Carbon Aerogel-Supported Iron for Gasification Gas Cleaning: Tars Decomposition

Abstract

Tar removal from gasification gases is a determinant step to guarantee the operational feasibility of gasification-to-chemicals/energy systems. However, this is a very complex process requiring catalytic materials to proceed under reasonably low temperatures and to convert the tars into fuel gases (i.e., CHx). The use of Fe-based catalysts for application has been reported before, however, there are still unsolved questions related to its stability and interaction with some species of gasification gases. Therefore, we evaluated carbon-supported Fe for the decomposition of tar using simulated gasification gases, and toluene, naphthalene, and benzene as models for tar. The effects of temperature (565 < T < 665 °C) and co-feeding CO on the catalytic activity and stability were inspected at laboratory and bench scales. The activity of catalysts for decomposing tars was in the following order: benzene > toluene e > naphthalene. Moreover, there was evidence validating a reversible elemental step toluene⇔benzene over the Fe surface. The characterization of the spent catalysts evidenced the oxidation of the active phase and the carbon deposition on the surface. The formation of FexOy caused a marked loss of activity. Conversely, the carbides were stable and still active for tar decomposition.