Copper -exchanged Y-zeolites

Butyrolactone reacts rapidly and reversibly with ammonia or an amine forming 4-hydroxybutyramides, which dissociate to the starting materials when heated. At high temperatures and pressures, the hydroxybutyramides slowly and irreversibly dehydrate to pyrrolidinones this dehydration is accelerated by use of a copper-exchanged Y-zeolite or magnesium silicate. 

H. K. Beyer, J. Horvath, F. Reti, Catalytic cracking and dehydrogenation of butanes and neopentane on reduced copper-exchanged Y-zeolites, React. Kinet. Catal Lett., 1980, 14, 395 01. 

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