1-Pentene isomerization over zeolites studied by in situ IR spectroscopy

The skeletal isomerization of 1-pentene at 1.2 bar total pressure and 30 mbar 1-pentene partial pressure was investigated by in situ IR measurements over FER and BEA zeolites. If the reaction was carried out isothermally a small loss of Brønsted acid sites due to coke formation, a constant conversion and a high selectivity to isopentenes was found over FER. A loss of acid sites and a decrease in conversion was found over BEA, but the selectivity to isomerization increased remarkably. The pore size of FER favored the monomolecular reaction of 1-pentene and suppressed bimolecular reactions. In the bigger pores of BEA initially dimerization–cracking and hydrogen transfer reactions leading to a coke layer took place then the skeletal isomerization of 1-pentene prevailed.