ANALYSIS OF TEMPERATURE-PROGRAMMED DESORPTION FROM POROUS CATALYSTS IN A FLOW SYSTEM

Publisher Website
Google Scholar
Abstract
A comparison is reported between experimental and simulation results obtained from temperature-programmed desorption (TPD) spectra for H2 and CO from Ni/SiO2 catalysts. The gas/solid system is selected as representative of these adsorbates interacting with a Group-VIII metal. Intraparticle concentration gadients can be minimized by using a bed of small porous catalyst particles perfused by a flow of carrier gas while under these conditions axial concentration gradients in the bed cannot be avoided. Previous models providing design criteria for analysis of TPD curves predict these conclusions, yet are overly restrictive. When allowance is made for repulsive interactions between adsorbates, it is found that significant redistribution of the adsorbate within the bed occurs. This results in nearly uniform adsorbed concentration profiles which are obtained when experimental conditions are selected properly. Consequently, specific guidelines can be offered to guide the experimentalist and methods are thus proposed to obtain TPD curves which are indicative of the desorption kinetics of the adsorbate.