Page 157 - Advances in Eco-Fuels for a Sustainable Environment

128 Advances in Eco-Fuels for a Sustainable Environment

5.6 Effect of microwave absorber on pyrolysis process

Suriapparao and Vinu [47] inferred that microwave pyrolysis of waste engine oil yield
varied with increasing the temperature. The saturated hydrocarbons are 40%, 55%,
and 50%, obtained at the temperatures of 300°C, 400°C, and 500°C, respectively.
Also, this study revealed that there was a high content of aromatic benzene derivatives
at higher and lower temperatures and the chain length decreases as temperatures
increase. This shows the temperature at which the work should be carried on. This
study revealed that the temperature must be around 400°C for maximum output of
saturated hydrocarbons.
The microwave absorbers, catalysts, or susceptors have a tremendous effect on the
pyrolysis temperature, the pyrolysis time, and the time taken to reach the temperature.
In the selective production of products in bio-oil, a uniform composition mixture of
municipal solid waste (MSW) was subjected to microwave-assisted pyrolysis by using
10 different susceptors, which also served as catalysts. The susceptors were associated
with different categories such as metal powders (aluminum, iron), carbonaceous mate-
rials (activated carbon, graphite), silica beads and nano-TiO 2 , oxide mixtures (cement,
garnet, fly ash), and a ceramic material (SiC). The primary goals in employing these
susceptors were to evaluate (i) bio-oil, char, and gas yields, (ii) composition and quality
of bio-oil, from model MSW mixtures, and (iii) the average heating rates achieved with
these materials. These experiments were conducted using 20g of municipal solid waste
at a 5:1 mass ratio of MSW, and a susceptor and a microwave power of 450W [14].
This experiment depicts the ratio of higher heating value (HHV) of pyrolysis oil to
the HHV of municipal solid waste or the initial raw material of the pyrolysis process.
The HHV ratio (1.99) was higher while using the graphite as the microwave absorber
with a 1:1 feed to catalyst ratio. Then it is followed by the other susceptors, including
garnet (1.87), aluminum (1.82), and iron (1.75) with a 5:1 ratio [14].
The same works show that both saturated and unsaturated hydrocarbons are equally
obtained when SiC and activated carbon are used as the susceptors and gives more
saturated hydrocarbons than the silica beads and others. Aluminum and silica beads
also give a good amount of required composition. Considering the oil composition, the
percentages of bio-oil were 42.34%, 32.38%, 30.78%, 26.14%, 41.09%, 26.46%,
19.29%, 37.44%, 44.52%, and 15.61% when aluminum, activated carbon, garnet,
iron, silica beads, cement, titanium oxide, silicon carbide, granite, and flew ash were
used, respectively [14].

5.7 Pyrolysis of automotive waste

The automotive industry mainly comprises production and maintenance sectors. The
recycling process of the parts and the material can be used for automobile components
manufacturing through automotive waste management. Automobile manufacturing
increased to 58 million units by 2002 [48]. There has been a subsequent increase
in automotive waste in recent years. The wastes are converted into valuable products
and energy for further uses [39]. Out of large amounts of automotive wastes, most of