Changes in mordenite upon various pretreatments. Part 1.—Structural rearrangements

Abstract

The structural rearrangements of two mordenites, one dealuminated, upon various heat treatments have been studied by X-ray diffraction and i.r. spectrometry. The simultaneous changes in unit cell parameters and in i.r. band frequency or intensity allow some conclusions to be drawn. The removal of chemical aluminium creates a large number of SiOH groups while simultaneously a partial recrystallization occurs with formation of new Si—O bonds. Dry air treatment of the two zeolites does not modify them much. Heating the mordenite, dealuminated or not, under a wet atmosphere at 500°C removes a different type of aluminium atoms with simultaneous structural rearrangement giving new Si—O bonds.