AN UP-TO-DATE AUTOMATED INSTRUMENT FOR THE CHARACTERIZATION OF MICROPOROUS MESOPOROUS SOLIDS/

A high vacuum gravimetric system for measuring adsorption and desorpti on processes is presented. The system has been constructed using the n ewest technology, both with regard to the instrument hardware and soft ware. This provides a system working over a wide pressure range, able to implement small pressure steps and monitor small weight changes, al l continuously under the control of a computer through a modern graphi cal user-interface. The use of a microbalance allows measurements from gases and liquids with saturation pressures as low as 1 mbar. Great f lexibility of the system has been maintained, both in terms of the har dware and the software, allowing easy reconfiguration to the special r equirements of the particular experiment. An example is the availabili ty of a Fourier transform infrared (FTIR) instrument which allows the simultaneous generation of IR spectra of the adsorbed surfaces species under the same pressure and temperature conditions as the isotherm de velops. The function of the system is illustrated with the results fro m the measurement of adsorption/desorption isotherms of cyclopentane o n a variety of very different adsorbents, including nonporous, micropo rous, and mesoporous solid oxides. (C) 1997 American Institute of Phys ics.