CATALYTIC PYROLYSIS-GAS CHROMATOGRAPHY

A new technique which allows the rapid catalytic testing of a small amount of solid (3-10 mg) has been developed and tested on standard ethylbenzene 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 chromatograph. Test results with H+-ZSM-5 zeolite, as the fixed bed, obtained under different experimental conditions of flow rate and amount of catalyst, show that data can be evaluated and compared with standard methods, provided they are referred to the same space velocity. All other standard catalytic characterisation parameters (temperature, conversion, selectivity, including estimates of the difference between the activation 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, ethylbenzene). Since a small concentration of ethylbenzene with respect to the zeolite is required for each test, coking phenomena (which reduce the catalyst activity) cannot be observed.