Decomposition of heptylbenzene by supercritical water

The oil sands are naturally occurring mixtures of sand or clay, water and an extremely dense and viscous form of petroleum called bitumen. Challenges of bitumen production including low mobility, difficulties in transportation to refineries, and limited bitumen refining capacity, make it necessary to upgrade bitumen. There are a number of upgrading processes including carbon rejection, hydrogen addition, and physical separation. The catalytic cracking is the traditional process to convert bitumen into lighter and high value fuels though the catalyst is deactivated in the presence of metals and asphaltenic molecules. The dramatic change of ion product and dielectric constant of water at supercritical condition makes it as acid catalyst. Long-chain n-alkylbenzenes are the simplest chemicals models of the alkyl aromatic moieties. So, in this study, Heptylbenzene (HPB) is used as a model compound and water is used instead of catalyst. The reaction was carried out in a batch reactor made by AKICO. The temperature profile at different molar ratio of HPB and water was observed during the study. The ability of supercritical water (SCW) to decompose alkylbenzene, like heptylbenzene, was also studied at 450 °C and 40 MPa. Heptylbenzene decomposed into light hydrocarbons (like, toluene, ethylbenzene, butylbenzene, propylbenzene etc.), heavy hydrocarbons (like, pyrene, m-terphenyl etc.) and gases under above mentioned conditions. Significant proportions of heptylbenzene were converted during the reaction with SCW. The obtained results suggest that water acts as a chemical reagent above its critical point (374 °C and 22.1 MPa).