Mechanistic classification and benchmarking of polyolefin depolymerization over silica-alumina-based catalysts

Area of Science:

• Catalysis
• Materials Science
• Chemical Engineering

Background:

• Carbon-carbon bond cleavage is crucial for selective deconstruction of alkanes and polyolefins.
• Understanding catalyst mechanisms is key to optimizing chemical processes.
• Product distribution offers insights into reaction pathways.

Purpose of the Study:

• To classify catalytic reaction pathways based on product distribution.
• To evaluate Co, Ni, and Ru nanoparticle catalysts on various supports.
• To develop an activity-mechanism map for catalyst benchmarking and discovery.

Main Methods:

• Deconstruction of n-hexadecane using supported metal nanoparticle catalysts (Co, Ni, Ru) on silica-alumina, Zeo-Y, and ZSM-5.
• Analysis of product distribution (carbon range, unsaturation, isomerization) to differentiate reaction mechanisms (monofunctional-hydrocracking, bifunctional-hydrocracking, hydrogenolysis).
• Depolymerization of polyethylene using ZSM-5-based catalysts.

Main Results:

• Product distributions successfully differentiated between monofunctional-hydrocracking, bifunctional-hydrocracking, and hydrogenolysis mechanisms.
• Catalyst performance varied based on metal nanoparticles and support materials.
• An activity-mechanism map was constructed to visualize and compare catalyst performance.

Conclusions:

• Product distribution analysis is a powerful tool for classifying catalyst mechanisms in dealkanation and polyolefin depolymerization.
• The developed activity-mechanism map provides a framework for benchmarking catalysts and identifying those for specific product outcomes.
• This systematic approach accelerates catalyst discovery for efficient polyolefin waste recycling.