Inorganic Functional Materials
Dr. Sebastian Wohlrab
- Fig.: Research areas for catalysts and membranes on the field of methane conditioning and conversion.
Selected examples for process-oriented materials development
LPG separation using zeolite membranes
A more sophisticated seeding technique for the generation of MFI membranes was developed for this process. Basically, MFI slurries are used for the activation of inert Al2O3 supports for heterogeneous crystallization. The resulting MFI seed layer acts both as heterogeneous nucleation side and as flexible distance holder between support and MFI membrane suppressing defect formations during thermal template removal. Currently, the separation of natural gas is investigated under realistic process conditions using such mechanically stabilized membranes.
Oxygen removal from biogas
Methane from biogas contains typically up to 5000 ppm (0.5 %) oxygen. However, distinct lower values are permitted when supplying into the gas grid. In order to improve the quality of biomethane the newest project of our group is about materials development for the reduction of oxygen in biomethane. Therefore, mainly process-adapted reduction catalysts as well as novel inorganic absorbents are in development. In case of success a technology for the removal of oxygen to concentrations below 10 ppm should be available.
Membrane reactors for the production of syngas
Perovskite membranes can be used for the production of pure oxygen. Ionic conduction via the oxygen lattice of the perovskite is used for a high selective separation of the oxygen from the air feed. An interesting application of this property is the usage of enriched oxygen in the permeate room of such a perovskite membrane for chemical reactions. Membrane reactors were developed for the partial oxidation of methane to syngas. Furthermore, stable perovskites against carbon dioxide and derived membranes are in the focus of our research. Currently perovskite membranes for the selective oxidation of methane are under investigation.
Selective oxidation catalysts for the conversion of methane
The influence of the nature of support materials on the catalytic performance of VOx is currently investigated. Especially, the almost catalytically unexplored nanoporous glasses can be synthesized with a narrow pore size distribution and with pore sizes ranging from 1 to 1000 nm. Pore volumes between 0.1 and 1.1 cm3/g and inner surfaces up to 500 m2/g can be provided in such materials. The broad flexibility in the geometric properties makes such materials promising candidates for the application as improved support materials. The suppression of overoxidation during an oxidative conversion of methane can be optimized while supporting in restrictive reaction rooms is required.
