Effect of deposited coke profiles on transient temperatures during regeneration of a fixed bed catalytic reactor

Regeneration of Fixed-Bed Catalytic Reactors Deactivated by Coke: Influence of Operating Conditions and of Different Pretreatments of the Coke Deposits

“…An increase in the total gas flowrate would be expected to lower the external mass-transfer resistance, thus increasing the reaction rate. However, under the conditions used in this work, the process is controlled by the intraparticle diffusion resistance (Byrne et al, 1986), which makes this effect negligible. It must also be taken into account that, for a given oxygen concentration in the feed, an increase in the total gas flowrate would increase the amount of oxygen fed to the reactor (and, therefore, the amount of oxygen reacted on the whole of the catalyst bed).…”

“…The main concern during oxidative regeneration is the possibility of large temperature rises caused by the exothermic combustion of the coke deposits (around 108 kcal/mol of coke if a composition of CH 0.5 is taken as representative and combustion to CO 2 and H 2 O is assumed). When the coke-forming reaction is carried out in a fixed-bed reactor, an in situ regeneration gives rise to a high-temperature front that moves along the bed as the coke deposits are burnt off (e.g., Byrne et al, 1986;Brito et al, 1993;Royo et al, 1994). The maximum temperature within this high-temperature front must be limited in order to avoid catalyst sintering, damage to the reaction equipment, and unsafe operation conditions.…”

Catalyst sintering in fixed‐bed reactors: Deactivation rate and thermal history

“…each of the thermocouples reached its maximum temperature. A high-temperature wave progresses along the bed as time increases, corresponding to the displacement of the reaction zone where most of the oxygen input to the reactor is consumed (Byrne et al, 1986). Figure 3 shows the thermal history for different reactor regions during two full cycles (operation-coking and regeneration).…”

Modelling of butene‐1 dehydrogenation in a fixed bed reactor — bed and pellet profiles

“…However, with the development of a noninvasive technique using the differential attenuation that a neutron beam undergoes as it passes through different points in a coked fixed bed reactor, the experimental determination of coke profiles in such a reactor is possible without destroying the integrity of the reactor. This technique developed by Byrne et al (1985) has been extensively studied for coking both by series and parallel processes (Byrne et al, 1986).…”