Sealed Reactor Research Articles

Mechanistic Study of the Electrochemical Reduction of CO2 in Aprotic Ionic Liquid in Air.

The capture and electrochemical conversion of dilute CO2 in air is a promising approach to mitigate global warming. Aiming to increase the efficiency of the electrochemical reduction of CO2, we fabricated electrodes and developed a custom-designed sealed electrochemical reaction system to study the mechanism of this conversion. The performance of three metal electrodes, Ag, Cu, and SUS 316 L, was compared in an aprotic ionic liquid as the electrolyte to monitor the CO2 concentration and chemical reactions using a CO2 sensor and diffuse reflectance infrared Fourier transform spectroscopy and Raman spectroscopy in CO2/N2 (400 ppm CO2 and 99.96 % N2) or synthetic air (400 ppm CO2, 21 % O2, and 79 % N2). The CO2 concentration decreased at negative potentials and was more drastic in synthetic air than in CO2/N2. At negative potential in synthetic air, IR revealed carbon monoxide, carbonate, or peroxydicarbonate on the Ag, Cu, or SUS 316L electrodes, respectively. Reaction intermediates were identified using Raman spectroscopy. Superoxide (O2⋅-), produced by the reduction of O2 on each electrode, promotes the electrochemical reduction of CO2 whose reduction potential is higher on the negative side than that of O2. This research deepens our understanding of the electrochemical capture/release and conversion of dilute CO2.

Magnetic transition magnetocaloric and supercapacitor behavior in synthesized Sn0.6Mn0.1Ge0.3Te alloys

This study comprehensively investigates the structural, microstructural, vibrational, magnetic, and magnetocaloric properties of novelty Sn0.6Mn0.1Ge0.3Te alloys synthesized using the sealed tube solid-state reaction method. The observed magnetic behavior showcases a transition from paramagnetic (PM) to ferromagnetic (FM) phases at the Curie temperature TC = 29 K. Notably, magnetic entropy change (−ΔSM), relative cooling power (RCP), and refrigerant capacity (RC) are calculated as 1.5 J/kg-K, 42.05 J/kg, and 37.39 J/kg, respectively, under a magnetic field of 60 kOe. Arrott curve analysis further validates the magnetic phase transition, affirming a second-order transition between FM and PM phases. Critical exponents (β, γ, and δ) are derived from field-dependent magnetic entropy changes around the second-order transition and strongly agree with the mean field model. These critical exponents establish a clear correlation between critical behavior and magnetocaloric effects, reinforcing the potential of Sn0.6Mn0.1Ge0.3Te alloys for magnetocaloric applications. Investigations into the electrochemical properties of the alloy have indicated that it exhibits a specific capacitance of 152.9 F/g at a scan rate of 20 mV/s, demonstrating a predominantly pseudocapacitive charge storage mechanism. Additionally, the alloy has proven to be highly stable, retaining 94.2 % of its specific capacitance after 10,000 cycles.

Waste plastics upcycled for high-efficiency H2O2 production and lithium recovery via Ni-Co/carbon nanotubes composites

The disposal and management of waste lithium-ion batteries (LIBs) and low-density polyethylene (LDPE) plastics pose significant environmental challenges. Here we show a synergistic pyrolysis approach that employs spent lithium transition metal oxides and waste LDPE plastics in one sealed reactor to achieve the separation of Li and transition metal. Additionally, we demonstrate the preparation of nanoscale NiCo alloy@carbon nanotubes (CNTs) through co-pyrolysis of LiNi0.6Co0.2Mn0.2O2 and LDPE. The NiCo alloy@CNTs exhibits excellent catalytic activity (Eonset = ~0.85 V) and the selectivity (~90%) for H2O2 production through the electrochemical reduction of oxygen. This can be attributed to the NiCo nanoalloy core and the presence of CNTs with abundant oxygen-containing functional groups (e.g., –COOH and C–O–C), as confirmed by density function theory calculations. Overall, this work presents a straightforward and green approach for valorizing and upcycling various waste LIBs and LDPE plastics.

An indirect Z-scheme heterostructure of nano-gold layer immobilized Cu-Al-doped SrTiO3 and CoOx-WO3 for photocatalytic CO2 reduction

Perovskite oxides have emerged as promising photocatalysts for CO2 reduction to valuable chemicals and fuels. However, conventional perovskite oxide photocatalysts often suffer from inefficient charge separation and bulk charge recombination, negatively impacting overall photoactivity. In this work, we present a novel immobilized perovskite oxide-based photocatalyst sheet featuring an indirect Z-scheme heterostructure composed of Cu-loaded Al-doped SrTiO3 (Cu-ASTO) and CoOx-loaded WO3 (CoOx-WO3) with an ultrathin (20 nm) gold interlayer serving as a conductive bridge. We tested this photocatalyst sheet in a sealed reactor containing a CO2-saturated aqueous solution of 0.1 M NaHCO3 and a side window to allow irradiation. Under irradiation with a 300 W Xe lamp, the Cu-ASTO/Au/CoOx-WO3 immobilized photocatalyst sheet produced methane (CH4) at a rate of 2.676 µmol cm-2 h−1 and methanol (CH3OH) at 0.517 µmol cm-2 h−1. We attribute the superior activity of this catalyst to the all-solid-state indirect Z-scheme heterostructure that greatly extends the lifespan of photoinduced charge carriers and enhances the CO2 photoconversion reaction. In experiments conducted outside, we demonstrated the immobilized photocatalyst's performance under natural sunlight, producing CH4 at 0.307 µmol cm-2 h−1 and CH3OH at 0.069 µmol cm-2 h−1. This work provides design ideas for developing robust immobilized photocatalyst systems for the scalable operation of the CO2 photoreduction process and broadening the scope of applications for perovskite heterostructure photocatalysts.

Microwave-Assisted Synthesis of 5-Substituted 3-Amino-1,2,4-triazoles from Aminoguanidine Bicarbonate and Carboxylic Acids

The effect of the molar ratio between reagents, reaction time and temperature on the yield of 5-substituted 3-amino-1,2,4-triazoles obtained by the direct condensation of carboxylic acids with aminoguanidine bicarbonate under acid catalysis conditions was studied. As a result, a general green straightforward synthesis of the title compounds bearing aliphatic substituents or a phenyl ring was developed using sealed reaction vials under controlled microwave synthesis conditions that are suitable for the application of volatile starting carboxylic acids. Our straightforward synthetic method proposed in this work increases the synthetic accessibility of these widely used building blocks and therefore is able to significantly expand the structural diversity of compounds containing a triazole moiety for the needs of drug discovery.

Experimental studies on noncentrosymmetric Nd3Se4: Strongly correlated noncollinear ferromagnet

We have synthesized polycrystalline Nd3Se4 by the solid state sealed tube reaction route followed by structural characterization and magnetic property measurements. The temperature-dependent magnetization studies reveal the existence of competing magnetic interactions below the ferromagnetic ordering (TC ≈ 48.4 K). The observation of hysteresis in the isothermal magnetization M(H) data with the coercive field of ≈ 0.25 T at 2 K indicates dominant ferromagnetic interactions in the applied field. The nonsaturating behavior of M(H) data at higher applied field and kinks in corresponding dM/dHvs. H plots suggest the coexistence of multiple magnetic interactions at low temperatures. Using the M(T,H=2 T) data, the Rhodes-Wohlfarth ratio (qc/qs) has been estimated to be ≈ 3.6, which supports the itinerant magnetism in Nd3Se4. These competing interactions have been further investigated by AC-susceptibility measurements at various excitation frequencies. The χ′ reduces drastically with an increase in the applied DC field, as observed from isothermal field-dependent AC-χ studies. Additionally, the strong correlation between delocalized charge and localized magnetic moments is evident from ρ(T) measurements at H = 0 and 5 T. The ρ(T,H=0 T) data shows a clear drop having quadratic temperature dependence, below TC. Furthermore, the inter-dependence between electrical transport and magnetism has been established firmly through negative magnetoresistance, in which the maxima correspond to the coercive field obtained from M(H) data.

Utilizing reactive polysulfides flux Na2Sx for the synthesis of sulfide solid electrolytes for all-solid-state sodium batteries

Sulfide solid electrolytes are attractive for the development of all-solid-state sodium batteries owing to their high ionic conductivities and formability. While the performance related to ionic conductivity and additional functions is strongly influenced by composition and crystal polymorphs, the use of delicate and less stable sulfide starting materials limits their variability.In this study, we propose a universal and convenient synthesis method for sulfide solid electrolytes utilizing Na2Sx polysulfide flux as a stoichiometric reactant. These polysulfides mitigate synthetic constraints by eliminating the requirement for unstable sulfide starting materials. They efficiently react with raw materials, including single elements, under ambient pressure, without the necessity for a sealed reaction vessel.Na3BS3 glass, and Na2.88Sb0.88W0.12S4 solid electrolytes was prepared by using Na2Sx working as lowly volatile flux to prepare. Na2S and S immediately reacted with each other without sulfur vaporization, and stoichiometric Na2Sx liquid was formed at temperatures above 500 °C. The Na2Sx flux itself oxidized B, Sb, and W uniformly at moderate temperatures, and stoichiometric electrolytes were obtained in a one-step process without sealed vessels and a vacuum condition. In addition, Na3BS3 glass was produced by direct quenching at 700 °C. The obtained Na2.88Sb0.88W0.12S4 demonstrated the extremely high ionic conductivity of 125 mS cm−1 at 25 °C, due to the stoichiometric substitution of WS42−.

Pre-extraction of Li from spent lithium-ion batteries through an Ethanol-Water vapor thermal reduction approach

Pre-extraction of lithium from spent lithium-ion batteries (LIBs) is highly required to obtain a high recovery rate of lithium. Here, we report an ethanol–water vapor thermal reduction approach in a sealed reactor to selectively recycle lithium and transition metal oxides (TMOs) from spent LIBs. Spent cathode materials were converted to LiOH and TMO by the reduction of water-alcohol vapor at a temperature of 350–400 °C. More than 99 % of the Li in LiCoO2 was selectively extracted from LiCoO2 at 370 °C for 2 h and at 400 °C for 0.8 h. The selective extraction is co-driven by water and alcohol that enable the reduction of LiCoO2 and release water-soluble LiOH and water-insoluble TMOs. In addition, the water–vapor thermal reduction method is applicable to selectively recovery Li from different types of cathode materials such as NCMs and lithium manganese oxide. The pre-selective extraction ensures a high lithium recovery rate and a reagent-saving manner. We envision that the vapor thermal recovery method could help recycle spent LIBs by an environmentally friendly and economically reasonable way.

Rare earth removal from pyroprocessing fuel product for preparing MSR fuel

A series of experiments were performed to produce a fuel source for a molten salt reactor (MSR) through pyroprocessing technology. A simulated LiCl–KCl–UCl3-NdCl3 salt system was prepared, and the U element was fully recovered using a liquid cadmium cathode (LCC) by applying a constant current. As a result, the salt was purified with an UCl3 concentration lower than 100 ppm. Subsequently, the U/RE ingot was prepared by melting U and RE metals in Y2O3 crucible at 1473 K as a surrogate for RE-rich ingot product from pyroprocessing. The produced ingot was sliced and used as a working electrode in LiCl–KCl–LaCl3 salt. Only RE elements were then anodically dissolved by applying potential at −1.7 V versus Ag/AgCl reference electrode. The RE-removed ingot product was used to produce UCl3 via the reaction with NH4Cl in a sealed reactor.

Preparation of NiAl-AlMg6 Functionally Graded Composite Using the Energy of a Highly Exothermic Ti-C Mixture during Self-Propagating High-Temperature Synthesis.

A functionally graded composite NiAl-AlMg6 was prepared using the pressure of gaseous reaction products (impurity gases) produced during the synthesis of reactive powders in a sealed reactor. It has been shown that this method can be used to prepare a NiAl/AlMg6 composite with both chaotically oriented pores in the NiAl layer and unidirectionally oriented pores (lotus-type pores). The pore shape in NiAl was found to be dependent on the pressure of the impurity gases and hydrogen present in the starting titanium powder. A mechanism for pore formation in NiAl and AlMg6 composite during SHS is proposed. Thus, functionally graded high-temperature composites can be produced by SHS in a sealed reactor using the chemical reaction energy and the pressure of impurity gases and hydrogen. Additionally, minimizing the influence of impurity gases on the contact zone increases the interface area between NiAl and AlMg6.

Microwave-assisted synthesis of Pt/C catalyst at high temperatures for PEM fuel cells

In this work, Vulcan XC-72 supported platinum electrocatalysts (Pt/C) are synthesized by using a two-step, microwave-assisted polyol method. The effect of synthesis conditions on the properties of Pt/C electrocatalysts is investigated at various temperatures (140–200 °C) and corresponding autogenous-pressures (1.0–7.5 bar) at a constant synthesis duration of 35 min. A completely sealed reaction vessel is used to heat the polyol mixture above its boiling point of 140 °C. Catalysts are characterized by XRD, TGA, FTIR, BET, SEM, TEM, Cyclic voltammetry (CV), and the results are compared with the properties of commercial Pt/C. Pt/C catalyst synthesized at 160 °C exhibits the highest ECSA of 69.2 m2/g Pt, highest Pt loading efficiency of 92%, narrowest Pt particle size distribution with an average of 3.6 nm, and Pt crystallite size of 2.3 nm. SEM and TEM confirm the formation of micron-sized Pt agglomerations for the catalysts synthesized at 180 and 200 °C. Characterization studies show that the polyol method presented in this study is suitable for synthesizing Pt/C catalysts which have comparable properties to commercial Pt/C.

A New Process for Efficient Recovery of Rhodium from Spent Carbonyl Rhodium Catalyst by Microreactor.

Triphenylphosphine acetylacetone carbonyl rhodium (ROPAC) is an important catalyst in the petrochemical industry, and its deactivated waste catalyst holds significant value for recovery. This study focuses on the existing forms of rhodium (Rh) in waste catalysts and the current status of traditional processes. A green, efficient, and continuous recovery technique was developed using a sealed stainless steel microchannel reactor. The influence of reaction temperature, reaction time, and phase ratio on the Rh recovery rate was investigated, and the process parameters were optimized using response surface methodology (RSM). The results indicate that the magnitude of the impact on the Rh recovery rate follows the order: reaction temperature > reaction time > phase ratio. The optimized process parameters were determined as follows: a reaction time of 29 min, a reaction temperature of 110 °C, and a phase ratio of 1:1, with a corresponding maximum recovery rate of Rh of 66.06%. Furthermore, secondary treatment was performed on the organic phase after primary recovery using the same process conditions, resulting in an overall Rh recovery rate of 95.6%, indicating satisfactory recovery efficiency. Moreover, the application of FTIR and ICP-OES analysis provided definitive evidence that the oxidative dissociation of the rhodium-phosphine chemical bond by H2O2 within ROPAC leads to the conversion of Rh+ into Rh3+. Subsequently, Rh forms chloroaquorhodium (III) complexes that enter the aqueous phase, enabling effective recovery of Rh.

Performance Prediction of Solid Oxide Fuel Cells Based on a Neutral Network Model

Predicting various parameters in a fast and accurate way plays an important role for the development of high-temperature sealed reactors such as the solid oxide fuel cells (SOFCs). However, the analysis of SOFC performance parameters mainly focuses on the development of multiphysics models, which is complicated and slow, causing inefficiency in the prediction of key parameters. In our study, a neural network prediction model of SOFCs was developed in combination with the deep learning method. The neural network model was trained by using the results from a multiphysics model validated by experiments. The trained SOFC neural network model was found to have good consistency with the simulation results of multiphysics model. The neural network model was further utilized in a system-level model to provide fast and accurate prediction of the system performance.Keywords: SOFC, Multiphysics model, Neural network model, System simulation

Magnetic Memory and the Promising Magnetocaloric Effect of Sn0.6Cr0.1Ge0.3Te Solid Solution Synthesized by Sealed Tube Solid-State Reaction

Magnetic Memory and the Promising Magnetocaloric Effect of Sn_0.6Cr_0.1Ge_0.3Te Solid Solution Synthesized by Sealed Tube Solid-State Reaction

Recovery of degraded LiCoO2 through a CO2 -assisted low-temperature thermal reduction approach

Recycling spent lithium-ion batteries (LIBs) using chemical-saving and energy-effective pathways has been pursued to minimize the secondary environmental footprints. In this study, a sealed stainless-steel reactor was selected to achieve CO2-assisted low-temperature thermal reduction of spent LiCoO2 by carbon at 500 °C. The thermal reduction was provoked by the in-situ generated CO that resulted from the reaction of carbon and CO2. More importantly, MgCO3 was used as a CO2 holder to provide CO2 at elevated temperatures and MgO can be used to absorb CO2 to regenerate MgCO3, enabling the CO2 as a clean additive in the reduction reaction. Using this low-temperature reduction coupled with the carbonate pyrolysis approach, the selective recovery of Li reached 94.21%. The spatial isolation of MgCO3 at the bottom layer, graphite at the middle layer, and LiCoO2 at the top layer in the same reactor avoids complex separation. In addition, LiCoO2 is directly regenerated by the obtained CoO/Co3O4 and Li2CO3, and regenerated LiCoO2 exhibits good electrochemical performance with a discharge capacity retention of 94.0% after 300 cycles. Overall, the carbonate pyrolysis in the close-reactor is a promising approach to achieving a low-temperature reduction reaction by using CO2 as a clean agent to recycle spent LIBs.

Eco-friendly synthesis of a novel adsorbent from sugarcane and high-pressure boiler water

ABSTRACT The development of industrial process in line with the circular economy and the environmental, social and corporate governance (ESG) is the foundation for sustainable economic development. Alternatives that make feasible the transformation of residues in added value products are promising and contribute to the repositioning of the industry towards sustainability, due to financial leverage obtained from lesser operational costs when compared with conventional processes, therefore increasing the company competitivity. In this study, it is presented a promising and innovative technology for the recycling of agro-industrial residues, the sugarcane bagasse and the high-pressure water boiler effluent, in the development of a low-cost adsorbent (HC-T) using the hydrothermal carbonization processes and its application in the adsorption of herbicide Diuron and Methylene Blue dye from synthetic contaminated water. The hydrothermal carbonization was performed in a Teflon contained inside a sealed stainless-steel reactor self-pressurized at 200°C, biomass-to-effluent (m/v) ratio of 1:3 and 24 h. The synthesized material (HC) was activated in an oven at 450°C for 10 min, thus being named adsorbent (HC-T) and characterized by textural, structural and spectroscopic analyses. The low-cost adsorbent HC-T presented an 11-time-fold increase in surface area and ∼40% increase in total pore volume in comparison with the HC material. The kinetic and isotherm adsorption experiment results highlighted that the HC-T was effective as a low-cost adsorbent for the removal of herbicide Diuron and Methylene Blue dye from synthetic contaminated waters, with an adsorption capacity of 35.07 (63.25% removal) and 307.09 mg g−1 (36,47% removal), respectively.

Digitizing protocols into single reactors for the one-pot synthesis of nanomaterials

Digitizing protocols into single reactors for the one-pot synthesis of nanomaterials

Recycling Spent Lithium-Ion Batteries Using Waste Benzene-Containing Plastics: Synergetic Thermal Reduction and Benzene Decomposition.

Spent lithium-ion batteries (LIBs) and benzene-containing polymers (BCPs) are two major pollutants that cause serious environmental burdens. Herein, spent LIBs and BCPs are copyrolyzed in a sealed reactor to generate Li2CO3, metals, and/or metal oxides without emitting toxic benzene-based gases. The use of a closed reactor allows the sufficient reduction reaction between the BCP-derived polycyclic aromatic hydrocarbon (PAH) gases and lithium transition metal oxides, achieving the Li recovery efficiencies of 98.3, 99.9, and 97.5% for LiCoO2, LiMn2O4, and LiNi0.6Co0.2Mn0.2O2, respectively. More importantly, the thermal decomposition of PAHs (e.g., phenol and benzene) is further catalyzed by the in situ generated Co, Ni, and MnO2 particles, which forms metal/carbon composites and thus prevent the emissions of toxic gases. Overall, the copyrolysis in a closed system paves a green way to synergistically recycle spent LIBs and handle waste BCPs.

Charge redistribution enhanced oxygen reduction of carbon-based electrocatalyst

The surface charge distribution is regarded as a key factor affecting the electrocatalytic performance. Herein, we report a strategy to regulate the surface charge distribution in carbon-based electrocatalyst to enhance its activity and stability in oxygen reduction reaction (ORR). The sample obtained in a sealed reactor N,S co-doped carbon encapsulate Co9S8 nanoparticles (Co9S8@CNS-S) exhibits excellent ORR performance. X-ray photoelectron spectroscopy, kelvin probe force microscopy and density functional theory simulation were used to investigate the mechanism of performance improvement. The enhanced ORR activity was due to the exposed more positive charge of surface carbon atoms by N, S elements doping synergistic with Co9S8 nanoparticles (NPs). The improved ORR stability was attributed to the carbon layer combination with Co9S8 NPs which greatly suppresses the generation of H2O2, thus avoiding the erosion of H2O2 on carbon layer during electrocatalysis. This work provides a strategy to regulate electrocatalyst surface charge distribution to achieve active and stable ORR electrocatalyst.

4-Этоксиметилен-2-фенил-5(4Н)-оксазолон в реакциях с различными гетероциклическими аминами

The analysis of the literature data has showed that there is no information on the behavior in 5(4H)-oxazolones with amines under the conditions of a sealed vessel reactor, which makes it possible to obtain heterocyclic systems with different amines. We have developed and presented an easy, fast, reliable and innovative method for the preparation of a new series of compounds with synthetic and biological potential, based on the interaction of 4-ethoxymethylene-2-phenyl-5(4H)-oxazolone and heterocyclic amines with different ring sizes and sets heteroatoms using a sealed vessel reactor. Based on the results obtained, it has been found that the transformation proceeds by the mechanism of nucleophilic addition of Michael. The scheme of the conducted interaction has been discussed. Initially, the amino group of the amine used is attacked at the exocyclic C=C bond of the initial substrate, ethoxymethylenexazolone, proceeding with the elimination of a well-leaving ethoxy group in the form of an ethanol molecule, which leads to the final 4-hetarylaminomethylidene derivatives of oxazol-5(4H)-one. In the course of the work, it has been found that the use of a sealed vessel reactor makes it possible to reduce the time of transformations, to achieve an increase in selectivity and yields of target products compared to the usual type of activation of the reaction mixture, such as boiling in ethanol. It has been shown that not only the type of activation, but also the nature of the solvent used affects the rate of the reaction. It has been found that under these conditions the transfor mation proceeds with the preservation of the oxazol-5(4Н)-one ring. Control over the course of reactions, determination of individuality and identification of the obtained compounds have been carried out by TLC, elemental analysis, IR-, NMR spectroscopy.