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Cracking of Toxic Waste 147

catalysts are able to reduce the operating temperatures of waste oil degra-
dation in order to produce alternate oils from them. These waste motor oils
are collected and are tested for concentration of different materials in them.
The spent catalyst used was zeolite which was regenerated with the use of a
certain method. The waste oil was mixed with the spent catalyst in a reactor
and heated till a temperature of 300–370°C. The mixture was continuously
stirred with the help of a magnetic stirrer. The diesel oil in vapor form was
collected and condensed and was analyzed for its weight and viscosities. The
yield of diesel oil generated was about 43%.
Catalytic microwave pyrolysis of waste engine oil using metallic py-
rolysis char [10]: The engine waste oil used in this experiment was shell
10W-40, which was collected from engine crankcase of unleaded fuels.
The oil was filtered and analyzed for different metal content present in it.
Particulate carbon was used as a microwave-absorbent to heat the waste
oil. The particulate carbon was first heated to remove the water content
present in it. The process for preparing metallic char is (1) microwave
pyrolysis of waste oil at 550°C; (2) Sieving a couple of times to get the
particle size in the range of 20–30 μm; (3) Calcination at 600°C for 1 h
in air; and (4) Desiccation. Now pyrolysis of waste oil was competed us-
ing the metallic char as a catalyst. When analyzed, it was found that the
metallic char had a strong influence on the pyrolysis oil and products.
Concentrations and molecular nature were greatly influenced by the ad-
dition of metallic char as a catalyst.

10.5.1.2 Co-pyrolysis
The process of co-pyrolysis is the same as that of the process of pyroly-
sis, except this process involves two or more substances as raw materials.
One of the raw materials is bio-based waste, while the other material is
fossil-based waste. Even this process requires inert atmospheres and absence
of oxygen. The process of co-pyrolysis is more profitable than the process
of pyrolysis of biomass alone. The basic steps involved in the co-pyrolysis
process are: (1) preparation of samples, (2) co-pyrolysis, and (3) condensa-
tion. Prior to the process of co-pyrolysis, the sample should be dried and
ground to remove the moisture content from the sample. Many studies
have shown that the use of co-pyrolysis is able to improve the character-
istics of pyrolysis oil, e.g., increase the oil yield, reduce the water content,
and increase the caloric value of oil. When oil from biomass is completely
mixed with the oils from plastic or tyres, unstable mixture forms, which
breaks after a certain amount of time.