Deactivation Kinetics of Solid Acid Catalyst with Laterally Interacting Protons.

Area of Science:

• Catalysis
• Chemical Kinetics
• Materials Science

Background:

• Solid acid catalysts are crucial for alkylation reactions.
• Catalyst deactivation limits efficiency and product selectivity.
• Understanding proton behavior is key to improving catalyst performance.

Purpose of the Study:

• To investigate the impact of lateral proton interactions on catalyst deactivation kinetics.
• To model the inhomogeneity of proton reactivity over time.
• To analyze the influence of these interactions on product selectivity and deactivation rates.

Main Methods:

• Simulations of deactivation kinetics for the alkylation of propylene with isobutane.
• Comparison of catalyst models with and without lateral proton interactions.
• Utilizing mean field kinetic equations and stochastic simulations.
• Development of a nonlinear dynamics model for proton dynamics.

Main Results:

• Lateral proton interactions induce proton reactivity inhomogeneity, accelerating deactivation.
• Initial catalyst deactivation is molecular, involving stable carbenium ion formation, not pore blocking.
• The lateral interaction model shows higher initial selectivity but lower overall stability.
• Two deactivation pathways identified: reactant oligomerization and carbenium ion deprotonation.
• Stochastic simulations reveal island formation of intermediates, increasing deactivation rates at high selectivity.

Conclusions:

• Lateral proton interactions significantly influence solid acid catalyst deactivation.
• Proton reactivity inhomogeneity and carbenium ion formation are primary deactivation mechanisms.
• Catalyst design must balance initial selectivity with long-term stability.
• Discrepancies between mean field and stochastic simulations are attributed to frustrated proton state percolation.