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The pilot-scale pyrolysis of scrap tires in a continuous rotary kiln reactor was investigated at temperatures between 450 and 650 °C. As the reactor temperature increased, the char yield remained constant with a mean of 39.8 wt %. The oil yield reached a maximum value of 45.1 wt % at 500 °C. The pyrolytic derived oils can be used as liquid fuels because of their high heating value (40−42 MJ/kg), excellent viscosity (1.6−3.7 cS), and reasonable sulfur content (0.97−1.54 wt %). The true-boiling-point distillation test showed that there was a 39.2−42.3 wt % light naphtha fraction in the pyrolytic oil. The volatile aromatics were quantified in the naphtha fraction using gas chromatography−mass spectrometry. The maximum concentrations of benzene, toluene, xylene, styrene, and limonene in the oil were 2.09 wt %, 7.24 wt %, 2.13 wt %, and 5.44 wt %, respectively. The abundant presence of aromatic groups was also confirmed by functional group Fourier transform infrared analysis. The concentration of polycyclic aromatic hydrocarbons such as fluorine, phenanthrene, and anthracene increased with increasing temperature. The pyrolytic char was composed of mesopores with a Brunauer−Emmett−Teller (BET) surface area of about 89.1 m2/g. The char after carbon dioxide activation had a high BET surface area of 306 m2/g at 51.3% burnoff. The relationship between the surface area and the carbon burnoff was almost linear. Both the original pyrolytic char and the activated char have good potential for use as adsorbents of relatively large molecular species.

Manufacturing of nanostructured materials and functional devices offers many exciting opportunities for scientists and engineers to contribute substantially in renewable energy utilization, environmental compliance, and product development. In the past two decades, gas-phase flame synthesis has not only proved to be one of the most scalable and economical technologies for producing well-controlled nanostructured materials, including single metal-oxide, mixed-oxide nanocomposite, and carbon nanostructures, but also has been recognized as a new low-cost fabrication method of nano-devices. In this paper, we focus our review mainly on the recent trends in specific applications of flame aerosol synthesis in the last decade, e.g., usage of a substrate in stagnation geometry with controlled particle temperature-time history, application of external fields to control particle characteristics, development of advanced spray technique for doping synthesis of nanocomposites of multicomponent metal oxides or carbon-metal oxides, and fabrication of nanomaterial-based functional devices. For the possibility to improve the design and operation of flame aerosol reactors, in situ optical diagnostics for either gas phase or particle phase in flame field, along with multi-scale modeling and simulation employing gas-phase chemistry, population balance method, molecular dynamics, and nanoscale particle dynamics are summarized.

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