On the determination of the activation energy of solid-state reactions from the maximum reaction rate of isothermal runs

AbstractMany reactions of interest occur in the solid state, or with low mobility of the reactants or products, with the result that the physical mechanisms operative during the reaction determine the shape of the reaction rate-time profile; i.e. topochemistry is important. However, often improper account is taken of the physical mechanisms, resulting in erroneous values for the activation energy and kinetic constants.An improved method of analysis is suggested, allowing the mechanisms of reaction to be determined explicitly. This thus allows the activation energy and kinetic constants to be determined with good theoretical justification. The method has been verified by studying the thermal decomposition of barium azide, where the activation energy was determined to better than 1%. The operative mechanisms so determined are in agreement with visual observations and the literature.

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Kinetic Analysis of the Decomposition of Calcium Carbonate Using Danyang Limestone

Materials Science Forum ◽

10.4028/www.scientific.net/msf.510-511.502 ◽

2006 ◽

Vol 510-511 ◽

pp. 502-505 ◽

Cited By ~ 1

Author(s):

Sang Hwan Cho ◽

Sung Min Joo ◽

Jin Sang Cho ◽

Young Hwan Yu ◽

Ji Whan Ahn ◽

...

Keyword(s):

Activation Energy ◽

Calcium Carbonate ◽

Kinetic Parameter ◽

Kinetic Analysis ◽

Heating Rate ◽

Reaction Rate ◽

Decomposition Temperature ◽

Final Point ◽

Maximum Reaction

Non-isothermal behaviors of calcium carbonate using Danyang limestone were investigated. It was attempted to provide non-isothermal data with a precision sufficient for the determination of reliable decomposition behaviors and for the estimation of accurate kinetic parameter. The decomposition temperature of calcium carbonate on the onset, peak and final point were measured. Reaction rate was decreased and maximum reaction temperature was increased with increasing heating rate. Activation energy of Danyang limestone was 45.14㎉/㏖ and 50.80㎉/ ㏖ by Kissinger method and Freeman method, respectively.

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Modelling and Multi-Objective Optimization of the Sulphur Dioxide Oxidation Process

Processes ◽

10.3390/pr9061072 ◽

2021 ◽

Vol 9 (6) ◽

pp. 1072

Author(s):

Mohammad Reza Zaker ◽

Clémence Fauteux-Lefebvre ◽

Jules Thibault

Keyword(s):

Sulphuric Acid ◽

Sulphur Dioxide ◽

Variable Number ◽

Inlet Temperature ◽

Multi Objective Optimization ◽

Absorption Column ◽

Maximum Reaction Rate ◽

Multi Objective ◽

Maximum Reaction

Sulphuric acid (H2SO4) is one of the most produced chemicals in the world. The critical step of the sulphuric acid production is the oxidation of sulphur dioxide (SO2) to sulphur trioxide (SO3) which takes place in a multi catalytic bed reactor. In this study, a representative kinetic rate equation was rigorously selected to develop a mathematical model to perform the multi-objective optimization (MOO) of the reactor. The objectives of the MOO were the SO2 conversion, SO3 productivity, and catalyst weight, whereas the decisions variables were the inlet temperature and the length of each catalytic bed. MOO studies were performed for various design scenarios involving a variable number of catalytic beds and different reactor configurations. The MOO process was mainly comprised of two steps: (1) the determination of Pareto domain via the determination a large number of non-dominated solutions, and (2) the ranking of the Pareto-optimal solutions based on preferences of a decision maker. Results show that a reactor comprised of four catalytic beds with an intermediate absorption column provides higher SO2 conversion, marginally superior to four catalytic beds without an intermediate SO3 absorption column. Both scenarios are close to the ideal optimum, where the reactor temperature would be adjusted to always be at the maximum reaction rate. Results clearly highlight the compromise existing between conversion, productivity and catalyst weight.

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