Reaction catalytic cracking

Accordingly, work has been done on series of n-paraffins,. isoparaffins, naphthenes, aromatics, and naphthene-aromatics which have been chosen as representative of the major components of petroleum. In addition, olefins, cyclo-olefins, and aromatic olefins have been studied as a means of depicting the important secondary reactions of the copious amounts of unsaturates produced in the majority of catalytic cracking reactions. A silica-zirconia-alumina catalyst was used principally it resembles closely in cracking properties typical commercial synthetic silica-alumina catalysts. 

Aromatics are in a sense unique in their catalytic cracking reactions. The aromatic ring contains the equivalent of six double bond or pi electrons, which are, however, mutually stabilized by strong resonance energy. We may postulate an association between a carbonium ion and these electrons in a generalized sense ... 

We conclude, therefore, that the mechanisms of catalytic cracking reactions on nickel metal and nickel carbide are closely comparable, but that the latter process is subject to an additional constraint, since a mechanism is required for the removal of deposited carbon from the active surfaces of the catalyst. Two phases are present during reactions on the carbide, the relative proportions of which may be influenced by the composition of the gaseous reactant present, but it is not known whether the contribution from reactions on the carbide phase is appreciable. Since reactions involving nickel carbide yielded products other than methane, surface processes involved intermediates other than those mentioned in Scheme I, although there is also the possibility that if cracking reactions were confined to the metal present, entirely different chemical changes may proceed on the surface of nickel carbide. 

Calculated parameters for the compensation effects mentioned by Sinfelt (74) are given in Table III, D [for the dashed line in Fig. 5 of (74), eight metals] and Table III, E (the full line on the same graph, six metals). No acceptable obedience to Eq. (2) could be found in other Arrhenius parameters for catalytic cracking reactions on a group of different metals (151, 212, 213). 

Like the paraffins, naphthenes do not appear to isomerize before cracking. However, the naphthenic hydrocarbons (from C9 upward) produce considerable amounts of aromatic hydrocarbons during catalytic cracking. Reaction schemes similar to that outlined here (page 131) provide possible routes for the conversion of naphthenes to aromatics. 

Riser the part of the bubble-plate assembly which channels the vapor and causes it to flow downward to escape through the liquid also the vertical pipe where fluid catalytic cracking reactions occur. 

Figure 6. The Mobil series of catalytic cracking reaction models, a) The Mobil 3-Lump model b) the Mobil 10-Lump model (4,5,7).

Calculation of the Adsorption Enthalpy of n-Paraffins in Nanoporous Crystalline and Ordered Acid Catalysts, and Its Relation with the Activation Energy of the Monomolecular Catalytic Cracking Reaction... 

As an example of a unimolecular decomposition reaction, we study the monomolecular catalytic cracking reaction of //-paraffins in high-silica acid zeolites or other crystalline or ordered acid porous materials, in this section [97-102],... 

Figure 1. Product distribution of catalytic cracking reaction using n-hexadecane,...

Neutrality is satisfied by a cation (e.g., M+) which is usually Na+ derived from the salts used in the synthesis. When the cation is exchanged with a proton an acid site is created. This is the key active site for catalytic cracking reactions. The first exchange is with NH4+ which when heat-treated decomposes to NH3 and the H+ is retained on the zeolite. The acid zeolite is designated HZ... 

The kinetics of feed conversion, minor product formation, and catalyst decay in catalytic cracking are well-described in a unified hypothesis by quantifying the fates of the carbenium ions which one expects to find in a given catalytic cracking reaction. 

Catalytic cracking reactions involve the combined effects of reaction and adsorption phenomena. Thus, adequate kinetic modelling should consider heterogeneous representations distinguishing between the chemical species, reactants and products, distributed between gas/solid phases. 

C. J. Adams, M. J. Earle, and K. R Seddon, Catalytic cracking reactions of polyethylene to light alkanes, Green Chemistry, 21 (2000). 

A rare earth metal-exchanged Y-type (REY) zeolite catalyst was found to be an effective catalyst for the catalytic cracking of heavy oil. The influence of the reaction conditions and the catalytic properties of REY zeolite on the product yield and on gasoline quality have been described above. In this section, a reaction pathway is proposed for the catalytic cracking reaction of heavy oil, and a kinetic model for the cracking reaction is developed [14,33]. 

Effect of coke deposition on catalyst texture during catalytic cracking reaction. 

Experimental data from cracking cycles of 1 to 2 minutes at various temperatures indicate that the true activation energy for the catalytic cracking reaction is probably about 10,000 calories/mole (73). Higher apparent values of 15,000 to 20,000 calories/mole calculated from long-... 

Example 7.4 Design a packed-bed reactor for the gas-phase, heterogeneous catalytic cracking reaction... 

We have shown that additive coke (Cat]j) has much less impact on catalyst activity than catalytic coke (Ccal) at the same coke-on-catalyst level, but the initial catalyst deactivation rate during ARO cracking is greaier than ihat of VGO cracking because of the fast deposition of additional coke on the caialyst surface. The general correlations developed in this paper can be conveniently u sod in the modeling of catalytic cracking reaction kinetics. 

The model we describe in this work has the objective of constituting a preliminary study for the development of models that are able to explain, at the same time, both the product distribution and the decay of activity that is observed in the catalytic cracking reactions the description of the decay of activity implies also that on is able to estimate the amount of coke deposited on the surface of the catalyst. 

---