Small benchtop reactors are a very powerful tool at this stage. On the one hand, their small footprint means that various reactors can be operated in smaller spaces, diminishing potential variation. Additionally, their smaller size means that smaller quantities of chemicals are needed, decreasing the costs of this phase. Automated parallel reactors reduce the potential for human error, thus increasing the reliability of the data obtained.
3. Raw material and product handling
During the first stages of the process development pipeline, high-purity reactants are routinely used. This allows for the characterization of the chemical reaction and the mechanisms that control it. However, high-purity reactants are costly and not viable at a larger scale. Using lower purity reactants can bring some issues into the pipeline, first and foremost, the reduction of the efficiency of the process. Additionally, some of the potential substances that the raw material contains can result in additional reactions. This can be a particular issue when storing either raw materials or by-products. These chemicals might be susceptible to decomposition reactions, which can have some intrinsic risks.
Different raw materials can be tested using lab-bench reactors, allowing for the interpolation and extrapolation of yields after a thorough characterization of the material used in the reaction. Secondly, using smaller quantities can reduce potential risks, as the heat released during decomposition scales up with the amount of material.
4. Safety considerations
The majority of chemical reactions used in industry are exothermic. This means that heat is released into the system as the chemical reaction progresses. The main consequence is the increase of the temperature inside the vessel. Thermal runaway processes can occur if the chemical reaction rate increases as the temperature rises. These are characterized by their positive feedback loop behavior: the higher the temperature, the more energy is released, and so on. As mentioned in the previous section, the amount of heat generated by reactions is proportional to the amount of mass.
Testing for safety in smaller vessels has a number of advantages, some of them mentioned in this blog post (e.g. cost reduction). Additionally, small volumes have a larger exchange surface, which allows for quicker heat exchange with the surroundings, and thus, the temperature inside of the vessel does not reach dangerous levels. However, this might be a downfall, as it would not replicate the conditions that could occur at larger scales, as larger vessels are not as efficient at dissipating heat. This is when the phi factor is fundamental, allowing for the correction of this value.
5. Pilot testing
Transitioning to industrial scale is always a giant step that can come with great benefits. Nevertheless, if the scale-up process is not performed appropriately, it can create significant costs and delays. One of the main issues that larger vessels have is that the control capacities inside reactors containing thousands of liters are not as efficient as in small volumes.
Small and medium size pilot testing experiments offer better controlled environments, allowing for fine-tuning of the process parameters and a better understanding of the process. This information is fundamental for the effective design of the reactor and optimization of the operation methodologies.
Bridging the benchtop to industrial transition