mordenite

mordenite

Mordenite (MOR) is a crystalline silicon aluminate, formed from silicon oxygen tetrahedron or aluminum oxygen tetrahedron connected by oxygen bridge bond. Rhombic system, crystal acicular, fibrous, aggregates for bundles and radial, white. The maximum and minimum diametersare 0.7nm and 0.58nm, with an average of 0.66nm. The main channel is 12 rings, and the si /Al ratio (SiO2/Al2O3 mole ratio is 8-20).

In the crystal structure of mordenite, there are not only four-membered ring, six-membered ring and eight-membered ring, but also five-membered ring, and the five-membered ring accounts for a large proportion. Five-membered rings are connected in parallel in pairs, that is, two five-membered rings share two tetrahedrons. Pairs of five-membered rings can then be linked to another pair of five-membered rings by an oxygen bridge, forming a four-membered ring where they are linked. If further rings are connected to each other, they can be enclosed into eight-membered rings and twelve-membered rings. The crystals of mordenite are made up of many such layers superimposed together and joined together in appropriate ways. Therefore, in the crystal of mordenite formed A lot of straight cylindrical pores, the largest diameter is composed of twelve binary ring straight cylindrical pores, this is the main channel of mordenite, its cross section is oval, long axis diameter of 0.695nm, short axis diameter of 0.581nm, they seem to be bundles of bundles, which is similar to A, The cage pores of zeolite X and Y are very different. In fact, the straight cylindrical pores are somewhat torsional, and the layers are not superimposed directly on each other, but displaced from each other. As a result, its average diameter may decrease from 0.66nm to 0.4nm. There are also small channels to communicate with each other between the main channels of mordenite, but because these small pore size (about 0.39nm) is very small, the general molecule is not easy to go in, only in the main channel. The crystal of mordenite can be regarded as A two dimensional space for molecular entry and exit, while the A, X and Y types are three dimensional space.

Due to the high ratio of silicon to aluminum and more five-membered rings, mordenite has high acid resistance and thermal stability. It is insoluble in acid at room temperature. Mordenite is often used as gas drying, purification and sewage treatment adsorbent, catalyst carrier, etc.