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.
We consider the contact process on a random graph with fixed degree distribution given by a power law. We follow the work of Chatterjee and Durrett [2], who showed that for arbitrarily small infection parameter λ, the survival time of the process is larger than a stretched exponential function of the number of vertices, n. We obtain sharp bounds for the typical density of infected sites in the graph, as λ is kept fixed and n tends to infinity. We exhibit three different regimes for this density, depending on the tail of the degree law.
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