Regeneration of coked catalysts—modelling and verification of coke burn-off in single particles and fixed bed reactors

Abstract

The regeneration of a coked naphtha reforming catalyst (Pt/Re– Al 2 O 3 ) was studied by kinetic investigations on the effective rate of coke burn-off. For temperatures of industrial relevance for the catalyst, i.e., below 550 ∘ C (deactivation), the coke burn-off within the cylindrical particles ( d P ≈ 2 mm ) is determined by the interplay of chemical reaction and pore diffusion; limitation by external mass transfer can be excluded for T < 750 ∘ C . Based on the parameters of the intrinsic kinetics and of the structure of the catalyst (porosity, tortuosity), the regeneration process is modelled and discussed both on the level of a single particle and in a technical fixed bed reactor. The results of modelling are compared with data from lab-scale investigations (coke profiles within the particles) and the performance data of the regeneration in an industrial fixed bed reactor (moving reaction zone); the agreement of calculation and measurement is in both cases complete.