N. Zandi Atashbar, Ali A. Ensafi, Amir Hooshmand Ahoor,

Nowadays, discard of 24 million tons used diesel engine oil per year is a significant challenge for human health and environment. Thus, waste conversion into more valuable products like fuel can be the best solution. This work covered catalytic converting the waste engine oil into fuel, gas, and char products of pyrolysis, based on multivariate experimental design. Hence, nano-CeO2/SiO2, as a catalyst, was synthesized
and characterized by different analytical methods. As the main aim of this work, this efficient catalyst is used to achieve low-level sulfur fuel from inexpensive, not eco-friendly and available waste engine oil. Thus, the ability of liquid product as a successfully applicable substitute for diesel fuel was also assessed. Furthermore, the modeling and optimization of pyrolytic fuel production based on the process factors, including operating temperature, the flow rate of argon, catalyst amount and time, were conducted. The properties of pyrolytic fuel produced in the optimizing conditions (554
C, 128 mL min1 Ar, 8.8 wt% nano-CeO2/SiO2, and 95.0 min) were compared with commercial diesel fuels as represented flash point of 49.0 ± 2.9
C, the cetane number of 42.0 ± 1.8, and gross calorific value of 44.9 ± 3.2 MJ kg1. Moreover, application of nano-CeO2/SiO2 as the catalyst caused the reduction of sulfur level contained in pyrolytic fuel from 0.9 to 0.02 wt%. As the result of this research, catalytic pyrolysis of waste engine oil by nano-CeO2/SiO2 concluded rich liquid fuel product (60.7 wt%) with low sulfur (0.02 wt%) and inorganic
pollutants (0.01 wt%) as diesel fuel.