A predictive kinetic model has been developed for fluid catalytic cracking (FCC). The kinetic scheme involves lumped species consisting of paraffins, naphthenes, aromatic rings, and aromatic substituent groups in light and heavy fuel oil fractions. The kinetic model also incorporates the effect of nitrogen poisoning, aromatic ring adsorption, and time dependent catalyst decay. The rate constants for these lumped species are invariant with respect to charge stock composition. The predictive capabilities of the model have been verified for wide ranges of charge stocks and process conditions.In this work, a wide variety of charge stocks were cracked in a fluidized dense-bed reactor. Detailed analysis of the molecular compositions of the charge stocks and products provided the necessary data to develop a predictive kinetic model. Rate constants and activation energies were calculated for lumped species including paraffins, naphthenes, aromatic rings, and aromatic substituent groups. The reliability of the kinetic predictions for various charge stocks over a wide range of process conditions has been shown. CONCLUSIONS AND SIGNIFICANCEThe reaction kinetics of catalytic cracking is presented, based on a reaction scheme that includes paraffins, naphthenes, aromatic rings, and aromatic substituent groups in light and heavy fuel oil fractions. The kinetic model also accounts for nitrogen poisoning, aromatic adsorption, and time dependent catalyst decay. The conversion of Gross.Correspondence concerning this paper should be addressed to Benjamin these lumped species to gasoline, light products, coke, heavy fuel oil, and light fuel oil can be readily calculated by these kinetics. In addition, the detailed composition of the heavy and light fuel oil fractions can be tracked, increasing the utility of the model for predicting recycle behavior and physical properties of the products. The invariant kinetic parameters (rate constants and activation energies) allow the conversion and product selectiv-dimensions and operating conditions for maximum thermal efficiency and/or McGill University minimum operating cost. Application of these basic principles is illustrated Montreal, Quebec by the design of an industrial size, spray drying chamber for a specific feed solution and production rate. SCOPEThe growing importance of spray drying is abundantly evident from the ever increasing number of industrial applications in the production of pharmaceuticals, detergents, food products, pigments, ceramics, and a large number of organic and inorganic chemical compounds. In sylvania.

A kinetic mathematical model of catalytic cracking is described which accounts for conversion and gasoline yield in isothermal fixed, moving, and fluid bed reactors. The model has been tested and verified by using laboratory moving bed data with a commercial gas oil and catalyst. I t is shown that under certain conditions, the selectivity behavior and maximum gasoline yield of fixed, fluid, and moving bed reactors will be identical. Maximum gmoline yield is defined in terms of both the kinetic parameters and the process variables for fixed, moving, and fluid bed reactors.The catalytic cracking of a petroleum gas oil results in a broad spectrum of a products ranging from hydrogen and methane to heavy polymeric material adhering to the catalyst as coke. This range of products is normally separated into marketable fractions such as liquid petroleum gas, gasoline, light fuel oil, etc. Most attempts to describe the reaction kinetic behavior of catalytic cracking have been limited to the conversion behavior. Conversion is typically defined as that fraction of the original charge oil which has been converted to the gasoline boiling range and lighter. The work of Blanding ( 2 ) , of Andrews (1 ), and of Weekman (1 6 ) are examples of the kinetics of catalytic cracking conversion.Theoretical treatments of the effect of various types of catalyst decay on the selectivity of fixed bed reactions have been made by Froment and Bischoff ( 6 ) , and by Masamune and Smith (8). Sagara, Masamune, and Smith ( 1 3 ) have treated catalyst decay in terms of time dependent effectiveness factors for isothermal and nonisothermal cases. Carberry and Gorring ( 3 ) have shown the consequences of progressive pore mouth poisoning, and Olson (10) has extended this work and showed the effects of an adsorbing guard chamber. Sada and Wen ( 1 2 ) have analyzed the effects of pore mouth poisoning on selectivity behavior, and Chu ( 4 ) has included a Langmuir-Hinshelwood kinetic model to study adsorptive catalyst fouling. Ozawa and Bischoff (11) employed, a linear decay law based on carbon formed in describing the kinetics of n-hexadecane cracking on silica-alumina catalyst. Recently, Szepe and Levenspiel ( 1 4 ) in a general study of catalyst deactivation have shown that a simple mth order decay law is adequate to describe many cases of catalyst fouling.In earlier work (16), it was shown that conversion kinetics, when coupled with catalyst decay, adequately describe a wide range of conversion behavior. In the present paper, the kinetic description will be extended to include gasoline production and the subsequent recracking of gasoline. The gasoline selectivity model has been generalized to include the instantaneous behavior of fixed bed reactors as well as the steady state behavior of moving, fluid, or riser type of reactors. T H E SELECTIVITY MODELIn the present treatment, we will reduce the broad spectrum of catalytic cracking charge stocks and products into a three-component system, namely, the original charge material, the gasoline boiling fract...

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