An Organic Template/Ammonium-Free Strategy to Obtain Ultrastable Y with Intracrystalline Mesoporosity

Ultrastable Y (USY) with intracrystalline mesoporosity as the main active component plays a crucial role in the fluid catalytic cracking (FCC) of heavy oil. To obtain this material, mesoporous NaY was first synthesized using an organic template and then treated through multistep ammonium ion exchange/hydrothermal treatment. However, this complex procedure results in high synthesis costs and environmental pollution. In this article, a simple and effective strategy called "heteroatom substitution" was developed to introduce intracrystalline mesopores into zeolite NaY. The products obtained by this method exhibited a well-ordered microstructure with a large external surface area. XRD, XPS, and TOF-SIMS analyses confirmed that Li atoms were incorporated into the zeolite framework. In the subsequent procedure, a process known as "gas-phase ultrastabilization" was conducted by the direct reaction of solid zeolite NaY with gas-phase SiCl4. This process could lead to the simultaneous removal of aluminum and sodium from the zeolite framework. As a result of this, USY with intracrystalline mesoporosity exhibited significantly enhanced catalytic cracking properties toward heavy oil.