Applications of new high resolution evolved gas analysis systems for the characterisation of catalysts using rate-controlled thermal analysis

The advantages of using rate-controlled thermal analysis (RCTA) methods in the thermal characterisation of catalysts are described, The use of these methods is demonstrated by the temperature programmed reduction of vanadium pentoxide, the measurement of the number and type of acid sites in clays by temperature programmed desorption of cyclohexylamine, and temperature programmed reaction, which is illustrated by the dehydration of propan-2-ol over an acid-activated montmorillonite clay. It is shown that the new system has advantages in the study of the kinetics of reactions and in improving resolution when used to characterise the thermal decomposition of catalyst precursors. New evolved-gas analysis systems for characterising heterogeneous catalysts are described, in which a variety of RCTA methods is used. The systems are computer-controlled and use a variety of furnaces, permitting samples from a few microgrammes to fifty milligrammes to be studied, under pressures ranging from ultra high vacuum to one atmosphere. The furnace chosen for a particular experiment is linked to one of a number of gas detectors (hygrometers, katharometers and mass spectrometers), the output of which completes the control loop. The most important component of the system is the versatile software which supports a range of RCTA modes, including conventional linear heating rate, constant reaction rate, and other control strategies developed in this work.