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A novel procedure for the removal of carbonaceous deposits from zeolites using ozone-enriched oxygen is described. Pentasil zeolites (SiO,/Al,O, mole ratios 35, 70) were studied and deactivated using methanol conversion to hydrocarbons and o-xylene isomerisation. Low temperature ozone reactivation was found to restore the catalyst activity for these reactions and hence can be considered as an alternative procedure to high temperature oxygen reactivation currently utilised industrially. Ozone reactivation was found to increase slightly the catalyst lifetime and also to reduce the initial methane yield when compared with oxygen reactivation.

An investigation of the mechanism of the water-gas shift reaction over a cobalt-manganese oxide catalyst (Co : Mn = 1 : 1) is described using both kinetic and model reagent studies. The reaction of methanol, ethanol and formic acid are discussed, and these reagents are used as model reactants to probe the reaction mechanism. Based on these kinetic and model reactant studies a mechanism for the water-gas shift reaction is proposed for this catalyst system. It is considered that the mechanism proceeds according to the following steps : (i) water dissociatively adsorbs to form surface hydroxy and hydride species, (ii) subsequent CO adsorption and oxidative addition of the surface hydroxy species lead to the formation of a surface formate species, (iii) decomposition of the formate species via 8-elimination to give gas-phase CO, and surface hydride and (iv) combination of two surface hydride species giving gas-phase H,.

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