Enhancement of ethylene production by alkali metal doping of MoVSb mixed oxide catalyst for ethane oxidative dehydrogenation

Hydrothermally prepared Mo-V-Sb mixed oxides doped with alkali metal cations (Li+, Na+, K+, Rb+, or Cs+) show a significantly improved catalytic behavior in the oxidative dehydrogenation of ethane (ODH) compared to conventional alkali metal-free MoVSbO catalysts. Initial selectivity to ethylene above 95 % was held up to 20 % of ethane conversion for all alkali metal promoted MoVSbO catalysts, as well as lower ethylene overoxidation at higher ethane conversion, with differences depending on the alkali metal employed. Thus, from Li to K, the enhanced catalytic performance follows a bottom-up trend as increasing the size of the cation. An intermediate behavior is observed though for the catalyst doped with Cs cations, with the highest atomic radius. The K-doped MoVSbO catalyst is the least prone to both ethane total oxidation and ethylene overoxidation, which enables up to 90 % selectivity to ethylene at ethane conversion higher than 65 %.

Automated summary

Hydrothermally prepared Mo-V-Sb mixed oxides doped with alkali metal cations (Li+, Na+, K+, Rb+, or Cs+) exhibit enhanced catalytic performance in the oxidative dehydrogenation of ethane compared to alkali metal-free MoVSbO catalysts. The selectivity to ethylene is maintained above 95% at up to 20% ethane conversion for all alkali metal promoted catalysts, with lower ethylene overoxidation observed at higher ethane conversion, depending on the alkali metal used. Among the catalysts, the K-doped MoVSbO catalyst shows the least susceptibility to both ethane total oxidation and ethylene overoxidation, achieving 90% selectivity to ethylene at ethane conversion higher than 65%.