Co-pyrolysis Of Residual Oil And Polyethylene In Sub-critical Water

Pyrolysis of residual oil and co-pyrolysis of residual oil/polyethylene in sub-critical water were applied at temperatures of 673 to 713 K and water densities of 0.10 to 0.30 g/cm3, respectively. At varied water densities, the phase structure of residual oil/sub-critical water may evolve between two extremes:the superheated steam/liquid oil two-phase structure and the micro-emulsion one. In the latter structure, asphaltenes in the form of micelles are highly dispersed in the continuous phase consisting of the dense sub-critical water with favorable diffusivity properties, accelerating the diffusion of aromatic radicals formed in asphaltene micelles into the water phase. By co-pyrolysis of polyethylene with residual oil in the dense sub-critical water, H-rich hydrocarbons as the potential H-donors are released into the water phase. Dealkylation of aromatic radicals thus can be accomplished with the desired mechanism through which the production of coke-inducing components is controlled. The presence of the dense sub-critical water promotes the contact of aromatic radicals from the pyrolysis network of residual oil with H-donors from that of polyethylene, which guarantees the coupling of the pyrolysis networks. As a result, the product distribution of the pyrolysis of residual oil is optimized together with the significantly depressed coke formation.