routes of APIs . In a hydrogenation , the molecule is reduced by gaseous hydrogen on a solid or dissolved heavy metal catalyst . This is a multiphase heterogeneous transformation , which is of high interest . 1 Gaseous hydrogen should be transported from the gas phase into the liquid reaction mass to the catalyst with a known and appropriate rate ( mass transport ). Hydrogenations are often highly exothermic and their selectivity depends on temperature . The released reaction energy must be transferred as efficiently as possible to the heating and cooling medium of the reactor ( heat transfer ) to control the temperature . Reactor geometry , chemical kinetics and process parameters have a direct influence on the effectiveness , efficiency and quality of the products . If hydrogenations are not performed properly , heavy metal may leak from the catalyst , temperature control may not be effective , side products may be formed or selectivity may be poor . The basis of the toolbox was a commercially available Dynochem model for hydrogenations . The model was improved and adjusted in a loop process ( Figure 2 ). To make smart lab experiments we constructed geometrical comparable stirrers and baffles for our standard lab reactors , so mixing properties , for example , could be described by fluid dynamic algorithms . Hydrogen transport ( mass transfer ) and heat transfer were evaluated at all reactor scales and built into mathematical equations . Digital twins of a lab and a 60 bar autoclave at 6,000L plant scale were created , based on experimental data . With the assistance of MiniPlant 4.0 , a consortium of Swiss companies and the FHNW that is dedicated to creating a platform for improved technology transfer from chemical development to industrial application , we even constructed a completely geometrically identical reactor at the FHNW . This can be used to improve and challenge the algorithms to be used on geometrically different multi-purpose equipment with are geometrical different . ( Within our project , we have also created a geometrically identical 1L autoclave with identical fluid dynamics and heat transfer properties . We had to find new ways to achieve this , by reducing the area available for heating and cooling to mimic the identical area-to-volume
Figure 2 - The life cycle of predictive models
16 SPECIALITY CHEMICALS MAGAZINE ESTABLISHED 1981