Periodic Open Cell Structures as a truly-engineered alternative to randomly packed catalytic bed

14.04.2021

-  Andrés Eduardo Aquino, Institute of Chemical Reaction Engineering, Hamburg University of Technology -

Experimental fixed bed reactors have seen little to no technological improvements since its first conceptualization. Most experimental reactors work on the same fundamental basis. In a typical laboratory fixed bed reactor the concentration of chemical species and temperature can be only measured at the inlet and outlet of the reactor, or in more sophisticated devices, in several discrete sampling points. Moreover most of industrial fixed bed reactors are randomly packed with catalyst pellets which does not offer a truly engineered approach with tailor-made flow properties. Within the I3 Lab “Smart Reactors” project we are working at the Institute of Chemical Reaction Engineering on the integration of two “state of the art” technologies. 

On one hand spatial profile reactors are a new development for in-situ measurements in laboratory/pilot scale reactors. The concept of spatial measurement refers to the measurement of the kinetically relevant variables within the reactor bed such as molar concentration of species or molar flow rates (Ci(z), ni(z)) and temperature in the fluid phase (Ti(z)) as a function of the spatial coordinate z. This technique was developed by Horn et.al [1]. On the other hand catalyst coated 3D printed Periodic Open Cells Structures (POCS) open the opportunity to easily modify the flow path through the structure to enhance the contact between chemicals and catalyst providing a tailor-made alternative to randomly packed beds.

The “first of its kind” liquid phase spatial profile reactor as shown in Figure 1 was successfully built and several measurements were conducted using as case of study the environmentally friendly liquid phase partial oxidation of propylene to propylene oxide with hydrogen peroxide over TS-1 catalyst [2]. 

The experiments were conducted at industrial conditions, that is, 30 bar and 40°C with conventional TS-1 pellets, which underlines the potential of the spatial sampling technique. A coating procedure was successfully tested and POCS were coated with TS-1 catalyst as shown in Figure 2. 

References

[1] Horn, Raimund, et al. "Reactor for in situ measurements of spatially resolved kinetic data in heterogeneous catalysis" Review of Scientific Instruments 81.6 (2010): 064102.

[2] Russo, V., et al. "Chemical and technical aspects of propene oxide production via hydrogen peroxide (HPPO process)" Industrial & Engineering Chemistry Research 52.3 (2013): 1168-1178.