High-resolution 1H nuclear magnetic resonance study of hydrogen sulphide adsorption on heterogeneous catalysts

Abstract

Solid-state high-resolution ¹H n.m.r. spectra of H₂S adsorbed on Al₂O₃, NaOH/Al₂O₃, K₂CO₃/Al₂O₃, HF/Al₂O₃, H₃PO₄/SiO₂, K₂CO₃/SiO₂ catalysts and NaX, NaY, H-ZSM-5 zeolites have been studied.

The dissociative H₂S adsorption on Al₂O₃, and Al₂O₃ modified with KOH, K₂CO₃ and HF as well as on zeolite catalysts was found as indicated by the lines from SH^– species at –1.6 to –2.0 ppm for Al₂O₃, modified Al₂O₃ and ZSM-5, and at –3.7 to –4.3 ppm for NaX, NaY zeolites. H₂S adsorbed without dissociation, giving a line at 1.2–1.8 ppm, was observed at increased surface coverage. For Al₂O₃, modified Al₂O₃, K₂CO₃/SiO₂ and H-ZSM-5 the dissociative adsorption occurred on the coordinatively unsaturated Al sites while Na⁺ cations in the zeolite cavities of NaX and NaY zeolites are responsible for H₂S dissociation. Only physically adsorbed H₂S was observed on H₃PO₄/SiO₂ catalyst.