Phosphorus-Stabilized Hierarchical ZSM-5 for Enhanced Hydrothermal Stability and Selective 1-Hexene Cracking

Area of Science:

• Materials Science
• Catalysis
• Chemical Engineering

Background:

• Hierarchical zeolites offer improved mass transport and accessibility.
• Controlling acidity and stability is crucial for zeolite catalysts.
• ZSM-5 zeolites are widely used in industrial catalytic processes.

Purpose of the Study:

• To synthesize hierarchical phosphorus-doped ZSM-5 zeolites using a one-step method.
• To investigate the effect of phosphorus doping on zeolite properties and catalytic performance.
• To optimize catalyst design for improved selectivity and stability.

Main Methods:

• One-step synthesis using ammonium dihydrogen phosphate.
• Characterization using XRD, N2 sorption, SEM, XPS, NMR, Py-IR, and NH3-TPD.
• Catalytic cracking of 1-hexene to evaluate performance.

Main Results:

• Hierarchical P-doped ZSM-5 zeolites maintained crystallinity and porosity with uniform phosphorus dispersion.
• The optimal catalyst (PHZ-1) retained 60.3% of its Bro̷nsted acid sites after steaming, compared to 20.2% for undoped HZ.
• PHZ-1 achieved 97.4% conversion and 58.5% propylene yield in 1-hexene cracking, outperforming HZ.

Conclusions:

• Framework P-Al coordination optimizes Bro̷nsted acidity and suppresses hydrogen-transfer reactions.
• Hierarchical P-doped ZSM-5 zeolites demonstrate superior catalytic performance and stability.
• These materials show significant potential for industrial catalytic applications.