Staged Catalytic Gasification/Steam Reforming of Pyrolysis Oil

Abstract

Gasification/steam reforming of pyrolysis oil was studied in a staged reactor concept, which consisted of an inert fluidized bed and a catalytic fixed bed. Methane and C2−C3 free syngas is produced at a single temperature around 800 °C at atmospheric pressure. By lowering the temperature of the fluidized bed (432−500 °C), its function is changed from a gasifier to an evaporator, and in this way the subsequent catalyst bed actually sees vaporized pyrolysis oil compounds (instead of a fuel gas), which it can more readily convert to syngas. However, the temperature of the fixed bed cannot be too low (min 700 °C) to avoid excessive carbon deposition. System calculations show that when pressurized (30 bar) pyrolysis oil gasification/reforming is considered, the catalytic exit bed temperature should be high (900−1000 °C) to reach sufficient enough methane conversion when syngas is the desired product. When only steam is added at elevated pressure, the H2/CO ratio readily increases, which is desired for hydrogen production. For other applications (e.g., Fischer−Tropsch), carbon dioxide probably has to be recycled to keep the H2/CO ratio around 2−3. The lower heating value efficiency of pyrolysis oil gasification/reforming is comparable to the lower end of the reported range of commercial methane steam reforming.