HYDRODENITROGENATION CATALYSIS STUDIED BY REVERSED-FLOW GAS-CHROMATOGRAPHY

Many important parameters of surface catalysed reactions can be determined simultaneously, under non-steady state conditions using Reversed-Flow Gas Chromatography. A simple, slightly modified gas chromatograph is required. The distorted diffusion bands, obtained experimentally for reactant and product(s), can be analysed mathematically, using simple PC programs, to give the pre-exponential factors and the exponential coefficients of a function consisting of the sum of two-four exponential functions of time. From these, and some geometrical and diffusional characteristics of the reaction cell, the values of adsorption, desorption and reaction rate constants, the overall mass transfer coefficients in the gas and in the solid catalyst, and the adsorption equilibrium constant, for both reactant and product(s) can be calculated. The above parameters were determined at various temperatures and over three catalysts for the hydrodenitrogenation of piperidine to n-pentane, an industrially important hydrotreating process. The results obtained can help to understand the mechanism of reactions on solid surfaces and to confirm experimentally theoretical calculations on adsorption and surface reactions.