Thermodynamic analysis of fuel oil blended stock(FOBS) model compound, n-eicosane to hydrogenvia oxidative cracking

Abstract

Petrochemical refineries worldwide experience a common problem: the accumulation of fuel oil blended stock (FOBS). FOBS are any leftover oil blended with other similar unfinished oils, to make a final refined product. FOBS are not only of no value, but also it triggers storage and environmental concern. One way to overcome this is to upgrade FOBS into higher value-added product through oxidative cracking process. In this study, FOBS potential as a feed was investigated to produce hydrogen by utilizing n-eicosane as the model compound. A thermodynamic equilibrium analysis based on the total Gibbs energy minimization method was performed for n-eicosane cracking to hydrogen in the presence of oxygen. The effects of different reactants ratio, temperature and pressure, were studied. Equilibrium product compositions of n-eicosane at temperatures of 573 K–1273 K, pressure of 0-20 bar, n-eicosane/oxygen ratios (EO) (0.5:0.5, 0.7:0.3, 0.8:0.2, 0.9:0.1, 0.95:0.05) were analysed. It was discovered that the main product of oxidative cracking is hydrogen and methane. Furthermore, the results showed that the optimum reactant ratio for hydrogen and methane production is EO ratio 0.95:0.05. A network of reaction mechanisms has been postulated to explain the overall complex reactions happening in the process.