Direct Synthesis of Highly Siliceous ZnO-FAU Zeolite with Enhanced Performance in Hydrocarbon Cracking Reactions
Deependra Parmar, Adam J. Mallette, Noemi Linares, Sarah A. Saslow, Tanguy Terlier, James J. Strohm, Lee P. Barber, Heng Dai, Javier García‐Martínez, Jeffrey D. Rimer
Abstract
The hydrothermal stability and catalytic activity of zeolite Y (faujasite, FAU) is highly dependent on its composition. High silicon content is often desirable for catalytic applications; however, direct synthesis of faujasite with high silicon content (Si/Al > 2.5) is nontrivial. Here, we present an organic-free synthesis of FAU-type zeolite with Si/Al = 3.4 using zinc oxide as a modifier. A combination of spectroscopy and microscopy techniques confirms that ZnO is well-distributed within zeolite pores as extra-framework species, and the nature of these species differs from bulk ZnO and framework zinc in Zn-FAU crystals. We demonstrate that the increased Si/Al ratio leads to improved hydrothermal stability, while catalytic cracking of 1-hexene and cumene show that ZnO-FAU exhibits a significantly longer lifetime compared to in-house and commercial zeolite Y. Collectively, this study presents a facile and efficient method to prepare more siliceous FAU with enhanced catalytic performance.