Kinetic Modeling of Catalytic Cracking of Gas Oil Feedstocks:  Reaction and Diffusion Phenomena

Abstract

Catalytic cracking experiments of vacuum gas oil on fluid catalytic cracking (FCC)-type catalysts are carried out in a fluidized bench-scale batch Chemical Reactor Engineering Centre (CREC) riser simulator reactor. These experiments are conducted under operating conditions similar to those of the industrial FCC process in terms of temperature, catalyst-to-oil ratio, partial pressure of reactant and products, and reaction times. The crystallite size of the supported zeolite is varied between 0.4 and 0.9 microns with both activity and selectivity being monitored. A five-lump kinetic model describing the catalytic cracking of vacuum gas oil is considered, which accounts for diffusional constraints experienced by hydrocarbon species while evolving in the zeolite pore network. This study provides insights into the effect of intracrystalline diffusion in the catalytic cracking of heavy feedstocks. Results show that the catalyst with the smaller crystallite size provides higher activity and selectivity for desirable intermediate products (gasoline) and lower selectivity for terminal products (coke).

Heterogeneous Catalytic Oxidation by MFU‐1: A Cobalt(II)‐Containing Metal–Organic Framework

“…Both external mass transfer (rate of transport to the outer surface) and internal mass transfer (rate of intracrystalline transport) increase in importance with increasing particle size. [27,28] It is often observed in zeolite catalysis that the internal mass transfer is the rate-determining step. [28] Therefore, initial reaction rates with respect to catalyst loading were determined for crystals obtained from solvothermal and microwave synthesis ( Figure 5).…”

“…[27,28] It is often observed in zeolite catalysis that the internal mass transfer is the rate-determining step. [28] Therefore, initial reaction rates with respect to catalyst loading were determined for crystals obtained from solvothermal and microwave synthesis ( Figure 5). …”

Heterogene Oxidationskatalyse durch MFU‐1, eine Cobalt(II)‐haltige Metall‐organische Gerüststruktur

“…Sowohl Filmdiffusion (Geschwindigkeit des Transports zur äußeren Oberfläche) als auch Porendiffusion (Geschwindigkeit des intrakristallinen Transports) gewinnen mit zunehmender Partikelgröße an Bedeutung. [27,28] In der Zeolithkatalyse wird häufig beobachtet, dass die Porendiffusion geschwindigkeitslimitierend ist. [28] Daher ermittelten wir die Anfangsreaktionsgeschwindigkeiten in Abhängigkeit von der Katalysatorbeladung für Kristalle aus der Solvothermal-und der Mikrowellensynthese (Abbildung 5).…”

“…[27,28] In der Zeolithkatalyse wird häufig beobachtet, dass die Porendiffusion geschwindigkeitslimitierend ist. [28] Daher ermittelten wir die Anfangsreaktionsgeschwindigkeiten in Abhängigkeit von der Katalysatorbeladung für Kristalle aus der Solvothermal-und der Mikrowellensynthese (Abbildung 5).…”

Modelling of the Riser Reactor in a Resid Fluidised-bed Catalytic Cracking Unit Using a Multigrain Model for an Active Matrix-zeolite Catalyst

“…[3][4][5][6] In most of the models, the FCC riser is modelled as a plug flow reactor with no slip between the gas and liquid phases. An FCC riser model using a five-lump kinetic model describing the catalytic cracking of vacuum gas oil was proposed by AlSabawi et al [7]. This model accounts for both reaction and diffusion in the zeolite crystallites, a constituent of FCC catalysts.…”