Chemical process intensification

Handling reagent-sensitive reactions:

Reagent precipitation (process limitation) or side-product formation (selectivity loss) at high concentration require high dilution conditions. This implies the need for large reactor vessels, large volumes of solvent for the production of little amount of desired product. The patented concept of Volume Intensified Dilution (VITO-VID®) was developed in first instance for the pharmaceutical industry in the production of macrocyclic molecules (similar products were observed in the fragrances industry) and allows the simulation of diluted conditions, by continuous solvent recycle to a reagent mixing tank and controlled reagent addition from the mixing to the reaction tank, with following advantages:

• > 85 % reduction of solvent use which significantly decreases process mass intensity (PMI)
• Increase in product selectivity (some cases 50 % gain) and possibility to have continuous product isolation by adapted operation

Homogeneous catalyst recycle:

The use of homogeneous catalysts avoids limitation in reagent supply to catalytic active sites, resulting in higher turnovers. However, these are applied in batch processes, mostly based on noble metals and require adequate recovery. The heterogenisation of such catalysts can be applied to ensure easy catalyst recovery after reaction and compatibity to continuous operation modes. However lower activities can be obtained and activity loss by catalyst leaching cannot always be avoided. Coupling of membrane filtration for recovery of expensive homogeneous catalyst can be a good compromise for applications in the fine chemical industry, via different strategies:  

• Low catalyst stability: consecutive batch reaction and separation within the same reactor vessel at room temperature allows maximal catalyst lifetime and recovery
• High catalyst stability: in-situ catalyst recovery allows operation in continuous or fed-batch mode and increased productivities with the same reactor vessel

Compatible membrane separation process:

In contrast to distillation and extraction, adequate membrane technology can be operated at given reaction conditions as applied in the conversion tank. A broad range of ceramic and polymeric-based membrane modules and GMP/ATEX equipment are commercially available for such application. Membrane-based separation is a mature technology and equipment can easily be coupled to existing tank reactors.