- Title
- The use of a novel chemical system towards improving waste tyre pyrolysis and the quality of waste tyre pyrolysis products
- Creator
- Tsipa, Phuti Cedric
- Creator
- Iwarere, Samuel
- Subject
- Tires -- Recycling
- Subject
- Rubber chemicals
- Subject
- Rubber, Reclaimed
- Date Issued
- 2023-12
- Date
- 2023-12
- Type
- Doctorial theses
- Type
- text
- Identifier
- http://hdl.handle.net/10948/62666
- Identifier
- vital:72912
- Description
- Pyrolysis process is one of the most efficient methods in the waste tyre recycling sector at this moment, hence the attention it is receiving. However, this process has some limitations, with the main one being that it is non-conventional and typically energy intensive. In addition, its resultant products have been reported to have significantly poorer properties relative to their virgin counterparts, making it difficult to incorporate them in the mainstream of raw materials. For instance, waste tyre pyrolysis oil typically has poor fuel properties, high sulfur content, high amount of polycyclic aromatic hydrocarbons (PAHs) and strong unpleasant odour; on the other hand, the quality of the recovered carbon black is dependent on the feedstock and the pyrolysis process conditions. Hence the need for further research and development to make the process effective and improve the quality of resultant products. The aim of this research project was to study the impact of pre-pyrolysis treatment of tyre crumbs and post-pyrolysis treatment of the oil using a novel chemical system on the quality/composition of the resultant products. In addition, the study compared the impact of pre- and post-pyrolysis treatments on the optimum pyrolysis time and temperature (energy). The equipment employed in this study included a vertical fixed bed pyrolysis pilot reactor (modified to suit the reaction/experiment) as well as characterization techniques such as fourier transform infrared (FTIR), elemental analysis (carbon, hydrogen, nitrogen and sulfur – CHNS analysis), gas chromatography coupled to mass spectrometer (GCMS), gas chromatography coupled to flame photometric detector (GCFPD), thermo-gravimetric and derivative analysis (TG/DTG isothermal analysis, and proximate analysis) and scanning electron microscope (SEM). The highlight of the findings is that chemically pre-treating tyre crumbs with a mixture of protonic acid and organic solvent before pyrolysis significantly lowered the temperature required to pyrolyze them, from around 400-500 ℃ to 100-115 ℃. This meant that by using the chemical treatment on waste tyres a lot of energy can be saved. In addition, the sulfur content in the oil fraction was reduced from a total of 1.7 wt% to a total of about 0.2 wt%. This also showed that the contaminants in oil were significantly reduced. The oil was condensed into three (3) collectors for fractionation; in collector 2 was about 54 % of the total oil with sulfur content of about 0.015 wt%. The PAHs amounts were also lowered, as literature indicated that PAHs are mostly formed at around 600-700 ℃. It was also found that the oil produced from post-pyrolysis treatment of oil has a petroleum-like smell, whereas the pre-pyrolysis treated oil has a tyre-like pungent odour. Furthermore, the post-pyrolysis treated oil contains higher contents of alkanes and benzene, toluene, xylene (BTX). Findings of this study have a profound potential impact on the waste tyre recycling industry; for example, reduced production energy cost due to lowered temperature required for pyrolysis, improved quality of the products such as lowered sulfur and PAHs content as well as improved quality of the residual char and odour.
- Description
- Thesis (PhD) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2023
- Format
- computer
- Format
- online resource
- Format
- application/pdf
- Format
- 1 online resource (xxi, 185 pages)
- Format
- Publisher
- Nelson Mandela University
- Publisher
- Faculty of Science
- Language
- English
- Rights
- Nelson Mandela University
- Rights
- All Rights Reserved
- Rights
- Open Access
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| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | SOURCE1 | Tsipa, PC 2.pdf | 589 KB | Adobe Acrobat PDF | View Details Download |