Applications of Fourier Transform Infrared Spectroscopy to in Situ Catalyst Surface Studies

摘要

Fourier transform infrared spectroscopy (FTIR) is a powerful tool for studying surface species present on supported catalysts during normal reaction conditions of high temperature and/or pressure. A special high-throughput optical bench has been used to optimize the sensitivity of this system for high optical density catalyst samples. The infrared cell is designed to operate at high vacuum for adsorption studies or as a recycle-flow reactor. Improvements in spectral subtractions have been obtained by the precise repositioning of samples in the ir beam. The enhanced performance resulting from these modifications has been instrumental in improving the sensitivity for infrared surface studies of the reactions C sub 6 H sub 6 + 3H sub 2 reversible C sub 6 H sub 12 and 2CO + O sub 2 implies 2CO sub 2 over a Pt/Al sub 2 O sub 3 catalyst. The bonding and geometry of benzene chemisorbed on the Pt surface have been determined from the infrared spectra. Simultaneous reaction rate and surface coverage measurements have also been made during CO oxidation on Pt/Al sub 2 O sub 3 . Hysteresis effects in both reaction rate and CO surface coverage are observed. The ir spectra indicate that islands of CO form on the Pt surface during reaction. (ERA citation 81:025982)