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

摘要

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 Br?nsted (Al-OH-Si) ones. The lanthanum species are very stable in modified zeolites even at the temperature of 650K. The average frequency of the O-H stretching in lanthanum species is 3758cm~(-1), while the frequency of the O-H stretching in H-ZSM-5 is 3646cm~(-1). The reaction path of more stable carbenium formation is considered. The activation barrier is 42.93kcal/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.