Synergistic dealumination-silication via a binary CHCl3-SiCl4 vapor treatment for NaY: Steering mesopore evolution and Si(1Al) enrichment

A synergistic vapor-phase strategy using CHCl 3 and SiCl 4 regulates pore structure and acidity in NaY zeolite. • A one-step process constructs a hierarchical micro-mesoporous structure with Al-depleted bulk and Al-enriched surface layer. • Controllable mesopore evolution by tuning the imbalance between CHCl 3 -guided dealumination and SiCl 4 -assisted silication. • A system with Brønsted acidity (framework Si(1Al)) and Lewis acidity (extra-framework Al) is built. To overcome micropore diffusion limitations and acid site regulation in FCC zeolite catalysis, this study develops a synergistic vapor-phase modification using SiCl 4 and CHCl 3 . By tuning the agent ratio, pore structure and acid distribution are optimized while preserving NaY framework integrity. The synergy is not a simple combination but a dynamic process featuring CHCl 3 -guided dealumination and SiCl 4 -assisted silication with a moderate imbalance. CHCl 3 selectively removes Al from Al-rich sites, preserving framework Al predominantly as Si(1Al) units, which generate abundant Brønsted acid sites (BAS) and promote diffusion pathways. Meanwhile, SiCl 4 repairs framework defects and anchors extracted Al as highly dispersed extra-framework Lewis acid sites (LAS). This cooperative interaction creates a hierarchical micro-mesoporous structure with a low-Al bulk and an Al-rich surface layer, retaining abundant BAS while introducing strong LAS-achieving balanced acidity. In n-octane cracking, this architecture enhances diffusion, suppresses hydride transfer, and improves light olefin (C 3 –C 4 ) selectivity. This work provides insights into zeolite structure-performance relationships for rational catalyst design. A synergistic vapor-phase modification creates a zeolite with a hierarchical micro-mesoporous structure, featuring a low-aluminum bulk and an aluminum-rich surface. This architecture optimizes pore connectivity and acid site distribution for enhanced cracking performance. Download: Download high-res image (406KB) Download: Download full-size image