Alkylation on Solid Acids. Part 2. Single-Event Kinetic Modeling

The reaction network of isobutane alkylation with butenes over proton-exchanged Y-zeolites was generated at the elementary-step level of carbenium-ion chemistry by means of the Boolean relation matrix approach. A significant reduction in the number of model parameters from 3130 to 14 was accomplished by expressing elementary-step rate coefficients in terms of the single-event concept together with the application of the Evans-Polanyi relationship, the stabilization energy concept, and thermodynamic constraints. The deactivation was expressed in terms of site coverage by higher oligomers. For parameter estimation, the complete kinetic model was embedded into a model for the fixed-bed reactor used in the experimental investigation. Nonlinear regression led to parameter values in line with the rules of carbenium-ion chemistry. The simulation of the transient behavior of the fixed-bed reactor illustrates how deactivation occurs in a narrow zone moving through the catalyst bed leading to a typical breakthrough in the product composition with process-time.