Scheme 2. Proposed Catalytic Cycle for C₄H₈O Ring-Opening with CH₃OH in CH₃CN Solvent Over Zr-BEA Zeolites.

We expect an identical set of steps over the Al-BEA materials, although the structure of the intermediates differs due to proton transfer to the reactive species. All adsorption steps are currently assumed as reversible. Steps to form 1M2B and 2M1B are denoted as ¹C or ²C, to signify nucleophilic attack on the primary and secondary carbons in the epoxide ring, respectively. For brevity, we do not show the reversible adsorption of CH₃CN molecules (step 1) in this cycle. We portray only reactions with molecularly adsorbed CH₃OH and C₄H₈O and not dissociatively bound oxygenates, although we expect each scenario may occur.