Deactivation and Regeneration of a Reforming Catalyst

Coke formation is the main reason for catalyst deactivation in catalytic reforming but also in other refinery and petrochemical processes, for example, during catalytic cracking of vacuum gasoil or hydrodesulfurization. The regeneration is conducted in fixed beds by carefully adding small amounts of O2 in N2 at about 400-530 °C. 

Temperatures higher than 550 °C must be avoided as the reforming catalyst loses surface (sintering) and mechanical resistance above 550 °C (Le Page, 1978). The first reactor usually contains about 3 wt% coke and less than 1 wt% after regeneration. The coke content increases in the direction of flow as the content of aromatics (coke precursors) increase. In the last reactor, a content of 20% coke may be reached prior to regeneration. 

1 Coke Burn-Off within a Single Catalyst Particle 

To understand and to model coke burn-off within a single particle the intrinsic kinetics (without any resistance by diffusion), mass transfer by pore diffusion and external diffusion, and structural parameters of the catalyst have to be taken into account. 

Intrinsic Kinetics of Coke Burn-Off The intrinsic kinetics of deactivation and regeneration of a reforming catalyst have been studied by Kern et al. (Kern, 2003 Kem and Jess, 2005 Ren et al., 2002). The main results are  

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