fig1

Figure 1. (A) ¹H NMR spectra under magic-angle spinning of (i) thermally activated ZSM-5, (ii) protonated and (iii) deuterated ASA: as-prepared catalyst (red line) and after H/D exchange with benzene (dashed blue line). The shaded spectra correspond to the NMR spectra of protons close to Al atoms, i.e., BAS. It was obtained as the difference between ¹H NMR spectra recorded with and without the recoupling of ¹H-²⁷Al dipolar interactions; (B) Solid-state NMR measurement of ¹H-²⁷Al distances for (i and ii) BAS and (iii and iv) other silanol groups in (i and iii) thermally activated ZSM-5 and (ii and iv) partially deuterated ASA. Reprinted with permission from Ref.^[17]. Copyright 2023, Royal Chemical Society. NMR: Nuclear magnetic resonance; ASA: amorphous silica-alumina; BAS: Brønsted acid sites.