الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
The two-stage process was used to convert Plastic wastes to carbon nanomaterials. In this system, two horizontal reactors were used; one for the thermal pyrolysis of polymer waste and the other for the decomposition of cracked gases to form CNTs on the surface of Ni-Mo/Al2O3 catalysts with different Ni content (5 and 10 wt. %). Several conclusion points can be obtained from the present work as follow:
1. The 10%Ni-Mo/Al2O3 catalyst exhibited higher catalytic growth activity than the 5%Ni-Mo/Al2O3 catalyst for CNTs production. On the other hand, the catalyst containing 5%Ni produced CNTs with higher quality than that containing 10%Ni based catalyst.
2. Using LDPE as a carbon source, the optimum pyrolysis temperature in terms of CNTs yield was 700 °C. TGA data illustrated that the thermal stability of the as-produced CNTs over 10%Ni-Mo/Al2O3 catalyst is nearly similar at all pyrolysis temperatures. Raman spectra confirmed that the pyrolysis of LDPE at high temperatures (700 and 800 oC) produced CNTs with high quality and purity.
3. The optimum decomposition temperature for the highest CNTs yield was 650 oC, using the 10%Ni-Mo/Al2O3 catalyst. The Raman spectra, XRD, TGA and TEM data proved that the growth temperature of 750 oC is the optimum temperature for producing CNTs with the best quality and the highest thermal stability. CS-CNTs material was obtained at the decomposition temperature of 600 oC, whereas CNTs were obtained at higher decomposition temperatures.
4. The pre-reduction of the 10%Ni-Mo/Al2O3 catalyst for 1h was effective for improving the yield of CNTs than the un-reduced one.
5. The yield of CNTs increased with increasing the N2 gas flow rate from 10 sccm to reach the maximum value at 30 sccm, after that the CNTs yield slightly decreased with further increasing the N2 flow rate up to 50 sccm. Raman spectra showed that the quality as well as the morphology of the as-grown CNTs was nearly identical at all different N2 flow rates.
6. Different polymer wastes such as HDPE, LDPE, PET, PP or PS were studied as carbon sources for CNTs production at pyrolysis temperature of 700 oC and growth temperature of 650 oC using 10%Ni-Mo/Al2O3 catalyst. Among them, both LDPE and PP were regarded as the most suitable sources of carbon in terms of CNTs yield and quality. This can be attributed to their ability to produce large gases fraction during the pyrolysis step. However, PET or PS waste was not favorable as a carbon source due to the low extent of gaseous molecules obtained during the pyrolysis. On the other hand, an intermediate yield of CNTs was obtained when using HDPE as a source of carbon.
Finally, we can confirm that the current process provides a simple and promising method for production of high quality MWCNTs as a valuable product.