Main technical indicators of mordenite molecular sieve

Introduction

Mordenite is also called mordenite. One of the main mineral components of zeolite ore.

The silicon to aluminum ratio (molar ratio) of mordenite is 25. Powder form with a particle size of about 2 microns.

Mordenite has not only four-membered rings, six-membered rings, eight-membered rings, etc., but also five-membered rings in its crystal structure, and the five-membered rings account for a large proportion. Five-membered rings are connected in pairs in parallel, that is, two five-membered rings share two tetrahedrons. The paired five-membered ring can be connected to another paired five-membered ring through an oxygen bridge, and then a four-membered ring is formed at the connected place. If further rings are connected to each other, they can form an eight-membered ring and a twelve-membered ring. The twelve-membered ring is elliptical, and its maximum and minimum diameters are 0.7nm and 0.58nm, with an average of 0.66nm. In fact, the crystals of mordenite are made up of many such layers superimposed on each other and connected by appropriate means. Therefore, many straight cylindrical pores are formed in the crystals of mordenite. The largest diameter is the straight cylindrical pore composed of twelve-membered rings. This is the main pore channel of mordenite with an elliptical cross section and a major axis diameter. They are 0.695nm and the minor axis diameter is 0.581nm. They are like a bunch of tubes, which is very different from the cage-shaped pores of A, X and Y zeolites. In fact, the straight cylindrical pores are twisted to a certain degree, and the layers are not overlapped directly opposite each other, but have a certain displacement between each other. Therefore, its average diameter may be reduced from 0.66nm to 0.4nm. The main pores of mordenite also have small pores that communicate with each other. However, due to the small diameter of these small pores (about 0.39nm), it is generally difficult for molecules to enter and can only enter and exit through the main pores. The crystals of mordenite can be considered as a two-dimensional space for the entry and exit of molecules, while A-type, X-type and Y-type are three-dimensional space.

Mordenite has high acid resistance and thermal stability due to its high silicon-to-aluminum ratio and many five-membered rings. Insoluble in acid at room temperature.

Purpose

It is widely used in chemical, environmental protection, agriculture, light industry, petroleum, construction and other sectors.

The crystal structure is a 12-membered ring with moderate acidity. The product silicon-to-aluminum ratio can be adjusted by acid according to the requirements of the applied catalytic reaction.

1. Catalyst for toluene disproportionation and xylene isomerization in petrochemical industry.

2. C5 and C6 alkane isomerization catalyst in refinery.

3. Catalyst for methanol to dimethyl ether and methylamination catalyst in fine chemical industry.

4. Dehydrate and dry the adsorbent.

5. Used to eliminate air pollution and sewage treatment agent.

6. Trimethylbenzene isomerization catalyst.