Synthesis of aggregation-resistant MFI nanoparticles

Zeolites with particles of nm-scale size and restricted aggregation propensity were designed by decoration of zeolite surface with specific functional groups to address the problem of irreversible aggregation of respective nanoparticles. Highly crystalline MFI nano zeolites synthesized using hydrothermal method were functionalized with silanes of different nature (monodentate vs. polydentate, hydrophobic vs. hydrophilic) to investigate the influence of the type of surface functional groups on the stability of zeolite nanoparticles against aggregation in solution, accessibility of acid sites located in zeolite framework, and catalytic properties of resulting hybrid materials. The as-prepared materials were characterized by XRD, DLS, nitrogen adsorption, and adsorption of acetonitrile followed by FTIR, solid state 29Si and 27Al NMR, ICP-OES, TEM. Finally, we investigated the catalytic performance of designed materials in acylation of p-xylene to demonstrate that surface functionalization does not lead to deterioration of catalytic activity of the zeolite nanoparticles. Characterization data and catalytic results confirmed the improved stability of prepared nanoparticles with reasonable accessibility of acid sites. This finding can be used for preparation of aggregation-resistant zeolites dispersible in liquid-phase reaction mixtures in order to mimic homogeneous catalytic systems.