Stabilizing Effect of a Template on Phosphorus-Modified ZSM-5 Zeolites

Phosphorus modification is a prevalent technique for enhancing the hydrothermal stability and adjusting the acidity of zeolite catalysts. The relation between the structure of phosphorus-modified zeolite catalysts and their catalytic performance has been studied using ZSM-5 zeolites. However, phosphorus modification of ZSM-5 zeolites is usually performed after template removal via calcination, and the phosphorus modification of ZSM-5 zeolites without template removal has not been comprehensively studied. This study comparatively examines the phosphorus modification of ZSM-5 before and after template removal during aromatization of 1-octene. The structures of both catalyst samples (with and without template removal) were characterized via X-ray diffraction, nuclear magnetic resonance spectroscopy, infrared spectroscopy, and temperature-programmed desorption of ammonia and correlated with their catalytic performance. Results indicate that phosphorus modified ZSM-5 zeolites without template removal exhibit superior catalytic activity to those with template preremoval in the aromatization of 1-octene and hydrothermal treatment. The stabilizing effect of the template on phosphorus-modified ZSM-5 zeolites during the aromatization reaction and hydrothermal treatment is discussed based on comprehensive characterization of both the P-modified ZSM-5 catalysts. This study elucidates the influence of the template on P-modified zeolite catalysts and offers a new reference for the post-treatment of zeolites.