Design of zeolite-based catalysts by Le Chatelier's principle

Abstract Thermal macroeconomics (TM), an axiomatic approach to macroeconomics based on the mathematical structure of thermodynamics, is presented. Within the domain of exchange economies, TM deduces relations between aggregate properties of an economy, concerning quantities and flows of goods and money, without recourse to microeconomic foundations concerning individual economic agents. Despite the restricted scope of this initial treatment, TM has three important payoffs. 1) It provides a new and solid foundation for aspects of standard macroeconomics: the existence of market prices, the value of money, the meaning of inflation, the symmetry and negative-definiteness of the macro-Slutsky matrix, and the Le Chatelier–Samuelson principle, without relying on implausibly strong rationality assumptions over individual microeconomic agents. 2) It generates new results, including implications for money flow and trade when two or more economies are put in contact, using new concepts such as economic entropy and temperature; these concepts can be given economic interpretations as aggregate utility and the inverse marginal aggregate utility of money, respectively. 3) It holds the prospect for extensions of economic interest, such as to include production and consumption, via connection to non-equilibrium thermodynamics. More broadly, we hope that the economic analogue of entropy (governing the possible transitions between states of economic systems) may prove to be as fruitful for the social sciences as entropy has been in the natural sciences.

Wood-derived biomass fly ash (BFA) was investigated as an alternative to, or in combination with, coal fly ash (CFA) to partially replace Portland cement in concrete. Four different BFA samples were physically and chemically characterised. The colour of the BFAs was within the typical range for or slightly darker than CFA, with fineness similar to or noticeably coarser than this. The BFAs had various particle types and sizes, along with a greater surface area and particle density than the CFA. The BFAs also had high calcium and sulfate contents and low silica, alumina and iron contents, with limited amorphous phases. Alkali and chloride levels indicate that these may need to be considered with regard to concrete durability, although Le Chatelier tests suggested little implication for volume stability. While similar early mortar strengths were obtained for the BFA and CFA mixes, in some cases, by 90 days those with CFA had the highest strengths, suggesting little pozzolanicity for BFA. Their high alkalinity and soluble mineral levels suggest potential as a pozzolanic activator, which was confirmed for CFA and BFA combinations with Portland cement in mortar and concrete. With further work, this approach could provide a possible route to address availability issues for the two materials.

Effect of asymmetric forward rolling (AFR) on the microstructure, texture, mechanical properties, and Portevin–Le Chatelier behavior of AA5052 alloy

The article discusses the method of integrating the discipline of Chemistry with the disciplines of the professional cycle through the study of the basic laws of chemistry, such as the basic law of thermochemistry, Avogadro's law and the Le Chatelier principle and their application in solving military- applied problems.

Le Chatelier’s Principle and Field-Induced Change in Magnetic Entropy Leading to Spin–Lattice Partitioning and Magnetization Plateau

In a 1987 article of the last author dedicated to the memory of a pioneer of classical plasticity Aris Philips of Yale, the last author outlined three examples of self-organization during plastic deformation in metals: persistent slip bands (PSBs), shear bands (SBs) and Portevin Le Chatelier (PLC) bands. All three have been observed and analyzed experimentally for a long time, but there was no theory to capture their spatial characteristics and evolution in the process of deformation. By introducing the Laplacian of dislocation density and strain in the standard constitutive equations used for these phenomena, corresponding mathematical models and nonlinear partial differential equations (PDEs) for the governing variable were generated, the solution of which provided for the first time estimates for the wavelengths of the ladder structure of PSBs in Cu single crystals, the thickness of stationary SBs in metals and the spacing of traveling PLC bands in Al-Mg alloys. The present article builds upon the 1987 results of the aforementioned three examples of self-organization in plasticity within a unifying internal length gradient (ILG) framework and expands them in 2 major ways by: (i) introducing the effect of stochasticity and (ii) capturing statistical characteristics when PDEs are absent for the description of experimental observations. The discussion focuses on metallic systems, but the modeling approaches can be used for interpreting experimental observations in a variety of materials.

<p>The study investigates the Portevin–Le Chatelier (PLC) effect in the cold-rolled Al-Mg alloy EN AW-5754. The tensile tests were performed on dog bone specimens at test speeds of 10, 20, and 50 mm/min. Digital image correlation (DIC) and infrared thermography were used to monitor strain rate and temperature changes. The results showed a strong correlation between PLC line propagation, strain rate variations, and temperature changes. Regardless of the test speed, the characteristic jagged shape of the material was observed due to the PLC effect. As the deformation progressed, both the strain rate and the temperature increased, with the changes being more pronounced at higher test speeds. DIC and infrared images show that temperature peaks correspond to moments of increased plastic deformation and sudden drops in strain rate. The formation of overlapping PLC lines also showed the random and unpredictable nature of the phenomenon.</p>

Using high-purity oxygen (O2) for electrofixation would increase the production cost of hydrogen peroxide (H2O2) because of requiring complex pre-treatment procedures. Atmospheric air is an abundant source, but the direct air electrofixation has proved to be very challenging, that in common conception against nitrogen (N2) in the system. According to the Le Chatelier's principle, O2 concentration is diluted by N2 (78%) in atmospheric air, which reduces overall reaction rates/equilibrium. Here we report a catalyst system where the presence of N2 does not impose an adverse effect; rather, it is beneficial for activity. We combine both theoretical and experimental analyses to elucidate the underlying mechanisms, unlocking the critical function of electronic spin, arising from the strong synergy between iron oxide (FeOx) and nickel-metal organic frameworks (Ni-MOF) that optimizes the activation of O2 in air. Consequently, the catalyst for direct air electrofixation has demonstrated an exceptional H2O2 yield rate (262.6mg h-1 cm-2) and Faradaic efficiency (95.61%), outperforming its high-purity O2 counterpart (184.32mgh-1cm-2 and 67.06%). We expect the present findings providing an additional dimension to leverage systems beyond the constraint of traditional rules.

Abstract Using high‐purity oxygen (O2) for electrofixation would increase the production cost of hydrogen peroxide (H2O2) because of requiring complex pre‐treatment procedures. Atmospheric air is an abundant source, but the direct air electrofixation has proved to be very challenging, that in common conception against nitrogen (N2) in the system. According to the Le Chatelier's principle, O2 concentration is diluted by N2 (78%) in atmospheric air, which reduces overall reaction rates/equilibrium. Here we report a catalyst system where the presence of N2 does not impose an adverse effect; rather, it is beneficial for activity. We combine both theoretical and experimental analyses to elucidate the underlying mechanisms, unlocking the critical function of electronic spin, arising from the strong synergy between iron oxide (FeOx) and nickel‐metal organic frameworks (Ni‐MOF) that optimizes the activation of O2 in air. Consequently, the catalyst for direct air electrofixation has demonstrated an exceptional H2O2 yield rate (262.6 mg h−1 cm−2) and Faradaic efficiency (95.61%), outperforming its high‐purity O2 counterpart (184.32 mg h−1 cm−2 and 67.06%). We expect the present findings providing an additional dimension to leverage systems beyond the constraint of traditional rules.

Abstract The efficient conversion of CO2 to light olefins via CO2‐modified Fischer‐Tropsch synthesis (CO2‐FTS) with high selectivity and yield remains a critical challenge. Here, the Fe3O4‐FeCo‐Fe5C2 ternary catalyst was successfully constructed. Notably, the different contents of Co doping optimized the heterogeneous catalytic interface of the FeCo alloy clusters, which promoted the targeted conversion of CO2 to light olefins in high yield (22.4%) and effectively suppressed the generation of CO (4.4%). The study shows that the formation of FeCo alloy clusters significantly promotes the forward progression of the Reverse Water‐Gas Reaction (RWGS), which can greatly enhance the conversion of CO2 and inhibit the formation of CO according to Le Chatelier's principle. Moreover, the FeCo alloy clusters significantly promoted the rapid formation of CHx and induced the chain growth of CHx on Fe5C2 phase. Hence, the clever construction of FeCo alloy clusters significantly strengthens the kinetic coupling between the RWGS and FTS reactions. Additionally, the in‐situ structural evolution of the catalysts, along with the real‐time formation process of the products, was monitored through in‐situ characterization. This work is promising to provide an effective strategy for CO2 hydrogenation to achieve high yields of light olefins over FeCo alloy clusters.

Denton's redox-neutral catalytic Mitsunobu reaction is remarkable in that it translates a reaction traditionally driven by the consumption of sacrificial chemical reagents to an additive-free catalytic manifold. Rational attempts to improve the system have been met with only marginal improvements, and a lack of consensus concerning the rate-determining step continues to limit effective reaction development. Here, we analyze the reaction mechanism focusing on a critical, largely overlooked element: the removal of water using a Dean-Stark apparatus. Experimental analysis of the water removal process, coupled with extensive kinetic simulations, demonstrates that the overall rate of the reaction is intimately tied to the rate of water removal. This process can be viewed as a transition between potential energy surfaces and, consequently, subsequent steps of the reaction can progress spontaneously in the absence of water, allowing an explanation of how Le Chatelier's principle, a thermodynamic effect, can have a profound kinetic influence over the rate of the reaction. We identify three bottlenecks in the reaction that inform catalyst design. Additionally, we (a) clarify the ongoing discussion regarding the rate-determining step, (b) provide clear advice concerning future reaction design taking into account the role of water and, (c) discuss the redox-neutral catalytic Mitsunobu reaction in the context of formally endergonic esterification reactions, noting parallels with ratchet mechanisms. Finally, we highlight general principles of catalyst/reaction design that emerge from our analysis and implement our findings to demonstrate a 50% rate acceleration resulting from improved water removal, a substantially greater reaction enhancement than previously obtained from computationally guided catalyst structural changes.

Inhibition of manganese ion migration and dissolution by selective ions sieving effect of MOF-based solid electrolytes.

Self-healing is a fundamental ability inherent in humans, plants, and other living organisms. To date, a variety of materials with self-healing properties have been developed. However, these materials usually require external inputs such as electric potentials or healing agents to initiate or promote self-healing reactions. Herein, we present a novel self-healing mechanism that operates without any external input, utilizing the dynamic equilibrium between the solid-state and dissolved materials. We employed organic–inorganic perovskites to validate our strategy. Single-particle spectroscopy and imaging demonstrated the spontaneous self-healing of perovskites after photodamage under dynamic equilibrium conditions. Furthermore, we found that perovskites can generate hydrogen in both healed and damaged states. Remarkably, the perovskites exhibited hydrogen generation over four cycles of photodamage and self-healing. The proposed concept and experimental results provide valuable insights for the development of energy conversion and storage systems with improved long-term durability.

Nanostructures composed of transition metal sulfides (TMS) exhibit excellent electrochemical properties, rendering them well suited for use in supercapacitor applications. Nevertheless, the conventional synthesis method restricts the synthesis of nanostructures in TMS and the investigation of the synthesis mechanism. In view of the above considerations, a novel synthesis method: liquid-assisted sintering is proposed. This approach retains the advantages of solvothermal synthesis of nanomaterials while providing insight into the reaction mechanism and avoiding densification from sintering. The synthesis mechanism of this method is also revealed by the synthesis of Ni3S4/Co3S4. The synthesis process is influenced by Le Chatelier's principle, forming a three-step cyclic reaction. This in turn leads to cathode materials with heterojunction structures. The cathode material possesses excellent electrochemical properties. The best devices can achieve an energy density of 57.7 W h kg-1 at a power density of 102.4 W kg-1 and maintain an energy density of 21.7 W h kg-1 at a power density of 3547.8 W kg-1. This work provides a new way to make nanomaterials and develop electrode materials for supercapacitors.

Carbon dioxide emissions from cement production are a current environmental challenge. This research attempted to evaluate the pozzolanic reaction of residuals from coal-fired power plants, such as coal bottom ash (CBA) and coal boiler slag (CBS), as a supplementary cementitious material to lessen the deleterious effect on the environment. The residues’ fineness modulus and specific gravity were determined using the No. 325 sieve and Le Chatelier flask, respectively. Chemical characterizations were conducted using X-ray diffraction (XRD) and X-ray fluorescence (XRF). The results indicated that the percent passing of both residues was greater than 66%, as the American Society for Testing Materials (ASTM) requires, and their specific gravity was comparable to that of cement. Subsequently, in concrete specimens, 20% of the weight of cement was replaced by CBA and CBS to determine the strength development of fresh and hardened characteristics compared with the control specimens. Experimental findings revealed that by the 90th day, concrete made with CBA achieved 98% of the compressive strength of the control concrete, while the concrete made with CBS reached 79% of the control concrete’s compressive strength. Moreover, CBA-based concrete achieved 97% of the flexural strength of the control concrete, while CBS-based concrete outperformed the control by 2% on the 90th day. A lower severity level of chloride ion penetration by both CBA- and CBS-based concrete was achieved in the rapid chloride penetration test, indicating the durability of the concrete.

Introduction. The influence of the chemical and mineralogical composition of Portland cements and the chemical base of superplasticizers on the magnitude and kinetics of autogenic (contractional) shrinkage of concretes from highly mobile and self-compacting concrete mixtures has been revealed. The relevance of the issue is due to the commonly overlooked role of autogenic shrinkage in the formation of the field of temperature-shrinkage stresses in the early hardening period of massive monolithic structures. In order to calculate intrinsic stresses, data on the magnitude and kinetics of autogenic shrinkage are required, and the insufficiency and some inconsistency of data on the effect of superplasticizing additives on the magnitude and kinetics of autogenic shrinkage, depending on the material composition of cement and the chemical and mineralogical composition of clinker, are critical to the expediency of obtaining new data on the issue. The objective of the work is to develop scientific ideas about the influence of prescription factors and material properties on the quantitative and qualitative parameters of autogenic shrinkage using the example of materials commonly used in the production of monolithic reinforced concrete structures in the Rostov region.Materials and methods. Experimental studies were conducted using six Portland cements from four manufacturers that are fast-hardening according to GOST 31108-2020 classification. Superplasticizing additives based on polycarboxylate esters and naphthalene formaldehydes in a dosage of 0.5% of the commercial product were employed. The properties of cements are identified according to GOST 30744-2001 and GOST 310.5-88. Deformations of the hardening cement paste (stone) were determined by means of the Le Chatelier method. The amount of autogenic shrinkage of concrete was determined by the calculation method based on the amount of autogenic shrinkage of cement, taking into account the true value of the I/C of concrete and the concentration of aggregate in concrete.Results. The ratio of "autogenic shrinkage/total contraction" of the investigated cements with additives at the age of 5 days was 0.37–0.74, the quantitative values of the total contraction of the studied cements in combination with additives at the age of 5 days ranged from 2.93 to 3.43 ml/100 g of cement, which does not contradict the available data. Change in the amount of autogenic shrinkage in the presence of additives at the age of 5 days was from 0.64 to 1.65 relative to the nonadditive standard. The effect of additives on the kinetics of autogenic shrinkage was manifested both in acceleration or deceleration, and in the absence of any effect. The calculated value of autogenic shrinkage of concretes of classes B25–B35 from highly mobile and self-sealing mixtures at the age of 5 days ranged from 0.36 to 1.18 mm/m.Discussion and Conclusion. Scientific ideas about the kinetics of autogenic shrinkage have been developed depending on the type of cements and additives. In order to describe the change in autogenic shrinkage over time, a formula similar to the formula EN 1992-1-1 for the change in concrete strength over time is set forth. The classification of concretes according to the kinetics of autogenic shrinkage is suggested. The patterns of changes in the amount of autogenic shrinkage of concretes from highly mobile and self-compacting

The molecular virial theorem relates kinetic and potential energies (T & V) to total energy and forces (E & R·∂E/∂R); it is a useful tool for analyzing the data, but does not provide clues on the origin of the stability of the "bonded" state. A strict conceptual distinction between cause and effect is recommended. Depending on the physical relationships, the induced change of one variable of the system leads to a resulting change of another variable; relaxation or response of the system can either moderate this change (in the sense of Le Chatelier's principle), enhance it, or even reverse it. Such unexpected, paradoxical behavior is common in reality and in daily life. As two examples of conceptual mix-up in molecular chemistry, we discuss details of the origin of the steric pair-pair repulsion and of the internal rotation barrier in ethane.

Engineering the formulation of an Mn-based positive electrode is a viable strategy for producing an efficient aqueous zinc-ion battery. However, Mn dissolution and the byproducts result in capacity fading, thus limiting its electrochemical performances. To solve the undesirable issues, the concept of in-situ forming the positive electrode/electrolyte interface on the commercial MnO2 is designed, with the help of introducing the Dioctyl Phthalate into the ZS-based electrolyte (2 M ZnSO4 + 0.2 M MnSO4), designated as ZS-DOP electrolyte. An advanced three-dimensional chemical and imaging analysis on a model material reveals the dynamic formation of positive electrode/electrolyte interface. The formed organic interface effectively suppresses the corrosion of the electrolytes with its hydrophobicity, and adjusts the pH value according to Le Chatelier’s Principle to inhibit the production of by-products. Specifically, the pouch cell assembled with the ZS-DOP electrolyte attains a reversible capacity of ~2.5 Ah and powers the unmanned aerial vehicle. Furthermore, photovoltaic energy storage applications deliver a stable capacity of 0.5 Ah and realize the power supply for mobile phones and other electronic devices. Our results facilitate the development of in-situ surface protection on the positive electrode in aqueous zinc-ion battery, providing insights into its practical application.

Serrated flow behavior mediated via nano‐twinning and phase transformation in FeCoCrNiMo0.2 high‐entropy alloy at cryogenic temperatures