Generation of carbon nanotubes (CNTs) from feedstocks of polyethylene terephthalate (PET or PETE) polymers is challenging, unlike the generation of CNTs from polyolefinic polymers (polyethylene and polypropylene) or from polystyrene polymers. 
The low yield of gaseous pyrolyzates from PET, particularly the very low content of hydrocarbons (HC) among the gaseous products is not optimal for generation of nanotubes, as it is the hydrocarbons that serve as carbon donors for their growth on the catalytic substrates. Moreover, extensive research reveals that benzoic acid is not an appropriate carbon donor substance for CNT generation. This problem is attributed to (a) synergistic effects between electron-withdrawing groups impeding dehydrogenation of benzene rings, thus keeping them stable, and (b) catalyst poison rendering the catalyst inert. Hence, it is obvious that the generation of the plentiful and potentially catalyst-poisoning and, hence CNT-preventing, benzoic acid needs to be suppressed/prevented in the pyrolysis of PET. 
Technology Overview
This invention is based on a method of CNT generation from PET feedstocks by pyrolyzing PET at elevated temperatures and reacting the pyrolyzate gases with limestone-based additives. In either case, they decompose to mixtures of pyrolyzate gases. Thereafter, such gases can act as carbon-growth agents for carbon nanomaterials on catalytic surfaces. Experiments conducted in the Northeastern University Combustion and Air Pollution Laboratory showed that by adding powders of calcium hydroxide or calcium oxide to PET and then pyrolyzing the PET + additive mixture resulted in good contact between additives. 
- High-temperature pyrolysis of PET generates solids, liquids, and gases
- Conducting the polymer pyrolysis at the absence of calcium-based additives (such as oxide, hydroxide, and carbonate) forms gases that impede the formation of carbon nanotubes
- Conducting the polymer pyrolysis at the presence of calcium-based additives (such as oxide, hydroxide, and carbonate) promotes the formation of carbon donor gases that facilitate the formation of carbon nanotubes
- Strengthening nanocomposite materials for structural applications
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Patent Information:
For Information, Contact:
Mark Saulich
Associate Director of Commercialization
Northeastern University
Chuanwei Zhuo
Carbon nanotubes
Energy Technology