Mechano-catalytic conversion of polypropylene over zeolite-based materials

Area of Science:

• Polymer Chemistry
• Catalysis
• Chemical Engineering

Background:

• Chemical recycling offers a sustainable route for converting polyolefins into valuable chemicals.
• Current methods like catalytic pyrolysis and mechano-chemistry have limitations in activity, selectivity, and yield.
• Zeolite catalysts show promise but face deactivation challenges in mechanical processes.

Purpose of the Study:

• Investigate zeolite-based catalysts for polypropylene conversion using ball milling and kneading.
• Address catalyst deactivation issues in mechano-chemical recycling.
• Explore synergies between mechano-chemical and thermo-chemical approaches.

Main Methods:

• Utilized zeolite catalysts in ball milling at room and elevated temperatures.
• Developed a direct mechano-catalysis approach by immobilizing zeolite on grinding spheres.
• Investigated catalytic kneading of molten polypropylene.

Main Results:

• Zeolite catalysts exhibited high activity in ball milling, dependent on acid site density.
• Catalyst deactivation occurred rapidly in ball milling due to framework collapse.
• Immobilization of zeolite on grinding spheres sustained activity and reduced catalyst loading.
• Catalytic kneading showed initial synergy but was limited by viscosity decrease.

Conclusions:

• Direct mechano-catalysis with immobilized zeolite offers a pathway to overcome catalyst deactivation in polyolefin recycling.
• Combining mechano-chemical and catalytic pyrolysis presents challenges but holds potential for efficient chemical recycling.
• Further research is needed to optimize these processes for industrial application.