Full-crystalline monolithic EU-1 zeolite: sustainable synthesis and its applications in the hydroisomerization of ethylbenzene with meta-xylene

摘要

EU-1 zeolite is employed as an active component of a catalyst for isomerization or hydroisomerization of C8 aromatics (i.e., xylenes, ethylbenzene) in petrochemical processes to increase the para-xylene yield. However, conventional manufacturing of EU-1-based catalysts involves the production of mother liquors for zeolite synthesis which usually contain plentiful unreacted raw materials, or the negative impact of incorporated binders in mass transfer during reactions over shaped catalysts. Herein, we developed a novel route to prepare the monolithic EU-1 zeolite, and used it as an active component of a catalyst for hydroisomerization of ethylbenzene with meta-xylene. Recrystallization of the shaped zeolite precursors composed of incompletely crystallized zeolites with amorphous silica and alumina powders as binders in recycled mother liquor led to formation of the monolithic EU-1 zeolite. Transformation of binder species to a full-zeolitic phase was corroborated comprehensively by characterization methods. Compared with the conventionally fabricated counterpart, the monolithic EU-1 zeolite possessed similar mechanical strength, high crystallinity, and high acidity and, in particular, enhanced mesoporosity, which led to improved catalytic performances in hydroisomerization reactions. Our developed synthetic strategy provides an effective way to produce the monolithic EU-1 zeolite, but is also a reference for the sustainable production of other types of zeolitic materials for energy-related applications.