A Cooperative OSDA Blueprint for Highly Siliceous Faujasite Zeolite Catalysts with Enhanced Acidity Accessibility

Abstract

Ac ooperative OSDAs trategy is demonstrated, leading to novel high-silica FAUzeolites with alarge potential for disruptive acid catalysis.I nb ottom-up synthesis,t he symbiosis of choline ion (Ch + )a nd 15-crown-5( CE) was evidenced, in af orm of full occupation of the sodalite (sod) cages with the trans Ch + conformer,i nduced by the CE presence.C Ei tself occupied the supercages along with additional gaucheC h + ,b ut in synthesis without CE, no trans was found. The cooperation, and thus the fraction of trans Ch + ,was closely related to the Si/Al ratio,akey measure for FAU stability and acidity.Assuch, abottom-up handle for lowering the Al-content of FAUa nd tuning its acid site distribution is shown.Amechanistic study demonstrated that forming sod cages with trans Ch + is key to the nucleation of high-silica FAU zeolites.T he materials showed superior performances to commercial FAUz eolites and those synthesized without cooperation, in the catalytic degradation of polyethylene.

Realizing Fast Synthesis of High‐Silica Zeolite Y with Remarkable Catalytic Performance

“…Chemie (9)(10)(11), far lower than that of pristine seeds. The mismatch between the relatively high yields and significantly reduced SAR of the etched seeds suggests the dissolution of silica species from Si-rich seeds and the deposition of liquid-phase Al species.…”

Nitrogen- and Halogen-Free Multifunctional Polymer-Directed Fabrication of Aluminum-Rich Hierarchical MFI Zeolites

“…Four consecutive pyrolysis-regeneration cycles were also carried out. During these tests, the spent catalysts were regenerated by calcination at 700 °C, then reused in subsequent reaction cycles [ 40 , 41 ]. Two different temperatures, T20 and T50, at which 20 wt% and 50 wt% of the LDPE is pyrolyzed to hydrocarbons, are compared to evaluate the performances of the various ZSM-5 zeolites.…”

Realizing Fast Synthesis of High‐Silica Zeolite Y with Remarkable Catalytic Performance

“…During our manuscript preparation, Dusselier et al. reported the synthesis of high‐silica Y with SAR up to 12.8 (crystallization for 5 days, ≈38 % yield) by using 15‐crown‐5 and choline ion as co‐OSDAs [11] …”

“…Enhancing temperature is a direct way to fasten the crystallization kinetics [14] . Unfortunately, the crystallization temperature of zeolite Y hitherto cannot exceed 130 °C [11, 15] . Further increasing the temperature always causes phase transformation and impurities [16] .…”

“…During our manuscript preparation, Dusselier et al reported the synthesis of high-silica Y with SAR up to 12.8 (crystallization for 5 days, � 38 % yield) by using 15-crown-5 and choline ion as co-OSDAs. [11] Besides the improvement of framework SAR, another long-standing challenge for the synthesis of zeolite Y is how to break the kinetic limitations on the growth of high-silica framework. Significantly prolonged time is generally required for a well-crystallized product with slightly improved SAR.…”