Abstract
A simple esterification reaction is used to demonstrate standard procedures for determining the thermokinetic parameters of an exothermic reaction from adiabatic calorimetric data. The influence of variations in the heat capacity of the sample due to changes in temperature and concentration is explored. Shortcomings in the simple interpretation of adiabatic data are identified and isothermal heatflow calorimetry is used to reveal autocatalytic effects which were not apparent from the adiabatic experiments. A more rigourous interpretation of the adiabatic and isothermal data is outlined and used to predict the conditions which can lead to exothermic runaway in a batch reactor. Mathematical simulation of the conditions in a jacketed reactor is used to demonstrate the importance of developing reliable kinetic expressions before assessing the safety of a batch process.
Zusammenfassung
Anhand einer einfachen Veresterungsreaktion wurden Standardverfahren zur Ermittlung thermokinetischer Parameter exothermen Reaktionen aus adiabatischen kalorimetrischen Daten demonstriert. Dabei wurde der Einfluß von Temperatur und Konzentration auf Änderungen der Wärmekapazität untersucht. Fehler bei der einfachen Interpretation adiabatischer Daten wurden identifiziert und isotherme Wärmeflußkalorimetrie wurde angewendet, um autokatalytische Effekte aufzuzeigen, die sich anhand der adiabatischen Experimente nicht ersehen lassen. Es wurde eine gründlichere Interpretation adiabatischer und isothermer Daten umrissen und verwendet, um die Bedingungen vorherzusagen, die in einem Kesselreaktor zu einem exothermen Davonlaufen der Reaktion führen. Mathematische Simulation der Bedingungen in einem Mantelkessel wurde angewendet, um zu zeigen, von welch großer Bedeutung die Entwicklung zuverlässiger kinetischer Ausdrücke ist, bevor man die Sicherheit einer Reaktion in einem Kesselreaktor beurteilt.
Article PDF
Similar content being viewed by others
Explore related subjects
Discover the latest articles, news and stories from top researchers in related subjects.Avoid common mistakes on your manuscript.
Abbreviations
- A :
-
pre-exponential factor s−1
- E :
-
activation energy kJ·mol−1
- C p :
-
specific heat capacity of sample kJ·kg−1·K−1
- C pc :
-
specific heat capacity of sample container kJ·kg−1K−1
- C PP :
-
specific heat capacity of products kJ·kg−1·K−1
- C pr :
-
specific heat capacity of reactants kJ·kg−1·K−1
- k T :
-
reaction rate constant s−1
- n :
-
order of reaction
- m c :
-
mass of container kg
- m s :
-
mass of sample kg
- qg :
-
rate of heat generation kJ·s−1
- R :
-
universal gas constant kJ·mol−1·K−1
- S :
-
surface aream 2
- t :
-
time s
- t o :
-
onset time (isothermal data) s
- t f :
-
final time (isothermal data) s
- T :
-
temperature K
- T f :
-
final temperature (adiabatic data) K
- T i :
-
initial temperature (adiabatic data) K
- T j :
-
jacket temperature (isothermal data) K
- T r :
-
reactant temperature (isothermal data) K
- U :
-
heat transfer coefficient W·m −2·K−1
- x :
-
conversion (fraction of original substance converted to product)
- Δ T ad :
-
adiabatic temperature rise (instrumental) K
- ΔH:
-
heat of reaction kJ·kg−1
- Φ :
-
thermal dilution factor
- ad:
-
adiabatic
- is:
-
isothermal
References
D. T. Townsend and J. C. Tou, Thermochim. Acta, 37 (1980) 1.
R. L. Rogers, ‘The advantages and limitations of adiabatic dewar calorimetry in chemical hazard testing. International Symposium on Runaway Reactions’, AIChE, 1989, p. 281.
H. K. Fauske and J. C. Leung, Chemical Eng. Progress, 81 (1985) 39.
J. Singh, ‘PHI-TEC: Enhanced vent sizing calorimeter application and comparison with existing devices’, International Symposium on Runaway Reactions’, AIChE, 1989, p. 313.
R. Reisen and B. Grob, Swiss Chem., 7 (1985) 39.
Physical Properties Data Service, The Institute of Chemical Engineers, Rugby, UK.
T. Yvernault, Compt. Rend., 233 (1951) 411.
T. Yvernault, Compt. Rend., 235 (1952) 167.
J. M. Zaldivar, H. Hernandez and C. Barcons, ‘Development of a mathematical model and a numerical simulator for a reaction calorimeter. FISIM, RC1 version, Technical note No 1.90.109, Commission of the European Communities, Joint Research Centre, Ispra Italy, 1990.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Snee, T.J., Barcons, C., Hernández, H. et al. Characterisation of an exothermic reaction using adiabatic and isothermal calorimetry. Journal of Thermal Analysis 38, 2729–2747 (1992). https://doi.org/10.1007/BF01979748
Issue Date:
DOI: https://doi.org/10.1007/BF01979748