Shallow-bed reactor design for the autothermal oxidative dehydrogenation of ethane over MoVTeNbOx catalysts

We use a cell model with eggshell type catalyst particles to present a comprehensive ignition-extinction analysis of the oxidative dehydrogenation of ethane (ODHE) in autothermal operation. Our results reveal that external mass transfer could increase the ratio of ethane to oxygen on the catalyst surface, improving ethylene selectivity but decreasing ethane conversion. We show that ethylene selectivity is reduced, and a smaller region of multiplicity exists when diffusional limitations exist in the catalyst, which highlights the need for eggshell particles with a thin active layer. We also examine the impact of ethane to oxygen ratio, space time, catalyst particle size, and active layer thickness on the ignition and extinction behavior. A multi-layered bed with eggshell catalyst particles is proposed to optimize oxygen conversion and ethylene selectivity. Our results indicate the possibility of autothermal operation of the ODHE process with much higher productivity compared to traditional multi-tubular reactors.