Kinetics cracking

MODELING OF BITUMEN OXIDATION AND CRACKING KINETICS USING DATA FROM ALBERTA OIL SANDS... 

A number of mechanistic modeling studies to explain the fluid catalytic cracking process and to predict the yields of valuable products of the FCC unit have been performed in the past. Weekman and Nace (1970) presented a reaction network model based on the assumption that the catalytic cracking kinetics are second order with respect to the feed concentration and on a three-lump scheme. The first lump corresponds to the entire charge stock above the gasoline boiling range, the second... 

Blanding (10) first proposed the second order cracking kinetics for FCC. Krambeck (11) theoretically demonstrated that conversion in systems with a large number of parallel reactions can be approximated by simple second order kinetics. More recently, Ho and Aris (12) have developed a further mathematical treatment of this concept. An inhibition term was incorporated into the second order cracking kinetics for gas oil conversion to account for competitive adsorption. The initial cracking rate is then given by ... 

FCC catalyst testing prior to use in commercial reactors is essential for assuring acceptable performance. Purely correlative relations for ranking catalysts based on laboratory tests, however, can be erroneous because of the complex interaction of the hydrodynamics in the test equipment with the cracking kinetics. This paper shows how the catalyst activity, coke-conversion selectivity and other product selectivities can be translated from transient laboratory tests to steady state risers. Mathematical models are described which allow this translation from FFB and MAT tests. The model predictions are in good agreement with experimental data on identical catalysts run in the FFB, MAT and a laboratory riser. 

Summary of Cumene-Cracking Kinetics Reported in the Literature... 

Sundaram, K.M. and G.F. Fioment, Modeling of Thermal Cracking kinetics. 3. Radical Mechanisms for the Pyrolysis of Simple Paraffins, Olefins, and Their Mixtures., Ind. and Eng. Chem. Fund., 17,174—182,1978. 

Diebold, J. P., The Cracking Kinetics of Depolymerized Biomass Vapors in a Continuous, Tubular Reactor, Thesis T-3007, Colorado School of Mines, Golden, CO, 1985. 

The results obtained in our search for optimal simulation conditions can also be interpreted in terms of the effect of reactor conditions on the cracking kinetics. 

The modelling of naphtha cracking in particular is very complex and the simulation programs make assumptions about the overall cracking kinetics. These are modified by experience of operation in real crackers. There are several approaches to developing the models. 

L. L. Oliveira and E. Biscaia Catalytic cracking kinetic models. Parameter estimation and model evaluation. Industrial and Engineering Chemistry Research, 28, 264-271 (1989). 

The overall cracking kinetic constant (or, in the case of nonlinear kinetics, the overall frequency factor) is the same for all oligomers. 

Such adsorption effects, are of course, well known in catalytic reactions over other heterogeneous systems. For a detailed discussion of the effect on catalytic cracking kinetics by molecules which do not compete, compete with near equal strength, and strongly compete with the reactant for adsorption on catalyst sites, the reader is referred to the classic work of Prater, Weisz, and associates (46, 72). 

Diebold, J. P. (1985) The Cracking Kinetics of Depoiymerized Biomass Vapors in a Continuous, Tubular Reactor. M. S. Thesis, Dept, of Chemical and Petroleum-Refining Engineering, Colorado School of Mines, Golden, Colorado. Liden, A. G. (1985) A Kinetic and Heat Transfer Modelling Study of Wood Pyrolysis in a Fluidized Bed. MASc Thesis, Dept, of Chemical Engineering, University of Waterloo. 

Modeling of Bitumen Oxidation and Cracking Kinetics Using Data from Alberta Oil Sands... 

Plank and Nace 2) made integral reactor studies of the inhibition of cumene cracking by some basic nitrogen compounds, styrene and cumene hydroperoxide. The catalyst used was of the same type used by Prater and Lago in their studies of cracking kinetics but with different surface areas obtained by steam treatment. 

R. W. Maatman Socony Mobil Oil Co.) We have not measured directly the value of Bo. In order to calculate Kp we need only kzBo, which we have measured. Prater and Lago ) have used the existing cumene kinetic data to calculate Bo from absolute rate theory. They attain a value for the catalyst used in our study of Bo = 0.87 X 10 sites/sq. m. We are continuing the study of the cumene cracking kinetics. This study should yield directly the value of Bo. 

Modelling Catalytic Cracking Kinetics Using Estimated Adsorption Equilibrium Constants... 

Behar F., Budzinski H., Vandenbrouke M. and Tang Y. (1999) Methane generation from oil cracking kinetics of 9-methylphenanthrene cracking and comparison with other pure compounds and oil fractions. Energy Fuels 13, 471-481. 

Comparison of the theoretical calculations of RTC and cold cracking kinetics with the experimental data for heavy crude oil (Zaikin and Zaikina, 2008) is given in Figures 15.20 and 15.21. The calculations using a self-consistent set of the design parameters are in a good agreement with the experiment. 

Sundaram, K. and Proment, G. Modefing of thermal cracking kinetics. 3. radical mechanisms for the pyrolysis of simple paraffins, olefins, and their mixtures. Industrial ... 

Eventually AE source is represented by the moment tensor Mpq and the source-time function S(t). This implies that crack kinetics is represented by S(t), which is solved by the deconvolution analysis (Wadley 1981). In contrast, crack kinematics are represented by the moment tensor. In order to characterize crack kinematics, as a conclusion, the determination of the moment tensor is inevitable. 

Sowerby, B. Becker, S. J., Modeling Catalytic Cracking Kinetics Using Estimated Adsorption Equilibrium Constants, In Dynamics of Surfaces and Reaction Kinetics in Heterogeneous Catalysts, Froment, G. F. Waugh, K. C. (Eds.), Elsevier, 1997. 

To describe the kinetics of catalytic cracking the three lump model was used in combination with three different catalyst deactivation model. Overall gas oil cracking kinetic constants (k or k ) along with the decay parameters for the three decay models were determined for four feedstock-catalyst combinations. An example of these evaluations is presented in Table 4. 

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