Regis J. Pellet

Skeletal isomerization of n-butylenes to isobutylene on zeolites

The conversion of normal olefins such as n-butylenes can be converted to branched olefin species such as isobutylene by skeletal isomerization over zeolite-based catalysts having pore sizes of at least about 4.5 Angstroms and a pore structure characterized by intersecting 10-MR and 8 MR channels. The zeolite-based catalysts have sufficient acidity to catalyze the skeletal isomerization of normal olefins. The catalysts can be used to produce isoolefins for reaction with alcohols in integrated processes to produce alkyl tertiary alkyl ethers such as MTBE.

Copper-Triazole Interaction and Coolant Inhibitor Depletion

To a large extent, the depletion of tolyltriazole (TTZ) observed in several field tests may be attributed to the formation of a protective copper-triazole layer. Laboratory aging studies, shown to correlate with field experience, reveal that copper-TTZ layer formation depletes coolant TTZ levels in a fashion analogous to changes observed in the field. XPS and TPD-MS characterization of the complex formed indicates a strong chemical bond between copper and the adsorbed TTZ which can be desorbed thermally only at elevated temperatures. Electrochemical polarization experiments indicate that the layer provides good copper protection even when TTZ is absent from the coolant phase. Examination of copper cooling system components obtained after extensive field use reveals the presence of a similar protective layer.