Fig. 3

The MS spectra of short-lived cationic species. Short-chain alcohols dehydration was performed on acidic zeolites: H-Beta with methanol (a), and H-ZSM5 with methanol (b), ethanol (c), isopropanol (d), butanol (e), and pentanol (f). The mass range 160–180 was enlarged and put on top of the figures with elemental compositions of the main peaks (red). Alcohols were injected at 10 μL/s and the reaction temperature was kept at 623 K. The resolution was set as 30,000 for full MS scans. [2MH]⁺, [2MH-H₂O]⁺, and [MH-H₂O]⁺ were protonated dimer, dehydrated dimer, and dehydrated monomer of the reacted alcohol