Characterization and Testing of Catalyst for Removal of Ammonia and Hydrogen Sulfide From Biomass Gasification Gas

Biomass gasification is a thermochemical conversion process which produces syngas or producer gas containing primarily carbon monoxide (CO), carbon dioxide (CO₂), nitrogen (N₂), and hydrogen (H₂). Contaminants such as ammonia (NH₃) and hydrogen sulfide (H₂S) are also produced due to the presence of sulfur, nitrogen, and inorganics in the biomass. These impurities cause problems with downstream applications of the gas by deactivating and poisoning catalysts and acting as precursors for toxic emissions among others. A catalytic reactor was designed and developed to reduce the levels of ammonia and hydrogen sulfide from a simulated syngas stream. Hydrotalcites, due to their basic character, show promise to reversibly adsorb H₂S under reducing conditions as seen from their applications in Fluid Catalytic Cracking (FCC) processes. A hydrotalcite catalyst was prepared and calcined for use in the reactor. The catalyst used was characterized before and after the experiments. The removal efficiencies of the contaminants over the catalyst were evaluated. Calcined hydrotalcite showed activity for the removal process and its properties will be fine tuned for further improvement of its removal efficiency. The final results will highlight the simultaneous removal efficiencies of hydrogen sulfide and ammonia over calcined hydrotalcite under various reaction conditions.