Investigation of sulfidation and regeneration of a ZnO-adsorbent used in a biomass tar removal process based on catalytic steam reforming

摘要

In the field of allothermal biomass gasification with steam in a fluidized bed, the removal of tar is the critical step in the process chain. In the approach presented in this work, in a catalytic steam reforming process the tar species are converted to permanent gas components by means of a Ni-catalyst at 500 degrees C. The issue with catalysts based on nickel is that these are poisoned by sulfur components in the synthesis gas. This leads to an increased catalyst deactivation and consequently to elevated operating costs of the facility. The main sulfur species in the synthesis gas of an allothermal steam gasifier is hydrogen sulfide (H2S). In order to reduce the sulfur-related deactivation of the Ni-catalyst, zinc oxide (ZnO) can be used as an upstream adsorbent to remove the main sulfur compound H2S.