(560hb) Hydrogen and Carbon Nanomaterials Production from Pyrolysis of Waste Plastics with Bimetallic Catalyst: Product Characterization and Formation Mechanism

Flexible pyrolysis of waste plastics for valuable products like hydrogen and carbon nanomaterials can be seen as an ideal option to wisely recycle the considerable quantities of waste plastics around the world. However, the role of catalyst for plastic pyrolysis and the growth mechanism of carbon nanomaterials need further investigation. Catalytic pyrolysis of plastic was performed in a two-stage fixed bed reaction system with bimetallic catalyst, and the effects of pyrolysis temperature and feedstock feeding rate on hydrogen and carbon nanotubes production were studied. The morphology and structure of solid carbon products were observed by electron microscopes, while the presence of metal and catalyst composition for carbon nanotubes growth was analyzed by selected area electron diffraction (SAED) and X-ray diffraction. The purity and graphitization of carbon nanotubes were examined by temperature programmed oxidation (TPO) and Raman analysis. Results show that the two metals in the bimetallic catalyst contributed different catalytic role for hydrogen and carbon production. The carbon precursors from plastic pyrolysis were decomposed into amorphous carbon and then catalyzed into graphite carbon layer with the interaction with catalyst metal. The growth of carbon nanotubes followed the vapor-liquid-solid process, while the carbon structure was significantly affected by the operational temperature and feedstock feeding rate.