Desulfurization of Biomass Syngas Using ZnO-BasedAdsorbents: Long-Term Hydrogen Sulfide Breakthrough Experiments

摘要

Dry-bedadsorptive desulfurization of biomass-based syngas withlow to medium sulfur content using ZnO was investigated as an alternativeto the conventional wet scrubbing processes. The technical feasibilityof ZnO-based desulfurization was studied in laboratory-scale H S breakthrough experiments. The experiments were set up toutilize realistic H S concentrations from gasificationand therefore long breakthrough times. Experiments were performedin a steam-rich model biosyngas in varying conditions. The long-termbreakthrough experiments showed apparent ZnO utilization rates between10 and 50% in the tested conditions, indicating intraparticle mass-transferresistances partly due to space velocity and particle size constraintsas well as the most likely product-layer resistances as evidencedby the large spent adsorbent surface area decrease. An empirical deactivationmodel to estimate full breakthrough curves was fitted to the laboratory-scaleexperimental data. Breakthrough experiment in tar-rich syngas wasalso performed with the conclusion that ZnO performance is not significantlyaffected by hydrocarbons despite carbon deposition on the particlesurfaces.