(308d) Microwave Assisted Catalytic Conversion of Ethane to Aromatics for a More Efficient Approach over a Conventional Fixed Bed Reactor

The mechanism of ethane dehydroaromatization over a 4%Mo-0.5%Fe/ZSM-5 catalyst was tested in a 6.650 GHz microwave fixed bed reactor (MW) and compared to a conventional fixed bed reactor (CFB). Over 80% ethane conversion was achieved under microwave irradiation at 375°C bulk temperature. The conventional fixed bed required a corresponding temperature of 660°C to achieve the same conversion as the microwave fixed bed reactor. The selectivity’s of the catalyst were compared after 10 minutes of time-on-stream where the conversion of ethane was the same and reactant stream concentrations were fully developed. The CFB had a higher selectivity to aromatics; however, the MW presented a selectivity to ethylene of 26.5% higher than the CFB. The MW high selectivity to ethylene suggest that the aromatization reaction was limited possibly do to ethylene’s inability to rapidly diffusion into the pores of the zeolite structure. This was attributed to the overall low bulk temperature of the catalyst bed or uneven heat distribution throughout the catalyst bed. TPO analysis of CFB showed three distinct orders of coke formation, whereas the microwave resulted in a single higher order temperature burring coke. Less total coke formation was observed on the MW spent catalyst, this was attributed to the low bulk temperature in the microwave which suppressed the formation of amorphous coke on the catalyst surface.