A. Fasi et al., Cyclodimerisation and cyclotrimerisation during the ring-opening reactionsof ethylene sulfide (thiirane) over acidic molecular sieves and alumina, CATAL LETT, 76(1-2), 2001, pp. 95-98
The transformations of ethylene sulfide were studied at three reaction temp
eratures (423, 473 and 523 K) on different acidic molecular sieves (HZSM-5,
HY and AlMCM-41) and alumina in a pulse system. The main reaction pathways
were found to be desulfurisation, cyclo-oligomerisation, the latter being
more important. In this reaction channel mainly direct dimer (six-membered
ring: 1,4-dithiane) and trimer (1,4,7-trithiacyclononane) formation occurre
d. The former product was always predominant, however, 1,4,7-trithiacyclono
nane was also significant, especially on molecular sieves with larger pore
openings and alumina. At elevated temperatures 2-methyl-1,3-dithiolane (a f
ive-membered cyclic molecule) was also detected. This molecule was formed i
n the highest amount on HZSM-5 among the catalysts applied revealing that a
more constrained environment is advantageous for this dimerisation type to
occur.