Initiated pyrolysis of heavy oil in the presence of near-critical water

The initiated pyrolysis of heavy oil in the presence of near-critical water (near-CW) was investigated with density functional theory (DFT) calculation and experimental characterization. Theoretical calculation indicated the thermodynamic feasibility of forming hydrocarbon radicals in heavy oil with the aid of appropriate radical initiators. By introducing ditertbutyl peroxide (DTBP) into heavy oil, the H-abstraction of Hβ atoms distributed mainly in the fractions of saturates, resins, and asphaltenes occurs, forming hydrocarbon radicals located on aliphatic chains with priority. At the temperature of 653 K and water density of 0.30 g/cm3, it was experimentally confirmed that the introduced DTBP was capable of initiating the pyrolysis of heavy oil. After 15 min's reaction, the pyrolysis products centered toward the fraction of aromatics whose weight proportion in the liquid product increased drastically by ca. 25.0 wt.%. Meanwhile, only a negligible coke yield of 0.5 wt.% was collected.

Graphical abstractWith the introduction of DTBP into heavy oil, the H-abstraction of Hβ atoms distributed mainly in the fractions of saturates, resins, and asphaltenes occurs, by which the pyrolysis of heavy oil in the presence of near-critical water is effectively initiated at relatively lower temperatures.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The initiated pyrolysis of heavy oil in the presence of near-CW was investigated. ► Hydrocarbon radicals can be formed by introducing DTBP into heavy oil. ► Pyrolysis of heavy oil in near-CW is effectively initiated by the introduced DTBP. ► The initiated pyrolysis of heavy oil can be run under mild condition.