Publication Details (including relevant citation information):
Organic Process Research & Development, 2010, 14, 524-536
An enhanced small-scale reaction calorimeter has been built for nonisothermal applications. Its unique design, combining compensation heater and heat flow sensors together with a solid intermediate thermostat is particularly suited for data oriented process development (determination of chemical reaction parameters, i.e. rate constants, reaction enthalpies, and reaction monitoring with optional in situ devices) in a wide range of applications in chemical and life-science oriented industries. The performance of the calorimeter is successfully demonstrated for kinetic investigation under nonisothermal conditions. Three different methods for determining the time-resolved reaction heat have been tested. The first is based on the traditional heat balance, the second on the twin principle, while the third is a novel method based on a rigourous heat flow modelling using mathematical finite methods. As a case study, we investigated the esterification of n-butanol with acetic anhydride catalysed by tetramethylguanidine using a temperature ramp from 30 to 80 degrees C. Each method accounts differently for the dynamics and the heat accumulation in the system. However, all three methods show minor differences in the resulting kinetic parameters and reaction enthalpies. In this temperature range, kinetic and mechanistic analysis resolved two competitive parallel catalytic and noncatalytic steps.
Address (URL): http://pubs.acs.org/doi/abs/10.1021/op900298x