Density functional theory study of relevant properties of lanthanum species and 1-butene activation over lanthanum modified zeolite

Abstract

The structure and acidity of lanthanum species of modified zeolites have been investigated by using the density functional theory. The mechanism of 1-butene activation has also been studied with the effect of the channel wall in the zeolites. Lanthanum sites are computed to be less acidic than the Brønsted (Al–OH–Si) ones. The lanthanum species are very stable in modified zeolites even at the temperature of 650 K. The average frequency of the O–H stretching in lanthanum species is 3758 cm⁻¹, while the frequency of the O–H stretching in H-ZSM-5 is 3646 cm⁻¹. The reaction path of more stable carbenium formation is considered. The activation barrier is 42.93 kcal/mol. There is no π-complex presented in the adsorption states and the reaction mechanism is different from the catalytic cracking reactions on H-ZSM-5 zeolites.