Kinetic analysis of temperature-programmed desorption Original Research Article

In this work, a procedure to analyse temperature-programmed desorption (TPD) data is introduced and it is applied to the thermal desorption of hydrogen from a supported nickel catalyst. The procedure is established on general transient kinetic methodology and model fitting to experimental TPD data. Surface heterogeneity of the catalyst is accounted for by introducing sufficient number of different adsorption states into the model. The rapid readsorption occurring in the system is considered by describing the intrinsic dynamics of an adsorption state as a quasi-equilibrium adsorption/desorption between the gas phase and the surface.H2-TPD from a commercial alumina-supported nickel was used as a test case for the analysis procedure. One objective was to obtain information relevant to a catalytic hydrogenation reaction on this catalyst. In addition to H2-TPD, the adsorptive properties of the catalyst were characterised by static hydrogen chemisorption and dynamic pulse chemisorption experiments. The model with two-adsorption states was able to describe the TPD experiments in the temperature range 323–673 K. The estimated adsorption equilibrium and capacity values were of physically meaningful order of magnitude.