Catalytic and Noncatalytic Gasification of Pyrolysis Oil

Abstract

Gasification of pyrolysis oil was studied in a fluidized bed over a wide temperature range (523−914 °C) with and without the use of nickel-based catalysts. Noncatalytically, a typical fuel gas was produced. Both a special designed fluid bed catalyst and a crushed commercial fixed bed catalyst showed an initial activity for syngas (H2 and CO) production at T > 700 °C. However, these catalysts lost activity irreversibly and elutriation from the fluid bed occurred. The equilibrium catalytic activity suffered from incomplete reforming of hydrocarbons (CH4). In all the experiments the carbon to gas conversion was incomplete, which was mainly caused by the formation of deposits and the slip of microcarbonaceous particles. A two-stage reactor concept, which consisted of a sand fluidized bed followed by a fixed catalytic bed, was proposed and tested. This system uncouples the atomization/cracking of the oil and the catalytic conditioning of the produced gases, enabling protection of the catalyst and creating opportunities for energy efficiency improvements. In a bench scale unit of this reactor (0.5 kg oil/h), methane and C2−C3 free syngas (2.1 Nm3 CO + H2/kg dry oil, H2/CO = 2.6) with a low tar content (0.2 g/Nm3; dry, N2 free gas) was produced in a long duration test (11 h).