Facile and seed-direct synthesis of pure EUO zeolite with enhanced catalytic performance

The preparation of pure EUO zeolite under conventional conditions usually takes more than three days, limiting the application of the EUO zeolite. It is widely acquainted that the seed-assisted synthesis of zeolites without organotemplates is inexpensive, environmentally-friendly and lead to Al-rich products. However, synthesis with EUO seeds in the absence of organic-templates always leads to the formation of impurity phases. In this work, EUO zeolite (s-EUO) is successfully obtained by seed-directed synthesis without organotemplates. This is the first seed- directed synthesis of pure EUO zeolite with special Al source. Physicochemical characterization results show that the synthesized s-EUO zeolite exhibits high crystallinity and high specific surface area, and contains uniform crystals and plenty acidic sites. The s-EUO crystallization (by this method) occurs in a considerably shorter time (18 h) and in a more mild condition (160 °C, static state), compared to that of the conventional EUO zeolites (c-EUO, 72 h at 180 °C, at rotation) in the presence of organotemplate. Moreover, the catalytic performance of the H-form of the s-EUO zeolite is enhanced to that of the c-EUO zeolite for m-xylene isomerization, confirming the NH₃-TPD results. (paper)