Hydro-treatment of Athabasca vacuum tower bottoms in supercritical toluene with microporous activated carbons and metal–carbon composite

Highly porous biomass-derived activated carbon (denoted as BAC) and the BAC-supported NiMo catalyst (Ni–Mo/BAC), as well as a novel highly porous metal–carbon composite (Ni–Mo–BAC) were prepared and tested for hydro-treatment of Athabasca vacuum tower bottoms (AVTB) in supercritical toluene at 380 °C. All the BAC-based catalysts were very effective for HDAs of AVTB, converting asphaltenes to maltenes (MA) with toluene insoluble (TI) as a by-product. The BAC and Ni–Mo–BAC catalysts, having much greater BET surface areas and containing significant amount of micropores, were exceptionally active for HDAs of the AVTB in supercritical toluene, leading to an AS removal efficiency of 68% and 79%, respectively. The hydro-treatment of AVTB in supercritical toluene with the BAC-based catalysts also led to 21–25% S removal and 30–32% N removal. The metal–carbon composite (Ni–Mo–BAC) showed exceptionally high activity in HDAs of AVTB in supercritical toluene, which might be accounted for by its unique properties of maintaining at a high BET surface area and porous structure during the AVTB treatment. The possible roles of the carbon-based catalysts and supercritical toluene in hydro-conversion of AVTB were discussed.