Reaction Behavior Research Articles

Effect of Nonreactive Minerals on Acid-Etching Hydraulic Fracture Behavior and Conductivity in Carbonate Rocks

Summary Nonreactive minerals, such as quartz and talc, are frequently observed in carbonate reservoirs due to the sedimentary environment and geological processes. However, scant attention has been given by scholars to the impact of these nonreactive minerals on acid-etched fracture morphology and conductivity during acid fracturing. To clarify the acid flow and reaction behavior in carbonate rock composed of complex minerals, a mineral characterization model simultaneous for calcite, dolomite, and nonreactive minerals is first developed in this paper. Then, combined with the thermal-hydraulic-chemical coupling acid-etching model, it can study the impact of mineral content and distribution on the acid-etching fracture behavior. In addition, the acid-etching model is validated by acid-etching laboratory experiments, and the acid-fracture conductivity model is also established by testing the conductivity of rock slabs with different mineral compositions. Based on the new model, the effects of different mineral compositions on the acid flow behavior, effective acid penetration distance (EAPD), and conductivity were investigated. The research results show that the mechanism of nonreactive mineral to increase EAPD depends on the initial hydraulic fracture width, mineral distribution, and content. The acid concentration profile along the fracture length has the feature of segmentation when the circumferential flow phenomenon occurs. With the increase of the nonreactive mineral content, the EAPD increasing rate in the calcite-nonreactive mineral interaction distribution formation is faster than that in calcite-dolomite. The impact of the nonreactive mineral on conductivity is large in limestone but can be ignored in dolomite. These findings can provide guidance for the design of acid fracturing in such siliceous carbonate reservoirs.

PbSO4 reaction mechanism in oxygen and reduction atmospheres during co-smelting process with primary lead material.

At present, lead-containing wastes have increasingly become the raw materials together with primary lead concentrate for lead production to meet the ever-increasing lead demand market. PbSO4 is the dominant component in the lead-containing wastes, nevertheless, its reaction behavior during lead smelting is not sufficiently investigated. This study investigated PbSO4 decomposition behaviors and phase transformation mechanisms at oxidizing and reductive atmospheres and various gas flow rates. The investigations reveal that increasing the temperature and decreasing the oxygen partial pressure of the decomposition atmosphere can accelerate PbSO4 decomposition degree. PbSO4 decomposition intensity under different atmospheres follows the order of reducing atmosphere>inert atmosphere>oxidizing atmosphere. PbSO4 decomposition path was identified: at a non-reductive atmosphere, the decomposition of PbSO4 belongs to a multi-step decomposition process, PbSO4 gradually decompose into xPbO·PbSO4 (x=1, 2, 4 in turn) and finally PbO. At a reductive atmosphere, the multi-step decomposition process was accelerated significantly, at the same time, the reduction decomposition path PbSO4→PbS was increasingly dominant with the extension of decomposition time. PbS and Pb were generated successively. Therefore, a suitable reducing atmosphere is suggested to co-smelt PbSO4-bearing wastes in primary lead smelting furnace.

Effect of Ferrite Phase Content on Hydration Reaction, Mechanical Properties, and Chloride-Binding Behavior of Ordinary Portland Cement

Effect of Ferrite Phase Content on Hydration Reaction, Mechanical Properties, and Chloride-Binding Behavior of Ordinary Portland Cement

How Microsolvation Affects the Balance of Atomic Level Mechanism in Substitution and Elimination Reactions: Insights into the Role of Solvent Molecules in Inducing Mechanistic Transitions

Solvents play a crucial role in ion–molecule reactions and have been used to control the outcome effectively. However, little is known about how solvent molecules affect atomic-level mechanisms. Therefore, we executed direct dynamics simulations of the HO−(H2Ow) + CH3CH2Br system to elucidate the dynamics behavior of chemical reactions in a microsolvated environment and compared them with previous gas-phase data. Our results show that the presence of a single water solvent molecule significantly suppresses the direct mechanism, reducing its ratio from 0.62 to 0.18, thereby promoting the indirect mechanism. Spatial effects and prolonged ion–molecule collisions combine to drive this mechanism shift. Among them, water molecules impede the reactive collisions of HO− and CH3CH2Br, while at the same time, the attractive interaction of hydrogen bonds between ions and molecules produces long-lived intermediates that favor the indirect mechanism. On the other hand, microsolvation also affects the reaction preference of the SN2 and E2 channels, which is more conducive to stabilizing the transition state of the SN2 channel due to the difference in solute–solvent interactions, thus increasing the competitiveness of this pathway. These results emphasize the profound influence of solvent molecules in regulating reaction selectivity and underlying microscopic mechanisms in more complex systems.

Investigation of The Plasma Reaction Behavior of a Coke Oven Gas with Trace Oxygen in a Coaxial DBD Reactor

Investigation of The Plasma Reaction Behavior of a Coke Oven Gas with Trace Oxygen in a Coaxial DBD Reactor

Nucleophilic and Electrophilic Molybdenum Terminal Oxo Complexes by Coordination-Induced Bond Weakening of Hydroxo O-H Bonds.

The extent of coordination-induced bond weakening in aquo and hydroxo ligands bonded to a molybdenum(III) center complexed by a dianionic, pentadentate ligand system was probed by reacting the known complex (B2Pz4Py)Mo(III)-NTf2, I, with degassed water or dry lithium hydroxide. The aquo adduct was not observed, but two LiNTf2-stabilized hydroxo complexes were fully characterized. Computational and experimental work showed that the O-H bond in these complexes was significantly weakened (to ≈57 kcal mol-1), such that these compounds could be used to form the diamagnetic, d2 neutral terminal molybdenum oxo complex (B2Pz4Py)Mo(IV)O, 2, by hydrogen atom abstraction using the aryl oxyl reagent ArO• (Ar = 2,4,6-tri-tert-butylphenyl). Oxidation of the neutral hydroxo derivative further facilitated the production of 2 by significantly enhancing the acidity of the hydroxyl proton. Speciation in these processes was probed by electrochemical and chemical experiments. The terminal oxo complex 2 was smoothly oxidized by one electron to the cationic [(B2Pz4Py)Mo(V)O]+[A]- derivatives [2]+[A]- (A = NTf2 or Al[OC(CF3)3]4 depending on the oxidizing agent used). Both Mo(IV) and Mo(V)+ oxo complexes were fully characterized with their nucleophilic and electrophilic reaction behavior probed by conducting reactions with the Lewis acid B(C6F5)3 and the Lewis base PPh3. Neutral oxo complex 2 reacts only with the Lewis acid, while the cationic [2]+[A]- reacts only with PPh3, the former by adduct formation and the latter via phosphine oxidation.

Fe-supported perlite applied for the degradation of Rhodamine B dye by Heterogeneous Fenton reaction

This study aimed to evaluate a technique of Fe ion impregnation on perlite mineral and assess its behavior in a heterogeneous Fenton-like reaction, at room temperature and under acidic and alkaline conditions in the removal of Rhodamine B dye. For the catalyst preparation, a suspension of heptahydrated ferrous sulfate (FeSO4.7H2O) was used, followed by thermal treatment (calcination). Different doses of H2O2 (35% v/v) were applied to evaluate dye removal rates. Fe leaching in reaction media was analyzed. Rhodamine B removal at pH 4, 7, 9, 10, and 11 had the respective removal rates of 99.8%, 57.4%, 73.1%, 77.5%, and 96.9% in 240 minutes of reaction. At pH 12, there was 99.7% removal in 110 minutes of reaction. Reactions performed with low dosages of hydrogen peroxide showed, at pH 4 and 11, removal percentages of 95.8% and 90.2%, respectively, in 150 minutes of reaction. Under the same conditions, at pH 12, the removal percentage was 98.6% in 105 minutes. The synthesized catalyst exhibited satisfactory activity under acidic and alkaline conditions, for three cycles, showing promise for applications in heterogeneous Fenton reactions on a large scale.

Behavior of sonochemical reaction in small pipe

Abstract The behavior of sonochemical reactions in a small pipe was investigated by indirect ultrasonic irradiation while circulating potassium iodide solution. At a high electric power, the quenching of sonochemical reactions was observed. The reaction rate increased with the liquid flow velocity in the pipe. The reaction rate changed periodically with the distance between the pipe and the liquid surface, and exhibited minimum and maximum values at every quarter of the wavelength of ultrasound. By placing a reflector on the liquid surface, the reaction was accelerated. Formation of standing wave in the pipe significantly enhanced the reaction rate.

Unraveling the Meaning of Effective Uptake Coefficients in Multiphase and Aerosol Chemistry.

ConspectusReactions of gas phase molecules with surfaces play key roles in atmospheric and environmental chemistry. Reactive uptake coefficients (γ), the fraction of gas-surface collisions that yield a reaction, are used to quantify the kinetics in these heterogeneous and multiphase systems. Unlike rate coefficients for homogeneous gas- or liquid-phase reactions, uptake coefficients are system- and observation-dependent quantities that depend upon a multitude of underlying elementary steps. As such, uptake coefficients adopt complex scaling behavior with reactant concentrations and other physicochemical properties of the interface, making predictions of γ particularly challenging.Typically, γgas is obtained by measuring the loss rate of a gas-phase molecule above a liquid or solid surface, relative to its collision frequency. By definition, γgas ≤ 1. Highly efficient reactions proceed at or near the gas-surface collision frequency and exhibit values of γgas near unity. Alternatively, heterogeneous kinetics are often measured using the consumption rate of a condensed phase reactant normalized to the gas-surface collision frequency, yielding instead an effective uptake coefficient (γeff). In many cases, γeff and γgas are not equal, yielding additional insights into the nature of the reaction. For example, substantial diffusive limitations in the condensed phase may inhibit reactivity, yielding γeff ≪ γgas. In contrast, γeff > γgas in the presence of condensed phase secondary reactions, with values of γeff often exceeding 1 for the case of radical chain reactions.In this Account, we will discuss how measurements of γeff in aerosol can uniquely reveal the origins of complex physical and chemical behavior in multiphase reactions under laboratory conditions. For example, measurements of the scaling of γeff with shell thickness during the ozonolysis of core-shell aerosol yields insight into the relative transport and reaction time scales of gaseous oxidants, while measurements of γeff, as a function of relative humidity (RH) during OH radical oxidation of hygroscopic citric acid aerosol, highlight the role that mixing times of particle-phase reactants play in determining aerosol reaction kinetics. Additionally, the scaling of γeff with oxidant and trace gas concentrations during the oxidation of long-chain hydrocarbons in aerosols by OH radicals and chlorine atoms provides distinctive signatures of the underlying competition between free radical propagation and termination mechanisms. Finally, it is shown how changes in γeff that are induced by careful selection of the molecular structure of the particle-phase reactant help to identify new reaction pathways, such as alternative mechanisms for lipid peroxidation, and to report on the reaction kinetics of short-lived reactive species, including Criegee Intermediates. Together, these examples will demonstrate how proper experimental design and accurate measurements of an effective uptake coefficient can be used to interrogate the fundamental steps governing complex multiphase reaction mechanisms.

Reaction behaviors and mechanisms of in-situ carbothermal reduction in spent lithium batteries

Reaction behaviors and mechanisms of in-situ carbothermal reduction in spent lithium batteries

CosIn: A statistical-based algorithm for computation of space-speed time delay in pedestrian motion

Precise assessment of Space-speed time delay (TD) is critical for distinguishing between anticipation and reaction behaviors within pedestrian motion. Besides, the TD scale is instrumental in the evaluation of potential collision tendency of the crowd, thereby providing essential quantitative metrics for assessing risk. In this consideration, this paper introduced the CosIn algorithm for evaluating TD during pedestrian motion, which includes both the CosIn-1 and CosIn-2 algorithms. CosIn-1 algorithm analytically calculates TD, replacing the numerical method of discrete cross-correlation, whereas the CosIn-2 algorithm estimates the TD from a statistical perspective. Specifically, the CosIn-1 algorithm addresses the precise computation of TD for individual pedestrians, while the CosIn-2 algorithm is employed for assessing TD at the crowd scale, concurrently addressing the imperative of real-time evaluation. Efficacy analyses of the CosIn-1 and CosIn-2 algorithms are conducted with data from single-file pedestrian experiments and crowd-crossing experiments, respectively. During this process, the discrete cross-correlation method was employed as a baseline to evaluate the performance of both algorithms, which demonstrated notable accuracy. This algorithm facilitate the precise evaluation of behavior patterns and collision tendency within crowds, thereby enabling us to understand the crowds dynamics from a new perspective.

Effect of temperature on reaction and degradation behaviors during CO2 and H2O gasification reactions of coke in same conversion ratio

Effect of temperature on reaction and degradation behaviors during CO₂ and H₂O gasification reactions of coke in same conversion ratio

Study of dispersion characteristics and flame propagation, deflagration reaction behaviours of vapor liquid two-phase anhydrous hydrazine and DT-3/air mixtures

Study of dispersion characteristics and flame propagation, deflagration reaction behaviours of vapor liquid two-phase anhydrous hydrazine and DT-3/air mixtures

Thermal and chemical reaction behaviors during spontaneous ignition caused by pressurized hydrogen released under different concentrations of methane addition

Thermal and chemical reaction behaviors during spontaneous ignition caused by pressurized hydrogen released under different concentrations of methane addition

Reaction behavior of CO2 gas in a new three-phase gas-liquid-liquid stripping process for lithium recovery

Reaction behavior of CO2 gas in a new three-phase gas-liquid-liquid stripping process for lithium recovery

PtRu Intra‐Cluster Electron Modulation Accelerates Multi‐Scenario Hydrogen Evolution Reaction

AbstractThe development of advanced nanomaterial manufacturing technology and the in‐depth analysis of the structure‐activity relationship are conducive to the sustainable development of platinum‐based catalysts in terms of low cost and high performance. The in situ conversion of Pt4+ and Ru3+ is creatively achieved into highly dispersed, small‐sized heterojunction clusters in the confined space by reductant preset framework materials, and these clusters benefited from the hollow carbon spheres gap supramolecular self‐assembly strategy to achieve high exposure. The intra‐cluster Ru→Pt electron transfer and induced electronic structure modulation enhance the adsorption and activation of H2O molecules at the interface, accelerating the desorption coupling of [H] at the Pt or Ru site. As a catalyst, PtRu/BNHCSs have achieved significant hydrogen production from electrolyzed water in multiple scenarios, exceeding the performance of the commercial Pt/C catalyst. These scenarios include high‐current water splitting to hydrogen in both pH‐neutral and simulated seawater, direct seawater hydrogen production, and anion‐exchange membrane integrated continuous and efficient electrolytic hydrogen production. In situ Fourier transform infrared and in situ Raman interface monitoring techniques reveal the interfacial adsorption behavior of H2O, providing important experimental and theoretical insights for understanding and revealing the synergistic effect and the interfacial reaction behavior of intra‐cluster atoms of PtRu heterojunction.

Mechanism-Inspired Synthesis of Poly(alkyl malonates) via Alternating Copolymerization of Epoxides and Meldrum's Acid Derivatives.

Direct incorporation of malonate units into polymer backbones is a synthetic challenge. Herein, we report the alternating and controlled anionic copolymerization of epoxides and Meldrum's acid (MA) derivatives to access poly(alkyl malonates) using (N,N'-bis(salicylidene)phenylenediamine)AlCl and a tris(dialkylamino)cyclopropenium chloride cocatalyst. This unique copolymerization yields a malonate-containing repeat unit while releasing a small molecule upon MA-derivative ring-opening. Mechanistic and computational studies reveal that the nature of the small molecule released influences overall polymerization kinetics, side reaction behavior, and molecular weight control. Controlled copolymerization of MA derivatives with a range of epoxides ultimately yields a library of new poly(alkyl malonates) with diverse and tunable thermal properties.

Study on the Curing Behaviors of Benzoxazine Nitrile-Based Resin Featuring Fluorene Structures and the Excellent Properties of Their Glass Fiber-Reinforced Laminates.

Benzoxazine and o-phthalonitrile resin are two of the most eminent polymer matrices within high-performance fiber-reinforced resin-based composite materials. Studying the influence modalities of their structures and forming processes on performance can furnish a theoretical basis for the design and manufacturing of superior performance composite materials. In this study, we initially incorporated a fluorene structure into the molecular main chain through molecular design to prepare a fluorene-containing benzoxazine nitrile-based resin. The polymerization reaction behavior and process of this resin were monitored meticulously using differential scanning calorimetry and infrared spectroscopy. Meanwhile, by manipulating the pre-polymerization reaction conditions, the impact of the pre-polymerization reaction on the polymerization behavior of the resin monomer was investigated, respectively. Subsequently, diverse glass fiber-reinforced resin-based composite materials were fabricated via hot-pressing in combination with a programmed temperature rise process. Through the characterization of structural strength and thermomechanical properties, it was found that the composite laminates all manifested outstanding bending strength (~600 MPa) and modulus (>30 GPa). Nevertheless, with the elevation of the post-curing temperature, the structural strength and modulus of the composite materials displayed distinct variation laws. This study also discussed the variation laws of the thermal properties of the composite materials by analyzing the glass transition temperature and crosslinking density. Additionally, the interface bonding effect between the glass fiber and the resin matrix was deliberated through the analysis of the cross-sectional morphology of the composite laminates. The results demonstrated that this work proposes an improved matrix resin system with outstanding thermal stability and mechanical properties that broadens the foundation and ideas for subsequent research.

Photocoloring Reaction Behavior in Spironaphthooxazine Nanoparticles under Nanosecond Pulse Laser Irradiation

Photocoloring Reaction Behavior in Spironaphthooxazine Nanoparticles under Nanosecond Pulse Laser Irradiation

A case study for Improving the performance of CaO-activated slag by the reaction behavior of CaO and NaHCO3

In Alkali-Activated Slag, a contradiction exists among pH, setting speed, and strength development. In this study, the reaction behavior between CaO and NaHCO3 is harnessed to regulate the setting speed while optimizing the material properties. The results demonstrated that the pore solution pH of Alkali-Activated Slag rose to over 12.4. At C5S100, the workability and setting time of the material were comparable to or even surpassed those of ordinary Portland cement. It exhibited a compressive strength of 53.9 MPa at 28 days, which was an 85.2 % increase compared to C5S0, and over 70Mpa at 90 days. Additionally, in the microscopic characterization tests, the composite activator facilitates the dissolution hydration of slag, generating more hydration products. This leads to a more compact structure and lower porosity, thereby enhancing the overall performance. This composite activator strategy effectively reconciled the conflict between the practicality of Alkali-Activated Slag and the setting speed and strength development.