Regeneration Temperature Research Articles

Optimisation of cooling performance and water consumption of a solid desiccant-assisted indirect evaporative cooling system using response surface methodology

Solid desiccant-assisted dew-point indirect evaporative cooling (SD-DPIEC) systems have gained considerable attention as a potential eco-friendly alternative to vapour-compression cooling systems in building cooling applications. However, one major drawback of these systems is their substantial water consumption during evaporative cooling. To tackle this issue, this study aims to improve the cooling efficiency and water utilisation of an SD-DPIEC system using response surface methodology (RSM). This research focuses on optimising four key parameters: supply air temperature, humidity ratio, water consumption rate and coefficient of performance (COP). The independent variables encompass the ambient temperature, relative humidity, regeneration temperature, and recirculation air ratio. Employing a multi-objective optimisation approach via the desirability function, the optimised SD-DPIEC system is subsequently tested in two prevalent weather patterns in Australia. The results demonstrated that the regression models derived from RSM exhibited commendable predictive capability, with the determination coefficient R2 and Adequate Precision exceeding 0.97 and 40.46, respectively. The outcomes revealed that the system attained its optimal performance with a supply air temperature of 20.36°C, humidity ratio of 12.56 g/kg, a water consumption rate of 3.11 kg/hr, and COP of 2.03 under the ambient temperature of 33.79°C, relative humidity of 68.48%, regeneration temperature of 51.78°C, and recirculation air ratio of 60 %. Based on the optimisation results, a case study was undertaken to evaluate the system's applicability in representative Australian climates. The results demonstrated that the system could uphold air conditions with the supply air temperature below 19°C and humidity ratio below 11.51 g/kg under the studied Australian climates.

System design of a novel open-air brayton cycle integrating direct air capture

The Direct Air Capture (DAC) technology is essential for achieving carbon neutrality, as it enables processes with net-negative CO2 emissions. However, its widespread commercialization faces significant challenges due to high energy requirements. Numerous attempts have been made to address this issue through thermal integration, yet the fundamental challenge of the high cost associated with extracting large volumes of low-concentration CO2 from ambient air remains unresolved. In this study, the integration of Open-Air Brayton Cycle (OABC) as a solution to enhance overall system utilization by simultaneously utilizing large volumes of ambient air is introduced. Various OABC coupled temperature swing adsorption based DAC system layouts are analyzed while considering different regeneration temperatures, and the results revealed the optimal configurations that significantly reduce energy cost per captured unit of CO2 with high purity and recovery. By combining an equilibrium short-cut model for temperature swing adsorption with process simulation methodologies, this research proposes the concept of “energy cost”—a metric that represents the amount of CO2 captured against the energy penalty incurred by integrating DAC with OABC systems. The findings demonstrate that combining DAC and OABC systems could yield high purity and recovery rates of CO2 through strategic thermal management and advanced adsorbent usage, offering a synergistic approach to carbon capture from an energy consumption perspective.

Low-temperature and in-situ regenerable ozone decomposition in aircraft with zeolite-encapsulated manganese-oxo cluster catalyst

Eliminating Ozone (O3) in aircraft cabin via catalytic decomposition is of vital importance to passenger health and oil tank anti-explosion. However, commercial catalysts work constantly at high temperature and need take-out regeneration after deactivation, causing high energy consumption and tedious maintenance. Here we attempt to address this issue by developing a manganese-oxo cluster encapsulated zeolite with initial wetness impregnation and microwave drying coupled method. Time-dependent O3 decomposition test show that the efficiency on the optimized sample was kept over 95 % for 98 h at low-temperature (−5 °C) and superhigh space velocity (720000 h−1), and well reproduced after mild regeneration (180 °C by air for 1 h, the lowest temperature for reversible regeneration of O3 catalyst reported ever). Combined EXAFTS, XPS, and DFT calculations reveal the mechanism: luxuriant charge transfer path within the [Mn3O3]n+ cluster accommodated in FAU supercage facilitates the allocation of electrons released from the rate-controlling step, rendering lower barrier energy and stabilized state of manganese for O3 decomposition. An application strategy of “cold air direct-processing and periodic in-situ regeneration” was patterned by robust performance on washcoated structured catalysts. This work affords new insights for upgrading aircraft O3 decomposition and presents metal-oxo zeolite as a platform to tailor practical catalysts.

Carbon dioxide capture from open air using covalent organic frameworks.

Capture of CO2 from the air offers a promising approach to addressing climate change and achieving carbon neutrality goals1,2. However, the development of a durable material with high capacity, fast kinetics and low regeneration temperature for CO2 capture, especially from the intricate and dynamic atmosphere, is still lacking. Here a porous, crystalline covalent organic framework (COF) with olefin linkages has been synthesized, structurally characterized and post-synthetically modified by the covalent attachment of amine initiators for producing polyamines within the pores. This COF (termed COF-999) can capture CO2 from open air. COF-999 has a capacity of 0.96 mmol g-1 under dry conditions and 2.05 mmol g-1 under 50% relative humidity, both from 400 ppm CO2. This COF was tested for more than 100 adsorption-desorption cycles in the open air of Berkeley, California, and found to fully retain its performance. COF-999 is an exceptional material for the capture of CO2 from open air as evidenced by its cycling stability, facile uptake of CO2 (reaches half capacity in 18.8 min) and low regeneration temperature (60 °C).

Comparative performance assessment of different halide composites in sorption cooling system: A dynamic approach

The adsorption technique presents a promising approach for cooling, heat storage, and gas storage. This study focuses on the viability of adsorption in cooling applications, specifically utilizing various halide salts in conjunction with thermal energy, highlighting its potential as an energy-efficient solution for modern energy demands. A dynamic numerical model is developed and used to study the performance of transverse finned reactor-based adsorption cooling system (ACS) with different halide composite salts. The simulations are carried out at different supply pressures ranging from 3.55 bar to 7.28 bar corresponding to saturation pressure of ammonia at an evaporator temperature ranging from −5 ℃ to 15 ℃ during adsorption. The desorption process is simulated at different regeneration temperatures with a required desorption pressure of 17.28 bar corresponding to saturation pressure at condenser operating temperature of 40 ℃. The average cooling power produced in first 60 min of system operation at an evaporator temperature of −5 ℃ is 4.89 W, 207 W, 206 W and 925 W with the use of BaCl2, CaCl2, SrCl2 and MnCl2 composites respectively. The theoretical maximum coefficient of performance (COP) obtained are 0.31, 0.365, 0.308 and 0.552 with BaCl2, CaCl2, MnCl2 and SrCl2 respectively. The cooling power (CP) is increasing with increase in evaporator temperature. The shortest adsorption completion time is observed at 15 ℃ of evaporator temperature with all metal halides used. The lowest adsorption time is observed with MnCl2 composite salt and highest with BaCl2 composite salt. The regeneration time of all composite salt beds is decreasing with increase in regeneration temperature.

Enhanced adsorption and regeneration performances for methyl mercaptan capture by a metal–organic framework incorporated in a mesoporous silica

Cu-modified adsorbent is widely used in removing S-containing odor pollutant, such as methyl-mercaptan (CH3SH). Increasing the dispersion of adsorptive sites and improving the regeneration cycle efficiency are two important problems. In this work, a copper metal–organic framework (MOF) was synthesized by in-situ growing the Cu-MOF on SBA-15. Micro-morphology characterizations revealed that the Cu-MOFs grew inside the SBA-15 mesopore channels and showed a good dispersion. When the hybrid (Cu-MOF in SBA-15) and the Cu-MOFs were compared for the CH3SH removal, the hybrid removed 1.70-mol CH3SH per mol of Cu in the adsorbent. This adsorbent capacity was far bigger than Cu-MOFs (0.70 mol·mol−1) and resulted from a better Cu-MOFs dispersion in SBA-15. Additionally, an easy and energy-saving hydrothermal method was put forward for the regeneration of the used adsorbent at 80 °C. The capacity of the regenerated material was higher than 70 % for at least 6 cycles. In addition, the regeneration temperature was far lower than that (> 350 °C) generally utilized in previous reports investigating cycled adsorption of CH3SH. The enhanced regeneration performances were attributed to the confinement effect of the SBA-15, which restrained the ligand around the Cu coordination centers. This work confirms the effective removal of odor-gas using a cost-effective regenerable adsorbent.

Experimental study of four-step thermal swing adsorption cycle to upgrade biogas obtained from anaerobic digestion

Biogas is a renewable source of energy that when upgraded can be adopted as a reliable and sustainable alternative. This study evaluates the performance of thermal swing adsorption technology applying resistive heating, in upgrading biogas obtained from anaerobic digestion to biomethane. Commercial coconut shell-based activated carbon was used as an adsorbent in the four-step cycle process to capture carbon dioxide, using a fabricated adsorption model. The influence of minor gas constituents of biogas in carbon dioxide breakthrough curves was analyzed. Dynamic adsorption tests were carried out to evaluate the system performance in carbon dioxide capture. The maximum regeneration temperature of 60 ℃ was found to have peak carbon dioxide concentration of 39% in the waste gas, maximum energy requirements of 0.1538kWh per cycle, and an energy efficiency of 87%. This is a good trade-off between adsorbent recovery and system energy efficiency. The adoption of thermal swing adsorption technology in biogas upgrading systems is a viable alternative for water-deficient regions.

Simulation of electrostatic particulate matter sensor regeneration based on the particulate deposition patterns

Purpose This study aims to establish a multi-physics-coupled model for an electrostatic particulate matter (PM) sensor. The focus lies on investigating the deposition patterns of particles within the sensor and the variation in the regeneration temperature field. Design/methodology/approach Computational simulations were initially conducted to analyse the distribution of particles under different temperature and airflow conditions. The study investigates how particles deposit within the sensor and explores methods to expedite the combustion of deposited particles for subsequent measurements. Findings The results indicate that a significant portion of the particles, approximately 61.8% of the total deposited particles, accumulates on the inside of the protective cover. To facilitate rapid combustion of these deposited particles, a ceramic heater was embedded within the metal shielding layer and tightly integrated with the high-voltage electrode. Silicon nitride ceramic, selected for its high strength, elevated temperature stability and excellent thermal conductivity, enables a relatively fast heating rate, ensuring a uniform temperature field distribution. Applying 27 W power to the silicon nitride heater rapidly raises the gas flow region's temperature within the sensor head to achieve a high-temperature regeneration state. Computational results demonstrate that within 200 s of heater operation, the sensor's internal temperature can exceed 600 °C, effectively ensuring thorough combustion of the deposited particles. Originality/value This study presents a novel approach to address the challenges associated with particle deposition in electrostatic PM sensors. By integrating a ceramic heater with specific material properties, the study proposes an effective method to expedite particle combustion for enhanced sensor performance.

Ligand extension of aluminum fumarate metal-organic framework in transferring higher water for adsorption desalination

This article presents the synthesis and characterization of a new microporous metal organic framework (MOF) for adsorption desalination for the first time. The new MOF, designated as “Al-t,t-Ma”, is an analogue of aluminum fumarate (Al-Fum) and is fabricated via ligand extension method. Firstly, the MOF is synthesized, and then characterized by XRD, FTIR spectroscopy, TEM, SEM, TGA and N2 adsorption techniques. Secondly, the water adsorption experiments on the pristine Al-Fum and Al-t,t-Ma are performed for a wide temperature (30 °C ≤ T ≤ 80°C) and pressure (0 < P/Ps ≤ 0.9) ranges. The water adsorption isotherms, kinetics, hydro-thermal stabilities as well as the isosteric heat of adsorption (Qst) are evaluated. Thirdly, based on the experimentally confirmed isotherms, kinetics and isosteric heats data, the adsorption assisted desalination (AD) system is modelled and simulated. Finally, the performances of AD system employing Al-Fum and Al-t,t-Ma MOFs are calculated in terms of the performance ratio (PR) and specific daily water production (SDWP) under various half cycle times (100 s ≤ tcycle ≤ 1000 s) and regeneration temperatures (55°C ≤ Tregen ≤ 80°C). As compared with the pristine Al-Fum, the pore volume of Al-t,t-Ma MOF is found 115 % higher. The proposed Al-t,t-Ma MOF possesses higher water transfer (+57.5 % more) with promising hydro-thermal stability. Employing Al-t,t-Ma MOF as porous adsorbent, the SDWP is achieved 28 m3 per tonne of MOFs per day at the regeneration temperature of 55°C. These results confirm that Al-t,t-Ma MOF is a competent candidate for adsorption desalination.

Synergistic ionic liquid encapsulated MIL-101 (Cr) metal-organic frameworks for an innovative adsorption desalination system

The transformations of brackish water into freshwater employing porous materials such as metal-organic frameworks (MOFs) show a great potential for a green environment. But the adsorption-based desalination slows down due to slow water adsorption/desorption rates and inadequate water storage capacity in conventional adsorbents. Therefore, the restructuring of porous MOFs increases water storage and transfer rates. This paper presents a comprehensive investigation on the fabrication of ionic liquid encapsulated MIL-101 (Cr) MOFs (metal-organic frameworks), and its interactions with water for desalination applications. Firstly, the pristine MIL-101 (Cr) is encapsulated with various types/amounts of ionic liquids. Next, these MOFs are characterized via SEM (Scanning electron microscope), FTIR (Fourier transform infrared), XRD (X-ray diffraction), TGA (Thermal gravimetric analysis), N2 adsorption techniques. The water adsorption on these MOFs is performed experimentally for a wide temperature (30–80 °C) and pressure (0 < P/Ps < 0.95) ranges. The effects of the size (or type) as well as the encapsulation ratio of ionic liquids on water adsorption behaviors are conducted. Based on the experimentally proven water adsorption (isotherms and kinetics) data, an AD (adsorption desalination) system is modelled and simulated. Finally, the AD performances in terms of the specific daily water production (SDWP) and performance ratio (PR) are parametrically studied with respect to various regeneration temperature (50–80 °C) and cycle times (100 s–1000 s). It is found that by ionic liquid encapsulation, the water uptakes/offtake rates are expedited up to 48% (for adsorption)/55% (for desorption), respectively. In addition, the water transfer (Δq) improves up to 45% more than the parent MIL-101(Cr) MOFs. Furthermore, the SDWP increases from 38 to 56 m3 of water per tonne of MOFs per day at the regeneration temperature of 70 °C. The simulation results also show that the ionic-liquid-encapsulated MIL-101 (Cr) MOFs generates water (>25 m3 water per tonne of IL-MOFs) at the regeneration temperature of 50 °C and is potential for the next generation desalination applications.

Experimental evaluation of a hydrogel composite desiccant wheel for dehumidification with high water uptake and low regeneration temperature

Rotary dehumidification, a key method for continuous solid adsorption dehumidification, is extensively utilised in various industrial and practical applications. The performance of the adsorbent within the desiccant wheel is a major determinant of its energy efficiency in practical applications. While studies on Metal Organic Frameworks (MOFs) and polymer desiccant wheels exist, the majority of rotary dehumidification systems continue to employ traditional adsorbents like silica gel and zeolite, which are plagued by low dehumidification capacity and high energy consumption issues. Super hygroscopic hydrogel, enhanced with a hygroscopic agent, has gained prominence in air treatment because of its outstanding hygroscopicity and low regeneration temperature. With the goal of integrating advanced materials into practical engineering applications and mitigating the heat and mass transfer loss and adsorption/desorption performance degradation due to volume expansion and viscous agglomeration post-water uptake in large-scale super hygroscopic hydrogel applications, this study successfully developed a hydrogel wheel, measuring 350 mm in diameter and 200 mm in thickness, using a honeycomb-shaped glass fibre paper substrate. Experimental findings demonstrate that the hydrogel desiccant wheel outperforms both the MOF and commercial low-temperature silica gel wheels under all tested environmental conditions. This advantage is particularly noticeable at 15 °C and 30 % Relative Humidity (RH), where the moisture content differential (Δd) in the hydrogel system is 2.96 g/kg, 1.89 times greater than the MOF system’s 1.56 g/kg and 5.19 times higher than the silica gel’s 0.57 g/kg. Furthermore, the controlled variable method was used to assess the impact of each operational parameter on the hydrogel wheel’s performance in both low and high moisture conditions, offering design insights for engineering applications.

Energy Performance of Zeolite-Based Drying Bead Desiccants Used to Dry Paddy Rice.

This study utilizes differential scanning calorimetry and thermogravimetric analysis to assess the total energy required to regenerate saturated zeolite-based drying beads (DBs) used to dry paddy rice. We quantify the required heat energy for DB regeneration by calculating the area under the curve in a heat flow rate versus time graph, with the end of the regeneration process indicated by stabilization of the DB weight. Our findings suggest that at DB regeneration temperatures ranging from 120 to 350 °C, the process varied from 813 to 22 min, demonstrating that higher temperatures lead to faster regeneration speeds. The total energy used for regeneration showed similar values at 250 and 350 °C, averaging around 2032 and 2136 kJ per kg of dried DB, respectively. Additionally, the study showed that DBs can hold water between 28.7% and 54.4% higher than the manufacturer's specifications, suggesting a reduced quantity of DBs required for effective paddy rice drying. The overall required heat energy for the regeneration process was calculated at 4.86 MJ/kg, with a carbon intensity of approximately 275.61 g of CO2-eq per kg of water removed, resulting in lower values compared to conventional drying methods. The study underscores DB's possibility of lower total energy (thermal and electrical) consumption and greenhouse gas emissions, alongside its flexibility to regenerate with intermittent energy sources.

Open-cycle thermochemical energy storage for building space heating: Practical system configurations and effective energy density

Salt-hydrate thermochemical materials (TCM) are promising candidates for energy storage systems for building space heating due to their high theoretical energy density and the need for low regeneration temperature. However, water vapor is required to drive the hydration process of the TCM reactor, which poses a challenge during winter when water vapor is typically scarce. Using indoor air directly lowers the building's humidity to an unconformable level in practice, while the cold outdoor air contains limited moisture. Here we consider different integration strategies for open-cycle TCM reactors in buildings and develop a model to simulate their thermal performance across diverse buildings and climates, specifically for building space heating. The potential energy densities and the levelized cost of storage of the TCM reactor are evaluated in practical scenarios to demonstrate the load-shifting potential of TCM systems for heating applications. We use a strontium chloride (SrCl2)-based composite as the baseline and explore the impact of various reactor and material changes to the energy density and levelized cost of storage.

The preparation and investigation of ionic functional resins for deep dehydration of toluene

Toluene is a solvent and raw material widely used in industrial production. Reducing the water content of toluene to less than 10 mg/kg is of significant importance in fine chemicals. In this study, different ionic functional resins containing strong hydrophilic sulfonate groups were synthesized. These ionic functional resins exhibit an exceptional depth of toluene dehydration and an extremely high water absorption capacity. The most effective hydrogen functional resin has a water adsorption capacity of 679.7 mg/g, which is more than 2.5 times of 3A molecular sieve, and can dehydrate toluene from 180 mg/kg to less than 3 mg/kg. The specific surface area and pore size distribution of the resins were analyzed by nitrogen adsorption and desorption methods, and results show that these resins are mesoporous materials. The multilayer adsorption mechanism of the ionic functional resins was determined by fitting the adsorption isotherms using a Modified Dent model. The effects of contact time, oil-agent ratio, regeneration temperature, and number of regenerations were also investigated, and fixed-bed penetration curves were obtained to provide data for practical industrial applications. The results show that low-temperature drying at 80 °C is sufficient to regenerate the ionic functional resin. Finally, competitive adsorption studies with toluene and water reveal that the resin exhibit a higher affinity for water than for toluene.

Efficient separation of carbon dioxide and methane in high-pressure and wet gas mixtures using Zr-MOF-808

The capture and separation of carbon dioxide (CO2) has been the focus of a plethora of research in order to mitigate its emissions and contribute to global development. Given that CO2 is commonly found in natural gas streams, there have been efforts to seek more efficient materials to separate gaseous mixtures such as CO2/CH4. However, there are only a few reports regarding adsorption processes within pressurized systems. In the offshore scenario, natural gas streams still exhibit high moisture content, necessitating a greater understanding of processes in moist systems. In this article, a metal-organic framework synthesis based on zirconium (MOF-808) was carried out through a conventional solvothermal method and autoclave for the adsorption of CO2 and CH4 under different temperatures (45–65 °C) and pressures up to 100 bar. Furthermore, the adsorption of humid CO2 was evaluated using thermal analyses. The MOF-808 synthesized in autoclave showed a high surface area (1502 m2/g), a high capacity for CO2 adsorption at 50 bar and 45 °C and had a low selectivity to capture CH4 molecules. It also exhibited a fine stability after five cycles of CO2 adsorption and desorption at 50 bar and 45 °C − as confirmed by structural post-adsorption analyses while maintaining its adsorption capacity and crystallinity. Furthermore, it can be observed that the adsorption capacity increased in a humid environment, and that the adsorbent remained stable after adsorption cycles in the presence of moisture. Finally, it was possible to confirm the occurrence of physisorption processes through nuclear magnetic resonance (NMR) analyses, thus validating the choice of mild temperatures for regeneration and contributing to the reduction of energy consumption in processing plants.

High-barrier, flexible, hydrophobic, and biodegradable cellulose-based films prepared by ascorbic acid regeneration and low temperature plasma technologies

Regenerated cellulose (RC) films are considered a sustainable packaging material that can replace non-degradable petroleum-based plastics. However, their susceptibility to water vapor and oxygen can limit their effectiveness in protecting products. This study introduces a novel approach for enhancing RC films to create durable, flexible, hydrophobic, high-barrier, and biodegradable packaging materials. By exploring the impact of ascorbic acid coagulation bath treatment and plasma-enhanced chemical vapor deposition (PECVD) on the properties of RC films, we found that the coagulation bath treatment facilitated the organized reconfiguration of cellulose chains, while PECVD applied a dense SiOx coating on the film surface. The results demonstrated a significant enhancement in water vapor and oxygen barrier properties of the composite film, almost reaching the level of commercial barrier films. Moreover, the composite film displayed exceptional biodegradability, fully degrading in soil within 35 days. Additionally, it showcased impressive mechanical strength, hydrophobic characteristics, and freshness preservation, positioning it as a valuable option for bio-based high-barrier packaging applications.

Promotional effect of NaNO3/NaNO2 on CO2 adsorption performance of MgO sorbents

The magnesium oxide (MgO) sorbents doped with different NaNO3/NaNO2 molar ratios were prepared to improve their stability over multiple cycles. Regulating the NaNO3/NaNO2 molar ratio effectively improved the CO2 adsorption performance of the sorbent. The MgO sorbent with the NaNO3/NaNO2 molar ratio of 0.8 exhibited outstanding performance and stability. Characterization and density functional theory calculations confirmed the positive effects of the appropriate NaNO3 amount in improving the adsorption activity, whereas the suitable NaNO2 amount slowed the sintering step and improved stability. Notably, the molten salt remained stable during cycling and did not decompose even at high regeneration temperatures, guaranteeing the cyclic stability of the sorbent. Further characterization showed that the CO2 sorption drop in the first few cycles was ascribed to the decline in the active surface owing to the aggregation of MgO particles, incomplete regeneration of sorbents, and segregation of molten salt on the sorbent surface.

Novel MOF-303/G coated wire-finned heat exchanger for dehumidification applications–Experimental investigation

Adsorption dehumidification outperforms other technologies regarding moisture removal rate, lower energy consumption, and environmental friendliness. The selection of desiccant material, the heat exchanger used, and the method of regeneration significantly impact the performance of desiccant dehumidifiers in terms of water vapour removal rate and energy consumption. Metal-organic framework materials are a new class of microporous materials with high water adsorption characteristics compared to conventional desiccants like silica gel. In this work, a novel MOF-coated electrically heated wire finned heat exchanger was developed, and its performance was experimentally investigated. Wire-finned tubes coated with MOF-303/G outperformed other wire-finned tubes coated with Aluminium fumarate, MIL-100(Fe), MIL-100(Fe)/G, MOF-801 and MOF-801/G, achieving water uptake of 22 %. Also, the addition of graphene nanoplatelets during the synthesis of MOF-303 resulted in a significant enhancement of its thermal diffusivity to reach 0.184–0.23 mm2/s at temperatures ranging between 25 °C and 115 °C. The Coefficient of Performance (COP) for the developed multi-tube MOF-303/G coated heat exchanger was experimentally tested and compared to other desiccant-coated heat exchangers. Results showed that COP values ranging from 0.6264 to 1.02 to 1.2 at the regeneration temperatures of 45 °C, 60 °C and 70 °C, respectively, were achieved, which are higher than those reported in the literature.

Impact of sulfur exposure on high-temperature Cu speciation in SSZ-13 Zeolites

Metal active sites exchanged in zeolites dynamically change speciation under different reaction conditions, resulting in condition-dependent reactivity with gas molecules. This is of particular significance in chemical deactivation, such as sulfur poisoning of Cu-SSZ-13 zeolites used for NH3-assisted selective catalytic reduction (SCR) of NOx in diesel engine exhaust. Here, we employ computational techniques, combined with experiments and spectroscopies, to develop thermodynamic models for sulfur poisoning of zeolite framework-bound Cu dimers that form at high temperatures in Cu-SSZ-13 zeolites as a function of both the Al distribution and reaction conditions. Our results demonstrate that framework-bound Cu dimers that form under high temperature oxidative conditions are particularly susceptible to poisoning by SO2 and SO3. These Cu dimers react more exothermically with SOx species than Cu monomers, forming thermodynamically stable sulfur-containing Cu dimers that require high temperatures for catalyst regeneration.

Enhancing sustainability in sewage treatment: A least squares support vector regression-based modeling approach for optimizing regeneration conditions of iFeCu

Nanoparticles in wastewater treatment offer sustainable, efficient removal of persistent pollutants, with minimal resource usage and reusability. This study examines the reusability of immobilized iron‑copper nanoparticles (iFeCu) for sewage treatment. The effect of the regeneration condition of iFeCu including the regeneration time and temperature on the performance of iFeCu for sewage treatment was investigated. Moreover, a soft sensor model, namely principal component analysis discrimination analysis ensemble least squares support vector regression (PCA-DA-E-LSSVR) model was developed to predict the performance of iFeCu, and an online performance of the model was studied to evaluate its accuracy. Investigating regeneration conditions like time and temperature, it was found that iFeCu regenerated in 1 mol (M) sodium carbonate (Na2CO3) at 40 °C for 5 h performed comparably to that regenerated at 60 °C for 15 h. Higher regeneration temperatures (>40 °C) decreased carbon dioxide and monoxide emissions but reduced ammonia (NH3) removal by ∼22 %. Shorter regeneration times (<5 h) decreased Na2CO3-iFeCu interaction, leading to an ∼11 % NH3 removal reduction. The correlation coefficient, R2 value of 0.8514 was obtained for the proposed PCA-DA-E-LSSVR model. Overall, the developed model well-fits the nonlinear data in sewage treatment and provides acceptable ranges of online performance results.