Through pyridine infrared, we observed that the zeolite contained Lewis acid, and through 27Al NMR, we also observed the existence of six-coordinated Al species in the sample. However, by analyzing the structure-activity relationship of a series of bifunctional catalysts we prepared, we found that the n-heptane isomerization performance of metal/zeolite bifunctional catalysts was highly positively correlated with the ratio of Bronsted acid to Lewis acid in the zeolite, that is, the maximum yield of isomeric alkanes was not related to the absolute and relative content of B acid, nor to the absolute and relative content of L acid, but highly positively correlated with the ratio of B acid to L acid (B/L). Why? How to explain it?
