Oxygen Storage Research Articles

Syngas Production by Chemical Looping Dry Reforming of Methane over Ni-modified MoO3/ZrO2.

We investigated supported-MoO3 materials effective for the chemical looping dry reforming of methane (CL-DRM) to decrease the reaction temperature. Ni-modified molybdenum zirconia (Ni/MoO3/ZrO2) showed CL-DRM activity under isothermal reaction conditions of 650 °C, which was 100-200 °C lower than the previously reported oxide-based materials. Ni/MoO3/ZrO2 activity strongly depends on the MoO3 loading amount. The optimal loading amount was 9.0 wt.% (Ni/MoO3(9.0)/ZrO2), wherein two-dimensional polymolybdate species were dominantly formed. Increasing the loading amount to more than 12.0 wt.% resulted in a loss of activity owing to the formation of bulk Zr(MoO4)2 and/or MoO3. In situ Mo K-edge XANES studies revealed that the surface polymolybdate species serve as oxygen storage sites. The Mo6+ species were reduced to Mo4+ species by CH4 to produce CO and H2. The reduced Mo species reoxidized by CO2 with the concomitant formation of CO. The developed Ni/MoO3(9.0)/ZrO2 was applied to the long-term CL-DRM under high concentration conditions (20 % CH4 and 20 % CO2) at 650 °C, with two pathways possible for converting CH4 and CO2 to CO and H2 via the redox reaction of the Mo species and coke formation.

Preparation and Characterization of Multielement Composite Oxide Nanomaterials Containing Ce, Zr, Y, and Yb via Continuous Hydrothermal Flow Synthesis.

The synthesis of multielement composite oxide nanomaterials containing Ce, Zr, Y, and Yb was investigated using a micro confined jet mixer reactor operated in continuous mode under supercritical water conditions. The obtained nanoparticles were characterized using ICP-AES, SEM-EDS, FTIR, Raman spectroscopy, XRD, and TEM. All samples exhibited a uniform particle shape and a narrow particle size distribution. An analysis of the d-spacing results using selected electron area diffraction (SAED) patterns confirmed the production of cubic-phase crystals. A BET test was employed to determine the specific surface area of the prepared nanoparticles. OSC and TPR techniques were utilized to characterize the oxygen storage capacity and reduction performance of the obtained samples, with an analysis conducted to determine how the different proportions of elements affected the performance of multielement mixed oxides. The ionic conductivity of multielement composite oxide was measured using alternating current impedance spectroscopy (EIS), and the impact of Y, Ce, and Yb on the electrolyte material's ionic conductivity was analyzed.

Paper‐structured catalyst with a dispersion of ceria‐based oxide support for improving the performance of an SOFC fed with simulated biogas

AbstractSolid oxide fuel cells (SOFCs) can accept a direct feed of biogas for power generation; however, carbon deposition is a major obstacle to their practical application. When a paper‐structured catalyst (PSC) with a dispersion of Ni‐loaded flowerlike Ce0.5Zr0.5O2 (Ni/CZ(F)) was applied to the anode of an electrolyte‐supported cell (ESC), the open‐circuit voltage of the cell directly fed simulated biogas was increased from 0.87 to 0.98 V at 750°C. The rates of cell‐voltage degradation and coke formation of the ESC with the Ni/CZ(F)‐PSC during 100 h of operation were 4.3% kh−1 and 0.43 mg‐C g‐PSC−1 h−1, respectively, which were lower than those of an ESC with a Ni‐loaded PSC without the CZ(F) dispersion (10.4% kh−1 and 8.1 mg‐C g‐PSC−1 h−1, respectively). This performance improvement is attributed to the unique porous morphology and high oxygen storage capacity of CZ(F), which can contribute to the prevention of Ni agglomeration and the removal of coke from the catalyst surface, respectively. Thus, the Ni/CZ(F)‐PSC can function as a practically applicable reforming domain for an internal‐reforming biogas‐fueled SOFC.

Double-stable Ce-based oxide: Capturing atomic precious metals via Ostwald ripening for multicomponent three-way catalysts construction

Precious metal catalysts have been widely used to catalyze various reactions, particularly three-way catalysts for automobile exhaust purification. Pt, Pd, and Rh, which are dispersed on Ce-based oxides that store and release oxygen, serve as the active center of a catalyst. However, methods to construct multifunctional three-way catalysts to maximize their efficiency and stabilize them are lacking. In this study, Ce-based oxides with a double-stable mode were synthesized to capture and stabilize the precious metals Pt and Rh migrated by Ostwald ripening (OR), and a multicomponent three-way catalyst was accurately synthesized, which showed good catalytic activity and thermal stability. The origin of Ce-based oxides with a dual-stable mode was studied by TEM, XRD, oxygen storage/release capacity and rate test, and XPS. AC-STEM, EXAFS, in situ diffuse reflectance Fourier transform infrared, and H2 temperature-programmed reduction studied the OR migration of precious metals and the composition change after aging. Results showed that in the lean/rich oxygen alternating shift atmosphere containing CO, the proportion of OR migration of Pt and Rh precious metals whose initial state is single atoms can reach 100 %. This discovery provides a basic understanding of the sintering mechanism of precious metals, which is of great importance for the development and industrial application of three-way catalysts.

Effects of cold plasma treatment on reactive oxygen metabolism and storage quality of Brassica chinensis

Cold plasma (CP) is a promising non-thermal food preservation technique, which is used for the preservation of fruits and vegetables. In this study, we aimed to determine the effects of CP treatment on the reactive oxygen metabolism, antimicrobial properties, and antioxidant activities in Brassica chinensis during storage at 4 ± 1 °C for 10 days. Postharvest Brassica chinensis were treated with CP for 6 min (CP-6), 9 min (CP-9), and 12 min (CP-12). To maintain a balance between microbial spoilage and storage quality, CP-9 was considered to be the optimal treatment time. Compared with the control group, Brassica chinensis in the CP-9 group showed a 12.7% increased antioxidant capacity, a reduction of the microbial count by 0.7 lg CFU g−1, and a delay in weight loss and soluble solid content reduction. CP inhibited the generation of superoxide anions, improved the activity of reactive oxygen species scavenging enzymes, and delayed the decrease in total antioxidant capacity. Altogether, CP treatment can be considered an advantageous approach to improve the safety and quality of fresh vegetables.

Porosity in Sr1−xCaxFeO3-δ oxygen carriers: The role of surface area and pretreatment on storage activity

Perovskite oxides have generated interest as robust, low-temperature oxygen carrier materials for a variety of clean energy applications, including chemical looping gasification and air separations. Methods to improve O2 desorption kinetics are vital to allow these carriers to compete economically with traditional metal oxide carriers or cryogenic separations. Herein, we investigated the cumulative roles that surface area, pretreatment, and elemental composition have on the oxygen storage properties of a state-of-the-art carrier system, Sr1−xCaxFeO3-δ (x = 0.20, 0.25, 0.30) synthesized using multiple methods. Porous materials synthesized by the Pechini, or citrate, method had their surface area controlled using the synthesis temperature. The high surface area of the Sr0.7Ca0.3FeO3-δ materials is most beneficial at low operating temperatures, such as 350 and 400 °C, as their reduction rates are twice as fast as those obtained with their bulk counterparts. These effects are observed at higher operating temperatures and within a single composition, but temperature tunability using variable Ca2+ substitution in the Sr1−xCaxFeO3-δ overshadows the improvements gained from higher surface areas. Additionally, we establish that pretreatment in N2 at an elevated temperature is necessary to enhance kinetics further. For maximum efficiency, pretreatment at the synthesis temperature is suggested for the Pechini method-synthesized systems, whereas 800 °C is adequate for bulk materials.

Role of promoter on the catalytic activity of novel hollow bimetallic Ni–Co/Al2O3 catalyst in the dry reforming of methane process: Optimization using response surface methodology

In this research, the effect of promoter addition and its type on the catalytic performance and morphology properties of bimetallic Ni–Co catalysts on the novel hollow Al2O3 support was investigated in the dry reforming of methane (DRM) process. The response surface method (RSM) based on the optimal custom model was employed for maximizing CH4 and CO2 conversions, as well as H2 and CO yield. Four independent variables including Co to Ni mass ratio (0, 0.5, 1), DRM temperature (600, 650, 700 °C), CH4/CO2 molar ratio (1, 1.5, 2), and catalyst type (without promoter, with Mg or Y promoter) were selected for this purpose. Among three suggested optimized catalysts by the design expert, the yttrium-promoted one with 1 Co/Ni mass ratio (1Ni–Co–Y/Al) depicted the highest CH4 conversion of 86.50 %, CO2 conversion of 92.00 %, H2 yield of 85.11 %, and CO yield of 93.54 % at lower temperature of 679 °C and equal CH4/CO2 mole ratio of 1. The structural characterizations confirmed that the high activity of 1Ni–Co–Y/Al could be due to the better dispersed active sites and higher surface area of this catalyst compared with un-promoted and Mg-promoted samples. The time-on-stream performance of optimized catalysts at their optimized conditions was also compared experimentally, results of which showed more stability and activity of the Y-promoted sample during 12 h DRM reaction. The TGA, EDX, XRD, FESEM, and N2 physisorption techniques demonstrated the lower structural change and deposited carbon on the 1Ni–Co–Y/Al surface after reaction, which may be because of higher oxygen storage capacity (OSC) of this catalyst.

Prolong Submersion in the Swimming Pool without Neurological Outcome

Abstract Drowning can be defined as a chain of events of respiratory disability due to submersion or immersion in liquid with sequelae such as irreversible brain damage, heart failure, and death. The main organ in a drowning subject is the brain, which has almost zero energy and oxygen stores and hence needs a continuous supply of blood to fulfill its need for oxygen and loss of laryngospasm. This leads to massive aspiration, lung atelectasis, and edema. This unique and miracle case was a child submerged in a swimming pool for a prolonged period without receiving CPR, traveling from the drowning place to the present hospital around 30 km. The patient came from a small village where there were no facilities of ambulance inbuilt basic facilities or advanced life support. He was on a mechanical ventilator in the pediatric intensive care unit in the present institute. He was unconscious on admission. Recovered from all complications and was discharged without any neurological abnormalities. A 13-year-old boy was admitted to the pediatric emergency department with a history of drowning in a swimming pool; he was a nonswimmer and went with his friends who were swimmers, where he accidentally fell into the water without notice from other friends. After not finding him around, his friends searched for him. They found him immersed in water at the bottom of the pool for about 10–15 min, not receiving cardiopulmonary resuscitation (CPR) as nobody was trained. The primary diagnosis was drowning without neurological complications. Therapeutic interventions included a mechanical ventilator, intravenous antibiotics, intravenous steroids, chest physiotherapy. On discharge patient had no neurological complication except limping of right foot. After 1 month of follow up, central nervous system examination was within the normal limits. No limping was seen. No neurological deficit was observed. Drowning is a common etiology of accidental mortality in the pediatric age group. Most victims not treated with CPR at the site develop permanent neurological deficits. Proper and effective management can improve many complications caused due to drowning. Guidelines should be strictly followed in private/public swimming pools to have all duties of lifeguards who are trained in CPR. Drowning patients should be managed in hospitals with well-equipped mechanical ventilators, including trained staff.

Solar driven hydrogen and oxygen production for cooking and medical applications

The initiative for solar-driven hydrogen and oxygen production for cooking and medical applications is designed to revolutionize our approach to energy-intensive activities. This project integrates three crucial components: solar power generation, hydrogen and oxygen gas separation and storage, and the application of these gases for cooking and medical purposes. Through the use of solar panels, the project captures sunlight and converts it into electrical energy, fundamentally departing from conventional energy sources with its clean and renewable approach. The electrolyzer, powered by the harvested solar energy, then facilitates the separation of water into hydrogen and oxygen gasses, both stored meticulously in separate containers with stringent safety measures in place. The innovative aspect lies in the utilization of these clean gasses as a sustainable fuel source for cooking and medical applications. When these gasses combust, they recombine to form water vapour, releasing energy without the emission of harmful by-products. By emphasizing clean energy practices, this project significantly diminishes the carbon footprint associated with traditional cooking methods, offering a promising and ecofriendly alternative for households and communities. The success of this solar-driven hydrogen and oxygen production initiative holds the potential to transform our energy landscape, making strides towards a more sustainable and environmentally conscious future.

Perovskites as oxygen storage materials for chemical looping partial oxidation and reforming of methane.

The traditional partial oxidation, dry reforming and steam reforming of methane technologies are separated into two reactors for execution by chemical looping technology, which can avoid the defects exposed in the traditional process (avoiding carbon accumulation, reducing costs, etc.). The key to chemical looping technology is to find suitable oxygen carriers (OCs), which can store and release oxygen to form a closed loop in the chemical looping. The purpose of this review is to summarize the current status of perovskite oxides for partial oxidation and reforming of methane in chemical looping, describe the structure, oxygen capacity, oxygen migration rate and common synthesis methods of perovskites in chemical looping. In addition, the effects of impregnation loading, ion doping, and structural morphology on the catalytic conversion of CH4 by perovskite OCs and the reaction mechanism on the OCs are also discussed.

Nanostructured CeO2 photocatalysts: optimizing surface chemistry, morphology, and visible-light absorption.

Emerging photocatalytic applications of cerium dioxide (CeO2) include green hydrogen production, CO2 conversion to fuels, and environmental remediation of various toxic molecules. These applications leverage the oxygen storage capacity and tunable surface chemistry of CeO2 to photocatalyze the chosen reaction, but many open questions remain regarding the fundamental physics of photocatalysis over CeO2. The commonly ascribed 'bandgap' of CeO2 (∼3.1 eV) differs fundamentally from other photocatalytic oxides such as TiO2; UV light excites an electron from the CeO2 valence band into a 4f state, generating a polaron as the lattice distorts around the localized charge. Researchers often disregard the distinction between the 4f state and a traditional, delocalized conduction band, resulting in ambiguity regarding mechanisms of charge transfer and visible-light absorption. This review summarizes modern literature regarding CeO2 photocatalysis and discusses commonly reported photocatalytic reactions and visible light-sensitization strategies. We detail the often misunderstood fundamental physics of CeO2 photocatalysis and supplement previous work with original computational insights. The exceptional progress and remaining challenges of CeO2-based photocatalysts are highlighted, along with suggestions for further research directions based on the observed gaps in current understanding.

Low oxygen storage alleviates chilling injury in cherry tomatoes

Low oxygen storage alleviates chilling injury in cherry tomatoes

Singlet oxygen storage and controlled release for improving photodynamic therapy against hypoxic tumor

Photodynamic therapy (PDT) has been considered to become a promising tumor treatment method due to its non-invasiveness and low-risk. However, there are two factors that will affect the therapy efficacy....

Low oxygen storage impacts on blueberry fruit quality

Low oxygen storage impacts on blueberry fruit quality

Contrasting offspring dependence periods and diving development rates in two closely related marine mammal species.

Understanding the ontogeny of diving behaviour in marine megafauna is crucial owing to its influence on foraging success, energy budgets, and mortality. We compared the ontogeny of diving behaviour in two closely related species-northern elephant seals (Mirounga angustirostris, n = 4) and southern elephant seals (Mirounga leonina, n = 9)-to shed light on the ecological processes underlying migration. Although both species have similar sizes and behaviours as adults, we discovered that juvenile northern elephant seals have superior diving development, reaching 260 m diving depth in just 30 days, while southern elephant seals require 160 days. Similarly, northern elephant seals achieve dive durations of approximately 11 min on their first day of migration, while southern elephant seals take 125 days. The faster physiological maturation of northern elephant seals could be related to longer offspring dependency and post-weaning fast durations, allowing them to develop their endogenous oxygen stores. Comparison across both species suggests that weaned seal pups face a trade-off between leaving early with higher energy stores but poorer physiological abilities or leaving later with improved physiology but reduced fat stores. This trade-off might be influenced by their evolutionary history, which shapes their migration behaviours in changing environments over time.

Promoted Ni–Co bimetallic catalysts for glycerol dry reforming: Understanding the physiochemical properties and carbon formation

Glycerol dry reforming (GDR) is one of the alternatives for syngas production by utilizing glycerol, a by-product of biodiesel. This current work focusing on the effect of Ce, Ru and Pd as promoters on Ni–Co/Al2O3 catalysts. Ultrasonic-assisted impregnation was utilized to synthesize the catalysts and GDR was carried out by varying the reactant partial pressure CO2 to glycerol ranging from 10 to 40 kPa at 1073 K. Characterization studies showed that incorporation of promoter reduced Ni–Co agglomeration and increased metal dispersion on Al2O3 support. This resulted in smaller crystallite size and more consumption of H2 and CO2 based on H2-TPR and CO2-TPD analyses. Irrespective of reactant partial pressure, the catalytic performance was increased with following trend; Ni–Co/Al2O3 < Ce–Ni–Co/Al2O3 < Ru–Ni–Co/Al2O3 < Pd–Ni–Co/Al2O3. The best reactant partial pressure (CO2 and glycerol) was achieved at 20 kPa and the effect of competing reactant caused a significant decline in catalytic performance beyond 20 kPa. Oxygen storage capacity, basic nature and redox cycle of promoters assisting in the carbon reduction on catalysts surface. Overall, Pd–Ni–Co/Al2O3 recorded the highest catalytic activity and lowest carbon formation (7.25%) compared to other promoted catalysts credited to their smallest crystallite size (7.12 nm), great metal dispersion (77.4%, 2.95), highest H2 production, CO2 consumption and oxygen storage capacity.

Controlled atmosphere storage of krypton, xenon and oxygen inhibits yellowing and maintains quality of fresh peeled water chestnuts (Eleocharis dulcis)

Yellowing and quality (including total soluble solid (TSS), titratable acid (TA) and ascorbic acid (AA)) deterioration are the main reasons for affecting shelf life of fresh peeled water chestnuts (FPWCs). The use of controlled atmosphere (CA) storage of krypton (Kr), xenon (Xe) and O2 to keep food fresh has not been studied. The purpose of this study was to determine the effect of CA storage of Kr, Xe and O2 on the shelf life of FPWCs. FPWCs were treated with CA storage (Kr 40.4%, Xe 40.4%, O2 19.2%) (CA-(Kr, Xe, O2)). The N2 content, Kr content, Xe content, O2 content, CO2 content, degree of yellowing, eriodictyol and naringenin contents, polyphenol oxidase (PPO) activity, peroxidase (POD) activity, phenylalanine lyase (PAL) activity, weight loss, TSS content, TA content, AA content, texture and microbe of FPWCs were measured. The results indicate that CA-(Kr, Xe, O2) reduces the degree of yellowing by inhibiting the eriodictyol content, maintains the quality by reducing the weight loss and increasing TSS, TA and AA contents. In addition, it was found that CA-(Kr, Xe, O2) maintains the texture by increasing the hardness, springiness, gumminess and chewiness, and inhibits the growth of mesophile, yeast and mold. The results provide a new method for extending shelf life of FPWCs.

A machine learning study on a municipal solid waste-to-energy system for environmental sustainability in a multi-generation energy system for hydrogen production

Municipal solid waste (MSW)-to-energy systems have gained significant attention in recent years for their potential to produce renewable energy from waste. These systems involve the conversion of MSW into electricity, heat or fuel. One of the most promising applications of MSW-to-energy systems is the production of hydrogen, which is considered a clean and sustainable fuel. Machine learning algorithms have the potential to revolutionize the way MSW-to-energy systems are managed. The integration of machine learning into MSW-to-energy systems has the potential to significantly improve the sustainability and profitability of this industry. In this study, a novel integrated MSW-to-energy system is modeled to produce hydrogen, power, and oxygen and with capacities of heating water and air. Hydrogen production, power production, oxygen storage, hot water, hot air, and system emission are predicted using machine learning algorithms based on regression models with high validity and R2 values more than 99.8% having errors smaller than 1%. The reduced regression models are developed by eliminating the insignificant variables from the full algorithms using the analysis of variance. The findings reveal high accuracy for the reduced regression models while their errors slightly decrease to 2%. This suggests that the machine learning algorithms can also be used as an effective tool to further improve MSW-to-energy systems.

Impact of operation parameters and lambda input signal during lambda-dithering of three-way catalysts for low-temperature performance enhancement

A synthetic exhaust gas bench was dynamically operated to investigate the impact of temperature, amplitude, split cycle, mean lambda, gas hourly space velocity, and oxygen storage capacity on average pollutant conversion and product selectivity of three-way catalysts in periodic operation. As temperature and amplitude increase and oxygen storage capacity decreases, the optimal frequency for maximum pollutant conversion increases. This is consistent with faster desorption of CO and O2 from the catalyst, yielding free surface sites. Regarding the formation of secondary products, the optimal frequency for maximum pollutant conversion does not always correspond to minimal N2O and NH3 emissions. The split cycle variation reveals the enhancement of C3H8 and NO conversion after both lean-rich and rich-lean switches and C3H6 and CO conversion after rich-lean switches at the optimal frequency. As periodic operation does not affect existing engine settings or operating conditions, it is a cost-effective control strategy for meeting future emission limits.

Cu-Fe-Ni layered hydroxides / magnetic biochar composite as peroxymonosulfate activator for removal of enrofloxacin

In this research, an economical peroxymonosulfate (PMS) was employed as the oxidizing agent, while a sophisticated Cu-Fe-Ni layered hydroxides/magnetic biochar composite (MBC/CuFeNi LDHs, succinctly termed MC-1) functioned as a catalyst to mitigate the presence of enrofloxacin (ENR), a notably toxic contaminant discerned in water. The stratified architecture and intricate surface functional groups of the composite played pivotal roles in ENR's degradation. Metal oxides containing Cu, Fe, and Ni particularly exhibit excellent catalytic performance and oxygen storage capacity. The introduction of magnetic biochar (MBC) can reduce the aggregation of CuFeNi, and the rich functional groups on the surface of MBC can increase the content of functional groups on the surface of the composite, which helps to activate PMS. To be more precise, an impressive 91.6% of ENR was abated by the MC-1&PMS ensemble within a mere 20 min. Moreover, the catalytic dynamism of the MC-1&PMS synergy was predominantly ascribed to the production of hydroxyl (∙OH) radicals, complemented by sulfate (SO4∙-), singlet oxygen (1O2), and superoxide radicals (∙O2-). In the ensuing discourse, a conceivable degradation trajectory for ENR was postulated. Overall, this investigation furnishes novel perspectives in the conceptualization of heterogeneous carbon catalysts within the realm of advanced oxidation techniques.