Study of the Performance of Catalysts for Catalytic Cracking by Applying a Lump-Based Kinetic Model

Abstract

In catalytic cracking, catalysts selection is not a trivial task since a catalyst should exhibit a good hydrothermal stability as well as product distributions and qualities according to the necessities of the refinery. Cracking experiments at the bench scale in a fluidized confined-bed reactor at 789 K in the catalyst to oil range of 3.0-7.5 g/g using two industrial feeds have coupled to a five-lump kinetic model for a quantitative study of a set of cracking catalysts. To a gain insight into the catalysts performance, the assessment of raw rate coefficients has been complemented with a reaction pathways analysis. Primary cracking reactions are 1 order of magnitude higher than secondary ones, the gasoil to gasoline conversion being the fastest reaction. Up to 23% of the formed gasoline may undergo secondary cracking, more than 90% of it ending up in LPG. At the investigated conditions, coke formation is practically fully formed out of gasoline via secondary reactions and not from the gasoil. Cracking results are in concordance with catalyst properties, i.e., specific surface areas, and catalyst composition, e.g., the rate of secondary cracking of gasoline to LPG decreases with the zeolite and rare earths content.

The effects of magnesium of Zn–Mg–Al additives on catalytic cracking of VGO and in situ reduction of sulfur in gasoline

“…However, with the increase of Mg/Al molar ratio diesel yield showed an upward tendency, but slurry yield showed a downward tendency. Because gasoline was typically susceptible to secondary reaction and undergoes overcracking to produce LPG [8,24], therefore, the Lewis acidity of Zn/Al 2 O 3 additive enhanced the pre-cracking of slurry to form gasoline and diesel but reduced the secondary cracking of gasoline to form LPG [25].…”

“…However, they are limited by the high capital investment and operation costs, particularly the loss of octane number of gasoline in HDS process. Catalytic technologies, named as sulfur reducing additives, have been developed and should be the most economical and easiest implement among many new approaches, such as adsorption, oxidation, and extraction reactions for refineries [2,[6][7][8].…”

Kinetic study of catalytic cracking of heavy oil over an in-situ crystallized FCC catalyst

“…To optimize the kinetic parameters, an objective function [24] representing the difference between predicted and experimental yields for the six lumps was defined as E min a X set i¼1 X 6 j¼1 w j y exp i;j À y pre i;j 2…”

Quantitative correlations of cracking performance with physiochemical properties of FCC catalysts by a novel lump kinetic modelling method

“…80 Nowadays, the global demand for FCC catalyst is ever increasing. 81 According to the report [6] for the screening and selection of FCC catalysts [15][16][17][18][19][20][21][22]. De Lasa 113 et al [19] reported their work of 8-lump kinetic modelling and 114 FCC catalyst selection using a self-designed riser simulator.…”

“…The differential equations of the six-lump kinetic mod-313 els were solved using experimental data at 460, 480, 500 and 314 520°C by a Matlab program which was compiled according to 315 fourth order Runge-Kutta algorithm and the least square method. 316 To optimize the kinetic parameters, an objective function [22] Cat-I were obtained, respectively. As a typical operating tempera-362 ture of FCC unit, the corresponding cracking data of the two cata-363 lysts at 500°C were calculated.…”