Competition balance between mesoporous self-assembly and crystallization of zeolite: A key to the formation of mesoporous zeolite

A hierarchical meso-/microporous aluminosilicate has been synthesized through kinetic control over the competition balance between mesoporous self-assembly and microporous zeolite crystallization by using hexadecyl trimethyl ammonium bromide (CTAB) and tetrabutylammonium hydroxide (TBAOH) as meso- and micro-porogens, respectively. A very small pH value range of 11.10-11.30, which can be well tuned by added ethanol volume fraction and/or NaOH addition, was found to be suitable for the formation of mesoporous zeolite without phase separation. Balanced inorganic species adsorptions onto the meso- and microtemplates, and the subsequent electrostatic interaction between such adsorption-formed meso- and micro-colloids are discussed and proposed to be the two key underlined mechanisms in the successful synthesis. The material shows perfect crystallization of zeolite frameworks and relatively high surface area and meso-/micropore volumes. The prepared mesoporous zeolite showed much higher catalytic activity in the reaction between lauric acid and ethanol than those when using both amorphous mesoporous materials and conventional ZSM-5 zeolite as catalysts.