Repeated heating of fat oil may result in the formation of highly toxic aldehyde compounds. The oils having such compounds are considered as health hazards and therefore their repeated use is banned in many countries. Since huge quantities of the used oil need urgent disposal, this work is focused on the disposal of used oil for the resource recovery. The waste fat oil was converted into useful fuel through catalytic and non-catalytic pyrolysis. The catalyst was used to lower the oxygen content and to increase the amount of the hydrocarbons in the oil product. The pyrolysis reaction was catalyzed by three catalysts of the clinker type, namely ordinary Portland cement, white cement and burnt clay/clinker powder. The pyrolysis reactions were performed using a custom-made furnace and stainless steel pyrolyzer. Optimum temperature, time and catalyst quantity were identified for high liquid and gaseous fractions and low solid residue. The oil obtained during each reaction was characterized for chemical composition by using GC-MS technique. The oil product of simple pyrolysis, cement catalyzed, white cement catalyzed and clinker catalyzed pyrolysis had the hydrocarbon contents of 3%, 19%, 51% and 93%, respectively.

A huge amount of spent oils is produced in the world every day. These oils contain some toxic aldehydes, which affect human health. The disposal of used oils in sewers and drains not only raises the blockage and aesthetic problems but also pollutes the water resources. In the present work, spent fat oil (SFO) was converted into a combustible liquid and gaseous fuels by using a batch type reactor. For catalytic pyrolysis, the Portland cement raw mix, white cement raw mix, and powdered nonbrick or clay catalysts were used to convert SFO into useful fuels. The uncatalyzed pyrolysis took 60 min to convert SFO into liquid and gaseous fuels. The pyrolysis time was reduced to 30 min after catalyzing the reaction with a suitable catalyst. The white cement raw mix and clay catalysts promoted the formation of gaseous products, whereas the Portland cement raw mix promoted the formation of liquid fuel. The uncatalyzed pyrolysis of SFO produced only 3.527% hydrocarbons. Among the catalyzed reactions, the highest percentage of hydrocarbons (67.884%) was obtained with clay catalyst followed by the white cement (55.24%) and Portland cement (35.893%) formulations. The uncatalyzed reaction mainly produced fatty acids, the Portland cement and clay/burnt brick catalyzed reactions produced only esters, and the white cement catalyzed reaction produced a single fatty acid.