Staged Catalytic Gasification/Steam Reforming of Pyrolysis Oil

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 C(2)-C(3) free syngas is produced at a single temperature around 800 degrees C at atmospheric pressure. By lowering the temperature of the fluidized bed (432-500 degrees 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 degrees 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 degrees C) to reach sufficient enough methane conversion when syngas is the desired product. When only steam is added at elevated pressure; the H(2)/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 H(2)/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.