Hydrothermal Synthesis of Sodium–Mordenite in Pebble Form

Abstract

MORDENITE is one of the more common low-temperature sedimentary zeolites¹. It can be regarded as a hydration product of volcanic glasses and lavas and is, for example, formed by the crystallization of obsidian glass on exposure to a natural, acid hydrothermal solution at 230° C in a New Zealand borehole². Such observations have led to the industrial development of sodium–mordenite syntheses from naturally occurring materials, particularly volcanic glasses and pumice, in well denned experimental coiiditions³. Thus synthetic mordenites are usually formed as hard or semi-hard aggregates of extremely small crystals (≤20µ diameter) after hydrothermal preparation at high pH (c. 11.5) and temperatures ranging from 100° to 260° C.