Activation Energy Of Molecules Research Articles

Diffusion and Surface Reaction in Porous Cubical Catalyst: A Mathematical Approach

Background: Catalysts are the most vital part of any chemical industry. Catalyst is a substance that affects the rate of reaction, but the catalyst itself does not take part in the reaction. Catalysts offer different pathways of reaction by diffusing the reactant inside it to provide a large surface area within a small volume, thus, lowering the activation energy of molecules for reaction. Most of the catalytic reactions take place in a liquid- solid or gas-solid interface where catalysts are mostly porous in nature. Spherical and cubic-shaped catalyst particles are commonly used in different industries. Methods: In the first phase of the present study, the physics behind the diffusion inside the catalyst pellet has been discussed. In the second part, governing differential equations have been established at a steady-state condition. For solving the differential equation, the equation is made dimensionless. Physical boundary conditions were used to solve the diffusion equation. The assumption of writing the differential equation of the reaction is elementary. Then, the Thiele modulus is derived in terms of the reaction and geometrical parameter (Length). Results and Conclusion: In the third part, the differential equation is solved for firstorder reaction with some constant values of the Thiele modulus, and three-dimensional plots are obtained using numerical analysis. After that, the obtained Thiele modulus and effectiveness factor plot are compared to draw the conclusion of rate limiting reaction and internal diffusion.

DEVELOPMENT OF REQUIREMENTS AND SIMULATION OF THE PROCESS OF IGNITION OF EXPLOSION-HAZARDOUS MIXTURE BY A LOW VOLTAGE MEASURING CIRCUIT

The current lack of literature on the safe use of low-voltage measuring circuits in coal mines leads to the fact that they are trying to make unreasonable demands or simply prohibit their use under any far-fetched pretext. At the same time, measuring low-voltage circuits are an important integral component of diagnostics and information content of mining equipment control systems. This is due to the fact that the theory and models of the ignition of a methane-air mine atmosphere (MMA) solve problems in a narrow setting and cannot be used in the general mine case. The article identifies the conditions and parameters for the ignition of the MMA from the low-voltage measuring circuit (NVC),developed criteria for the ignition of the form the NVC, the existing model of the possible ignition process of the MMA from the NVTs is finalized. Currently, there are two theories of ignition of the HCV: thermal and ionic. From the author's point of view, the thermal model of VSH ignition from the electric discharge of the NSC is based on the analysis of the propagation of the temperature wave from some heat source in an inert environment. The thermal ignition model of VHS does not take into account many details of the physics of the combustion mechanism, such as the chain nature of individual acts of chemical interaction, the activation energy of molecules in the formation of active centers, and it is based on postulating some electric discharge. An assessment of the intrinsic safety and the possibility of self-expansion of the NVC flame core has been carried out. The approbation of research at three foreign conferences and the interest of foreign colleagues in them are shown. The article contains links to the state budget topics of the National Academy of Sciences of Ukraine and the numbers of state registration of Ukraine.

Fermat–Ostwald Principle

Fermat's principle of least time and Ostwald's law of intermediate stages are postulates concerning the physical processes that deal with light and heat energy flows, respectively. A comparative analysis of these processes shows that there is a close analogy between them. This suggests that the principle of least time can be applied to phase transitions of first kind concerned Ostwald's law. This supposition has been proven using the Maxwell-Boltzmann distribution law and an assumed correlation between two parameters of solids (heat conductivity and activation energy of molecules). Thus, a modification of Fermat's principle is obtained, which can be named Fermat-Ostwald principle.

Conformational Isomerization of 1,2-Difluoroethane in Solid Argon: Cage-Modified Reaction Barriers

Thermally induced rotational isomerization of trans-1,2-difluoroethane into the more stable gauche conformer in Ar matrices was studied over the temperature range 30−36 K by infrared spectroscopy. Photochemical generation of 1,2-difluoroethane in the matrix by two different mechanisms forms the product in singly and doubly substitutional argon lattice sites. Only the more stable doubly substitutional site is populated by the ordinary vapor deposition technique. At 33 K, the first-order rate constant for isomerization in the single site is 1.0 × 10-5 s-1 whereas the corresponding value for the double site is 5 × 10-3 s-1. Measurements of the temperature-dependent isomerization rates show that the activation energies for molecules in single and double sites are 15.0 ± 1.5 and 9.7 ± 0.8 kJ/mol, respectively. The latter value is close to a recent estimate of the gas phase reaction barrier (8.86 kJ/mol). This study provides an important example of how a reaction barrier is significantly modified by a solid-sta...

Application of programmable liquid thermodesorption under quasi-isothermal conditions to study physicochemical properties of liquid films and solid surfaces

The paper presents possible applications of differential thermal analysis for study of the physicochemical properties of liquid/solid systems, mainly through programmable liquid thermodesorption from the sample under quasi-isothermal conditions. The results prove its applicability in the determination of solid physicochemical properties, and particularly in calculations of adsorption potential distribution, the activation energy of molecules adsorbed on the surface and the surface heterogeneity by means of computer techniques.