Collaborative Pt-Ni Sites Enable CO-Tolerant Hydrocracking for Upcycling Polyolefin Waste

Area of Science:

• Chemical Engineering
• Materials Science
• Catalysis

Background:

• Plastic waste recycling via hydrocracking is crucial for sustainability.
• Carbon monoxide (CO) in crude hydrogen poisons conventional catalysts, limiting efficiency.
• Developing CO-tolerant catalysts is essential for economic viability.

Purpose of the Study:

• To develop a CO-tolerant catalytic system for efficient plastic waste hydrocracking.
• To investigate the mechanism of CO tolerance in a binary metal catalyst system.
• To convert polyethylene into valuable C3-C5 products.

Main Methods:

• Synthesized a catalytic system by blending silicalite-1 zeolite (S1)-encapsulated Pt-Ni binary metals with Ce-modified HY zeolite.
• Evaluated catalyst performance in polyethylene hydrocracking using crude hydrogen.
• Conducted sequential investigations to elucidate the catalytic mechanism.

Main Results:

• The Pt-Ni binary metal catalyst exhibited exceptional CO tolerance and high conversion of polyethylene to C3-C5 products.
• Monometallic Pt or Ni catalysts showed significant deactivation under the same conditions.
• A "two-way compensation" mechanism was identified, where Pt and Ni mutually compensate for functional losses in the presence of CO.

Conclusions:

• The developed Pt-Ni/S1/Ce-HY catalytic system offers a robust solution for plastic waste recycling.
• The synergistic effect between Pt and Ni is key to achieving CO tolerance and sustained catalytic activity.
• This approach enhances the economic feasibility of plastic hydrocracking by utilizing impure hydrogen sources.