Xiting Yue studies dynamic active sites in zeolite catalysis. Her current work demonstrates that the Brønsted acid site (BAS) in ZSM-5 zeolite can transform into the frustrated Lewis pair (FLP) upon adsorption of polar molecules. This discovery redefines the classical understanding of zeolite acidity and suggests that FLP-type reactivity may exist in conventional aluminosilicate frameworks under operating conditions.