Kinetics study and analysis of zeolite Y destruction

A series of zeolites, including USY zeolites without sodium, Na-USY at different Na contents, La-USY with different rare earth (RE) contents and La-Na-USY with RE and Na were prepared by an ion exchange method. They were investigated to understand the activation barriers for the destruction of Y zeolite structure under hydrothermal treatment and the effect of V using the solid-state kinetic model. The results showed that the pathways for Y zeolite destruction were dealumination, desiliconization and the disappearance of La–O bonds. Zeolites were destroyed by steam through acid hydrolysis, which was accelerated by V. In addition, Na and V exerted a synergistic effect on the framework destruction, and the formation of NaOH was the rate-determining step. The presence of RE elements decreased hydrolysis and stabilized the structure of the zeolites. The interaction between V and RE destroyed zeolite structure by eliminating the stabilizing La–O [RE–OH–RE]5+ bridges in the sodalite cages.

Graphical AbstractZeolite Y destruction investigated by a kinetics study and analysis, which shows the pathways for Y zeolite destruction are dealumination, desiliconization and the disappearance of La–O bonds.Figure optionsDownload full-size imageDownload as PowerPoint slide