Study of zeolite acidity by broad-line

Simulation of 4K broad-line 1H NMR spectra of solids, with Brönsted acid properties and loaded with known amounts of water, allows the determination of the concentrations of the species: H3O+, H2O...HO and of the remaining initial species: OH and H2O. This is an original method for studying the acid strength of solids. The following results concern HY zeolite taken as example. A parallel study using 1H HR-NMR (MAS) at ambient temperature confirms the results obtained by using both methods on HZSM-5 (1)

Disposal of CCl4 by disproportionation reaction with CH4

A method for disposal of ozone-depleting CCI4 by disproportionation reaction with CH4 to produce CH3Cl and CHCl3 has been investigated over various platinum-based catalysts. The catalysts were supported mainly on SiO2 and MgO and also modified by the addition of manganese to improve the catalyst lifetime. Platinumbased catalysts supported on SiO2, MgO, and MgAl2O4 showed stable activity and high selectivity to CH3CI at 730 K during the reaction time of 40 h. However, large amounts of carbon deposition as well as transformation of the supports to chlorinated forms were observed and resulted in catalyst deactivation during operation for longer periods. The catalysts modified with manganese have shown an enhancement of catalytic stability and selectivity to CH3CI. Furthermore, addition of a moderate amount of molecular oxygen (mole ratio Of O-2/CCl4 > 0.6) during the reaction over Mn-modified catalysts resulted in the efficient removal of deposited carbon and also the enhancement of selectivity to CH3CI-close3