Catalytic cracking of hydrocarbons in a novel Riser Simulator: Lump adsorption parameters under reaction conditions

Diffusion and adsorption selectivities of hydrocarbons over FCC catalysts

“…More pronounced, similar trends are shown by the apparent selectivities. Usually diffusion effects are not considered in the evaluation of adsorption parameters in the laboratory; for example, the assessment of Henry constants under reaction conditions was performed with data gathered at very short contact times, assuming that equilibrium is reached and that it is not affected by diffusion [36]. Also, the effect of concentration, that is, the Catoil ratio, on diffusion and adsorption in FCC catalysts has not been investigated.…”

Use of stirred batch reactors for the assessment of adsorption constants in porous solid catalysts with simultaneous diffusion and reaction. Theoretical analysis

“…To simplify the analysis, it is common to assume that the chemical reaction and the diffusive transport processes do not influence the amount of reactants adsorbed in the solid (e.g. Pruski et al, 1996). Nevertheless, in reacting systems where the molecular size of reactants or products is close to the size of the catalyst pores (for example, when molecular sieves are used), it is to be expected that diffusion plays a key role.…”

Kinetic and decay cracking model for a MicroDowner unit

“…This model involves a two-parameter function, which allows a very practical empirical representation of experimental data, but it is not well suited for comparing deactivation in different bench scale units where catalyst time-on-stream may be very different. There is another approach to catalyst deactivation, which assumes that poisoning is only due to coke deposited on the catalyst [13,15,17]. However, it should be taken into account that coke is not a very well defined component, and the chemistry of coke formation is complex.…”

“…Moreover, this task is hindered because of the very fast deactivation of the catalyst, which is very high with respect to the time scale of the process. Various models have been used to describe the deactivation in laboratory units like Microactivity Test (MAT) [10][11][12][13], fluidized beds [14], microriser [15], and recycle reactor [16,17]. The time-on-stream (TOS) model [10], which is widely used for fitting MAT data, represents catalyst activity as a function of time-on-stream.…”