Evaluation of 1,3-butadiene dimerization and secondary reactions in the presence and absence of oxygen.

Thermal stability evaluation of exothermic chemical reactions is of great importance to the safer design and operation of chemical processes. Dominant reaction stoichiometries and their thermochemistry parameters are key elements in the evaluation process. Identification of significant reaction pathways under possible process conditions will lead to an understanding of the overall thermodynamic and kinetic behavior. The kinetics of 1,3-butadiene (BD) is an excellent example of conjugated dienes that undergo addition reactions. At elevated temperatures, 1,3-butadiene monomers can dimerize exothermally, and as temperature increases, secondary exothermic reactions will take place. The very high temperature and pressure rates that these reactions can attain may lead to a reaction runaway or even a thermal explosion. BD is a vapor at ambient conditions, usually stored as a pressurized liquid, and is a carcinogen, so the experimental evaluation is potentially difficult and hazardous. In this paper, the thermal stability of BD is evaluated. Dimerization and other secondary reactions are investigated by experimental thermal analysis using an automatic pressure adiabatic calorimeter (APTAC), by theoretical computational quantum chemistry methods, and empirical thermodynamic-energy correlations. A theoretical approach is conducted to predict some of the BD reaction behavior. Results are compared to other literature data obtained using different experimental methods.

Evaluation of styrene-acrylonitrile copolymerization thermal stability and runaway behavior.

Evaluation of thermal stability and runaway behavior of any exothermic chemical system is of great importance for the design and operation of a chemical process. The evaluation process should be based on a thorough investigation of the reaction chemistry including reaction pathways, thermodynamic, and kinetic parameters. When addressing the reactivity hazards of any reacting system, the dominant pathway(s) should be identified. Identifying the main reaction pathway under specific conditions will lead to a better thermodynamic and kinetic characterization of the reacting system. In this article, the thermal stability and runaway behavior of styrene-acrylonitrile copolymerization reaction system in bulk is evaluated. Traditional thermal analysis techniques (calorimetric analysis) are combined with computational quantum chemistry methods and empirical thermodynamic-energy correlations. Reaction pathways are identified from the theoretical approach and verified by experimental measurements. The results of this analysis are compared to literature data for this system.