Isomerization of n-butene over pre-coked HZSM-5 and HFER

摘要

To elucidate the role of carbonaceous deposits for enhancing the selectivity of zeolite catalysts during n-butene skeletal isomerization, HFER and HZSM-5 were modified by pre-coking and silanization. After surface modification, the samples have been characterized by nitrogen and xenon sorption measurements as well as ~(129)Xe NMR spectroscopy. The nature of carbonaceous deposits formed during the pre-coking treatment was investigated by MALDI-TOF mass spectrometry. For mechanistic studies, ~(14)C-labeled olefins were added to the n-butene feed. The formation of an olefinic pool is proposed, I.e., isobutene selectivity is controlled by zeolite properties as well as thermodynamic conditions.