Interzeolite conversion of a clinoptilolite-rich natural zeolite into merlinoite

Abstract

The use of natural zeolites as precursors offers a valuable alternative in the search for new materials applied to zeolite synthesis. Each study focused on the interzeolitic conversion method plays a fundamental role in understanding the evolution from one zeolite to another. In this study, a natural zeolite containing the crystalline phases of clinoptilolite and mordenite, with HEU and MOR topologies, respectively, as per the coding assigned by the IZA, was employed as a precursor. Combined with potassium–aluminum hydroxide solutions at two different concentrations, followed by a conventional hydrothermal process with durations of 50 and 90h, characterization of both the precursor and resulting zeolite was performed. A conversion mechanism was proposed based on the structural similarity between the initial and target zeolites. To support these conclusions, characterization techniques such as X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectrometry, Fourier-transform infrared spectroscopy, inductively coupled plasma optical emission spectroscopy, and nitrogen adsorption were utilized. This process represents a potential pathway for the synthesis of merlinoite-type zeolites, MER.