Oil refining processes typically involves a coking process that results in a carbon rich solid waste hydrocarbon byproduct called petroleum coke (petcoke). The production rate of the petcoke is over 20 million tonnes per day. Recently, petcoke from Canadian oil sands in U.S. refineries has led to the appearance of large stockpiles adjacent to urban communities in Detroit and Chicago, because limited markets exist for this commodity. The petcoke has strong effects on human and animal health. The main threat to urban populations in the vicinity of petcoke piles is most likely fugitive dust emissions in the form of fine particulate matter. Current industrial processes for treating these kinds of such complicated waste hydrocarbons like direct gasification and combustion have environmental drawbacks centralized mainly in the high production of gaseous CO2.
In this study, we propose a nano-catalyzed oxy-cracking process that works at mild operating temperature and pressure for high solubilisation of petcoke in relatively low proportions of water. This would open the possibilities for an efficient disposition of petcoke which could be converted at low processing costs into a transportable stream or, through their selective adsorption, be anchored on active catalysts for converting them into lighter products, or alternatively be used efficiently as hydrogen generating source via catalytic steam gasification at much lower temperature than the conventional gasification process.
To understand the mechanism and the kinetics of such innovative technology, Quinolin-65 (Q-65) was selected as a model-oxy-cracking compound mimicking the solid waste hydrocarbons in aqueous-based solutions. In the first phase of this study, the reaction took place in a non-catalyzed batch process operated at optimized oxygen partial pressure and temperature. The preliminary results enabled us to propose a reaction pathway based on the radical reaction mechanism to describe the kinetic behavior of the oxy-cracked Q-65. Hence, kinetic experimental results indicated that the Q-65 oxidation undergoes a parallel consecutive reaction in which an oxidative decomposition took place in the first step producing different aromatic intermediates as confirmed by the NMR analysis. Further, the intermediates were oxy-cracked consecutively into different families of organic acids and small amount of solubilized CO2 as confirmed by the inorganic carbons analysis. To support our experimental findings, a theoretical computational modeling is conducted. Therefore, the complete radical reaction mechanism will be discussed and elaborated.