ADSORPTION AND SURFACE-CHEMISTRY OF LIGHT THIOLS ON NA-ZSM5 AND H-ZSM5

The adsorption of ethanethiol and n-butanethiol on H-ZSM5, Na-ZSM5, and SiO2 was investigated by means of IR spectroscopy and thermogravimetry. The stoichiometry at the adsorption sites and the surface chemistry for equilibrium pressures from 10(-5) to 1 mbar was determined. At equilibrium pressures below 10(-2) mbar, ethane- and butanethiol were found to adsorb on H-ZSM5 in three forms. Two of the structures are due to hydrogen-bonded thiol molecules and one due to protonated. On the alkali-metal-exchanged forms of ZSM5 the thiols adsorbed coordinatively via the sulfur atom. For butanethiol on Na-ZSM5, partial dissociation and the formation of new OH groups was observed.