Anwendung der Deoxydehydratisierung für die stoffliche Nutzung von Nachwachsenden Rohstoffen
- Application of the deoxydehydration for the utilization of renewable resources
Sandbrink, Lennart; Palkovits, Regina (Thesis advisor); Liauw, Marcel (Thesis advisor)
Dissertation / PhD Thesis
Dissertation, RWTH Aachen, 2016
The application of the deoxydehydration (DODH) for the conversion of biomass based substrates was investigated in terms of an industrial utilization of this reaction class. As alternative to the currently predominant closed reaction system a sparging gas reactor was identified, which offers a higher activity, selectivity and stability for homogeneous rhenium catalysts. Subsequently solid rhenium based supported catalysts were developed and examined towards activity and stability. Catalysts with oxidic support materials showed comparable activities to homogeneous reference catalysts, which could even be exceeded by utilizing activated carbons as catalyst support. Through a postsynthetic reduction step, the stability of the catalysts were improved. The highest stability was observed for ReOx/TiO2,which showed constant activity and selectivity over seven consecutive runs. For the active catalysts the rhenium composition was determined to be approximately Re(0):Re(IV):Re(VII) = 1:1:2. The developed heterogeneous catalysts were applied in a continuously run fixed bed reactor for the first time. In contrast to the batch experiments, a moderate deactivation was observed over long time on streams, which could be attributed to multiple deactivation mechanisms. Through adjustments of the reaction parameters the deactivation could be reduced and the efficiency could be increased fourfold.