The Effect of the Flow Nonuniformity on the Chemical Process in a Catalyst Grain in the Presence of Pore-Diffusion Resistance

2020 ◽  
Vol 61 (6) ◽  
pp. 903-906
Author(s):  
S. G. Zavarukhin ◽  
R. G. Kukushkin
Keyword(s):  
Chemical Process ◽  
Pore Diffusion ◽  
Diffusion Resistance ◽  
Flow Nonuniformity

scholarly journals Thermogravimetric Study of the Kinetics of the Reaction C + CO2 under Pore-Diffusion Control

Energies ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1886
Author(s):  
Igor Donskoy ◽  
Aleksandr Kozlov
Keyword(s):  
Activation Energy ◽  
Heterogeneous Reaction ◽  
Experimental Studies ◽  
Pore Diffusion ◽  
Diffusion Control ◽  
Diffusion Resistance ◽  
Problem Solution ◽  
Heating Rates ◽  
Carbon Gasification ◽  
Kinetics Of

This study presents experimental studies of charcoal gasification with CO2 at different heating rates (1, 5, 10, 20, and 50 K min−1). The kinetics of the reaction C + CO2 under pore-diffusion control is studied. We propose a new method for the proper determination of activation energy during the processing of thermogravimetric curves of porous carbon gasification under conditions of pore-diffusion resistance. The results of the inverse kinetic problem solution are compared with different hypotheses about the regime of the investigated heterogeneous reaction process (kinetic, diffusion, pore-diffusion). The change of reaction regimes from kinetic to diffusion is detected during charcoal gasification at different heating rates. At heating rates of 5–20 K min−1, the values of activation energy of carbon gasification reaction in the carbon dioxide atmosphere, obtained by the proposed method, closely match the data found in the previous studies. The use of diffusion models in the processing of thermogravimetric curves determines the conditions under which conventional kinetic models fail to provide adequate information about the temperature dependence of the heterogeneous reaction rate.

Film and Pore Diffusion Effects in Catalytic Vapor Phase Alkylation of Aniline

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Satyavathi Bankupalli ◽  
Viswanath Kotra ◽  
Vijaya Lakshmi Cheedipudi ◽  
Venkateshwar S
Keyword(s):  
Mass Transfer ◽  
Particle Size ◽  
Vapor Phase ◽  
Fixed Bed ◽  
Internal Resistance ◽  
Pore Diffusion ◽  
Effectiveness Factor ◽  
Fixed Bed Reactor ◽  
Diffusion Resistance ◽  
External Mass Transfer

Catalytic vapor phase alkylation of aniline with ethanol was effected in the presence of a zeolite catalyst in a fixed bed reactor at atmospheric pressure and moderate temperatures. Experimental runs were carried out at five different temperatures (350, 370, 390, 410 and 430 °C) with a constant aniline to ethanol ratio (1:5) and different catalyst loadings to find the limits of external and internal resistance zones. The resistance due to external mass transfer was overcome by operating at high velocities and the pore diffusion resistance was nullified by conducting experiments with different particle sizes of the catalyst. The effectiveness factor was determined experimentally and the optimum zone of operation where the diffusional resistances are absent was obtained for kinetic experiments to be conducted. The results indicated that below 0.6 cm/sec velocity external mass transfer was likely to influence the rate of reaction. The effect of pore diffusion was accounted for by the effectiveness factor which was nearly unity for an operative range of particle size < 2 mm. Pore diffusion will therefore play a role for a particle size > 2 mm.

EIS study of the corrosion behavior of an organic coating applied on Algerian oil tanker

2020 ◽  
Vol 117 (6) ◽  
pp. 610
Author(s):  
Nadia Hammouda ◽  
Kamel Belmokre
Keyword(s):  
Corrosion Protection ◽  
Electrochemical Impedance ◽  
Paint Film ◽  
Organic Coating ◽  
Diffusion Resistance ◽  
Double Layer Capacitance ◽  
Carbon Steel Surface ◽  
Chloride Environment ◽  
Oil Tanker ◽  
Epoxy Paint

Organic coatings are widely employed in the corrosion protection of most metal surfaces, particularly steel. They provide a barrier against corrosive species present in the environment, due to their high resistance to oxygen, water and ions transport. This study focuses on the evaluation of corrosion protection performance of epoxy paint on the carbon steel surface in chloride environment (3% NaCl) by Electrochemical Impedance Spectroscopy (EIS). The electrochemical behavior of painted surface was estimated by EIS parameters that contained paint film resistance, paint film capacitance and double layer capacitance. On the basis of calculation using EIS spectrums it was observed that pore resistance (Rpore) decreased with the appearance of doubled layer capacitance (Cdl) due to the electrolyte penetration through the film. This was further confirmed by the decrease of diffusion resistance (Rd) which was also the indicator of the deterioration of paint film protectiveness. Microscopic analyses have shown that oxidation dominates the corroded surfaces.

A Study of High Accident Risk for Chemical Process

2018 ◽  
Vol 6 (1) ◽  
pp. 63-70
Author(s):  
Dong Hoon Lee ◽  
Yong Taek Ju ◽  
heon kim ◽  
Kyo Shik Park
Keyword(s):  
Chemical Process ◽  
Accident Risk

HASTELLOY ALLOY B-2

Alloy Digest ◽  
1977 ◽  
Vol 26 (9) ◽  
Keyword(s):  
Corrosion Resistance ◽  
High Temperature ◽  
Physical Properties ◽  
Stress Corrosion Cracking ◽  
Heat Affected Zone ◽  
Chemical Process ◽  
Heat Treating ◽  
Cabot Corporation ◽  
Temperature Performance ◽  
Excellent Corrosion Resistance

Abstract HASTELLOY alloy B-2 has outstanding corrosion resistance in the as-welded condition. It is an improved wrought version of HASTELLOY alloy B with the same excellent corrosion resistance as alloy B, but with improved resistance to knife line and heat-affected zone attack. Alloy B-2 resists the formation of grain-boundry carbide precipitates in the weld heat-affected zone, thus making it suitable for most chemical process applications in the as-welded condition. This alloy also has excellent resistance to pitting and stress-corrosion cracking. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Ni-249. Producer or source: Stellite Division, Cabot Corporation.

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