Pillaring of smectites with Al-13 was studied in situ by infrared emission spectroscopy. Exchange of montmorillonite with Al-13 gave Al-OH and Al-H2O OH-stretching modes of Al-13 at 3682 and 3538 cm(-1) and at 3641 and 3334 cm(-1) for Al-13-hectorite. Al-13 conversion resulted in removal of the AI-OH mode >400 degrees C. The Al-H2O band was replaced by bands at 3574 and 3505 cm(-1) due to structural rearrangement within Al-13. The intensities diminished, but are still observed at 800 degrees C, suggesting that the pillar structure incompletely converted to "Al2O3." In hectorite the Al-13 completely converted upon calcination. Below 1750 cm(-1) the Al-13-montmorillonite displays bands at 642, 1008, 1321, 1402, and 1512 cm(-1). The 1512 cm(-1) band disappeared at 500 degrees C, followed by the other bands above 600 degrees C, The 642 cm(-1) band intensity diminished but is still observed at 800 degrees C. At 700 degrees C a new band is observed at 722 cm(-1) due to Al-O bond formation. The Al-13-hectorite displays bands at 1227, 1315, 1395, and 1510 cm(-1). The last three band intensities diminished but remained visible. The 1227 cm(-1) band disappeared above 500 degrees C. Expansion of saponite with Al-13 gave bands at 3626 and 3244 cm(-1), which disappeared at 700 degrees C, indicating that the transition to "Al2O3" is complete. The Mg-OH band is not influenced by calcination, indicating that the pillaring does not involve the octahedral clay layer. Below 1750 cm(-1) Al-13-saponite shows bands at 1316, 1424, and 1521 cm(-1). Calcination resulted in a disappearance of the 1521 and 1316 cm(-1) bands at 600 degrees C, while the 1424 cm(-1) band disappeared at 400 degrees C. The 1316 cm(-1) band is replaced by bands at 1269, 1314, and 1388 cm(-1) above 600 degrees C, due to formation of M-[IV]-O(H)-Al-[VI] linkages between pillars and tetrahedral clay layers.