CATALYTIC PYROLYSIS-GAS CHROMATOGRAPHY

A new technique which allows the rapid catalytic testing of a small am ount of solid (3-10 mg) has been developed and tested on standard ethy lbenzene dealkylation and disproportion reactions in mid-pore zeolites . It consists of an adaptation of a commercial pyrolyser, to function as a fixed bed catalytic reactor, connected on line to a gas chromatog raph. Test results with H+-ZSM-5 zeolite, as the fixed bed, obtained u nder different experimental conditions of flow rate and amount of cata lyst, show that data can be evaluated and compared with standard metho ds, provided they are referred to the same space velocity. All other s tandard catalytic characterisation parameters (temperature, conversion , selectivity, including estimates of the difference between the activ ation energies of different catalysts) can also be extracted directly. The exception is TOS (time on stream)which can be measured indirectly after injecting an excess of volatile organic reactant (here, ethylbe nzene). Since a small concentration of ethylbenzene with respect to th e zeolite is required for each test, coking phenomena (which reduce th e catalyst activity) cannot be observed.