Assessment of the Reaction Location of Skeletal 1‑Butene Isomerization over Ferrierite

The pore accessibility of fresh and spent ferrierite (FER) during skeletal 1-butene isomerization is assessed via probe molecule adsorption. Argon and nitrogen adsorption isotherms demonstrate that micropores become inaccessible within 24 h. Despite this, the catalyst remains active over 200 h and the yield of iso-butene continues to increase during the initial 100 h. Butene and toluene adsorption isotherms show that only small, linear hydrocarbons (kinetic diameter <5 Å) can enter the catalyst pore network. Hence, the pore size of FER is vital for this reaction due to the immobilization of catalytically active carbonaceous deposits at the pore mouths rather than shape selectivity