Design of a Transmission IR Cell for the High-Temperature Study of Transient Adsorption and Reaction in a Flow System

Abstract

Acquisition of adsorbate spectra under transient conditions at moderate temperatures and pressures with catalytic solids which adsorb strongly at IR wavelengths requires a carefully conceived cell design. A temperature-controlled, heated block cell with a built-in preheating coil, designed to permit in situ pressing of the catalyst wafers, was designed and built to meet these requirements. Measurements of CO oxidation on a CuO/silica catalyst employing step changes of O2 and CO partial pressures were conducted with the cell mounted in a Bomem FT-IR spectrophotometer, Model DA3.02. A time resolution of about 10 s was achieved with the use of a wafer of millimeter dimension, atmospheric pressure, and temperatures up to 260°C. Significant quantities of unreactive CO were found on the CuO surface.