Developing new compounds and transferring them to production requires us to understand the chemical route, process and parameters—the sooner, the better. When applied in the chemistry laboratory, established calorimetry technology provides critical information to develop safe and scalable processes on a milliliter scale. Reaction calorimetry is helping researchers adapt, giving them an ability to meet their goal of safer scale-up at the speed of modern manufacturing.
As nearly any researcher or engineer can tell you, when working to bring synthetic reactions to production scale, a thorough understanding of the properties of reactants and reaction mass is essential. Synthesis workstations are playing a growing role in gaining this critical information in many manufacturing scenarios. Good workstation designs tend to be compact, easy-to-use, and capable of providing reaction specifics such as start and end point as well as events such as induction, indication of power of the reaction and accumulation of reagents, precipitation and crystallization.
From these basics, a number of conclusions are typically drawn to identify and eliminate certain scalability risks. Broadly speaking, a given process can be determined “not critical,” “potentially critical,” and “highly critical” so Go/NoGo decisions can be made earlier. This saves time, eliminates reagent waste (as well as attendant disposal costs), and avoids detours in later process stages that can eat project budgets and keep products off the market longer than expected.
However, engineers involved in transferring processes from lab to plant also understand the importance of determining thermal risk. This includes delving into the hazardous potential of a chemical process more precisely, adequately evaluating it for: heat or mass transfer limitations; heat release patterns that don’t match heat removal capabilities; sub-optimal processing temperatures; dosing profiles that result in reactant accumulation; or issues such as spontaneous precipitation, fouling or viscosity changes.
This additional level of investigation can go a long way towards helping researchers and plant managers save money by allowing these issues to be solved during development rather than forcing the company to bear the costs of reworking an at-scale process—or worse yet, an accident. This is where reaction calorimetry comes in.
What is reaction calorimetry?
Reaction calorimetry helps researchers evaluate the chemical process and gain reliable information about non-scalable conditions and potential risks. It does so in a quantitative manner and can more accurately characterize chemical process criticality. Researchers gain important opportunities to make the reaction safer at scale.
Using a specially-designed workstation, researchers measure the heat released from a chemical reaction or physical process under process-like conditions, providing the reaction’s thermochemistry and kinetics fundamentals. From a single experiment, crucial information such as heat transfer, heat capacity and release rates as well as enthalpy and conversion can be derived. Subsequently, details such as accumulation of energy, adiabatic temperature increase (ΔTad)and maximum temperature of the synthesis reaction (MSTR) can be calculated.
Most importantly, this information can then be used to create a “Runaway and Criticality Graph” (Figures 1 and 2. This data essentially lets researcher see the accumulated energy related to a chemical reaction’s hazardous potential and describe the maximum reaction mass temperature increase in the event of cooling failure. Action can be taken to change the reaction or ensure that there are sufficient safety precautions in place to contain possible undesired secondary reactions. Combining the information about the desired reaction with the data of the undesired reaction allows creating the so-called criticality graph presenting the risks of a chemical process graphically.
The importance of reaction calorimetry
In the face of recent plant accidents in several countries with significant manufacturing bases, the importance of obtaining the type of information offered by reaction calorimetry cannot be underestimated. If a process is potentially subject to unreacted reagent accumulation, for example, reaction control may be lost in the event of a cooling failure. Of course, this worst-case scenario can lead to runaway—with dire consequences for the plant and even surrounding communities.