Abstract:
The presence of tires in open fields, households and landfills is a great threat to the wellbeing of the ecosystem around them. Tire creates an ideal breeding ground for disease carrying vermins and their possible ignition threatens the surrounding air quality due to the harmful gases produced during combustion. Pyrolysis of tires produces four valuable products namely; char, steel, tire pyrolytic oil (TPO) and noncondensable gases. TPO has been reported to have similar properties to commercial diesel fuel. The biggest challenge faced by TPO to be used directly in combustion engines is the available sulfur content of about 1.0% wt. Considering the stringent regulations globally for allowable sulfur content in liquid fuels, TPO therefore, requires deep desulfurization before commercialization.
In this study, different desulfurization techniques were applied to reduce the sulfur content in TPO. A novel study on combination of adsorptive and air-assisted oxidative desulfurization (AAOD) was developed for desulfurization of TPO. Different carbon materials were employed as catalyst and/or adsorbent for the AAOD system. The effect of operating conditions; catalyst/adsorbent dosage, H2O2/HCOOH ratio, reaction time, temperature and air flowrate were studied. Oxidation equilibrium was reached at 80 °C for both commercial activated carbon (CAC) and activated tire char (ATC) at a reaction time of 50 min. With a total oil recovery of more than 90% and the initial sulfur content of 7767.7 ppmw, the presence of air at a flow rate of 60 l/hr increased oxidation from 59.2% to 64.2% and 47.4% to 53% for CAC and ATC, respectively.
The use π-complexation sorbent was also applied to study the selectivity of such sorbents to organosulfur compounds (OSC) found in liquid fuels. The π-complexationbased adsorbent was obtained by ion exchanging Y-zeolite with Cu+ cation using liquid phase ion exchange (LPIE). Batch adsorption experiments were carried out in borosilicate beakers filled with modified Cu(I)-Y zeolite for both TPO and synthesized model fuels. For model fuels (MF), the selectivity for adsorption of sulfur compounds followed the order dibenzothiophene (DBT)> benzothiophene (BT)> Thiophene.
