1. Conclusions TAP approach can be effectively used for transport studies Experimental procedure and method for quantifying TAP results are presented The understanding gained with TAP results should help in quantifying the frequency for periodic regeneration and the key features needed for the optimal catalysts design and regeneration techniques for solid acid alkylation processes References: Nayak S. V., Ramachandran P. A., Dudukovic M. P., 2007 “Transport in nanoporous Beta and ultrastable Y zeolite”, AIChE,fall meeting Nayak S. V., Ramachandran P. A., Dudukovic M. P., 2008 “Adsorption-desorption and intraparticle diffusion model using LDF approximation”, in preparation Acknowledgement: NSF Grant, EEC-0310689 Adsorption/Desorption Studies on Solid Acid Alkylation Catalysts S.V. Nayak, M.P. Dudukovic, and P. A. Ramachandran Chemical Reaction Engineering Laboratory, Washington University in St.Louis Methodology Pulse valve Microreactor Mass spectrometer Catalyst Vacuum (10 -8 torr) Reactant mixture Temporal Analysis of Products (TAP) Pulse Response Experiment TAP Reactor Model: Accumulation - Transport Term = Reaction Rate Diffusion  Problem: Safety, environmental and reliability issues associated with current liquid acid alkylation technologies  Challenge: Develop and demonstrate an environmentally friendly and competitive Solid Acid Catalyst (SAC) technology to replace HF and H 2 SO 4 technologies  Different solid acid catalysts are tested for alkylation of isobutane and n-butene to form 2,2,4 trimethylpentane (gasoline) Zeolites Supported Nafion Hetropoly acids Ion exchange resins  Zeolites High product selectivity (~ 85 – 95 %) Rapid decrease in activity Introduction To understand and quantify the overall adsorption kinetics and transport processes of the reactant and products involved in Solid Acid Alkylation Processes Sub-Project Goal Modified residence time vs. inverse square root temperature for isobutane and argon over inert quartz particles Knudsen Diffusion TAP experimental responses of argon and isobutane over beta-zeolites Modified residence time vs. inverse square root temperature for isobutane and argon over beta-zeolities Results and Discussion Residence time divided by the square root molecular weight vs. inverse square root of temperature (Nayak et al., 2007) van’t Hoff plot for equilibrium constant (Nayak et al., 2007) Table1: Heat of Adsorption and pre-exponential factor (Nayak et al., 2007) The catalytic cycle in alkylation reaction catalyzed by zeolites Important questions How do organic molecules diffuse inside a nanoporous zeolite? How does the intra-crystalline channel network of a zeolite influence diffusion, adsorption/ desorption and reaction pathway of organic molecules? Occupied Pore Empty Pore Occupied Brønsted Acid Site Occupied Pore adsorption diffusion desorption Single Pulse TAP Experiments Inert zone Catalyst zone t Mean = Adsorption Capacity Spread = Diffusivity, Adsorption/ Desorption Constants Inert Zone I Zeolite Zone Inert Zone II Narrow Inlet BCVacuum BC at outletObserved Exit Flow Theoretical Representation of TAP Adsorption-Desorption and Intraparticle Diffusion model for Zeolite Zone Using LDF approximation (Nayak et al., 2008)