While an increase in the flow rate also caused a slight increase in the energy consumption for low regeneration temperatures, it resulted in a significant decrease under higher regeneration temperatures. Furthermore, the main drawback of low flow rate conditions is that most of the energy was consumed to remove the last 10 % of CO2 from the sorbent. Therefore, fluidization plays a significant role on the removal of CO2, especially between the 90 % and 100 % regeneration percentages.This work is the first study in the literature that has investigated the effects of fluidization on the desorption characteristics of CO2 under mono-mode microwave conditions. It was proved that fluidization reduced the energy consumption of CO2 desorption with higher microwave efficiency.

Preparation and thermal properties of zeolite 13X/MgSO4-LiCl binary-salt composite material for sorption heat storage

Thermal energy storage can play a pivotal role in waste heat recovery and solar energy thermal utilization by balancing the time and space-mismatch between supply and demand of energy. Thermochemical sorption heat storage technology has gained the enormous interest for its ability to make use of the low-grade thermal energy. However, the slow sorption reaction kinetics of sorbents remains an obstacle for the large-scale industrial applications of thermochemical sorption heat storage technology. In this study, a new type of zeolite 13X/MgSO4-LiCl composite sorbent material has been fabricated by impregnating zeolite 13X with the mixed solution of MgSO4 and LiCl. The structural characteristics and sorption heat storage performance of composite adsorbents with different mass ratios of MgSO4 and LiCl were studied experimentally by scanning electron microscopy (SEM), full-automatic specific surface area and pore analyzer (ASAP), and thermogravimetry analysis-differential scanning calorimetry (TGA-DSC). The results indicate that binary-salt sorbents show the faster sorption kinetics and higher water sorption capacity compared to single salt sorbents. When the mass ratio of MgSO4 and LiCl is 2:1, the zeolite 13X/MgSO4-LiCl composite sorbent (XML-2/1) has the best sorption heat storage performance. Under the sorption temperature of 25 °C and relative humidity (RH) of 60 %, the maximum sorption capacity is 0.24 g/g, and the corresponding heat storage density of 458.3 kJ/kg can be achieved. The results indicate that the zeolite 13X/MgSO4-LiCl composite adsorbent can improve the sorption rate and heat storage density. Compared with pure zeolite 13X and zeolite 13X/MgSO4 composite sorbents, the addition of LiCl can effectively improve the sorption rate and sorption heat storage capacity. The findings of this investigation could promote the growing body of research on the mixed salt (binary-salt or multiple-salt) composite materials and new insights can be offered by broadening the application of zeolite-based composite materials in low-grade thermal energy storage for space heating, which can guide further research and development in this field and ultimately help facilitate the transition toward the clean energy.

Tuning selectivity of acetic acid and alcohols by Brønsted and Lewis acid sites in plasma-catalytic CH4/CO2 conversion over zeolites

Plasma catalysis enables CH4/CO2 direct conversion to oxygenates under mild conditions. However, addressing complexity of oxygenate products is the main scientific challenge. Herein, the roles of Brønsted and Lewis acid site (i.e., BAS and LAS) in tuning the selectivity of acetic acid and alcohols have been comparatively investigated for the first time. BAS and LAS are provided by HZSM-5 and 13X zeolites, respectively, and their amounts are adjusted by steam treatment. Results reveal that BAS significantly promotes acetic acid formation, while LAS favors alcohols generation. In addition, Au supported zeolites show that Au3+-BAS synergy exhibits potential for acetic acid. In-situ FTIR spectra identify the bicarbonate (HCO3,ad) and formate (HCOOad) to be the primary surface species on BAS and LAS, respectively. Correspondingly, the pathways for acetic acid and methanol production are proposed based on catalyst characterizations and plasma diagnosis. This work opens up zeolite-based catalysts for selective CH4/CO2 conversion to oxygenates.

A Kinetic Study of Microwave‐Assisted Desorption of Co2 from Zeolite 13x

CO2 is the main contributor of the greenhouse gas emission which considerably accelerates climate change. The capture of CO2 requires the development of sustainable adsorption‐desorption processes, which can be upscaled to satisfy the industrial demands. It is well‐known that sustainable microwave (MW) heating leads to fast desorption of CO2 compared to conventional, but there is a lack of study on how to upscale this process. Here it is investigated a concept for the upscaled multi‐mode MW heating of zeolite 13X. The proposed concept is based on the non‐isothermal kinetic study of CO2 desorption, revealing a complex multi‐step process: activation of zeolite 13X below 40 °C and CO2 desorption at T &gt; 40 °C with Eact = 0 kJ mol−1. It was found that MW‐assisted CO2 desorption happens simultaneously with H2O desorption after zeolite MW‐activation. The mechanism of MW‐assisted desorption of CO2 has been proposed. Based on this mechanism, the parameters important for optimizing CO2 desorption process at a larger scale are offered together with an upscaled concept.

Zeolite 13X incorporated with Zn-Ce oxide nanocatalyst for removal of Reactive Red 120 dye: RSM-based approach.

In this study, the photocatalytic removal of Reactive Red 120 (RR120) dye was examined using zeolite 13X incorporated with Zn-Ce under UV irradiation. The synthesis of Zn-Ce nanoparticles incorporated with zeolite 13X was conducted through the co-precipitation method, and the features of the prepared nanocatalyst were analyzed using various techniques. The SEM and BET analyses indicated successful incorporation of ZnO-Ce oxides on the surface of zeolite 13X and a specific surface area of 359.39 m2/gm, respectively. Further, the average size of crystal grains was 28 nm. The response surface methodology (RSM) approach was employed to optimize operating parameters. The quadratic model suggested by the RSM approach, characterized by a high regression coefficient (R2 = 0.9632), indicates a high level of reliability. Moreover, under optimal conditions (catalyst loading of 4 mg, pH of 3, H2O2 amount of 0.2 mL, UV power of 25 W, and reaction time of 60 min), the highest RR120 dye removal percentage was 99.97%. Kinetic data indicated an increase in the reaction rate constant from 0.0631 to 0.1796 min-1. The zeolite 13X incorporated with Zn-Ce photocatalyst exhibited excellent stability over 5 cycles, with only a 5.50% decrease in RR120 dye removal yield. This study demonstrates the promising potential of zeolite 13X incorporated with Zn-Ce nanoparticles for the removal of RR120 dye from aqueous suspension.

Preparation and thermal properties of zeolite/MgSO4 composite sorption material for heat storage

Thermochemical sorption heat storage based on salt hydrates offers the potential advantages such as high energy density, negligible heat loss, small volume change and flexible working modes. Magnesium sulphate (MgSO4) is a high energy density hydrated salt available for the thermochemical sorption heat storage. In this work, different types of zeolites (including 3A, 5A and 13X zeolites) have been selected as mass-transfer-enhancing and structural stabilizing materials, and a series of zeolite/MgSO4 composites have been fabricated. To investigate the thermal energy storage performance of zeolite/MgSO4 composites, the properties of the composites, such as micro-morphology, pore structure, chemical composition and sorption-desorption behavior, have been characterized and analyzed. Results indicated that the mass transfer performance of the composite materials is significantly better than that of the pure zeolites. As the mass fraction of MgSO4 in the composite sorbents increases, the specific surface area and porosity of the composite sorbent decreases, and the sorption performance has been enhanced. Compared with 3A zeolite-based and 5A zeolite-based composites, 13X zeolite/MgSO4 composite materials show the best heat storage performance. At the condition of 25 °C and 60% RH, the 13XM20 has the highest sorption capacity of 0.21 g/g, which is 24% higher than that of pure zeolite 13X. Accordingly, the maximum heat storage density is 438.4 kJ/kg, which exhibits the superior heat storage performance among of the hydrated salt sorbents. The potential of 13X zeolite/MgSO4 as sorption heat storage material in efficient utilization of solar heat and low-grade industrial waste heat has been revealed.

Statistical analysis of parameters and adsorption isotherm models.

The present work intends to discuss parameter estimation and statistical analysis in adsorption. The Langmuir and Tóth isotherm models are compared for a set of carbon dioxide adsorption data on 13X zeolite from literature at different temperatures: 303, 323, 373, and 423 K. Statistical analyses were performed under frequentist and Bayesian perspectives. Under the frequentist statistical view, parameters were estimated using Maximum Likelihood estimation (MLE). Statistical analyses of parameters were performed by confidence regions in terms of elliptical approximation and likelihood region, while the evaluation of models was performed by chi-square statistics. The results showed that, for these nonlinear models, the elliptical region offers a poor approximation of the parameter estimates' confidence region, especially for the most correlated parameter pairs. Additionally, the four-parameter Tóth's equation yields less correlated parameters than the three-parameter Langmuir model. From a Bayesian perspective, the Markov chain Monte Carlo (MCMC) technique facilitated the reconstruction of the probability density functions of parameters as well as enabled the propagation of parametric uncertainties in the model responses. Finally, the accurate assessment of experimental uncertainty significantly influences the evaluation of models and their respective parameters.

Synthesis and Structural Analysis of High-Silica ERI Zeolite with Spatially-Biased Al Distribution as a Promising NH3-SCR Catalyst.

Erionite (ERI) zeolite has recently attracted considerable attention for its application prospect in the selective catalytic reduction of NOx with NH3 (NH3-SCR), provided that the high-silica (Si/Al > 5.5) analog with improved hydrothermal stability can be facilely synthesized. In this work, ERI zeolites with different Si/Al ratios (4.6, 6.4, and 9.1) are synthesized through an ultrafast route, and in particular, a high-silica ERI zeolite with a Si/Al ratio of 9.1 is obtained by using faujasite (FAU) as a starting material. The solid-state 29Si MAS NMR spectroscopic study in combination with a computational simulation allows for figuring out the atomic configurations of the Al species in the three ERI zeolites. It is revealed that the ERI zeolite with the highest Si/Al ratio (ERI-9.1, where the number indicates the Si/Al ratio) exhibits a biased Al occupancy at T1 site, which is possibly due to the presence of a higher fraction of the residual potassium cations in the can cages. In contrast, the Al siting in ERI-4.6 and ERI-6.4 proves to be relatively random.

Synthesis of zeolite molecular sieve 13X from coal-fired slag for efficient room temperature CO2 adsorption

Coal-fired slag (CFS) was used to successfully synthesize zeolite molecular sieve (ZMS) 13X by the alkali fusion hydrothermal method for efficient room-temperature CO2 adsorption. The optimum synthesis conditions of ZMS 13X were confirmed using the single-factor and Box-Behnken methods. With a specific surface area of 585.67 m2·g−1, the resultant ZMS 13X is a mesoporous material with good CO2 adsorption selectivity and cyclic performance. At 25 °C and 1 bar, the initial CO2 adsorption amount presented 3.69 mmol·g−1 and still maintained 3.37 mmol·g−1 of CO2 adsorption amount after 10 cycles. The Langmuir isotherm model can well describe the CO2 adsorption process of ZMS 13X as an entropy-decreasing physical adsorption process with the intermolecular interaction of van der Waals forces. Therefore, this work proposes a new strategy for the low-cost synthesis of ZMS 13 from the CFS solid waste for efficient room-temperature CO2 capture.

Desorbent swing adsorption process using ethylene to separate propane and propylene under isobaric conditions

The separation of olefin and paraffin using adsorption technology remains a significant challenge. This study proposes a novel desorbent swing adsorption (DSA) process using an olefin desorbent with a weaker adsorption affinity (C2: ethylene) to separate a paraffin/olefin mixture with a higher adsorption affinity (C3s: propane and propylene) under isobaric conditions, which is the reverse concept of using a desorbent with a stronger affinity in conventional DSA systems. The proposed DSA process effectively separates the C3 mixture because the deteriorating effects caused by the desorbent is minimized. Based on sequential breakthrough experiments with zeolite 13X DSA using ethylene, the efficient separation of a propylene dehydrogenation product (propane:propylene = 60:40 vol%) to produce polymer-grade propylene is achieved. It is confirmed that ethylene desorbent stream pushes out the adsorbed propylene and regenerates the adsorption bed without changing the pressure. The desorption step plays a key role in the separation performance of the proposed DSA process because the regenerated bed offers favorable conditions when filled with the weaker desorbent after the desorption step. The flowrate of the desorbent strongly affects the efficiency of propylene desorption. After validating the dynamic mathematical model using the experimental results, a two-bed DSA process using a six-step sequence that includes rinse export/import and idle steps is shown to achieve a propylene purity above 99.999 % (desorbent-free basis) with a recovery of 99.39 %, a productivity of 4.21 mol∙kg−1∙hr−1, and an ethylene usage of 7.59 mol∙kg−1∙hr−1. This study offers important insights into the development of adsorptive separation designs for olefin/paraffin separation.

Scaling up 3D printed hybrid sorbents towards (cost) effective post-combustion CO2 capture: A multiscale study

A 3D-printed sorbent containing polyethylene-imine and multi-walled carbon nanotubes (PEI-MWCNT) was studied for post-combustion carbon capture. In this work, the adsorbent was printed on a kg scale and characterized for CO2 adsorption through lab experiments. A 6-step VSA process was simulated using the lab data to capture CO2 from a representative 800 MW power plant. The adsorbent captured >70 % of the CO2 and 95 % CO2 purity was achieved. The levelized cost of electricity (LCOE) was 130.2 $/MWh and the costs of CO2 captured and avoided were 80 and 100.12 $/tonne. However, a zeolite 13X-activated carbon (13X-AC) monolith achieved a lower LCOE of 118.1 $/MWh, with the captured and avoided costs being 63 and 78.4 $/tonne, respectively. The LCOE value for the 13X-AC monolith was 5.1 % lower than a reference-packed bed system with Zeolite 13X pellets. The corresponding cost values were lower by 9.1 % and 13.9 %, respectively for the costs of CO2 captured and avoided. The lab experiments on the PEI-MWCNT sorbent revealed that further work is necessary to improve the thermal stability and stability with long-term storage of the precursor paste.

Thermodynamic analysis of adsorption carbon capture from limiting cycle to heat pump assisted cycle

Carbon capture technology has drawn much attention due to its potential on decarbonization in industries. However, there are still gaps between thermodynamic analysis and real operation process, which make it difficult for theoretical analysis of complex carbon capture system. This paper evaluates the performance of real cycle based on real process, and a carbon capture system integrated with heating and cooling are proposed to explore the energy saving strategies. Three physical adsorbents and one chemical adsorbent are evaluated and compared in terms of working capacity and heat consumption on three adsorption cycles. The results show that Mg-MOF-74 performs the best among the adsorbents due to its excellent adsorption capacity. When adsorption temperature is 25 °C, the minimum heat consumption is 2.14 GJ t−1 at desorption temperature of 129 °C. The absorption chiller is introduced to reduce adsorption temperature for increase of working capacity. Zeolite 13X with a lower adsorption heat performs better than Mg-MOF-74. And the minimum waste heat consumption is 6.02 GJ t−1 at adsorption temperature of 10 °C and desorption temperature of 105 °C, which is lower than 6.39 GJ t−1 of the reference case. When total waste heat is specified, the performance of the system can be improved significantly if around 20 % is supplied to absorption chiller. The results indicate the potential of absorption chiller and absorption heat transformer in adsorption carbon capture and find that the shifts of operation temperatures to low temperature region are beneficial for energy saving of carbon capture system.

Experimental investigation for enhancement of heat and mass transfer during regeneration of zeolite 13X-water pair

The effect of adding metal pieces in the adsorbent bed for enhancing the effective thermal conductivity and drying kinetics is investigated for the Zeolite 13X bed. Aluminum, stainless-steel pieces ranging in size from 1.5 cm to 2 cm, and aluminum oxide nanoparticles are chosen, and the total weight added to the bed is approximately 2 % of the adsorbent weight. The different semi-theoretical drying models like Lewis, Page, Logarithmic, Henderson, and Pabis and empirical models like Weibull and Gaussian model are used for the analysis. Adsorption and desorption of Zeolite 13X-water integrated with various metal pieces revealed a decrease in the adsorption capacity of adsorbents with metal pieces and increased bed moisture content for powdered aluminum oxide. It can be noticed that the desorption process was improved by including the metal pieces in the adsorbent bed.; Desorption rates range from 19.54 % for the bed mixed with straight aluminum pieces and 21.43 % for the bed filled with stainless steel. The desorption rates for the bed containing nanoparticles of aluminum oxide and spiral aluminum pieces are 20.48 % and 22.21 %, respectively. The experimental investigation on efficiency enhancement revealed that the desorption process of an adsorbent bed with straight aluminum pieces increased efficiency by 12.38 %, while the bed with aluminum oxide and stainless steel increased efficiency by 17.75 % and 23.20 %, respectively. The effectiveness of an adsorbent bed with spiral aluminum pieces is enhanced by 27.68 %. The drying kinetics analysis of zeolite 13x regeneration using semi-theoretical and empirical models which showed good agreement with experimental results.

Copper nanoparticles encapsulated in zeolite 13X for highly selective hydrogenation of CO2 to methanol

High dispersion of active metal is always approved for better catalytic performance in CO2 hydrogenation to methanol. Herein, a strategy was proposed to encapsulate copper nanoparticles in supercages of zeolite 13X, and hence the growth of copper nanoparticles can be controlled. In the present work, catalysts were prepared using ion-exchange and hydrogen reduction at a tiny positive pressure. The results show that as-synthesized catalyst consists of metallic copper and FAU-type zeolite. Excessive amount of copper will destroy zeolite frameworks, and the amount of 5.9 at% is appropriate for considerable BET surface area and ideal copper dispersion. Meanwhile, copper nanoparticles may grow outside from zeolite at high reduction temperatures (≥220 °C), resulting in serious surface area decline and metallic copper agglomeration. Afterwards catalytic tests reveal good stability of the optimal CX-220 catalyst in continuous reactions. The CX-220 achieves remarkably high methanol selectivity of ≥ 95% within wide ranges of reaction temperatures and reaction pressures. Further analyses reveal that the encapsulation of copper nanoparticles reduces micropores and enriches mesopores in zeolite. The apparent activation energy for methanol synthesis over CX-220 catalyst has been lowered to a very low level because of the unique microstructure, and thus the methanol synthesis reaction is dominant in CO2 hydrogenation for dramatic methanol selectivity. Therefore, this work gives important insights and applicable routes for catalysts analyses of CO2 hydrogenation to methanol.

A comprehensive study for improving the working parameters for the design of a PSA-based oxygen concentrator

Oxygen concentrators (OC) are medical devices that supply oxygen by separating nitrogen from the atmospheric air. The functionality of PSA-based OC majorly depends on internal pressure dynamics, cycle timing accuracy, orifice dimensioning for flow and pressure regulation, selection of zeolite, air moisture content, and others. This study aimed to develop an improved OC with sustainable performance by optimizing these key parameters. Initially, lithium and sodium-based zeolite adsorbents were experimentally compared, and it was determined that lithium-based 13X zeolite with particle size 0.4–0.8 mm is more effective for OC. An optimization study was performed for the orifice diameter for the required flow rate, purity, and pressure. The 1 mm hole diameter orifice was concluded to deliver the most optimal functionality. The results were validated via analytical and numerical study, which can further be interpolated for higher flow rate OC. After investigation, it was concluded that filters having zeolite with 10%–15% alumina would effectively remove moisture from the air for sustainable OC. An intensive experimental study was conducted to evaluate the cycle timing under optimum operating circumstances, and it was determined that the overall cycle timing is 12–14 s, with flushing accounting for 5%–8% and recharging accounting for 8%–10% of production time. The research developed 10 LPM OC with 95% purity, a recovery rate of 38.46%, and a BSF of 57.2 kgs/TPDO2. Later, the OC was certified by an ISO-13485 prototyping facility and tested in various hospitals, followed by commercialization. The system’s performance was found to be superior to that of other commercialized products.