Oxidative dehydrogenation (ODH) of ethane with O₂ as oxidant on selected transition metal-loaded zeolites

Ni-, Cu-, and Fe-loaded acidic and basic Y zeolites were synthesized, and their catalytic properties for oxidative dehydrogenation of ethane (ODHE) to ethylene were characterized. Acidic Ni-loaded Y zeolite exhibits an ethylene productivity of up to 1.08 g_{C2 H4} g_cat^{- 1} h^{- 1} with a selectivity of ∼75%. Acidic Cu- and Fe-loaded Y zeolites have an ethylene productivity of up to 0.37 g_{C2 H4} g_cat^{- 1} h^{- 1} and a selectivity of ∼50%. For the same metal, the acidity of the zeolite favors both ODHE productivity and ethylene selectivity. Extended X-ray absorption fine structure (EXAFS) studies show that Ni, present in particles on Ni/HY during the ODHE catalytic process, contains both Ni-Ni and Ni-O bonds, and that the ratio of oxidized Ni versus metallic Ni increases with the temperature. The insights these studies provide into the ODHE reaction mechanism are discussed.