A Reaction Extent Proof

2021 ◽  
Author(s):  
Diego Raposo
Keyword(s):  
Reaction Extent

scholarly journals Solar Metallurgy for Sustainable Zn and Mg Production in a Vacuum Reactor Using Concentrated Sunlight

2020 ◽  
Vol 12 (17) ◽  
pp. 6709 ◽  
Author(s):  
Srirat Chuayboon ◽  
Stéphane Abanades
Keyword(s):  
Carbon Black ◽  
Metal Oxides ◽  
Activated Charcoal ◽  
Carbothermal Reduction ◽  
Total Pressure ◽  
Operation Mode ◽  
Inert Atmosphere ◽  
Pure Metal ◽  
Reactor Outlet ◽  
Reaction Extent

Solar carbothermal reduction of volatile metal oxides represents a promising pyro-metallurgical pathway for the sustainable conversion of both metal oxides and sunlight into metal commodities and fuels in a single process. Nevertheless, there are several scientific challenges in discovering suitable metal oxides candidates for the ease of oxygen extraction from metal oxides to enhance the reaction extent and in designing reactors for the efficient absorption of incident solar radiation to minimize losses. In this study, ZnO and MgO were considered as volatile metal oxides candidates, and their reaction behaviors were studied and compared through gas species production rate, metal oxides conversion, and yield. A solar reactor prototype was developed to facilitate solar carbothermal reduction of ZnO and MgO with different reducing agents comprising activated charcoal and carbon black. The process was operated in a batch operation mode under vacuum and atmospheric pressures to demonstrate the flexibility and reliability of this system for co-production of metals (Zn/Mg) and CO. As a result, decreasing total pressure enhanced conversion of ZnO and MgO, leading to increased Zn and Mg. However, in the case of ZnO, CO yield decreased with decreasing total pressure at the expense of favored CO2 as a result of the decrease of residence time. In contrast, CO2 formation was negligible in the case of MgO, and CO yield thus increased with decreasing pressure. Using activated charcoal as the reducing agent exhibited better conversion of both ZnO and MgO than carbon black thanks to the higher available specific surface area for chemical reactions. MgO and ZnO conversion above 97% and 78%, respectively, and high-purity Mg and Zn content were accomplished, as evidenced by the recovered products at the reactor outlet and filter containing pure metal. In addition, Mg product exhibited strong oxidation reactivity with air, thus requiring inert atmosphere for the handling of Mg-rich powders to avoid direct exposure to air.

Direct evidence for the validity of assessing reaction extent by torque spectrum during reactive processing

Polymer ◽  
2020 ◽  
Vol 197 ◽  
pp. 122499 ◽  
Author(s):  
Yan Zhang ◽  
Jinxing Song ◽  
Xianhua Jin ◽  
Fei Li ◽  
Yongjin Li ◽  
...  
Keyword(s):  
Direct Evidence ◽  
Reactive Processing ◽  
Reaction Extent

Accurate Quantification of Two Key Time Points Used in the Determination of Hydroxyl Polyaluminum Species by Ferron Timed Spectrophotometry

2015 ◽  
Vol 98 (1) ◽  
pp. 225-229
Author(s):  
Jing Zhang ◽  
Xiaojing Yong ◽  
Dongyan Zhao ◽  
Qiuyi Shi
Keyword(s):  
Sulfonic Acid ◽  
Time Curve ◽  
Absorption Time ◽  
Time Points ◽  
Complete Reaction ◽  
Reaction Extent ◽  
Accurate Quantification ◽  
Time Point

Abstract The content of mononuclear Al (Ala%) changed with its determination time (ta) under different dosages of Ferron (7-iodo-8-hydroxyquinoline-5-sulfonic acid, [Ferron]), and the change of Ala% with [Ferron] at different ta was systematically investigated for the firsttime. Thus, the most appropriate ta was found with the optimal [Ferron]. Also, the judgment of the platform (flat or level portion) of the complete reaction on the absorption-time curve determined in the hydroxyl polyaluminum solution by Ferron timed spectrophotometry (Ferron assay) was first digitized. The time point (tb) of complete reaction between the medium polyaluminum (Alb)and Ferron reagent depended on the reaction extent, and time could not be used only to judge. Thus, the tb was accurately determined and reduced to half of original, which improved the experiment efficiency significantly. The Ferron assay was completely optimized.

scholarly journals New selective dissolution process to quantify reaction extent and product stability in metakaolin-based geopolymers

2019 ◽  
Vol 176 ◽  
pp. 107172 ◽  
Author(s):  
Márlon A. Longhi ◽  
Brant Walkley ◽  
Erich D. Rodríguez ◽  
Ana P. Kirchheim ◽  
Zuhua Zhang ◽  
...  
Keyword(s):  
Selective Dissolution ◽  
Dissolution Process ◽  
Reaction Extent

scholarly journals Tomography-Based Determination of Effective Transport Properties for Reacting Porous Media

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Sophia Haussener ◽  
Iwan Jerjen ◽  
Peter Wyss ◽  
Aldo Steinfeld
Keyword(s):  
Porous Media ◽  
Transport Properties ◽  
Strong Dependence ◽  
Convective Heat Transfer Coefficient ◽  
Packed Bed ◽  
Morphological Properties ◽  
High Resolution Computed Tomography ◽  
Thermochemical Transformation ◽  
Effective Transport ◽  
Reaction Extent

The effective heat and mass transport properties of a porous packed bed of particles undergoing a high-temperature solid–gas thermochemical transformation are determined. The exact 3D geometry of the reacting porous media is obtained by high-resolution computed tomography. Finite volume techniques are applied to solve the governing conservation equations at the pore-level scale and to determine the effective transport properties as a function of the reaction extent, namely, the convective heat transfer coefficient, permeability, Dupuit–Forchheimer coefficient, tortuosity, and residence time distributions. These exhibit strong dependence on the bed morphological properties (e.g., porosity, specific surface area, particle size) and, consequently, vary with time as the reaction progresses.

scholarly journals Chemo-Rheological Study of Hardening of Epoxy Modified Bituminous Binders with the Finite Element Method

2018 ◽  
Vol 2672 (28) ◽  
pp. 190-199 ◽  
Author(s):  
P. Apostolidis ◽  
X. Liu ◽  
C. Kasbergen ◽  
M.F.C. van de Ven ◽  
G. Pipintakos ◽  
...  
Keyword(s):  
Activation Energy ◽  
Mechanical Response ◽  
Chemical Interaction ◽  
Influential Factors ◽  
Polymerization Rate ◽  
Gel Point ◽  
Physical Factors ◽  
Modified Bitumen ◽  
Reaction Extent ◽  
Bituminous Binders

The chemical irreversible hardening of epoxy modified bitumen is affected by various physical factors and the successful application of this technology is directly linked with full understanding of chemo-rheological material characteristics. This study proposes a model to describe the material viscosity evolution during hardening of epoxy modified bitumen. The findings from numerical analyses performed to assess the mechanical response of epoxy modified bituminous binders are presented. Information of the chemical interaction of epoxy within a bituminous matrix was collected and all the influential factors have been determined. The proposed chemo-rheological model accounting for the polymerization of the epoxy in the bitumen was formulated and the sensitivity of material parameters, such as activation energy, reaction order and extent of hardening reaction until the gel point of epoxy modified binders, was demonstrated. Results of the analyses suggest that lower levels of activation energy increase the degree of hardening and the rate of viscosity development. By decreasing the hardening reaction until the gel point the achieved viscosity of epoxy modified bitumen was increased showing the importance of gel reaction extent on material viscosity evolution. The numerical studies have shown also that the polymerization rate in the epoxy modified bitumen is highly dependent on the temperature under various (non-) isothermal conditions. Also, the polymerization rate should be considered through all the material curing processes to avoid unwanted variations in the mechanical properties.

scholarly journals Tomography-Based Analysis of Radiative Transfer in Reacting Packed Beds Undergoing a Solid-Gas Thermochemical Transformation

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
Sophia Haussener ◽  
Wojciech Lipiński ◽  
Peter Wyss ◽  
Aldo Steinfeld
Keyword(s):  
Effective Properties ◽  
Packed Bed ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Thermochemical Transformation ◽  
Reaction Extent ◽  
Fluid Boundary ◽  
Point Correlation ◽  
Scattering Phase ◽  
Scattering Phase Function

A reacting packed-bed undergoing a high-temperature thermochemical solid-gas transformation is considered. The steam- and dry-gasification of carbonaceous materials to syngas is selected as the model reaction. The exact 3D digital geometrical representation of the packed-bed is obtained by computer tomography and used in direct pore-level simulations to characterize its morphological and radiative transport properties as a function of the reaction extent. Two-point correlation functions and mathematical morphology operations are applied to calculate porosities, specific surfaces, particle-size distributions, and representative elementary volumes. The collision-based Monte Carlo method is applied to determine the probability distribution of attenuation path length and direction of incidence at the solid-fluid boundary, which are linked to the extinction coefficient, scattering phase function, and scattering albedo. These effective properties can be then incorporated in continuum models of the reacting packed-bed.

Investigation on the Sintering Properties of Mullite Al2O3-70%

2014 ◽  
Vol 941-944 ◽  
pp. 2620-2625
Author(s):  
Chang He Gao ◽  
Jia Lin Sun ◽  
Yong Li ◽  
Jun Jie Zhang ◽  
Ji Li Zhang ◽  
...  
Keyword(s):  
Bulk Density ◽  
Phase Distribution ◽  
Sintering Temperature ◽  
Raw Materials ◽  
Phase Reaction ◽  
Crystal Water ◽  
Reaction Extent ◽  
Density Analysis ◽  
Sintering Properties ◽  
Bauxite Ore

This paper takes Al2O3-70% natural mullite raw bauxite ore (Referred to 70-ore) and Al2O3-70% bauxite based homogenized grogs green adobe (Referred to 70-grog), produced by Beijing Tongda Refractory Technologies Co.,Ltd.through wet homogenization and vacuum pug process, as raw materials. 70-ore and 70-grog are fired respectively at 1100°C, 1300°C, 1400°C, 1600°C for 4 hours. Research on the influence of sintering temperature on the phase compositin, microstructure and bulk density. Analysis on the phase reaction during the sintering process. The results show that: Phase distribution of 70-ore is uneven. α-Al2O3 decomposed by diaspore is difficult to contact with amorphous SiO2 decomposed by kaolinite, this makes α-Al2O3 particle be unable to dissolve into amorphous SiO2, and causes twice crystallizing of mullite reaction hardly to happen. After a series of homogenizing treament, diasepore and kaolinite phase of 70-grog distribute more uniformly, which don’t destory the ore structure, and accelerate the twice crystallizing of mullite reaction. Compared with 70-ore, the twice crystallizing of mullite reaction extent of 70-gorg is more thoroughly. Rising the sintering temperature is beneficial for the twice crystallizing of mullite reaction, the growth of mullite and the bulk density of mateials. The adobes produced through wet homogenization and vacuum pug process have a big volume shrinkage, so controlling the removal of crystal water,the formation and growth of mullite are the keys to get dense bauxite based homogenized grogs.

scholarly journals Reaction Extent and Mass Conservation(s)

2020 ◽  
Author(s):  
Diego Raposo
Keyword(s):  
General Chemistry ◽  
Chemical Reaction ◽  
Mass Conservation ◽  
Reaction Extent ◽  
Closed Systems ◽  
Over Time

A new proof to introduce reaction extent in General Chemistry courses, with mathematical and chemical arguments, is suggested, together with the relation between mass conservation (over time) and reaction extent conservation (between different substances in a chemical reaction) in closed systems<br>

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